U.S. patent application number 15/092897 was filed with the patent office on 2016-10-06 for method and device for transmitting sensor data of an implantable sensor to an external data processing unit.
The applicant listed for this patent is RAUMEDIC AG. Invention is credited to Karlheinz Gohler, Reinhard JURISCH, Peter PEITSCH.
Application Number | 20160287138 15/092897 |
Document ID | / |
Family ID | 46690474 |
Filed Date | 2016-10-06 |
United States Patent
Application |
20160287138 |
Kind Code |
A1 |
Gohler; Karlheinz ; et
al. |
October 6, 2016 |
METHOD AND DEVICE FOR TRANSMITTING SENSOR DATA OF AN IMPLANTABLE
SENSOR TO AN EXTERNAL DATA PROCESSING UNIT
Abstract
During the transmission of sensor data of an implantable sensor
with a measurement data recorder, an energy storage unit and a
transmitter unit to an external data processing unit with a
transmitter/receiver unit, a high-frequency energy carrier signal
is firstly emitted from an energy supply unit. At least a part of
the energy contained in the high-frequency energy carrier signal is
stored in the energy storage unit of the implantable sensor. After
the ending of the emission of the high-frequency energy carrier
signal, a sensor measurement is carried out using the measurement
data recorder of the implantable sensor. The measured sensor data
are transmitted from the transmitter unit of the implantable sensor
to the transmitter/receiver unit of the external data processing
unit. The result is a transmission method, in which interference
from the HF feed is avoided, with a compact design.
Inventors: |
Gohler; Karlheinz; (Zwonitz,
DE) ; PEITSCH; Peter; (Erfurt, DE) ; JURISCH;
Reinhard; (Meckfeld, DE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
RAUMEDIC AG |
Munchberg |
|
DE |
|
|
Family ID: |
46690474 |
Appl. No.: |
15/092897 |
Filed: |
April 7, 2016 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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14236721 |
Feb 3, 2014 |
9339189 |
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PCT/EP2012/064299 |
Jul 20, 2012 |
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15092897 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
A61B 5/4869 20130101;
A61B 5/0015 20130101; A61B 5/076 20130101; A61B 2562/08 20130101;
A61B 5/002 20130101; A61B 5/0031 20130101; A61B 5/01 20130101; A61B
5/14553 20130101; A61B 5/031 20130101; A61B 2560/0257 20130101;
A61B 90/98 20160201; A61B 2560/0219 20130101 |
International
Class: |
A61B 5/07 20060101
A61B005/07; A61B 90/98 20060101 A61B090/98 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 1, 2011 |
DE |
10 2011 080 192.8 |
Claims
1-11. (canceled)
12. A method for transmitting sensor data of an implantable sensor
(2) to an external data processing unit (3) comprising the
following steps: emitting a high-frequency energy carrier signal
from an energy supply unit (18), storing at least a part of the
energy contained in the high-frequency energy carrier signal in an
energy storage unit (8) of the implantable sensor (2), ending the
emission of the high-frequency energy carrier signal, reading of
identification data of the implanted sensor and identifying the
sensor, after the ending of the emission of the high-frequency
energy carrier signal, carrying out at least one sensor measurement
using a measurement data recorder (4) of the implantable sensor
(2), transmitting the measured sensor data from a transmitter unit
(13) of the implantable sensor (2) to a transmitter/receiver unit
(17) of the external data processing unit (3).
13. The method according to claim 12, comprising a monitoring of an
energy supply of the measurement data recorder (4) by the energy
storage unit (8) using a monitoring unit (16) of the implanted
sensor (2).
14. The method according to claim 12, comprising a conversion of
recorded analog sensor data to digital sensor data to be
transmitted before the transmission.
15. The method according to claim 12, wherein after the sensor
measurements have been carried out and before the measured sensor
data have been transmitted, the emission of the high-frequency
energy carrier signal is resumed.
16. The method according to claim 12, wherein the at least one
sensor measurement comprises a pressure measurement in the
implanted sensor, wherein said pressure measurement is carried out
independently of possible air pressure fluctuations in the
surroundings of the use of the implanted sensor.
Description
CROSS-REFERENCES TO RELATED APPLICATIONS
[0001] This application is a continuation of application Ser. No.
