U.S. patent application number 15/403845 was filed with the patent office on 2017-05-04 for digital asic sensor platform.
This patent application is currently assigned to Senseonics, Incorporated. The applicant listed for this patent is Senseonics, Incorporated. Invention is credited to Arthur E. Colvin, JR., Andrew DeHennis.
Application Number | 20170119288 15/403845 |
Document ID | / |
Family ID | 48946175 |
Filed Date | 2017-05-04 |
United States Patent
Application |
20170119288 |
Kind Code |
A1 |
DeHennis; Andrew ; et
al. |
May 4, 2017 |
DIGITAL ASIC SENSOR PLATFORM
Abstract
The present invention relates to an optical sensor that may be
implanted within a living animal (e.g., a human) and may be used to
measure the concentration of an analyte in a medium within the
animal. The optical sensor may wirelessly receive and may be
capable of bi-directional data communication. The optical sensor
may include a semiconductor substrate in which various circuit
components, one or more photodectors and/or a light source may be
fabricated. The circuit components fabricated in the semiconductor
substrate may include a comparator, an analog to digital converter,
a temperature transducer, a measurement controller, a rectifier
and/or a nonvolatile storage medium. The comparator may output a
signal indicative of the difference between the outputs of first
and second photodetectors. The measurement controller may receive
digitized temperature, photodetector and/or comparator measurements
and generate measurement information, which may be wirelessly
transmitted from the optical sensor.
Inventors: |
DeHennis; Andrew;
(Germantown, MD) ; Colvin, JR.; Arthur E.; (Mt.
Airy, MD) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Senseonics, Incorporated |
Germantown |
MD |
US |
|
|
Assignee: |
Senseonics, Incorporated
Germantown
MD
|
Family ID: |
48946175 |
Appl. No.: |
15/403845 |
Filed: |
January 11, 2017 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
13761839 |
Feb 7, 2013 |
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15403845 |
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61597496 |
Feb 10, 2012 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
A61B 5/14556 20130101;
A61B 5/14552 20130101; A61B 5/1459 20130101; A61B 5/1455 20130101;
A61B 5/1451 20130101; A61B 5/076 20130101; A61B 5/14551 20130101;
A61B 5/7225 20130101; A61B 5/6861 20130101; A61B 5/0031 20130101;
A61B 5/14532 20130101 |
International
Class: |
A61B 5/1459 20060101
A61B005/1459; A61B 5/07 20060101 A61B005/07; A61B 5/1455 20060101
A61B005/1455; A61B 5/00 20060101 A61B005/00; A61B 5/145 20060101
A61B005/145 |
Claims
1. An optical sensor for implantation within a living animal and
measurement of a concentration of an analyte in a medium within the
living animal, the optical sensor comprising: indicator molecules
having an optical characteristic responsive to the concentration of
the analyte, the indicator molecules being configured to interact
with the analyte in the medium within the living animal when the
optical sensor is implanted within the living animal; a
semiconductor substrate; a first photodetector mounted on or
fabricated in the semiconductor substrate and configured to output
a first analog light measurement signal indicative of the amount of
light received by the first photodetector; a second photodetector
mounted on or fabricated in the semiconductor substrate and
configured to output a second analog light measurement signal
indicative of the amount of light received by the second
photodetector, wherein the first and second photodetectors are
symmetrically arranged relative to a center line running between
the first and second photodetectors; a light source configured to
emit excitation light to the indicator molecules from an emission
point aligned on the center line running between the first and
second photodetectors; a temperature transducer mounted on or
fabricated in the semiconductor substrate and configured to output
an analog temperature measurement signal indicative of a
temperature of the optical sensor; a comparator fabricated in the
semiconductor substrate and configured to output an analog light
difference measurement signal indicative of a difference between
the first and second analog light measurement signals; an analog to
digital converter (ADC) fabricated in the semiconductor substrate
and configured to convert (i) the analog temperature measurement
signal to a digital temperature measurement signal, (ii) the first
analog light measurement signal to a first digital light
measurement signal, (iii) the second analog light measurement
signal to a second digital light measurement signal and (iv) the
analog light difference measurement signal to a digital light
difference measurement signal; an inductive element; an
input/output circuit fabricated in the semiconductor substrate and
configured to wirelessly transmit via the inductive element
measurement information and wirelessly receive via the inductive
element a measurement command and power; and a measurement
controller fabricated in the semiconductor substrate and configured
to: (i) in accordance with the measurement command, control the
light source; (ii) generate the measurement information in
accordance with (a) the digital temperature measurement signal, (b)
the first digital light measurement signal, (c) the second digital
light measurement signal and (d) the digital light difference
measurement signal; and (iii) control the input/output circuit to
wirelessly transmit the measurement information.
2. The optical sensor of claim 1, wherein the optical sensor is a
chemical or biochemical sensor.
3. The optical sensor of claim 1, wherein the first and second
photodetectors are fabricated in the semiconductor substrate.
4. The optical sensor of claim 3, wherein the first and second
photodetectors are photodiodes that have been monolithically formed
in the semiconductor substrate using a complimentary metal oxide
semiconductor (CMOS) process.
5. The optical sensor of claim 1, further comprising light source
mounting pads on the semiconductor substrate and configured such
that the light source, when mounted on the light source mounting
pads, has an emission point aligned on the center line running
between the first and second photodetectors; and wherein the light
source is mounted on the light source mounting pads.
6. The optical sensor of claim 1, further comprising an isolation
trough that electrically separates the first and second
photodetectors.
7. The optical sensor of claim 1, further comprising a nonvolatile
storage medium fabricated in the semiconductor substrate.
8. The optical sensor of claim 7, wherein the nonvolatile storage
medium has stored therein measurement calibration information, and
the measurement controller is configured to control the light
source in accordance with the measurement command and the
measurement calibration information.
9. The optical sensor of claim 7, wherein the nonvolatile storage
medium has stored therein identification information, the
input/output circuit is configured to wirelessly transmit via the
inductive element the identification information and the
measurement controller is configured to control the input/output
circuit to wirelessly transmit the identification information.
10. The optical sensor of claim 1, wherein the temperature
transducer is a band-gap based temperature transducer fabricated in
the semiconductor substrate.
11. The optical sensor of claim 1, wherein the comparator is a
transimpedance amplifier.
12. The optical sensor of claim 1, wherein the input/output circuit
comprises a rectifier fabricated in the semiconductor
substrate.
13. The optical sensor of claim 12, wherein the rectifier is a
Schottky diode.
14. The optical sensor of claim 1, wherein the measurement
information is digital measurement information.
15. The optical sensor of claim 1, wherein the indicator molecules
are signal channel indicator molecules, and the optical sensor
further comprises reference channel indicator molecules configured
to not interact with the analyte in the medium within the living
animal when the optical sensor is implanted within the living
animal; wherein the light source is configured to emit the
excitation light to the signal channel indicator molecules and
reference channel indicator molecules when turned on, the first
photodetector is configured to receive excitation light emitted by
the signal channel indicator molecules, and the second
photodetector is configured to receive excitation light emitted by
the reference channel indicator molecules.
16. The optical sensor of claim 1, wherein the living animal is a
living human being.
17. The optical sensor of claim 1, wherein the medium is
interstitial fluid.
18. The optical sensor of claim 17, wherein the analyte is
glucose.
19. The optical sensor of claim 17, wherein the analyte is
oxygen.
20. The optical sensor of claim 1, wherein the medium is blood.
21. The optical sensor of claim 1, wherein the indicator molecules
are fluorescent indicator molecules.
22. The optical sensor of claim 1, wherein the optical sensor has a
size and shape that permits said sensor to be implanted within the
living animal and wherein the measurement information is indicative
of the concentration of the analyte in the medium within the living
animal.
23. The optical sensor of claim 1, wherein the inductive element
comprises a coil.
24. The optical sensor of claim 1, wherein the inductive element
further comprises a ferrite core, and the coil is formed on the
ferrite core.
25. A sensor for implantation within a living animal and
measurement of a concentration of an analyte in a medium within the
living animal, the optical sensor comprising: indicator molecules
having an optical characteristic responsive to the concentration of
the analyte, the indicator molecules being configured to interact
with the analyte in the medium within the living animal when the
optical sensor is implanted within the living animal; a
semiconductor substrate; a photodiode fabricated in the
semiconductor substrate and configured to output an analog light
measurement signal indicative of the amount of light received by
the photodiode; a light source configured to emit excitation light
to the indicator molecules; an analog to digital converter
fabricated in the semiconductor substrate and configured to convert
the analog light measurement signal to a digital light measurement
signal; an inductive element; an input/output circuit fabricated in
the semiconductor substrate and configured to wirelessly transmit
via the inductive element measurement information and wirelessly
receive via the inductive element a measurement command and power;
and a measurement controller fabricated in the semiconductor
substrate and configured to: (i) in accordance with the measurement
command, control the light source; (ii) generate the measurement
information in accordance with the digital light measurement
signal; and (iii) control the input/output circuit to wirelessly
transmit the measurement information.
26. The sensor of claim 25, wherein the photodiode has been
monolithically formed in the semiconductor substrate using a
complimentary metal oxide semiconductor (CMOS) process.
27. The sensor of claim 25, further comprising light source
mounting pads on the semiconductor substrate, wherein the light
source is mounted on the light source mounting pads.
28. The sensor of claim 25, further comprising a nonvolatile
storage medium fabricated in the semiconductor substrate.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] The present application is a divisional of U.S. patent
application Ser. No. 13/761,839, filed on Feb. 7, 2013, which
claims priority to U.S. Provisional Application No. 61/597,496,
filed on Feb. 10, 2012, the entire disclosures of which are
incorporated herein by reference.
BACKGROUND
[0002] Field of the Invention
[0003] The present invention relates to optical sensors and, more
particularly, to optical chemical or biochemical sensors for
implantation within a living animal and measurement of a
concentration of an analyte in a medium within the living
animal.
[0004] Description of the Background
[0005] U.S. Pat. No. 5,517,313, which is incorporated herein by
reference in its entirety, describes a fluorescence-based sensing
device comprising indicator molecules and a photosensitive element,
e.g., a photodetector. Broadly speaking, in the context of the
field of the present invention, indicator molecules are molecules
where one or more optical characteristics of which is or are
affected by the local presence of an analyte. In the device
according to U.S. Pat. No. 5,517,313, a light source, e.g., a
light-emitting diode ("LED"), is located at least partially within
a layer of material containing fluorescent indicator molecules or,
alternatively, at least partially within a wave guide layer such
that radiation (light) emitted by the source strikes and causes the
indicator molecules to fluoresce. A high-pass filter allows
fluorescent light emitted by the indicator molecules to reach the
photosensitive element (photodetector) while filtering out
scattered light from the light source.
[0006] The fluorescence of the indicator molecules employed in the
device described in U.S. Pat. No. 5,517,313 is modulated, i.e.,
attenuated or enhanced, by the local presence of an analyte. For
example, the orange-red fluorescence of the complex
tris(4,7-diphenyl-1,10-phenanthroline)ruthenium(II) perchlorate is
quenched by the local presence of oxygen. Therefore, this complex
can be used advantageously as the indicator molecule in an oxygen
sensor. Indicator molecules whose fluorescence properties are
affected by various other analytes are known as well.
[0007] Furthermore, indicator molecules which absorb light, with
the level of absorption being affected by the presence or
concentration of an analyte, are also known. See, for example, U.S.
Pat. No. 5,512,246, which is incorporated by reference in its
entirety, which discloses compositions whose spectral responses are
attenuated by the local presence of polyhydroxyl compounds such as
sugars.
[0008] In the sensor described in U.S. Pat. No. 5,517,313, the
material which contains the indicator molecules is permeable to the
analyte. Thus, the analyte can diffuse into the material from the
surrounding test medium, thereby affecting the fluorescence of the
indicator molecules. The light source, indicator
molecule-containing matrix material, high-pass filter, and
photodetector are configured such that fluorescent light emitted by
the indicator molecules impacts the photodetector such that an
electrical signal is generated that is indicative of the
concentration of the analyte in the surrounding medium.
[0009] The sensing device described in U.S. Pat. No. 5,517,313
represents a marked improvement over devices which constitute prior
art with respect to U.S. Pat. No. 5,517,313. There has, however,
remained a need for sensors that permit the detection of various
analytes in the body of a living animal, e.g., a living human.
[0010] U.S. Pat. Nos. 6,330,464; 6,400,974; 6,711,423 and
7,308,292, which are incorporated herein by reference in their
entireties, each describe a sensing device comprising indicator
molecules and a photosensitive element that is designed for use in
the human body. Despite the advancements to the state of the art
represented by the sensing devices described in these patents,
there still a desire for improved sensing devices.
SUMMARY
[0011] In one aspect, the present invention provides an optical
sensor for implantation within a living animal and measurement of a
concentration of an analyte in a medium within the living animal.