14/236,721 filed Feb. 3, 2014, which claims the priority of Patent
Application Serial No. DE 10 2011 080 192.8, filed on Aug. 1, 2011,
pursuant to 35 U.S.C. 119(a)-(d), the content of which is
incorporated herein by reference in its entirety as if fully set
forth herein.
FIELD OF THE INVENTION
[0002] The invention relates to a method and a device for
transmitting sensor data of an implantable sensor to an external
data processing unit.
BACKGROUND OF THE INVENTION
[0003] Telemetry sensor mechanisms with implantable sensors are
known from the prior art, for example from U.S. Pat. No. 5,704,352
A, U.S. Pat. No. 6,083,174 A and WO 2010/107 980 A2.
[0004] Telemetry sensor devices of this type can be negatively
influenced by environmental conditions. Therefore, in the known
telemetry sensor mechanisms for transmitting energy to the
implantable sensor, a magnetic or electromagnetic field with a
minimum strength is often used, which can have negative effects on
the transmission of sensor data from the implantable sensor to the
external data processing unit. Attempts have partly been made in
the prior art to solve this problem with screens, which either does
not succeed sufficiently or only with a relatively large
outlay.
SUMMARY OF THE INVENTION
[0005] An object of the present invention is to develop a
transmission method and a transmission device of the type mentioned
at the outset in such a way that interference from the
high-frequency (HF) feed is avoided, with a compact design. In
particular, the sensor data determined should be substantially
independent of the spacing and relative position as well as the
environmental conditions of the implantable sensor and thus allow
reproducible measurements.
[0006] This object is achieved according to the invention by a
method for transmitting sensor data of an implantable sensor to an
external data processing unit having the steps of emitting a
high-frequency energy carrier signal from an energy supply unit,
storing at least a part of the energy contained in the
high-frequency energy carrier signal in an energy storage unit of
the implantable sensor, ending the emission of the high-frequency
energy carrier signal, after the ending of the emission of the
high-frequency energy carrier signal, carrying out at least one
sensor measurement using a measurement data recorder of the
implantable sensor, and transmitting the measured sensor data from
a transmitter unit of the implantable sensor to a
transmitter/receiver unit of the external data processing unit and
by a device for carrying out a method according to the invention
with an implantable sensor with a measurement data recorder, an
energy storage unit and a transmitter unit, with an external data
processor unit with a transmitter/receiver unit and with a control
unit to control a transmission method, and with an energy supply
unit.
[0007] According to the invention, it was recognised that it is
possible to design the transmission method in such a way that no
high-frequency emission takes place during the actual measurement.
The high-frequency field can then not disturb the measuring
process. During the actual measuring process, in other words when
carrying out the at least one sensor measurement, the measurement
data recorder is supplied by the energy storage unit of the
implanted sensor. The result is an HF interference-free
measurement, which accordingly has a high signal-to-noise ratio.
Sensitive sensors producing an analogue useful signal can be used
as implantable sensors. The same wireless, in particular inductive,
connecting section can be used for energy transmission and for data
transmission. This leads to a compact design of the device for
carrying out the transmission method. The energy supply unit may be
a component of the external data processing unit. The external data
processing unit can be configured as a pure measurement data
display without further processing. Alternatively, the external
data processing unit can further prepare the received measurement
data. The transmission method can be used in a telemetry
measurement, in particular during the monitoring of a patient. In
particular, the emission of the high-frequency energy carrier
signal can be ended on reaching the energy quantity required for
the measurement. In this case, no unnecessary energy is converted
into heat loss. Interference with the measurement operation or a
reduction in the wellbeing of the patient by unnecessarily
introduced heat loss is then avoided. Apart from the measured
sensor data, during the transmission step from the transmitter unit
of the implantable sensor to the transmitter/receiver unit of the
external data processing unit, further data, for example
identification and/or calibration data, can also be transmitted. An
ended emission of the high-frequency energy carrier signal can take
place depending on the transmission spacing between the implantable
sensor and the external data processing unit. This transmission
spacing can be measured in a known manner. In the case of a small
transmission spacing, the emission of the high-frequency energy
carrier signal can be ended at an earlier time than in the case of
a larger transmission spacing.