The optical sensor may comprise: indicator molecules, a
semiconductor substrate, a first photodetector, a second
photodetector, a light source, a temperature transducer, a
comparator, an analog to digital converter (ADC), an inductive
element, and a measurement controller. The indicator molecules may
have an optical characteristic responsive to the concentration of
the analyte. The indicator molecules may be configured to interact
with the analyte in the medium within the living animal when the
optical sensor is implanted within the living animal. The first
photodetector may be mounted on or fabricated in the semiconductor
substrate and may be configured to output a first analog light
measurement signal indicative of the amount of light received by
the first photodetector. The second photodetector may be mounted on
or fabricated in the semiconductor substrate and may be configured
to output a second analog light measurement signal indicative of
the amount of light received by the second photodetector. The first
and second photodetectors may be symmetrically arranged relative to
a center line running between the first and second photodetectors.
The light source may be configured to emit excitation light to the
indicator molecules from an emission point aligned on the center
line running between the first and second photodetectors. The
temperature transducer may be mounted on or fabricated in the
semiconductor substrate and may be configured to output an analog
temperature measurement signal indicative of a temperature of the
optical sensor. The comparator may be fabricated in the
semiconductor substrate and may be configured to output an analog
light difference measurement signal indicative of a difference
between the first and second analog light measurement signals. The
ADC may be fabricated in the semiconductor substrate and may be
configured to convert (i) the analog temperature measurement signal
to a digital temperature measurement signal, (ii) the first analog
light measurement signal to a first digital light measurement
signal, (iii) the second analog light measurement signal to a
second digital light measurement signal and (iv) the analog light
difference measurement signal to a digital light difference
measurement signal. The input/output circuit fabricated in the
semiconductor substrate and may be configured to wirelessly
transmit via the inductive element measurement information and
wirelessly receive via the inductive element a measurement command
and power. The measurement controller may be fabricated in the
semiconductor substrate and may be configured to: (i) in accordance
with the measurement command, control the light source; (ii)
generate the measurement information in accordance with (a) the
digital temperature measurement signal, (b) the first digital light
measurement signal, (c) the second digital light measurement signal
and (d) the digital light difference measurement signal; and (iii)
control the input/output circuit to wirelessly transmit the
measurement information.
[0012] In some embodiments, the optical sensor may be a chemical or
biochemical sensor. The first and second photodetectors may be
fabricated in the semiconductor substrate. The first and second
photodetectors may be photodiodes that have been monolithically
formed in the semiconductor substrate using a complimentary metal
oxide semiconductor (CMOS) process. The optical sensor of claim 1
may comprise light source mounting pads on the semiconductor
substrate. The light source mounting pads may be configured such
that the light source, when mounted on the light source mounting
pads, has an emission point aligned on the center line running
between the first and second photodetectors. The light source may
be mounted on the light source mounting pads.
[0013] In some embodiments, the optical sensor may comprise an
isolation trough that electrically separates the first and second
photodetectors. The optical sensor may comprise a nonvolatile
storage medium fabricated in the semiconductor substrate. The
nonvolatile storage medium may have stored therein measurement
calibration information, and the measurement controller may be
configured to control the light source in accordance with the
measurement command and the measurement calibration information.
The nonvolatile storage medium may have stored therein
identification information, the input/output circuit may be
configured to wirelessly transmit via the inductive element the
identification information, and the measurement controller may be
configured to control the input/output circuit to wirelessly
transmit the identification information.
[0014] In some embodiments, the temperature transducer may be a
band-gap based temperature transducer fabricated in the
semiconductor substrate. The comparator may be a transimpedance
amplifier. The input/output circuit may comprise a rectifier
fabricated in the semiconductor substrate. The rectifier may be a
Schottky diode. The measurement information may be digital
measurement information.
[0015] In one embodiment, the indicator molecules may be signal
channel indicator molecules, and the optical sensor may comprise
reference channel indicator molecules configured to not interact
with the analyte in the medium within the living animal when the
optical sensor is implanted within the living animal. The light
source may be configured to emit the excitation light to the signal
channel indicator molecules and reference channel indicator
molecules when turned on, the first photodetector may be configured
to receive excitation light emitted by the signal channel indicator
molecules, and the second photodetector may be configured to
receive excitation light emitted by the reference channel indicator
molecules
[0016] In some embodiments, the living animal may be a living human
being. The medium may be interstitial fluid or blood. The analyte
may be glucose. The analyte may be oxygen. The indicator molecules
may be fluorescent indicator molecules. The optical sensor may have
a size and shape that permits said sensor to be implanted within
the living animal, and the measurement information may be
indicative of the concentration of the analyte in the medium within
the living animal. The inductive element may comprise a coil. The
inductive element may comprise a ferrite core, and the coil may be
formed on the ferrite core.
[0017] In another aspect, the present invention provides a method
of controlling an optical sensor implanted within a living animal
to measure a concentration of an analyte in a medium within the
living animal. The method may comprise wirelessly receiving, by way
of an inductive element and an input/output circuit of the optical
sensor implanted within the living animal, a measurement command
and power. The input/output circuit may be fabricated in a
semiconductor substrate of the optical sensor. The method may
comprise, following receipt of the measurement command, turning a
light source of the optical sensor on and off one or more times.
The light source may be configured to, when turned on, irradiate
indicator molecules having an optical characteristic responsive to
the concentration of the analyte with excitation light. The
indicator molecules may be configured to interact with the analyte
in the medium within the living animal when the optical sensor is
implanted within the living animal. The method may comprise, while
the light source is turned on: (i) generating, by way of a
temperature transducer mounted on or fabricated in the
semiconductor substrate, a first analog temperature measurement
signal indicative of a temperature of the optical sensor; (ii)
generating, by way of a first photodetector mounted on or
fabricated in the semiconductor substrate, a first analog light
measurement signal indicative of the amount of light received by
the first photodetector; (iii) generating, by way of a second
photodetector mounted on or fabricated in the semiconductor
substrate, a second analog light measurement signal indicative of
the amount of light received by the second photodetector; and (iv)
generating, by way of a comparator fabricated in the semiconductor
substrate, an analog light difference measurement signal indicative
of a difference between the first and second analog light
measurement signals. The method may comprise, while the light
source is turned off: (i) generating, by way of the temperature
transducer, a second analog temperature measurement signal
indicative of a temperature of the optical sensor; (ii) generating,
by way of the first photodetector, a first analog ambient light
measurement signal indicative of the amount of light received by
the first photodetector; and (iii) generating, by way of the second
photodetector, a second analog ambient light measurement signal
indicative of the amount of light received by the second
photodetector. The method may comprise, while the light source is
turned on or turned off: (i) converting, by way of an analog to
digital converter (ADC) fabricated in the semiconductor substrate,
the first analog temperature measurement signal to a first digital
temperature measurement signal; (ii) converting, by way of the ADC,
the first analog light measurement signal to a first digital light
measurement signal; (iii) converting, by way of the ADC, the second
analog light measurement signal to a second digital light
measurement signal; (iv) converting, by way of the ADC, the analog
light difference measurement signal to a digital light difference
measurement signal; (v) converting, by way of the ADC, the second
analog temperature measurement signal to a second digital
temperature measurement signal; (vi) converting, by way of the ADC,
the first ambient analog light measurement signal to a first
digital ambient light measurement signal; and (vii) converting, by
way of the ADC, the second analog ambient light measurement signal
to a second digital ambient light measurement signal. The method
may comprise generating, by way of a measurement controller
fabricated in the semiconductor substrate, measurement information
in accordance with (i) the first digital temperature measurement
signal, (ii) the first digital light measurement signal, (iii) the
second digital light measurement signal, (iv) the digital light
difference measurement signal, (v) the second digital temperature
measurement signal, (vi) the first digital ambient light
measurement signal and (vii) the second digital ambient light
measurement signal. The method may comprise transmitting, by way of
the input/output circuit and inductive element, the measurement
information. The method steps may be performed while the optical
sensor is implanted within the living animal, and the measurement
information may be indicative of the concentration of the analyte
in the medium within the living animal.
[0018] In some embodiments, the optical sensor may be a chemical or
biochemical sensor. The method may comprise: reading calibration
information stored in a nonvolatile storage medium fabricated in
the semiconductor substrate and controlling the light source in
accordance with the calibration information. The method may
comprise transmitting, by way of the input/output circuit and
inductive element, identification information stored in a
nonvolatile storage medium fabricated in the semiconductor
substrate.
[0019] In some embodiments, the method may comprise, while the
light source is turned on, generating an analog light source bias
measurement signal and, while the light source is turned on or
turned off, converting, by way of the ADC, the analog light source
bias measurement signal to a digital light source bias measurement
signal. The measurement information may be generated in accordance
with the digital light source bias measurement signal. The method
may comprise determining, by way of a field strength measurement
circuit, whether the wirelessly received power is sufficient to
perform method steps.
[0020] In some embodiments, the indicator molecules may be signal
channel indicator molecules, and the method may comprise
irradiating the signal channel indicator molecules and reference
channel indicator molecules of the optical sensor with excitation
light emitted by the light source when turned on. The reference
channel indicator molecules may be configured to not interact with
the analyte in the medium within the living animal when the optical
sensor is implanted within the living animal. The method may
comprise receiving, by the first photodetector, light emitted by
the signal channel indicator molecules and receiving, by the second
photodetector, light emitted by the reference channel indicator
molecules.
[0021] In some embodiments, the living animal may be a living human
being. The medium may be interstitial fluid or blood. The analyte
may be glucose. The analyte may be oxygen. The indicator molecules
may be fluorescent indicator molecules.
[0022] In still another aspect, the present invention provides a
sensor for implantation within a living animal and measurement of a
concentration of an analyte in a medium within the living animal.
The optical sensor may comprise indicator molecules, a
semiconductor substrate, a photodiode, a light source, an analog to
digital converter (ADC), an inductive element, an input/output
circuit and a measurement controller. The indicator molecules may
have an optical characteristic responsive to the concentration of
the analyte. The indicator molecules may be configured to interact
with the analyte in the medium within the living animal when the
optical sensor is implanted within the living animal. The
photodiode may be fabricated in the semiconductor substrate and may
be configured to output an analog light measurement signal
indicative of the amount of light received by the photodiode. The
light source may be configured to emit excitation light to the
indicator molecules. The analog to digital converter may be
fabricated in the semiconductor substrate and may be configured to
convert the analog light measurement signal to a digital light
measurement signal. The input/output circuit may be fabricated in
the semiconductor substrate and may be configured to wirelessly
transmit via the inductive element measurement information and
wirelessly receive via the inductive element a measurement command
and power. The measurement controller may be fabricated in the
semiconductor substrate and may be configured to: (i) in accordance
with the measurement command, control the light source; (ii)
generate the measurement information in accordance with the digital
light measurement signal; and (iii) control the input/output
circuit to wirelessly transmit the measurement information.
[0023] In some embodiments, the photodiode may have been
monolithically formed in the semiconductor substrate using a
complimentary metal oxide semiconductor (CMOS) process. The sensor
may comprise light source mounting pads on the semiconductor
substrate, and the light source may be mounted on the light source
mounting pads. The sensor may comprise a nonvolatile storage medium
fabricated in the semiconductor substrate.
[0024] The above and other aspects and features of the present
invention, as well as the structure and application of various
embodiments of the present invention, are described below with
reference to the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0025] The accompanying drawings, which are incorporated herein and
form part of the specification, illustrate various embodiments of
the present invention. In the drawings, like reference numbers
indicate identical or functionally similar elements. Additionally,
the left-most digit(s) of the reference number identifies the
drawing in which the reference number first appears.
[0026] FIG. 1A is a simplified schematic, section view illustrating
an optical-based sensor embodying aspects of the present invention.
FIGS. 1B-1D are a perspective view, exploded perspective view, and
side view, respectively, showing the optical-based sensor in more
detail.
[0027] FIGS. 2A and 2B illustrate perspective views of an optical
sensor embodying aspects of the present invention.
[0028] FIG. 3A illustrates a cross-sectional end view of an
optical-based sensor embodying aspects of the present
invention.
[0029] FIG. 3B illustrates a cross-sectional end view of the
optical-based sensor in operation in accordance with an embodiment
of the present invention.
[0030] FIG. 3C illustrates a cross-sectional end view of an
alternative optical-based sensor embodying aspects of the present
invention. FIG. 3D illustrates a cross-sectional end view of the
alternative optical-based sensor in operation in accordance with an
embodiment of the present invention.
[0031] FIG. 4 is a schematic diagram illustrating the connection of
external sensor components of the semiconductor substrate in
accordance with an embodiment of the present invention having a
coil as the inductive element.
[0032] FIG. 5 is a block diagram illustrating the main functional
blocks of the circuitry of an optical sensor according to an
embodiment in which the circuitry is fabricated in the
semiconductor substrate.
[0033] FIG. 6 is block diagram illustrating the functional blocks
of the circuitry of an optical sensor according to an embodiment in
which the circuitry is fabricated in the semiconductor
substrate.
[0034] FIG. 7 illustrates the layout of a semiconductor substrate
in accordance with an embodiment of the present invention.
[0035] FIGS. 8 and 9 illustrate alternative layouts of a
semiconductor substrate in accordance with exemplary alternative
embodiments of the present invention.
[0036] FIG. 10 illustrates the layout of light source mounting pads
on a silicon substrate in accordance with an embodiment of the
present invention.
[0037] FIGS. 11 and 12 are a cross-sectional view and bottom view,
respectively, of a flip-chip mounted light emitting diode that may
be mounted to light source mounting pads on a silicon substrate in
accordance with an embodiment of the present invention.