[0008] A monitoring of an energy supply of the measurement data
recorder by the energy storage unit using a monitoring unit of the
implanted sensor ensures that no undesirably interfering influences
on the measurement result because of an insufficient energy supply
of the measurement data recorder. The monitoring can take place by
means of voltage comparison.
[0009] A conversion of recorded analogue sensor data to digital
sensor data to be transmitted before the transmission allows a
practically interference-free data transmission from the implanted
sensor to the external data processing unit. The conversion or else
a transmission of the AID-converted and intermediately stored data
can take place after a resumption of the HF emission, in other
words while the implanted sensor is already being charged again by
emission of the HF field.
[0010] A resumption of the HF emission after the sensor
measurements have been carried out and before the measured sensor
data have been transmitted leads to an HF field-free operating
phase of the implantable sensor being able to be kept very short
during the measurement data recording. This reduces the
requirements of the energy storage unit of the implantable sensor,
which can be correspondingly compact in configuration. The
transmission of the sensor data can then take place with the aid of
energy support by the high-frequency energy carrier signal emitted
during the transmission. The transmission of the measured sensor
data can take place by means of passive RFID technology.
[0011] The advantages of the device according to the invention
correspond to those which have already been described above with
reference to the method according to the invention. The measurement
data recorder can be configured as a pressure sensor, in particular
as a brain pressure sensor. Other sensor units for recording
physiological measurement data may also be used. The external data
processing unit has a control unit for controlling the transmission
method. In particular, the control unit is used to start and carry
out a measuring process.
[0012] An energy storage unit in the form of a capacitor is a
simply constructed energy storage unit of the implantable sensor.
In particular, a tantalum capacitor may be used.
[0013] The advantages of an A/D converter of the implanted sensor
for converting recorded analogue sensor data into digital sensor
data to be transmitted have already been described in conjunction
with the transmission method.
[0014] A monitoring unit of the implanted sensor for monitoring an
energy supply of the measurement data recorder by the energy
storage unit can be configured as a voltage comparator. The
advantages of the monitoring unit have also already been described
in conjunction with the transmission method.
[0015] It is ensured by means of a start unit for starting an HF
field-free measurement that a measurement using the measurement
data recorder only begins when the HF field is reliably switched
off. The start unit only transmits a signal to start the
measurement when the HF field has reliably ended.
[0016] A voltage sensor as the start unit allows a direct detection
of the ending of the HF field. A start signal being triggered as
long as the HF field exists is ruled out.
[0017] A time sensor as the start unit allows an uncomplicated
triggering of the start signal. In particular, a time delay
interval, which triggers the starting of the measurement after the
external data processing unit has been switched off, can also be
variably fixed.
[0018] An embodiment of the invention will be described in more
detail below with the aid of the drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0019] FIG. 1 schematically shows a device for transmitting sensor
data of an implantable sensor to an external data processing
unit;
[0020] FIG. 2 shows a flowchart of a sensor data transmitting
method using the device according to FIG. 1.
DESCRIPTION OF THE PREFERRED EMBODIMENT
[0021] A transmission device 1 is used to transmit sensor data of
an implantable or implanted sensor 2 to an external data processing
unit 3. The implanted sensor 2 is, for example, a brain parameter
sensor. The implanted sensor 2 is a sensor transponder. The
implanted sensor 2 has a measurement data recorder 4 to collect
physiological measurement data, for example to collect a brain
pressure, a blood or tissue oxygen content, a blood or tissue
composition, a water content or a temperature. The measurement data
recorder 4 is configured as a piezo-resistive pressure sensor. It
is also conceivable to provide a capacitive pressure sensor instead
of the piezoresistive pressure sensor. The measurement data
recorder 4 can also be designed as a strain sensor. It is also
conceivable, in addition to or as an alternative to the pressure
sensor, to provide a position sensor as the measurement data
recorder 4. The implanted sensor 2 can also have a plurality of
measurement data recorders in the manner of the measurement data
recorder 4, which can, for example, detect different measurement
data. The external data processing unit 3 may have an air pressure
sensor, not shown. The air pressure sensor allows the air pressure
of the environment to be taken into account during the
determination of an implant pressure by means of a pressure sensor
as the measurement data recorder 4. It is thereby possible to carry
out the pressure measurement in the implanted sensor 2
independently of possible air pressure fluctuations in the
surroundings of use of the implanted sensor 2.