[0038] FIG. 13 illustrates the layout of light source mounting pads
on a silicon substrate in accordance with an alternative embodiment
of the present invention.
[0039] FIG. 14 illustrates the functional blocks of circuitry
fabricated on a silicon substrate configured to support first and
second internal photodetectors and first and second external
photodetectors according to an exemplary embodiment of present
invention.
[0040] FIG. 15 illustrates an example of a sensor system, which
includes an optical sensor and a sensor reader, embodying aspects
of the present invention.
[0041] FIG. 16 illustrates a sensor control process that may be
performed by the optical sensor in accordance with an embodiment of
the present invention.
[0042] FIG. 17 illustrates a measurement command execution process
that may be performed by the optical sensor to execute a
measurement command received by the optical sensor in accordance
with an embodiment of the present invention.
[0043] FIG. 18 illustrates a measurement and conversion process
that may be performed in a step of the measurement command
execution process, in accordance with an embodiment of the present
invention.
[0044] FIG. 19 illustrates a get result command execution process
that may be performed by the optical sensor to execute a get result
command received by the optical sensor in accordance with an
embodiment of the present invention.
[0045] FIG. 20 illustrates a get identification information command
execution process that may be performed by the optical sensor to
execute a get identification information command received by the
optical sensor in accordance with an embodiment of the present
invention.
[0046] FIGS. 21A and 21B illustrate the timing of an exemplary
embodiment of a measurement and conversion process in accordance
with an embodiment of the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0047] FIG. 1A is a simplified schematic, section view of an
optical-based sensor ("sensor") 100 embodying aspects of the
present invention. FIG. 1B-1D are a perspective view, exploded
perspective view, and side view, respectively, showing the sensor
100 in more detail. In one non-limiting embodiment, sensor 100
includes a sensor housing 102 (i.e., body, shell, sleeve, or
capsule). The sensor housing 102 may include an end cap 113. In
exemplary embodiments, sensor housing 102 may be formed from a
suitable, optically transmissive polymer material, such as, for
example, acrylic polymers (e.g., polymethylmethacrylate
(PMMA)).
[0048] The sensor 100 may include indicator molecules 104.
Indicator molecules 104 may be fluorescent indicator molecules or
absorption indicator molecules. In some non-limiting embodiments,
sensor 100 may include a matrix layer 106 (i.e., graft or gel)
coated on or embedded in at least a portion of the exterior surface
of the sensor housing 102, with the indicator molecules 104
distributed throughout the matrix layer 106. The matrix layer 106
may cover the entire surface of sensor housing 102 (see FIG. 1A) or
only one or more portions of the surface of housing 102 (see FIGS.
1C and 1D). Similarly, the indicator molecules 104 may be
distributed throughout the entire matrix layer 106 or only
throughout one or more portions of the matrix layer 106.
Furthermore, as an alternative to coating the matrix layer 106 on
the outer surface of sensor housing 102, the matrix layer 106 may
be disposed on the outer surface of the sensor housing 102 in other
ways, such as by deposition or adhesion.
[0049] In some embodiments including a matrix layer 106, the matrix
layer 106 may comprises a biocompatible polymer matrix that is
prepared according to methods known in the art and coated on the
surface of the sensor housing 102. In certain embodiments, the
biocompatible matrix materials are permeable to the analyte.
Exemplary biocompatible matrix materials that may be used with
embodiments of the invention include some methacrylates (e.g.,
HEMA) and hydrogels that, advantageously, can be made selectively
permeable--particularly to the analyte--so as to perform a
molecular weight cut-off function. In an alternative embodiment
that does not include a matrix layer 106, instead of being
distributed throughout a matrix layer 106, the indicator molecules
104 could simply be coated on the surface of the sensor housing
102.
[0050] In the illustrated embodiment, the sensor 100 includes a
light source 108, which may be, for example, a light emitting diode
(LED) or other light source, that emits radiation, including
radiation over a range of wavelengths that interact with the
indicator molecules 104. For example, in the case of a
fluorescence-based sensor, light source 108 emits radiation at a
wavelength which causes the indicator molecules 104 to fluoresce.
In one non-limiting embodiment, light source 108 may be implemented
using, for example, LED model number EU-U32SB from Nichia
Corporation (www.nichia.com). However, other LEDs or light sources
may be used depending on the specific indicator molecules applied
to sensor 110 and the specific analytes of interested to be
detected.
[0051] In the illustrated embodiment, sensor 100 also includes one
or more photodetectors 110 (e.g., photodiodes, phototransistors,
photoresistors or other photosensitive elements) which, in the case
of a fluorescence-based sensor, is sensitive to fluorescent light
emitted by the indicator molecules 104 such that a signal is
generated by the photodetector 110 in response thereto that is
indicative of the level of fluorescence of the indicator
molecules.
[0052] As illustrated in FIGS. 1A, 1C, and 1D, some embodiments of
sensor 100 include one or more optical filters 112, such as high
pass or band pass filters. The one or more optical filters 112 may
cover a photosensitive side of the one or more photodetectors 110.
In one embodiment, one optical filter 112 may cover all of the one
or more photodetectors 110, but, in an alternative embodiment, each
of the one or more optical filters 112 may correspond to only one
of the one or more photodetectors 110 and cover only the one of the
one or more photodetectors 110. The one or more optical filters 112
may prevent or substantially reduce the amount of radiation
generated by the light source 108 from impinging on a
photosensitive side of the one or more photodetectors 110. At the
same time, the one or more optical filters 112 may allow light
(e.g., fluorescent light) emitted by indicator molecules 104 to
pass through and strike the photosensitive side of the one or more
photodetectors 110. This significantly reduces "noise" attributable
to incident radiation from the light source 108 in the light
measurement signals output by the one or more photodetectors
110.
[0053] As shown in FIGS. 1A and 1B, in some embodiments, sensor 100
may be wholly self-contained. In other words, the sensor may be
constructed in such a way that no electrical leads extend into or
out of the sensor housing 102 to supply power to the sensor (e.g.,
for driving the light source 108) or to transmit signals from the
sensor 100. Instead, in one embodiment, the sensor 100 may be
powered by an internal, self-contained power source, such as, for
example, microbatteries, micro generators and/or other power
sources. However, in one preferred embodiment, sensor 100 may be
powered by an external power source (not shown). For example, the
external power source may generate a magnetic field to induce a
current in an inductive element 114 (e.g., a coil or other
inductive element). Additionally, the sensor 100 may use the
inductive element 114 to communicate information to an external
data reader (not shown). In some embodiments, the external power
source and data reader may be the same device.
[0054] In some embodiments, sensor 100 includes a semiconductor
substrate 116. In the embodiment illustrated in FIGS. 1A-1D,
circuitry is fabricated in the semiconductor substrate 116. The
circuitry may include analog and/or digital circuitry. In a
non-limiting embodiment, the circuitry may be formed in the
semiconductor substrate 116 using a complimentary metal oxide
semiconductor (CMOS) process. However, other formation processes
(e.g., n-type metal-oxide-semiconductor (NMOS) or n-type
metal-oxide-semiconductor (PMOS)) may alternatively be used.
[0055] Also, although in some preferred embodiments the circuitry
is fabricated in the semiconductor substrate 116, in alternative
embodiments, a portion or all of the circuitry may be mounted or
otherwise attached to the semiconductor substrate 116. In other
words, in alternative embodiments, a portion or all of the
circuitry may include discrete circuit elements, an integrated
circuit (e.g., an application specific integrated circuit (ASIC))
and/or other electronic components discrete and may be secured to
the semiconductor substrate 116, which may provide communication
paths between the various secured components.
[0056] In some embodiments, the one or more photodetectors 110 may
be mounted on the semiconductor substrate 116, but, in some
preferred embodiments, the one or more photodetectors 110 may be
fabricated in the semiconductor substrate 116. For example, in a
non-limiting embodiment, the one or more photodetectors 110 may be
monolithically formed in the semiconductor substrate 116. For
instance, in one embodiment, the one or more photodetectors 110 may
be monolithically formed in the semiconductor substrate 116 using a
complimentary metal oxide semiconductor (CMOS) process (e.g., using
diffusions from the CMOS process). However, other formation
processes (e.g., NMOS or PMOS) may alternatively be used.
[0057] In some embodiments, the light source 108 may be mounted on
the semiconductor substrate 116. For example, in a non-limiting
embodiment, the light source 108 may be flip-chip mounted on the
semiconductor substrate 116. However, in some embodiments, the
light source 108 may be fabricated in the semiconductor substrate
116.
[0058] As shown in the embodiment illustrated in FIGS. 1A-1C, in
some embodiments, the sensor 100 may include one or more capacitors
118. The one or more capacitors 118 may be, for example, one or
more antenna tuning capacitors and/or one or more regulation
capacitors. The one or more capacitors 118 may be too large for
fabrication in the semiconductor substrate 116 to be practical.
Further, the one or more capacitors 118 may be in addition to one
or more capacitors fabricated in the semiconductor substrate
116.
[0059] In some embodiments, the sensor 100 may include a reflector
(i.e., mirror) 119. As shown in FIGS. 1A, 1C, and 1D, reflector 119
may be attached to the semiconductor substrate 116 at an end
thereof. In a non-limiting embodiment, reflector 119 may be
attached to the semiconductor substrate 116 so that a face portion
121 of reflector 119 is generally perpendicular to a top side of
the semiconductor substrate 116 (i.e., the side of semiconductor
substrate 116 on or in which the light source 108 and one or more
photodetectors 110 are mounted or fabricated) and faces the light
source 108. The face 121 of the reflector 119 may reflect radiation
emitted by light source 108. In other words, the reflector 119 may
block radiation emitted by light source 108 from entering the axial
end of the sensor 100. For example, in one embodiment, face 121 may
have a reflective coating disposed thereon, but, in other
embodiments, face 121 may be constructed from a reflective
material. In some alternative embodiments, instead of being
attached at an end of the semiconductor substrate 116, the
reflector 119 may be mounted on the top side of the semiconductor
substrate 116 (e.g., in a groove on the top side thereof).
[0060] According to one aspect of the invention, an application for
which the sensor 110 was developed--although by no means the only
application for which it is suitable--is measuring various
biological analytes in the living body of an animal (including a
human). For example, sensor 110 may be used to measure glucose,
oxygen, toxins, pharmaceuticals or other drugs, hormones, and other
metabolic analytes in, for example, the human body. The specific
composition of the matrix layer 104 and the indicator molecules 106
may vary depending on the particular analyte the sensor is to be
used to detect and/or where the sensor is to be used to detect the
analyte (e.g., in the blood or subcutaneous tissues). Preferably,
however, matrix layer 104, if present, should facilitate exposure
of the indicator molecules to the analyte. Also, it is preferred
that the optical characteristics of the indicator molecules (e.g.,
the level of fluorescence of fluorescent indicator molecules) be a
function of the concentration of the specific analyte to which the
indicator molecules are exposed.
[0061] To facilitate use in-situ in the human body, the sensor
housing 102, in one embodiment, is preferably formed in a smooth,
oblong or rounded shape. Of course, other shapes and configurations
could be used as well. Advantageously, in certain embodiments, the
sensor 100 is on the order of approximately 500 microns to
approximately 0.85 inches in length L and on the order of
approximately 300 microns to approximately 0.3 inches in diameter
D. In certain embodiments, the sensor 100 may have generally
smooth, rounded surfaces. This configuration facilitates the sensor
100 to be implanted into the human body, i.e., dermally or into
underlying tissues (including into organs or blood vessels) without
the sensor interfering with essential bodily functions or causing
excessive pain or discomfort. However, given its small size, the
sensor 100 may have different shapes and configurations and still
be implantable within a human without the sensor interfering with
essential bodily functions or causing excessive pain or
discomfort.
[0062] In some embodiments, a preferred length of the housing is
approximately 0.5 inches to 0.85 inches and a preferred diameter is
approx. 0.1 inches to 0.11 inches. However, in other embodiments,
the housing may be even smaller.
[0063] Moreover, it will be appreciated that any implant placed
within the human (or any other animal's) body-even an implant that
is comprised of "biocompatible" materials-will cause, to some
extent, a "foreign body response" within the organism into which
the implant is inserted, simply by virtue of the fact that the
implant presents a stimulus. In the case of a sensor, such as
sensor 100, which may be implanted within the body of a living
animal (e.g., a living human), the "foreign body response" is most
often fibrotic encapsulation, i.e., the formation of scar tissue.
Analytes (e.g., glucose and oxygen), the presence and/or
concentration of which the sensor 100 may be used to detect, may
have its rate of diffusion or transport hindered by such fibrotic
encapsulation. This is simply because the cells forming the
fibrotic encapsulation (scar tissue) can be quite dense in nature
or have metabolic characteristics different from that of normal
tissue.
[0064] To overcome this potential hindrance to or delay in exposing
the indicator molecules 104 to biological analytes, the sensor 100
may include a sensor/tissue interface layer. The sensor/tissue
interface layer may, for example, cause little or acceptable levels
of fibrotic encapsulation to form. In some embodiments, the
sensor/tissue interface layer may be according to any of the
sensor/tissue interface layer embodiments described in U.S. Pat.
No. 6,330,464, which is incorporated herein by reference in its
entirety.
[0065] FIGS. 2A and 2B illustrate perspective views of the sensor
100. In FIGS. 2A and 2B, the reflector 119, which may be included
in some embodiments of the sensor 100, is not illustrated. In the
embodiment illustrated in FIGS. 2A and 2B, the inductive element
114 comprises a coil 220. In one embodiment, coil 220 may be a
copper coil but other conductive materials, such as, for example,
screen printed gold, may alternatively be used. In some
embodiments, the coil 220 is formed around a ferrite core 222.
Although core 222 is ferrite in some embodiments, in other
embodiments, other core materials may alternatively be used.
[0066] In some embodiments, coil 220 is formed on ferrite core 222
by printing the coil 220 around the ferrite core 222 such that the
major axis of the coil 220 (magnetically) is parallel to the
longitudinal axis of the ferrite core 222. A non-limiting example
of a coil printed on a ferrite core is described in U.S. Pat. No.
7,800,078, which is incorporated herein in its entirety. In an
alternative embodiment, coil 220 may be a wire-wound coil. However,
embodiments in which coil 220 is a printed coil as opposed to a
wire-wound coil are preferred because each wire-wound coil is
slightly different in characteristics due to manufacturing
tolerances, and it may be necessary to individually tune each
sensor that uses a wire-wound coil to properly match the frequency
of operation with the associated antenna. Printed coils, by
contrast, may be manufactured using automated techniques that
provide a high degree of reproducibility and homogeneity in
physical characteristics, as well as reliability, which is
important for implant applications, and increases
cost-effectiveness in manufacturing.
[0067] In some embodiments, a dielectric layer may be printed on
top of the coil 220. The dielectric layer may be, in a non-limiting
embodiment, a glass based insulator that is screen printed and
fired onto the coil 220. In an exemplary embodiment, the one or
more capacitors 118 and the semiconductor substrate 116 may be
mounted on vias through the dielectric.
[0068] In the embodiment illustrated in FIGS. 2A and 2B, the one or
more photodetectors 110 include a first photodetector 224 and a
second photodetector 226. First and second photodetectors 224 and
226 may be mounted on or fabricated in the semiconductor substrate
116. In the embodiment illustrated in FIGS. 2A and 2B, sensor 100
may include one or more optical filters 112 even though they are
not shown.
[0069] FIGS. 3A and 3B illustrate a cross sectional end view of the
sensor 100 in accordance with an embodiment of the present
invention. In FIGS. 3A and 3B, the reflector 119, which may be
included in some embodiments of the sensor 100, is not illustrated.
As shown in FIGS. 3A and 3B, in some embodiments, the matrix layer
106 may have an indicator membrane 106' and a reference membrane
106''. In a non-limiting embodiment, indicator molecules 104
sensitive to an analyte (e.g., oxygen, glucose, etc.) may be
distributed throughout both the indicator membrane 106' and the
reference membrane 106'', the material of indicator membrane 106'
may be permeable to the analyte, and the material of reference
membrane 106'' may be impermeable to the analyte. Thus, while the
indicator molecules 104 in the indicator membrane 106' may be
affected by the presence and/or concentration of the analyte, the
indicator molecules 104 in the reference membrane 106'' may be
unaffected or generally unaffected by the presence and/or
concentration of the analyte.
[0070] In some embodiments, the sensor 100 may include one or more
signal channels (i.e., analyte sensing indicator channels) and one
or more reference indicator channels (i.e., reference channels). In
the embodiment illustrated in FIGS. 3A and 3B, the sensor 100 has a
signal channel (e.g., including the indicator membrane 106' and the
first photodetector 224) and a reference channel (e.g., including
the reference membrane 106'' and the second photodetector 226). The
signal channel and the reference channel may enable the sensor 100
to obtain an indicator measurement (via the signal channel) and a
reference measurement (via the reference channel). The reference
measurement may be used, for example, to obtain a more accurate
reading than can be obtained with the indicator measurement
alone.
[0071] In operation, as shown in FIG. 3B, the light source 108
(e.g., an LED) may emit excitation light 329 that travels within
the sensor housing 102 and reaches both the indicator and reference
membranes 106' and 106''. In a non-limiting embodiment, the
excitation light 329 may cause the indicator molecules 104
distributed in indicator and reference membranes 106' and 106'' to
fluoresce. As the indicator membrane 106' may be permeable to the
analyte in the medium (e.g., interstitial fluid (ISF) or blood)
into which the sensor 100 is implanted, the indicator molecules 104
in the indicator membrane 106' may interact with the analyte in the
medium and, when irradiated by the excitation light 329, may emit
indicator fluorescent light 331 indicative of the presence and/or
concentration of the analyte in the medium. As the reference
membrane 106'' may be impermeable to the analyte in the medium into
which the sensor 100 is implanted, the indicator molecules 104 in
the reference membrane 106'' may not interact with the analyte in
the medium and, when irradiated by the excitation light 329, may
emit reference fluorescent light 333 that is unaffected or
generally unaffected by the presence and/or concentration of the
analyte in the medium. The indicator fluorescent light 331 may be
received by the first photodetector 224, and the reference
fluorescent light 333 may be received by the second photodetector
226.
[0072] In some embodiments, the sensor 100 may include a baffle
327, which may, for example, inhibit cross-talk of light radiated
from the indicator molecules 104 in the indicator and reference
membranes 106' and 106''. In one embodiment, the baffle 327 may be
impervious to radiation that could affect the first and second
photodetectors 224 and 226 (e.g., the baffle may be painted black
or the like). Also, although not shown in FIGS. 3A and 3B, the
optical sensor 100 may additionally include one or more filters
(e.g., one or more filters 112) that may, for example, exclude the
wavelength or spectrum of light emitted by the light source
108.
[0073] In one embodiment, the indicator molecules 104 distributed
in the indicator membrane 106' may be the same as the indicator
molecules 104 distributed in the reference membrane 106'', but, in
another embodiment, the indicator molecules 104 distributed in the
indicator membrane 106' may be different from the indicator
molecules 104 distributed in the reference membrane 106''. In
addition, in one embodiment, only one type of indicator molecules
104 may be distributed in each of the indicator and reference
membranes 106' and 106'', but, in other embodiments, different
types of indicator molecules 104 may be distributed in each of the
indicator and reference membranes 106' and 106''. Also, U.S. Pat.
No. 6,330,464, which is incorporated herein by reference in its
entirety, describes various indicator molecules for use in
indicator and reference membranes and various signal and reference
channel configurations, which may be incorporated into different
embodiments in accordance with the present invention.
[0074] FIGS. 3C and 3D illustrate a cross sectional end view of the
sensor 100 in accordance with an alternative embodiment of the
present invention. In FIGS. 3C and 3D, the reflector 119, which may
be included in some embodiments of the sensor 100, is not
illustrated. As shown in FIGS. 3C and 3D, in some embodiments,
indicator molecules 104 sensitive to an analyte (e.g., oxygen,
glucose, etc.) may be distributed throughout the matrix layer/graft
106, which may be permeable to the analyte. The sensor 100 may have
a signal channel (e.g., including the indicator molecules 104 and
the first photodetector 224) and a reference channel (e.g.,
including the second photodetector 226). The signal channel and the
reference channel may enable the sensor 100 to obtain an indicator
measurement (via the signal channel) and a reference measurement
(via the reference channel). The reference measurement may be used,
for example, to obtain a more accurate reading than can be obtained
with the indicator measurement alone.
[0075] In operation, as shown in FIG. 3D, the light source 108
(e.g., an LED) may emit excitation light 329 that travels within
the sensor housing 102. Some of the excitation light 329 may reach
the indicator molecules 104 in the matrix layer 106. Some of the
excitation light 329 may be reflected from the matrix layer 106 as
reflection light 335. In a non-limiting embodiment, the excitation
light 329 that reaches the indicator molecules 104 may cause the
indicator molecules 104 to fluoresce. The indicator molecules 104
in the matrix layer 106 may interact with the analyte in the medium
and, when irradiated by the excitation light 329, may emit
indicator fluorescent light 331 indicative of the presence and/or
concentration of the analyte in the medium. The optical filter(s)
112, first photodetector 224, and second photodector 226 may be
configured so that the first photodetector 224 (primarily) receives
indicator fluorescent light 331 and the second photodector 226
(primarily) receives reflection light 335 and excitation light 329
that has reached second photodector 226 without having encountered
the matrix layer 106 (e.g., excitation light 328 received directly
from the light source 108 and/or received after being reflected
from the sensor housing 102). For instance, in some embodiments,
the optical filter(s) 112 may be configured to prevent light (e.g.,
reflection light 335 and excitation light 329) having the
wavelength of the excitation light 329 emitted by the light source
108 from reaching the first photodetector 224 and may be configured
to prevent light having the wavelength of the indicator fluorescent
light 331 emitted by the indicator molecules 104 from reaching the
second photodector 226.
[0076] In another alternative embodiment, both indicator molecules
104 sensitive to an analyte (e.g., oxygen, glucose, etc.) and
reference indicator molecules insensitive to the analyte may be
distributed throughout the matrix layer 106, which may be permeable
to the analyte. In other words, while the indicator molecules 104
in the matrix layer 106 may be affected by the presence and/or
concentration of the analyte, the reference indicator molecules in
the matrix layer 106 may be unaffected or generally unaffected by
the presence and/or concentration of the analyte. In operation, the
light source 108 may emit excitation light 329 that travels within
the sensor housing 102 and reaches the indicator molecules 104 and
the reference indicator molecules in the matrix layer 106. The
excitation light 329 may cause the indicator molecules 104 and the
reference indicator molecules to fluoresce at different
wavelengths. The indicator molecules 104 in the matrix layer 106
may interact with the analyte in the medium and, when irradiated by
the excitation light 329, may emit indicator fluorescent light 331
indicative of the presence and/or concentration of the analyte in
the medium. The reference indicator molecules in the matrix layer
106, when irradiated by the excitation light 329, may emit
reference fluorescent light 333 that is unaffected or generally
unaffected by the presence and/or concentration of the analyte in
the medium. The optical filter(s) 112 may prevent light having the
wavelength of the reference fluorescent light 333 emitted by the
reference indicator molecules from reaching the first photodetector
224 and may prevent light having the wavelength of the indicator
fluorescent light 331 emitted by the indicator molecules 104 from
reaching the second photodector 226. The optical filters 112 may
additionally prevent light having the wavelength of the excitation
light 329 from reaching the first photodetector 224 and second
photodector 226.
[0077] FIG. 4 is a schematic diagram illustrating contacts (i.e.,
pins, pads or connections) 428 that enable external sensor
components (i.e., sensor components external to the semiconductor
substrate 116) to electrically connect to circuitry fabricated in
the semiconductor substrate 116 according to one, non-limiting
embodiment of sensor 100 having a coil 220 as the inductive element
114. As shown in FIG. 4, in some embodiments, the coil 220 may be
connected to coil contacts 428a and 428b of the semiconductor
substrate 116. In a non-limiting example, the coil 220 may be
connected to coil contacts 428a and 428b in parallel with one or
more capacitors 118, which may be one or more tuning
capacitors.
[0078] As shown in FIG. 4, in some embodiments having one or more
photodetectors 110, such as first and second photodetectors 224 and
226, mounted on the semiconductor substrate 116, the mounted first
and second photodetectors 224 and 226 may be connected to
photodetector contacts 428c, 428d and 428e in the illustrated
manner. However, in embodiments having one or more photodetectors
110, such as first and second photodetectors 224 and 226,
fabricated in the semiconductor substrate 116, photodetector
contacts 428c, 428d and 428e may not necessary and may not be
included.
[0079] As shown in FIG. 4, in some embodiments having light source
108 mounted on the semiconductor substrate 116, the mounted light
source 108 may be connected to light source contacts 428f and 428g
in the illustrated manner. However, in embodiments in which the
light source 108 is fabricated in the semiconductor substrate 116,
light source contacts 428f and 428g are not necessary and may not
be included.
[0080] As shown in FIG. 4, in some embodiments, one or more
capacitors 118, which may be one or more regulation capacitors, may
be connected to contacts 428h and 428i. However, in other
embodiments, the sensor may not include a one or more regulation
capacitors, and the semiconductor substrate 116 may not include
contacts 428h and 428i.
[0081] The contacts 428 illustrated in FIG. 4 are not an exhaustive
list of all contacts that may be included on the semiconductor
substrate 116, and the illustrated external sensor components are
not an exhaustive list of all external sensor components that may
connect to the semiconductor substrate 116. Some embodiments of the
semiconductor substrate 116 may include one or more additional
contacts 428, and, in some embodiments, one or more additional
external sensor components may connect to the semiconductor
substrate 116. For example, non-limiting embodiments may include
one or more contacts 428 for an external temperature transducer,
one or more contacts 428 that enable circuitry fabricated in the
semiconductor substrate 116 to be reset and/or one or more contacts
428 that assist in testing of the circuitry fabricated in the
semiconductor substrate 116 (e.g., a demodulation out contact
connected to the output of a demodulator that may be fabricated in
the semiconductor substrate 116). Furthermore, in some embodiments,
one or more of the contacts 428 enabling electrical connection to
circuitry fabricated on the semiconductor substrate 116 may have
double pads. For example, in one non-limiting embodiment, all
contacts 428 may have double pads.