[0022] The measurement data recorder 4 is connected by a
bidirectional signal line 5 to a sensor circuit 6, by means of
which, on the one hand, the measurement data recorder 4 is
controlled and to which the recorded measurement data are
transmitted from the measurement data recorder 4. The sensor
circuit 6 is used to activate the measurement data recorder 4, for
example by means of a constant current source or a constant
voltage. Depending on the configuration of the measurement data
recorder 4, the signal line 5 may have one line, two lines or a
larger number of lines. In the configuration of the measurement
data recorder 4 as a piezo-resistive pressure sensor, two lines
being used for measurement data transmission and, additionally, two
feed or supply lines may be provided, which connect the measurement
data recorder 4 to the sensor circuit 6. Other types of sensors can
manage with the sensor circuit 6 by means of a smaller number of
lines, for example with two lines being used for measurement data
transmission.
[0023] The sensor circuit 6 is connected to an energy storage unit
8 of the implanted sensor 2 by means of an energy supply line 7. An
energy supply of the measurement data recorder 4 by means of the
sensor circuit 6 is ensured by the bidirectional signal line 5.
Optionally, the sensor circuit 6 can have further circuit parts,
for example an analogue multiplexer to switch over between a
plurality of measurement data recorders, at least one analogue
amplifier for signal conditioning or at least one A/D converter.
The energy storage unit 8 is a capacitor, in particular a tantalum
capacitor. The capacitor may have a capacitance in a range from 10
.mu.F to 1000 .mu.F. The value of the capacitance of the capacitor
may be adapted according to the application. In particular, the
current consumption, which is to take place, of the implantable
sensor 2 may determine a preferred value of the capacitance of the
capacitor. The current consumption should be as low as possible. In
the embodiment shown, the capacitor has a capacitance of 100
.mu.F.
[0024] The energy storage unit 8 is thus in particular arranged
after a voltage limiter and after a voltage stabiliser of the
transmitter unit 13. This ensures that electrical energy stored in
the energy storage unit 8 does not discharge again against a
charge. An undesired discharge is reliably prevented by said
arrangement of the energy storage unit 8. A discharge of this type
would basically be conceivable by means of the oscillation circuit
if the voltage limiter and the voltage stabiliser were not arranged
before the energy storage unit 8.
[0025] Furthermore, the arrangement of the energy storage unit 8
behind the voltage stabiliser ensures the possibility of using a
voltage sensor 36 as the start unit. This assumes that the
capacitance of a capacitor of the voltage sensor 36 is smaller than
the capacitance of the energy storage unit 8. In particular, the
capacitance of the energy storage unit 8 is larger by at least the
factor 100 than the capacitance of the capacitor of the voltage
sensor 36. In particular, the ratio of the capacitance of the
energy storage unit 8 to the capacitance of the capacitor of the
voltage sensor 36 is at least 150, in particular at least 200 and
in particular at least 300. This ensures that when the HF field is
switched off, on the one hand, the voltage at the voltage sensor 36
drops with sufficient speed. The voltage drop at the voltage sensor
36 takes place rapidly and in particular with a time delay of at
most 1 .mu.s. On the other hand, it is ensured that the voltage of
the energy storage unit 8 during the HF field-free measurement is
substantially constant and, in particular, does not drop. During
the measurement, the voltage of the energy storage unit 8 falls to
at most 85% of a starting voltage value of the energy storage unit
8, in particular to at most 90% and, in particular, to at most
95%.
[0026] The sensor circuit 6 has a bidirectional signal connection
via a signal line 9 to a microcontroller 10, in other words a
process computer unit. An A/D converter 11 is a component of the
microcontroller 10. Said A/D converter converts the analogue
measurement or sensor data recorded by the measurement data
recorder 4, which data are fed by the sensor circuit 6 to the
microcontroller 10, into digital sensor data to be further
transmitted. The A/D converter 11 may also be a component of the
sensor circuit 6.
[0027] The microcontroller 10 has a bidirectional signal connection
via a further signal line 12 to a transmitter unit 13 of the
implanted sensor 2 in the form of an RFID interface. The
transmitter unit 13 has a signal connection via feed line 14 to the
energy storage unit 8 and is used to charge the energy store 8 from
a part of the high-frequency energy emitted via the external data
processing unit 3.