[0082] FIG. 5 is a block diagram illustrating the main functional
blocks of the circuitry of sensor 100 according to an embodiment in
which the circuitry is fabricated in the semiconductor substrate
116. In the embodiment illustrated in the FIG. 5, the circuitry
fabricated in the semiconductor substrate 116 may include an
input/output (I/O) circuit 530, measurement controller 532 and
analog interface 534. The I/O circuit 530 may include an I/O
frontend block 536 and an I/O controller 538.
[0083] FIG. 6 is block diagram illustrating in more detail the
functional blocks of the circuitry of sensor 100 according to a
non-limiting embodiment in which the circuitry is fabricated in the
semiconductor substrate 116. As shown in the embodiment of FIG. 6,
in some embodiments, the I/O frontend block 536 of the I/O circuit
530 may be connected to the external inductive element 114, which
may be in the form of a coil 220, through coil contacts 428a and
428b. The I/O frontend block 536 may include a rectifier 640, a
data extractor 642, a clock extractor 644, clamp/modulator 646
and/or frequency divider 648. Data extractor 642, clock extractor
644 and clamp/modulator 646 may each be connected to external coil
220 through coil contacts 428a and 428b. The rectifier 640 may
convert an alternating current produced by coil 220 to a direct
current that may be used to power the sensor 100. For instance, the
direct current may be used to produce one or more voltages, such
as, for example, voltage VDD_A, which may be used to power the one
or more photodetectors 110. In one non-limiting embodiment, the
rectifier 640 may be a Schottky diode; however, other types of
rectifiers may be used in other embodiments. The data extractor 642
may extract data from the alternating current produced by coil 220.
The clock extractor 644 may extract a signal having a frequency
(e.g., 13.56 MHz) from the alternating current produced by coil
220. The frequency divider 648 may divide the frequency of the
signal output by the clock extractor 644. For example, in a
non-limiting embodiment, the frequency divider 648 may be a 4:1
frequency divider that receives a signal having a frequency (e.g.,
13.56 MHz) as an input and outputs a signal having a frequency
(e.g., 3.39 MHz) equal to one fourth the frequency of the input
signal. The outputs of rectifier 640 may be connected outputs of
rectifier 640 may be connected to one or more external capacitors
118 (e.g., one or more regulation capacitors) through contacts 428h
and 428i.
[0084] In some embodiments, the I/O controller 538 of the I/O
circuit 530 may include a decoder/serializer 650, command
decoder/data encoder 652, data and control bus 654, data serializer
656 and/or encoder 658. The decoder/serializer 650 may decode and
serialize the data extracted by the data extractor 642 from the
alternating current produced by coil 220. The command decoder/data
encoder 652 may receive the data decoded and serialized by the
decoder/serializer 650 and may decode commands therefrom. The data
and control bus 654 may receive commands decoded by the command
decoder/data encoder 652 and transfer the decoded commands to the
measurement controller 532. The data and control bus 654 may also
receive data, such as measurement information, from the measurement
controller 532 and may transfer the received data to the command
decoder/data encoder 652. The command decoder/data encoder 652 may
encode the data received from the data and control bus 654. The
data serializer 656 may receive encoded data from the command
decoder/data encoder 652 and may serialize the received encoded
data. The encoder 658 may receive serialized data from the data
serializer 656 and may encode the serialized data. In a
non-limiting embodiment, the encoder 658 may be a Manchester
encoder that applies Manchester encoding (i.e., phase encoding) to
the serialized data. However, in other embodiments, other types of
encoders may alternatively be used for the encoder 658, such as,
for example, an encoder that applies 8B/10B encoding to the
serialized data.
[0085] The clamp/modulator 646 of the I/O frontend block 536 may
receive the data encoded by the encoder 658 and may modulate the
current flowing through the inductive element 114 (e.g., coil 220)
as a function of the encoded data. In this way, the encoded data
may be transmitted wirelessly by the inductive element 114 as a
modulated electromagnetic wave. The wirelessly transmitted data may
be detected by an external reading device by, for example,
measuring the current induced by the modulated electromagnetic wave
in a coil of the external reading device. Furthermore, by
modulating the current flowing through the coil 220 as a function
of the encoded data, the encoded data may be transmitted wirelessly
by the coil 220 as a modulated electromagnetic wave even while the
coil 220 is being used to produce operating power for the sensor
100. See, for example, U.S. Pat. Nos. 6,330,464 and 8,073,548,
which are incorporated herein by reference in their entireties and
which describe a coil used to provide operative power to an optical
sensor and to wirelessly transmit data from the optical sensor. In
some embodiments, the encoded data is transmitted by the sensor 100
using the clamp/modulator 646 at times when data (e.g., commands)
are not being received by the sensor 100 and extracted by the data
extractor 642. For example, in one non-limiting embodiment, all
commands may be initiated by an external sensor reader (e.g.,
sensor 1500 of FIG. 15) and then responded to by the sensor 100
(e.g., after or as part of executing the command). In some
embodiments, the communications received by the inductive element
114 and/or the communications transmitted by the inductive element
114 may be radio frequency (RF) communications. Although, in the
illustrated embodiments, the sensor 100 includes a single coil 220,
alternative embodiments of the sensor 100 may include two or more
coils (e.g., one coil for data transmission and one coil for power
and data reception).
[0086] In an embodiment, the I/O controller 538 may also include a
nonvolatile storage medium 660. In a non-limiting embodiment, the
nonvolatile storage medium 660 may be an electrically erasable
programmable read only memory (EEPROM). However, in other
embodiments, other types of nonvolatile storage media, such as
flash memory, may be used. The nonvolatile storage medium 660 may
receive write data (i.e., data to be written to the nonvolatile
storage medium 660) from the data and control bus 654 and may
supply read data (i.e., data read from the nonvolatile storage
medium 660) to the data and control bus 654. In some embodiments,
the nonvolatile storage medium 660 may have an integrated charge
pump and/or may be connected to an external charge pump. In some
embodiments, the nonvolatile storage medium 660 may store
identification information (i.e., traceability or tracking
information), measurement information and/or setup parameters
(i.e., calibration information). In one embodiment, the
identification information may uniquely identify the sensor 100.
The unique identification information may, for example, enable full
traceability of the sensor 100 through its production and
subsequent use. In one embodiment, the nonvolatile storage medium
660 may store calibration information for each of the various
sensor measurements.
[0087] In some embodiments, the analog interface 534 may include a
light source driver 662, analog to digital converter (ADC) 664, a
signal multiplexer (MUX) 666 and/or comparator 668. In a
non-limiting embodiment, the comparator 668 may be a transimpedance
amplifier, in other embodiments, different comparators may be used.
The analog interface 534 may also include light source 108, one or
more photodetectors 110 (e.g., first and second photodetectors 224
and 226) and/or a temperature transducer 670. In a non-limiting,
exemplary embodiment, the temperature transducer 670 may be a
band-gap based temperature transducer. However, in alternative
embodiments, different types of temperature transducers may be
used, such as, for example, thermistors or resistance temperature
detectors. Furthermore, like the light source 108 and one or more
photodetectors 110, in one or more alternative embodiments, the
temperature transducer 670 may be mounted on semiconductor
substrate 116 instead of being fabricated in semiconductor
substrate 116.
[0088] The light source driver 662 may receive a signal from the
measurement controller controller 532 indicating the light source
current at which the light source 108 is to be driven, and the
light source driver 662 may drive the light source 108 accordingly.
The light source 108 may emit radiation from an emission point in
accordance with a drive signal from the light source driver 662.
The radiation may excite indicator molecules 104 distributed
throughout a matrix layer 106 coated on at least part of the
exterior surface of the sensor housing 102. The one or more
photodetectors 110 (e.g., first and second photodetectors 224 and
226) may each output an analog light measurement signal indicative
of the amount of light received by the photodetector. For instance,
in the embodiment illustrated in FIG. 6, the first photodetector
224 may output a first analog light measurement signal indicative
of the amount of light received by the first photodetector 224, and
the second photodetector 226 may output a first analog light
measurement signal indicative of the amount of light received by
the second photodetector 226. The comparator 668 may receive the
first and second analog light measurement signals from the first
and second photodetectors 224 and 226, respectively, and output an
analog light difference measurement signal indicative of the
difference between the first and second analog light measurement
signals. The temperature transducer 670 may output an analog
temperature measurement signal indicative of the temperature of the
sensor 100. The signal MUX 666 may select one of the analog
temperature measurement signal, the first analog light measurement
signal, the second analog light measurement signal and the analog
light difference measurement signal and may output the selected
signal to the ADC 664. The ADC 664 may convert the selected analog
signal received from the signal MUX 666 to a digital signal and
supply the digital signal to the measurement controller 532. In
this way, the ADC 664 may convert the analog temperature
measurement signal, the first analog light measurement signal, the
second analog light measurement signal and the analog light
difference measurement signal to a digital temperature measurement
signal, a first digital light measurement signal, a second digital
light measurement signal and a digital light difference measurement
signal, respectively, and may supply the digital signals, one at a
time, to the measurement controller 532.
[0089] In some embodiments, the analog interface 534 may also
include a backscatter functionality. For example, in one
embodiment, the backscatter functionality may be implemented by
impedance modulation through a loosely coupled transformer. The
impedance may be modulated by changing the power loading of
circuitry in the sensor 100.
[0090] In some embodiments, the circuitry of sensor 100 fabricated
in the semiconductor substrate 116 may additionally include a clock
generator 671. The clock generator 671 may receive, as an input,
the output of the frequency divider 648 and generate a clock signal
CLK. The clock signal CLK may be used by one or more components of
one or more of the I/O fronted block 536, I/O controller 538,
measurement controller 532 and analog interface 534. In a
non-limiting embodiment, the clock signal CLK may have a frequency
of 1.13 MHz, but, in other embodiments, other frequencies may be
used.
[0091] In a non-limiting embodiment, data (e.g., decoded commands
from the command decoder/data encoder 652 and/or read data from the
nonvolatile storage medium 660) may be transferred from the data
and control bus 654 of the I/O controller 538 to the measurement
controller 532 via transfer registers and/or data (e.g., write data
and/or measurement information) may be transferred from the
measurement controller 532 to the data and control bus 654 of the
I/O controller 538 via the transfer registers.
[0092] In some embodiments, the circuitry of sensor 100 may include
a field strength measurement circuit. In embodiments, the field
strength measurement circuit may be part of the input/output
circuit 530 or the measurement controller 532 or may be a separate
functional component. The field strength measurement circuit may
measure the received (i.e., coupled) power (e.g., in mWatts). The
field strength measurement circuit may detect whether the received
power is sufficient to run the sensor 100. For example, the field
strength measurement circuit may detect whether the received power
is sufficient to produce a certain voltage and/or current. In one
non-limiting embodiment, the field strength measurement circuit may
detect whether the received power produces a voltage of at least
approximately 3V and a current of at least approximately 0.5 mA.
However, other embodiments may detect that the received power
receives produces at least a different voltage and/or at least a
different current.
[0093] FIG. 7 illustrates the layout of a semiconductor substrate
116 according to an embodiment of the present invention. In the
embodiment shown in FIG. 7, first and second photodetectors 224 and
226 are fabricated in the semiconductor substrate 116, and the
semiconductor substrate 116 has light source mounting pads 772 and
774 for mounting light source 108. In one embodiment, light source
mounting pads 772 and 774 may connect to the anode and cathode,
respectively, of a light source 108 mounted on the semiconductor
substrate 116. In FIG. 7, the input/output (I/O) circuit 530,
measurement controller 532 and analog interface 534 (other than
first and second photodetectors 224 and 226 and light source 108)
is shown as circuitry 776. In the embodiment shown in FIG. 7, the
circuitry 776 is fabricated in the semiconductor substrate 116.
[0094] In non-limiting embodiments, the semiconductor substrate 116
may include an isolation trough 778. The isolation trough 778 may
isolate and electrically separate the first and second
photodetectors 224 and 226. In one embodiment, the isolation trough
778 may be formed on a center line running between the first and
second photodetectors 224 and 226. Also, in some embodiments, the
light source mounting pads 772 and 774 may be configured such that
the emission point of light source 108, when mounted on the light
source mounting pads 772 and 774, is aligned on the center line
running between the first and second photodiodes 224 and 226.
Similarly, in some embodiments in which the light source 108 is
fabricated in the silicon substrate 116, the emission point of the
fabricated light source 108 is aligned on the center line running
between the first and second photodiodes 224 and 226. In some
embodiments, the fabrication of symmetrical photodetectors 224 and
226 (i.e., photodetectors which are symmetrical relative to the
light source emission point) may realize dual channels that are
closer to being identical to each other than can be achieved by
using discrete parts (e.g., photodetectors mounted on the
semiconductor substrate 116). The nearly identical photodetector
channels may improve the accuracy of the sensor measurements. This
may be especially true when, in some embodiments, the nearly
identical dual photodetector channels are utilized as a signal
channel and a reference channel, respectively.
[0095] The layout of the first and second photodetectors 224 and
226 on silicon substrate 116 is not limited to the embodiment
illustrated in FIG. 7. Other embodiments may use different
photodetector layouts, such as, for example, those shown in FIGS. 8
and 9. FIG. 8 illustrates an embodiment of the silicon substrate
116 in which the photosensitive areas of the first and second
photodetectors 224 and 226 do not extend all the way between the
light source mounting pads 772 and 774. FIG. 9 illustrates an
embodiment of the silicon substrate 116 in which the photosensitive
areas of the first and second photodetectors 224 and 226 do not
extend above and below the light source mounting pads 772 and
774.
[0096] FIG. 10 illustrates the layout of the light source mounting
pads 772 and 774 on silicon substrate 116 according to one
embodiment of the silicon substrate 116. The light source mounting
pads 772 and 774 may be flip-chip LED mounting pads configured for
mounting of a flip-chip mounted LED, and light source 108 may be a
flip-chip mounted LED, such as, for example, the flip-chip mounted
LED 1180 illustrated in the cross-sectional view in FIG. 11. As
shown in the FIG. 11, flip-chip mounted LED 1180 may have an anode
1182, a cathode 1184, a cover layer 1186, a transparent electrode
1188, a p-type semiconductor (e.g., Gallium Nitride (GaN)) layer
1190, an n-type semiconductor (e.g., GaN) layer 1192, a substrate
(e.g., sapphire substrate) layer 1194 and/or a backside metal
(e.g., a gold tin alloy (Au--Sn)) layer 1196. FIG. 12 is a bottom
view of the flip-chip mounted LED 1180 shown in FIG. 11 and
illustrates the anode 1182 and cathode 1184, which connect to light
source mounting pads 772 and 774 when the flip-chip mounted LED
1180 is mounted on the silicon substrate 116.
[0097] Although FIG. 10 illustrates the layout of the light source
mounting pads 772 and 774 according to the one embodiment, other
embodiments may use other layouts, including other flip-chip LED
mounting pad layouts. For example, FIG. 13 illustrates the layout
of the light source mounting pads 772 and 774 on silicon substrate
116 according to one possible alternative embodiment of the silicon
substrate 116. Moreover, the silicon substrate 116 may be
implemented with different light source mounting pad layouts for
connecting to the different anode and cathode layouts of different
light sources.
[0098] In some embodiments, the silicon substrate 116 may be
configured to support one or more internal photodetectors 110
(i.e., one or more photodetectors fabricated in the semiconductor
substrate 116) and one or more external photodiodes 110. FIG. 14
illustrates an exemplary embodiment of the functional blocks of
circuitry fabricated on a silicon substrate 116 configured to
support first and second internal photodetectors 224a and 226a and
first and second external photodetectors 224b and 226b. Relative to
the embodiment illustrated in FIG. 6, the analog interface 534 of
the embodiment of the functional blocks of circuitry fabricated on
a silicon substrate 116 illustrated in FIG. 14 may additionally
include an input multiplexor (MUX) 1498. The input MUX 1498 may
selectively provide either the outputs of first and second internal
photodetectors 224a and 226a or the outputs of the first and second
external photodetectors 224b and 226b as outputs to the comparator
668 and/or signal MUX 666.
[0099] FIG. 15 illustrates an example of a sensor system including
sensor 100 and a sensor reader 1500 according to one embodiment of
the present invention. In the embodiment shown in FIG. 15, the
sensor 100 may be implanted, for example, near a patient's wrist.
For example, as shown in FIG. 15, in one non-limiting embodiment,
the sensor 100 may be implanted between the skin 1502 and
subcutaneous tissues 1504. In a non-limiting embodiment, the reader
1500 may be worn like a watch on the patient's arm. That is, the
reader 1500 may be attached to a wristband 1506. In some
embodiments, the reader 1500 may be combined with a conventional
watch. In a non-limiting embodiment, the wristband 1506 is an
opaque wristband that may reduce the amount of ambient light that
reaches the implanted sensor 100. However, in other embodiments,
the reader 1500 may not be worn or otherwise attached to the
patient, and the patient may simply bring the sensor 100 into
proximity of the reader 1500 by bringing the reader 1500 near the
patient's wrist. Furthermore, in some embodiments, the sensor 100
may be implanted in a part of the patient's body other than near
the patient's wrist, such as, for example, in the abdomen or an
upper part of the arm.
[0100] In some embodiments, the sensor reader 1500 may include a
transceiver 1508, a processor 1510 and/or a user interface 1512. In
one embodiment, the user interface 1512 may include a liquid
crystal display (LCD), but, in other embodiments, different types
of displays may be used. In some embodiments, the transceiver 1508
may include an inductive element, such as, for example, a coil. The
transceiver 1508 may generate an electromagnetic wave (e.g., by
using a coil) to induce a current in the inductive element 114 of
the sensor 100, which powers the sensor 100. The transceiver 1508
may also transmit data (e.g., commands) to the sensor 100. For
example, in a non-limiting embodiment, the transceiver 1508 may
transmit data by modulating the generated electromagnetic wave used
to power the sensor 100 (e.g., by modulating the current flowing
through a coil of the transceiver 1508). As described above, the
modulation in the electromagnetic wave generated by the reader 1500
may be detected/extracted by the sensor 100 (e.g., by data
extractor 642). Moreover, the transceiver 1508 may receive data
(e.g., measurement information) from the sensor. For example, in a
non-limiting embodiment, the transceiver 1508 may receive data by
detecting modulations in the electromagnetic wave generated by the
sensor 100 (e.g., by clamp/modulator 646), e.g., by detecting
modulations in the current flowing through the coil of the
transceiver 1508.
[0101] In some embodiments, the processor 1510 may output to the
transceiver 1508 the data to be transmitted to the sensor 100 and
may receive from the transceiver 1508 the data received from the
sensor 100. In one embodiment, the processor 1510 may serialize and
encode the data to be transmitted to the sensor 100 before
outputting it to the transceiver 1508 for transmission. Similarly,
the processor 1510 may decode and/or serialize the data received
from the sensor 100. In some embodiments, the data received from
the sensor 100 may be measurement information, and the processor
1510 may process the measurement information to determine a
concentration of an analyte. However, in other embodiments, the
sensor 100 may process the measurement information to determine a
concentration of an analyte, and the data received from the sensor
100 may be the determined concentration of the analyte. In some
embodiments, the processor 1510 may cause the user interface 1512
to display a value representing the concentration of the analyte so
that a user (e.g., the patient, a doctor and/or others) can read
the value. Also, in some embodiments, the processor 1510 may
receive from the user interface 1512 user input (e.g., a user
request for a sensor reading, such as the concentration of an
analyte).
[0102] In some embodiments, the sensor reader 1500 may include one
or more photodetectors. In one embodiment, the sensor reader 1500
may use the one or more photodetectors to detect ambient light,
and, if to much light is detected, issue a warning to the user via
user interface 1512. In some embodiments, the system including
sensor reader 1500 and sensor 100 may incorporate the methods for
ambient light detection and warning issuance described in U.S. Pat.
No. 7,157,723, which is incorporated herein by reference in its
entirety. Furthermore, in some embodiments, the sensor reader 1500
may include one or more input/output ports that enable transmission
of data (e.g., traceability information and/or measurement
information) and receipt of data (e.g., sensor commands and/or
setup parameters) between the sensor reader 1500 and another device
(e.g., a computer).
[0103] In some embodiments, such as, for example, those illustrated
FIGS. 7-9, where the circuitry 776 and first and second
photodetectors 224 and 226 may be fabricated in semiconductor
substrate 116, the semiconductor substrate 116 may provide a custom
integrated circuit that merges full functionality for an optical
sensor interface onto a single chip that needs only minimal
connections to external passive components (e.g., capacitors 118)
and/or a light source 108 (e.g., LED). In fact, in some
embodiments, the number of external components of sensor 100
connected to the circuitry fabricated the semiconductor substrate
116 may be reduced to five or fewer (e.g., one or more capacitors
118, inductive element 114 and/or light source 108). Furthermore,
in some embodiments, the light source 108 may also be fabricated in
the semiconductor substrate 116. The reduced external component
count and associated reduction in the number of connections may
contribute to improved sensor robustness and/or to reduce
manufacturing complexity.
[0104] According to aspects of the present invention, the circuitry
fabricated in semiconductor substrate 116, which may include one or
more photodetectors 110 and/or light source 108, may provide an
optical transduction along with the ability to receive and transmit
data through a remotely powered, wireless interface. In other
words, the functionality of sensor 100 may include remote powering
and bi-directional wireless data communication. The circuitry
fabricated in semiconductor substrate 116 may have the ability to
check the received power through its remotely powered interface as
well as check that the regulated voltages are sufficient to supply
power to all of the blocks.
[0105] As explained above, in some embodiments of the present
invention, the circuitry fabricated in semiconductor substrate 116
may also have the ability to execute diagnostic measurements that
check the integrity of various blocks (e.g., comparator 668 and/or
ADC 664) in the analog front end (e.g., analog interface 534) of
the chip. The one or more photodetectors 110 may provide the light
to current transduction, which may be processed further through the
integrated comparator (e.g., transimpedance amplifier) 668 and ADC
664. The analog interface 534 may also have a temperature
transducer 670, which, in some embodiments, may be an integrated,
band-gap based temperature sensor. In some embodiments, the
temperature transducer 670 may provide temperature as an
independent measurement and/or for optical or system compensation
since (e.g., in one embodiment) the output of the temperature
transducer 670 may be processed along with the fluorescence
information received through the one or more photodetectors
110.
[0106] In some embodiments, the analog interface 534, acting under
the control of the measurement controller 532, may execute a
measurement sequence (e.g., measurement command execution process
1700, which is described below with reference to FIGS. 17 and 18)
and then report the results to the sensor reader 1500. In one
embodiment, the measurement sequence may be a pre-loaded sequence
(i.e., a pre-stored timing sequence). In some embodiments, the
measurement sequence may have multiple time slots for one or more
measurements from first photodetector 224, one or more measurements
from second photodetector 226, one or more difference measurements
comparing the currents from first and second photodetectors 224 and
226, one or more temperature measurements of the silicon substrate
116 and/or sensor 100, one or more field current measurements
(i.e., measurements of the incident power received through the
inductive element 114), one or more excitation current source
regulation measurements (i.e., measurements to check that the light
source 108 is in regulation), one or more voltage measurements
and/or one or more diagnostic measurements to ensure proper
functionality of the various component blocks of the analog
interface 543. In various embodiments, the sensor 100 may be used
for continuous readout and/or power up on demand for a remotely
queried measurement.
[0107] In some embodiments, each of these measurements may be
digitized through ADC 664, which may also be fabricated in the
semiconductor substrate 116. Because the ADC 664 may convert one or
more analog measurements to digital measurements, in some
embodiments, the bi-directional wireless data communication may be
bi-directional, digital wireless data communication. Digital data
communication may have an improved signal integrity relative to
analog data communication, and, in some embodiments, the sensor 100
may utilize solely digital data communication as opposed analog
data communication. In a non-limiting embodiment, all or a portion
of the data is transmitted according to a known protocol that
includes a checksum.
[0108] FIG. 16 illustrates an exemplary sensor control process 1600
that may be performed by the optical sensor 100, which may be, for
example, implanted within a living animal (e.g., a living human),
in accordance with an embodiment of the present invention. The
sensor control process 1600 may begin with a step 1602 of
wirelessly receiving one or more commands and power. In one
embodiment, the power may be in the form of a modulated
electromagnetic wave the sensor 100 may receive. The modulated
electromagnetic wave may induce a current in inductive element 114,
and the input/output circuit 530 may convert the induced current
into power for operating the sensor 100 and extract and decode
commands from the induced current. In a non-limiting embodiment,
rectifier 640 may be used to convert the induced current into
operating power for the sensor 100, data extractor 642 may extract
data from the current induced in inductive element 114,
decoder/serializer 650 may decode and serialize the extracted data,
and command decoder/data encoder 652 may decode one or more
commands from the decoded and serialized extracted data. The one or
more decoded commands may then be sent to measurement controller
532 via the data and control bus 654. In some embodiments, the one
or more commands and power received by the sensor 100 may be
transmitted by the transceiver 1508 of sensor reader 1500.
[0109] In step 1604, the optical sensor 100 may execute the
received command. For example, in one embodiment, the optical
sensor 100 may execute the received command under control of the
measurement controller 532. Example command execution processes
that may be performed by the optical sensor 100 in step 1602 to
execute the received commands are described below with reference to
FIGS. 17-20.
[0110] Examples of commands that may be received and executed by
the sensor 100 may include measurement commands, get result
commands and/or get traceability information commands. Examples of
measurement commands may include measure sequence commands (i.e.,
commands to perform a sequence of measurements, and after finishing
the sequence, transmitting the resulting measurement information),
measure and save commands (i.e., commands to perform a sequence of
measurements and, after finishing the sequence, saving the
resulting measurement information without transmitting the
resulting measurement information) and/or single measurement
commands (i.e., commands to perform a single measurement). The
single measurement commands may be commands to save and/or transmit
the measurement information resulting from the single measurement.
The measurement commands may or may not include setup parameters
(i.e., calibration information). Measurement commands that do not
have setup parameters may, for example, be executed using stored
setup parameters (e.g., in nonvolatile storage medium 660). Other
measurement commands, such as measurement commands to both save and
transmit the resulting measurement information, are possible. The
commands that may be received and executed by the sensor 100 may
also include commands to update the stored the setup parameters.