[0028] A monitoring unit 16 has a signal connection via a
monitoring line 15 to the microcontroller 10. The monitoring unit
16 is used to monitor an energy supply of the microcontroller 10,
the sensor circuit 6 and the measurement data recorder 4 by the
energy storage unit 8. The monitoring unit 16 is configured as a
voltage comparator.
[0029] The microcontroller 10 and the monitoring unit 16 also have
an energy supply connection to the energy storage unit 8 via the
energy supply line 7.
[0030] The external data processing unit 3 has a
transmitter/receiver unit 17 in the form of an RFID reader and an
energy supply unit 18 in the form of a high-frequency generator (HF
generator). In addition, the external data processing unit 3
contains a control unit 19. The control unit 19 may, for example,
have a real time clock in order to provide stored measurement data
with a clear time signal, in particular with a time stamp. In
particular, the control unit 19 may contain components, which, for
example, allow a calculation of measurement values, their display,
their monitoring and their storage.
[0031] It is also conceivable for the energy storage unit 8 to be
configured as a battery and/or as an accumulator. In addition, the
implanted sensor 2 may have a real time clock in order to provide
stored measurement data with a clear time signal, in particular
with a time stamp. Furthermore, the implanted sensor 2 may have a
storage unit to store the measured measurement values. In this
case, the implanted sensor 2 would be at least occasionally
self-sufficient, in particular independently of the external unit
3, and could, in particular, be used without an RFID energy supply.
Antennas of the transmitter unit 13 and the transmitter/receiver
unit 17 are configured as coils, which are connected as an
oscillation circuit.
[0032] The transmitter unit 13 is used for a rectification,
limitation and stabilisation of a voltage induced in the HF field
feed, and a demodulation and modulation of the measurement data and
optionally other data.
[0033] A rectifier, voltage limiter or a voltage stabiliser can be
integrated in the transmitter unit 13 for the rectification,
limitation and stabilisation.
[0034] Furthermore, the voltage sensor 36, which measures the
voltage of the high-frequency field, is provided in the transmitter
unit 13. The voltage sensor 36 may also be arranged externally from
the transmitter unit 13. The voltage sensor 36 is configured as a
capacitor and has a capacitance of 10 nF. This makes it possible
for the capacitor, which is arranged, in particular, after the
rectifier in the transmitter unit 13, to be able to rapidly, in
other words with a small time delay of at most 1 ms, follow the HF
field.
[0035] In addition or as an alternative, a time sensor 37 may be
provided. The voltage sensor 36 and the time sensor 37 are
connected via the signal line 12 to the microcontroller 10.
[0036] The voltage sensor 36 is, in particular, arranged after a
voltage limiter, which brings about a decoupling of the
high-frequency oscillation circuit and the rectifier.
[0037] The control unit 19 controls the transmission process
described below with the aid of FIG. 2.
[0038] The control unit 19 emits via a control pulse the signal for
a switch-on step 20 to switch on an HF field, which is produced by
the energy supply unit 18. The HF field has a frequency of 13.56
MHz. Another carrier frequency for the HF field is also possible.
An emission of a high frequency (HF) energy carrier signal then
takes place via a wireless connecting section, the
transmitter/receiver unit 17 being used as an HF transmitter and
the transmitter unit 13 as an HF receiver. During the emission, in
a charging step 22, the energy storage unit 8 of the implanted
sensor 2 is charged. During the charging step 22, storage of at
least a part of the energy contained in the high-frequency energy
carrier signal thus takes place in the energy storage unit 8. The
charging time during the charging step 22 may be about 2 s. After
the ending of the charging process, the transmitter unit 13, in a
return step 23, transmits the information to the external data
processing unit 3 that the energy storage unit 8 is charged. The
charge state of the energy storage unit 8 can be monitored by means
of the monitoring unit 16. The charging step 22, in other words the
emission of the high-frequency energy carrier signal can take place
during a rigidly predetermined time period.
[0039] A reading and optionally writing of identification data of
the implanted sensor 2, for example an ID number, an operating
status, an operating version and/or calibration data, takes place
in a reading step 24. This ensures that a data transmission takes
place only with a desired sensor 2, which, for example, can be
clearly identified by an identification (ID) number. In particular,
this rules out incorrect measurements or incorrect allocations of
measurement values taking place, for example an allocation of
measurement values to an unintended patient, in particular when the
implanted sensor 2 is used for patient monitoring.