The examples of commands described above are not exhaustive of all
commands that may be received and executed by the sensor 100, which
may be capable of receiving and executing one or more of the
commands listed above and/or one or more other commands.
[0111] FIG. 17 illustrates a measurement command execution process
1700 that may be performed in step 1604 of the sensor control
process 1600 by the optical sensor 100 to execute a measurement
command received by the optical sensor 100 in accordance with an
embodiment of the present invention. The measurement command
execution process 1700 may begin with a step 1702 of determining
whether the wirelessly received power is sufficient to execute the
received measurement command. In other words, in step 1702, the
sensor 100 may determine whether the electromagnetic field or wave
that may induce a current in inductive element 114 is strong enough
to generate sufficient operating power for execution of the
received measurement command, which, as described below, may
include using light source 108 to irradiate indicator molecules
104. In one embodiment, step 1702 may be performed by a field
strength measurement circuit, which may be part of the measurement
controller 532 or may be a separate component of the circuitry 776
on the silicon substrate 116.
[0112] In some embodiments, if the sensor 100 determines in step
1702 that the wirelessly received power is insufficient to execute
the received measurement command, the measurement command execution
process 1700 may proceed to a step 1704 in which the sensor 100 may
transmit (e.g., by way of the input/output circuit 530 and
inductive element 114) data indicating that that the wirelessly
received power is insufficient to execute the received measurement
command. In some embodiments, the insufficient power data may
merely indicate that the power is insufficient, but in other
embodiments, the insufficient power data may indicate the
percentage of the power needed to execute the received measurement
command that is currently being received.
[0113] In one embodiment, upon detection that the received power is
insufficient, the measurement controller 532 may output
insufficient power data to the data and control bus 654. The data
and control bus 654 may transfer the insufficient power data to the
command decoder/data encoder 652, which may encode the insufficient
power data. The data serializer 656 may serialize the encoded
insufficient power data. The encoder 658 may encode the serialized
insufficient power data. The clamp/modulator 646 may modulate the
current flowing through the inductive element 114 (e.g., coil 220)
as a function of the encoded insufficient power data. In this way,
the encoded insufficient power data may be transmitted wirelessly
by the inductive element 114 as a modulated electromagnetic wave.
In some embodiments, the encoded insufficient power data wirelessly
transmitted by the sensor 100 may be received by the sensor reader
1500, which may display a message on user interface 1512 a message
indicating that the power received by the sensor 100 is
insufficient and/or the extent to which the received power is
insufficient.
[0114] In some embodiments, if the sensor 100 determines in step
1702 that the wirelessly received power is sufficient to execute
the received measurement command, the measurement command execution
process 1700 may proceed to a step 1706 in which a measurement and
conversion process may be performed. The measurement and conversion
process may, for example, be performed by the analog interface 534
under control of the measurement controller 532. In one embodiment,
the measurement and conversion sequence may include generating one
or more analog measurements (e.g., using one or more of temperature
transducer 670, light source 108, first photodetector 224, second
photodetecor 226 and/or comparator 668) and converting the one or
more analog measurements to one or more digital measurements (e.g.,
using ADC 664). One example of the measurement conversion process
that may be performed in step 1706 is described in further detail
below with reference to FIG. 18.
[0115] At step 1708, the optical sensor 100 may generate
measurement information in accordance with the one or more digital
measurements produced during the measurement and conversion
sequence performed in step 1706. Depending on the one or more
digital measurements produced in step 1706, the measurement
information may be indicative of the presence and/or concentration
of an analyte in a medium in which the sensor 100 is implanted. In
one embodiment, in step 1706, the measurement controller 532 may
receive the one or more digital measurements and generate the
measurement information.
[0116] At step 1710, the optical sensor 100 may determine whether
the measurement information generated in step 1708 should be saved.
In some embodiments, the measurement controller 532 may determine
whether the measurement information should be saved. In one
embodiment, the measurement controller 532 may determine whether
the measurement information should be saved based on the received
measurement command. For example, if the measurement command is a
measure and save command or other measurement command that includes
saving the resulting measurement information, the measurement
controller 532 may determine that the measurement information
generated in step 1708 should be saved. Otherwise, if the
measurement command is a measure sequence command or other
measurement command that does not include saving the resulting
measurement information, the measurement controller 532 may
determine that the measurement information generated in step 1708
should not be saved.
[0117] In some embodiments, if the sensor 100 determines in step
1710 that the measurement information generated in step 1708 should
be saved, the measurement command execution process 1700 may
proceed to a step 1712 in which the sensor 100 may save the
measurement information. In one embodiment, after determining that
the measurement information generated in step 1708 should be saved,
the measurement controller 532 may output the measurement
information to the data and control bus 654, which may transfer the
measurement information to the nonvolatile storage medium 660. The
nonvolatile storage medium 660 may save the received measurement
information. In some embodiments, the measurement controller 532
may output, along with the measurement information, an address at
which the measurement information is to be saved in the nonvolatile
storage medium 660. In some embodiments, the nonvolatile storage
medium 660 may be configured as a first-in-first-out (FIFO) or
last-in-first-out (LIFO) memory.
[0118] In some embodiments, if the sensor 100 determines in step
1710 that the measurement information generated in step 1708 should
not be saved, or after saving the measurement information in step
1712, the measurement command execution process 1700 may proceed to
a step 1714 in which the optical sensor 100 may determine whether
the measurement information generated in step 1708 should be
transmitted. In some embodiments, the measurement controller 532
may determine whether the measurement information should be
transmitted. In one embodiment, the measurement controller 532 may
determine whether the measurement information should be transmitted
based on the received measurement command. For example, if the
measurement command is a measure sequence command or other
measurement command that includes transmitting the resulting
measurement information, the measurement controller 532 may
determine that the measurement information generated in step 1708
should be transmitted. Otherwise, if the measurement command is a
measure and save command or other measurement command that does not
include transmitting the resulting measurement information, the
measurement controller 532 may determine that the measurement
information generated in step 1708 should not be transmitted.
[0119] In some embodiments, if the sensor 100 determines in step
1714 that the measurement information generated in step 1708 should
be transmitted, the measurement command execution process 1700 may
proceed to a step 1716 in which the sensor 100 may transmit the
measurement information. In one embodiment, after determining that
the measurement information generated in step 1708 should be
transmitted, the measurement controller 532 may output the
measurement information to the data and control bus 654. The data
and control bus 654 may transfer the measurement information to the
command decoder/data encoder 652, which may encode the measurement
information. The data serializer 656 may serialize the encoded
measurement information. The encoder 658 may encode the serialized
measurement information. The clamp/modulator 646 may modulate the
current flowing through the inductive element 114 (e.g., coil 220)
as a function of the encoded measurement information. In this way,
the encoded measurement information may be transmitted wirelessly
by the inductive element 114 as a modulated electromagnetic wave.
In some embodiments, the encoded measurement information wirelessly
transmitted by the sensor 100 may be received by the sensor reader
1500, which may display a value representing the concentration of
the analyte so that a user (e.g., the patient, a doctor and/or
others) can read the value.
[0120] In some embodiments, after the sensor 100 (a) transmitted
insufficient power data in step 1704, (b) determined in step 1714
that the measurement information generated in step 1708 should not
be transmitted or (c) transmitted measurement information in step
1716, the measurement command execution process 1700 that may be
performed in step 1604 of the sensor control process 1600 by the
optical sensor 100 to execute a measurement command received by the
optical sensor 100 may be completed, and, at this time, the sensor
control process 1600 may return to step 1602.
[0121] FIG. 18 illustrates a measurement and conversion process
1800, which is an example of the measurement and conversion process
that may be performed in step 1706 of the measurement command
execution process 1700, in accordance with an embodiment of the
present invention.
[0122] At step 1802, the sensor 100 may load setup parameters
(i.e., calibration information) for performing one or more
measurements in accordance with the received measurement command.
For example, in one embodiment, the measurement controller 532 may
load one or more setup parameters by setting up one or more
components (e.g., light source 108, first photodetector 224, second
photodetector 226, comparator 668 and/or temperature transducer
534) of the analog interface 534 with the setup parameters. In some
embodiments, the nonvolatile storage medium 660 may store saved
setup parameters. Further, as noted above, in some embodiments, the
measurement commands may or may not include setup parameters. In a
non-limiting embodiment, if the measurement command includes one or
more setup parameters, the measurement controller 532 may setup one
or more components of the analog interface 534 with the setup
parameters with the one or more setup parameters included in the
measurement command. However, if the measurement command does not
include one or more setup parameters, the measurement controller
532 may obtain saved setup parameters stored in the nonvolatile
storage medium 660 and setup one or more components of the analog
interface 534 with the saved setup parameters obtained from the
nonvolatile storage medium 660.
[0123] At step 1804, the sensor 100 may determine whether to
execute a single measurement or a measurement sequence. In some
embodiments, the measurement controller 532 may make the single
measurement vs. measurement sequence determination by referring to
the received measurement command (i.e., is the measurement command
to execute a single measurement or to execute a measurement
sequence?). For example, in some embodiments, if the measurement
command is a measure sequence command, a measure and save command
or other command for a measurement sequence, the measurement
controller 532 may determine that a measurement sequence should be
executed. However, if the measurement command is a single
measurement command, the measurement controller 532 may determine
that a single measurement should be executed.
[0124] In some embodiments, if the sensor 100 determines in step
1804 that a measurement sequence should be performed, the sensor
100 may perform measurement and conversion sequence steps 1806-1820
of measurement and conversion process 1800. However, in other
embodiments, the sensor 100 may perform a portion of measurement
and conversion sequence steps 1806-1820 and/or additional
measurement and conversion sequence steps.
[0125] At step 1806, the sensor 100 may perform a light source bias
measurement and conversion. For example, in some embodiments, while
the light source 108 is on (i.e., while the light source 108, under
the control of the measurement controller 532, is emitting
excitation light and irradiating indicator molecules 104), the
analog interface 534 may generate an analog light source bias
measurement signal. In one embodiment, the ADC 664 may convert the
analog light source bias measurement signal to a digital light
source bias measurement signal. The measurement controller 532 may
receive the digital light source bias measurement signal and
generate (e.g., in step 1708 of the measurement command execution
process 1700) the measurement information in accordance with the
received digital light source bias measurement signal. In a
non-limiting embodiment, the analog interface 534 may generate the
analog light source bias measurement signal by sampling the voltage
and the current in the output of the current source that feeds the
light source 108.
[0126] At step 1808, the sensor 100 may perform a light source-on
temperature measurement and conversion. For example, in some
embodiments, while the light source 108 is on (i.e., while the
light source 108, under the control of the measurement controller
532, is emitting excitation light and irradiating indicator
molecules 104), the analog interface 534 may generate a first
analog temperature measurement signal indicative of a temperature
of the sensor 100. In one embodiment, the temperature transducer
670 may generate the first analog temperature measurement signal
while the light source 108 is on. The ADC 664 may convert the first
analog temperature measurement signal to a first digital
temperature measurement signal. The measurement controller 532 may
receive the first digital temperature measurement signal and
generate (e.g., in step 1708 of the measurement command execution
process 1700) the measurement information in accordance with the
received first digital temperature measurement signal.
[0127] At step 1810, the sensor 100 may perform a first
photodetector measurement and conversion. For example, in some
embodiments, while the light source 108 is on (i.e., while the
light source 108, under the control of the measurement controller
532, is emitting excitation light and irradiating indicator
molecules 104), the first photodetector 224 may generate a first
analog light measurement signal indicative of the amount of light
received by the first photodetector 224 and output the first analog
light measurement signal to the signal MUX 666. The signal MUX 666
may select the first analog light measurement signal and, the ADC
664 may convert the first analog light measurement signal to a
first digital light measurement signal. The measurement controller
532 may receive the first digital light measurement signal and
generate (e.g., in step 1708 of the measurement command execution
process 1700) the measurement information in accordance with the
received first digital light measurement signal.
[0128] In a non-limiting embodiment, first photodetector 224 may be
a part of a signal channel, the light received by the first
photodetector 224 may be emitted by indicator molecules 104
distributed throughout the indicator membrane 106', and the first
analog light measurement signal may be an indicator
measurement.
[0129] At step 1812, the sensor 100 may perform a second
photodetector measurement and conversion. For example, in some
embodiments, while the light source 108 is on (i.e., while the
light source 108, under the control of the measurement controller
532 is emitting excitation light and irradiating indicator
molecules 104), the second photodetector 226 may generate a second
analog light measurement signal indicative of the amount of light
received by the second photodetector 226 and output the second
analog light measurement signal to the signal MUX 666. The signal
MUX 666 may select the second analog light measurement signal and,
the ADC 664 may convert the second analog light measurement signal
to a second digital light measurement signal. The measurement
controller 532 may receive the second digital light measurement
signal and generate (e.g., in step 1708 of the measurement command
execution process 1700) the measurement information in accordance
with the received second digital light measurement signal.
[0130] In a non-limiting embodiment, second photodetector 226 may
be a part of a reference channel, the light received by the second
photodetector 226 may be emitted by indicator molecules 104
distributed throughout the reference membrane 106'', and the second
analog light measurement signal may be a reference measurement.
[0131] At step 1814, the sensor 100 may perform a difference
measurement and conversion. For example, in some embodiments, while
the light source 108 is on (i.e., while the light source 108, under
the control of the measurement controller 532, is emitting
excitation light and irradiating indicator molecules 104), (i) the
first photodetector 224 may generate a first analog light
measurement signal indicative of the amount of light received by
the first photodetector 224, and (ii) the second photodetector 226
may generate a second analog light measurement signal indicative of
the amount of light received by the second photodetector 226. The
comparator 668 may receive the first and second analog light
measurement signals and generate an analog light difference
measurement signal indicative of a difference between the first and
second analog light measurement signals. The comparator 668 may
output the analog light difference measurement signal to the signal
MUX 666. The signal MUX 666 may select the analog light difference
measurement signal and, the ADC 664 may convert the analog light
difference measurement signal to a digital light difference
measurement signal. The measurement controller 532 may receive the
digital light difference measurement signal and generate (e.g., in
step 1708 of the measurement command execution process 1700) the
measurement information in accordance with the received digital
light difference measurement signal.
[0132] In a non-limiting embodiment, first photodetector 224 may be
a part of a signal channel, second photodetector 226 may be a part
of a reference channel, and the analog light difference measurement
signal may be indicative of the difference in light emitted by (a)
indicator molecules 104 distributed throughout indicator membrane
106' and affected by the concentration of an analyte in the medium
in which sensor 100 is implanted, and (b) indicator molecules 104
distributed throughout reference membrane 106'' and unaffected by
the concentration of the analyte in the medium in which sensor 100
is implanted.
[0133] At step 1816, the sensor 100 may perform a second
photodetector ambient measurement and conversion. For example, in
some embodiments, while the light source 108 is off (i.e., while
the light source 108, under the control of the measurement
controller 532 is not emitting light), the second photodetector 226
may generate a second analog ambient light measurement signal
indicative of the amount of light received by the second
photodetector 226 and output the second analog ambient light
measurement signal to the signal MUX 666. The signal MUX 666 may
select the second analog ambient light measurement signal and, the
ADC 664 may convert the second analog ambient light measurement
signal to a second digital ambient light measurement signal. The
measurement controller 532 may receive the second digital ambient
light measurement signal and generate (e.g., in step 1708 of the
measurement command execution process 1700) the measurement
information in accordance with the received second digital ambient
light measurement signal.
[0134] In a non-limiting embodiment, second photodetector 226 may
be a part of a reference channel, the light received by the second
photodetector 226 may be emitted by indicator molecules 104
distributed throughout the reference membrane 106'', and the second
analog ambient light measurement signal may be an ambient reference
measurement.
[0135] At step 1818, the sensor 100 may perform a first
photodetector ambient measurement and conversion. For example, in
some embodiments, while the light source 108 is off (i.e., while
the light source 108, under the control of the measurement
controller 532, is not emitting light), the first photodetector 224
may generate a first analog ambient light measurement signal
indicative of the amount of light received by the first
photodetector 224 and output the first analog ambient light
measurement signal to the signal MUX 666. The signal MUX 666 may
select the first analog ambient light measurement signal and, the
ADC 664 may convert the first analog ambient light measurement
signal to a first digital ambient light measurement signal. The
measurement controller 532 may receive the first digital ambient
light measurement signal and generate (e.g., in step 1708 of the
measurement command execution process 1700) the measurement
information in accordance with the received first digital ambient
light measurement signal.
[0136] In a non-limiting embodiment, first photodetector 224 may be
a part of a signal channel, the light received by the first
photodetector 224 may be emitted by indicator molecules 104
distributed throughout the indicator membrane 106', and the first
analog ambient light measurement signal may be an ambient indicator
measurement.
[0137] At step 1820, the sensor 100 may perform a light source-off
temperature measurement and conversion. For example, in some
embodiments, while the light source 108 is off (i.e., while the
light source 108, under the control of the measurement controller
532, is not emitting light), the analog interface 534 may generate
a second analog temperature measurement signal indicative of a
temperature of the sensor 100. In one embodiment, the temperature
transducer 670 may generate the second analog temperature
measurement signal while the light source 108 is off. The ADC 664
may convert the second analog temperature measurement signal to a
second digital temperature measurement signal. The measurement
controller 532 may receive the second digital temperature
measurement signal and generate (e.g., in step 1708 of the
measurement command execution process 1700) the measurement
information in accordance with the received second digital
temperature measurement signal.
[0138] Accordingly, in an embodiment in which sequence steps
1806-1820 of measurement and conversion process 1800 are performed,
the measurement controller 532 may generate measurement information
in accordance with (i) the first digital temperature measurement
signal, (ii) the first digital light measurement signal, (iii) the
second digital light measurement signal, (iv) the digital light
difference measurement signal, (v) the second digital temperature
measurement signal, (vi) the first digital ambient light
measurement signal and (vii) the second digital ambient light
measurement signal. In a non-limiting embodiment, the calculation
of the concentration of the analyte performed by the measurement
controller 532 of sensor 100 and/or sensor reader 1500 may include
subtracting the digital ambient light signals from the
corresponding digital light measurement signals. The calculation of
the concentration of the analyte may also include error detection.
In some embodiments, the measurement controller 532 may incorporate
methods for attenuating the effects of ambient light, such as, for
example, those described in U.S. Pat. No. 7,227,156, which is
incorporated herein by reference in its entirety. In some
embodiments, the measurement controller 532 may generate
measurement information that merely comprises the digital
measurement signals received from the analog interface 534.
However, in other embodiments, the measurement controller 532 may
process the digital signals received from the analog interface 534
and determine (i.e., calculate and/or estimate) the concentration
of an analyte in the medium in which the sensor 100 is implanted,
and the measurement information may, additionally or alternatively,
include the determined concentration.
[0139] In some embodiments, if the sensor 100 determines in step
1804 that a measurement sequence should be performed, the
measurement and conversion process 1800 may proceed to a step 1822
in which a single measurement and conversion is performed. In some
embodiments, based on the measurement command received, the single
measurement and conversion performed in step 1822 may be any one of
the measurements and conversions performed in steps 1806-1820.
Accordingly, in an example where step 1822 of the measurement and
conversion process 1800 is performed, the measurement controller
532 may receive only one digital measurement signal, and the
measurement information generated by the measurement controller 532
(e.g., in step 1708 of the measurement command execution process
1700) may, in one embodiment, simply be the one digital measurement
signal received by the measurement controller.
[0140] In some embodiments, light source 108 may be turned on
before execution of step 1806 and not turned off until after
execution of step 1814. However, this is not required. For example,
in other embodiments, the light source 108 may be turned on during
measurement portions of steps 1806-1814 and turned off during the
conversion portions of steps 1806-1814.
[0141] Furthermore, although FIG. 18 illustrates one possible
sequence of the measurement and conversion process 1800, it is not
necessary that steps 1806-1820 of the measurement and conversion
process 1800 be performed in any particular sequence. For example,
in one alternative embodiment, light measurement and conversion
steps 1806-1814 may be performed in a different order (e.g., 1808,
1812, 1814, 1810, 1806), and/or ambient light measurement and
conversion steps 1816-1820 may be performed in a different order
(e.g., 1818, 1820, 1816). In some embodiments, the light source on
temperature measurement may be used to provide an error flag in
each individual measurement (e.g., by using a comparator to
comparing the light source on temperature measurement to threshold
value). In another alternative embodiment, ambient light
measurement and conversion steps 1816-1820 may be performed before
light measurement and conversion steps 1806-1814. In still another
alternative embodiment, steps 1806-1820 of the measurement and
conversion process 1800 may be performed in a sequence in which all
of the steps of one of light measurement and conversion steps
1806-1814 and ambient light measurement and conversion steps
1816-1820 are completed before one or more steps of the other are
executed (e.g., in one embodiment, steps 1806-1820 may be performed
in the sequence 1806, 1808, 1810, 1818, 1816, 1812, 1814,
1820).
[0142] FIGS. 21A and 21B illustrate the timing of an exemplary
embodiment of the measurement and conversion process 1800 described
with reference to FIG. 18.
[0143] FIG. 19 illustrates a get result command execution process
1900 that may be performed in step 1604 of the sensor control
process 1600 by the optical sensor 100 to execute a get result
command received by the optical sensor 100 in accordance with an
embodiment of the present invention. The measurement command
execution process 1900 may begin with a step 1902 of retrieving
saved measurement information. For example, retrieved measurement
information may be saved during step 1712 of the measurement
command execution process 1700 shown in FIG. 17. In some
embodiments, measurement information is saved in the nonvolatile
storage medium 660. In response to a request from the measurement
controller 532, the nonvolatile storage medium 660 may output saved
measurement information to the data and control bus 654. In some
embodiments, the data and control bus 654 may transfer the
retrieved measurement information to the measurement controller
532. However, in alternative embodiments, the data and control bus
654 may transfer the retrieved measurement information to the
command decoder/data encoder 652 without first transferring the
retrieved measurement information to the measurement controller
532.
[0144] In some embodiments, the nonvolatile storage medium 660 may
output to the data and control bus 654 the measurement information
most recently saved to the nonvolatile storage medium 660. In some
alternative embodiments, the nonvolatile storage medium 660 may
output to the data and control bus 654 the oldest measurement
information most saved to the nonvolatile storage medium 660. In
other alternative embodiments, the nonvolatile storage medium 660
may output to the data and control bus 654 the measurement
information specifically requested by the measurement controller
532 (e.g., by an address sent to the nonvolatile storage medium 660
with a read request).
[0145] After the saved measurement information is retrieved, the
get result command execution process 1900 may proceed to a step
1904 in which the sensor 100 may transmit the retrieved measurement
information. In one embodiment, the measurement controller 532 may
output the retrieved measurement information to the data and
control bus 654. The data and control bus 654 may transfer the
measurement information to the command decoder/data encoder 652,
which may encode the retrieved measurement information. The data
serializer 656 may serialize the encoded retrieved measurement
information. The encoder 658 may encode the serialized retrieved
measurement information. The clamp/modulator 646 may modulate the
current flowing through the inductive element 114 (e.g., coil 220)
as a function of the encoded retrieved measurement information. In
this way, the encoded retrieved measurement information may be
transmitted wirelessly by the inductive element 114 as a modulated
electromagnetic wave. In some embodiments, the encoded retrieved
measurement information wirelessly transmitted by the sensor 100
may be received by the sensor reader 1500.
[0146] FIG. 20 illustrates a get identification information command
execution process 2000 that may be performed in step 1604 of the
sensor control process 1600 by the optical sensor 100 to execute a
get identification information command received by the optical
sensor 100 in accordance with an embodiment of the present
invention. The get identification information command execution
process 2000 may begin with a step 2002 of retrieving stored
identification information. In some embodiments, identification
information is stored in the nonvolatile storage medium 660. In
response to a request from the measurement controller 532, the
nonvolatile storage medium 660 may output identification
information to the data and control bus 654. In some embodiments,
the data and control bus 654 may transfer the retrieved
identification information to the measurement controller 532.
However, in alternative embodiments, the data and control bus 654
may transfer the retrieved identification information to the
command decoder/data encoder 652 without first transferring the
retrieved identification information to the measurement controller
532.
[0147] After the stored identification information is retrieved,
the get identification information command execution process 2000
may proceed to a step 2004 in which the sensor 100 may transmit the
retrieved identification information. In one embodiment, the
measurement controller 532 may output the retrieved identification
information to the data and control bus 654. The data and control
bus 654 may transfer the identification information to the command
decoder/data encoder 652, which may encode the identification
information. The data serializer 656 may serialize the encoded
identification information. The encoder 658 may encode the
serialized identification information. The clamp/modulator 646 may
modulate the current flowing through the inductive element 114
(e.g., coil 220) as a function of the encoded retrieved
identification information. In this way, the encoded identification
information may be transmitted wirelessly by the inductive element
114 as a modulated electromagnetic wave. In some embodiments, the
encoded identification information wirelessly transmitted by the
sensor 100 may be received by the sensor reader 1500.
[0148] The sensor 100 may be capable of executing other commands
received by the sensor. For example, the sensor 100 may perform a
setup parameter update execution process that may be performed in
step 1604 of the sensor control process 1600 by the optical sensor
100 to execute a command to update setup parameters. In some
embodiments, the setup parameter update execution process may
replace one or more setup parameters (i.e., initialization
information) stored in the nonvolatile storage medium 660. In one
embodiment, upon receiving a command to update setup parameters,
the measurement controller 532 may output one or more setup
parameters received with the command to the data and control bus
654, which may transfer the setup parameter(s) to the nonvolatile
storage medium 660. The nonvolatile storage medium 660 may store
the received setup parameter(s). In a non-limiting embodiment, the
received setup parameter(s) may replace one or more setup
parameters previously stored in the nonvolatile storage medium
660.
[0149] Embodiments of the present invention have been fully
described above with reference to the drawing figures. Although the
invention has been described based upon these preferred
embodiments, it would be apparent to those of skill in the art that
certain modifications, variations, and alternative constructions
could be made to the described embodiments within the spirit and
scope of the invention.
* * * * *