[0040] During the reading step 24, a data flow takes place from the
transmitter unit 13 via the connecting section 21 to the
transmitter/receiver unit 17. If during the reading step 24, a
writing of data also takes place, this takes place on the reverse
path.
[0041] After the reading and optionally writing step 24, the
control unit 19, in a transmitting step 25, emits a start signal to
carry out a process sequence, which contains a sensor measurement
using the measurement data recorder 4. This start signal is in turn
transmitted via the connecting section 21 to the implanted sensor
2. In an initialising step 26, an initialisation of the measurement
then takes place, in other words the measurement data recording, by
means of the microcontroller 10. The initialisation of the
measurement may, for example, last 50 ms. After the initialising
step 26, the microcontroller 10, in a return step 27, provides the
information that the measurement has been initialised. This
initialisation signal is transmitted via the connecting section 21
to the external data processing unit 3. As soon as the control unit
19 has received the initialisation signal, an ending of the
emission of the high-frequency energy carrier signal takes place in
a switch-off step 28 by corresponding activation of the energy
supply unit 18 by means of the control unit 19. The steps 24 to 27
can therefore still proceed during the charging process by means of
the emission of the high-frequency energy carrier signal. About 10
microseconds after the switching off of the high-frequency energy
carrier signal by the energy supply unit 18, the high-frequency
field is no longer present. Together with the switch-off step 28,
the external data processing unit 3 passes a switch-off signal to
the implanted sensor 2 via the connecting section 21. The
switch-off signal is, in particular, caused by the voltage sensor
36, which detects a change in the HF field and transmits this
change in the HF field to the microcontroller 10. In a detection
step 29, this switch-off signal is detected and processed by the
sensor circuit 6 of the implanted sensor 2. As an alternative to
the detection step 29, the measuring process can be started after
waiting for a fixed time period. The fixed time period may be in a
range of 1 .mu.s to 10 ms and, in particular be 100 .mu.s.
[0042] The waiting for the fixed time period takes place by means
of the time sensor 37. The time sensor 37 receives the switch-off
signal of the external data processing unit 3 and automatically
starts a time measurement. The time measurement is ended when the
fixed time period has been reached. After the expiry of the fixed
time period, the time sensor 37 transmits a measuring process start
signal.
[0043] It is also possible to use the voltage sensor 36 and the
time sensor 37 in combination. In this case, the method can be
carried out more reliably. It is, for example, conceivable for the
measurement to only begin when the two sensors have transmitted a
start signal. The disruption-free measurement is then more reliably
possible.
[0044] After the actual measuring process, in other words the
collection of measurement data by the measurement data recorder 4,
an activation of the A/D converter 11 and storage of the
measurement values recorded by the measurement data recorder 4
follow by interaction with the implant surroundings, in an
activation step 30. The microcontroller 10 is then put into a rest
state. A total current consumption of the circuit of the implanted
sensor 2 and also a measuring time are kept as low as possible
here.
[0045] A precisely defined time period after the switch-off step
28, which is defined to be longer than the conversion and storage
time in the framework of the measurement, a switching on of the
high-frequency energy carrier signal, in other words the HF field,
in turn takes place in a switch-on step 31, controlled by the
control unit 19, by means of the energy supply unit 18. This
precisely defined time period may be 50 ms. After the switch-on
step 31, the energy storage unit 8 is recharged in a recharging
step 32 via the connecting section 21. This recharging step 32 is
optional. After the recharging step 32, the information that the
energy storage unit 8 is charged is transmitted back in a return
step 33. This return step 33 is processed analogously to the return
step 23. As an alternative to this, a charging of the energy
storage unit 8 can in turn take place during a predetermined, fixed
time period.
[0046] After receiving the charging information by means of the
return step 33 or after waiting for the fixed time period, the
control unit 19 initiates a transmission of the measured and
converted measurement data via the connecting section 21. This
takes place in a read-out step 34, in which the digitally converted
measurement data and optionally further status information are sent
via the connecting section 21 via the implanted sensor 2 to the
external data processing unit 3. Monitoring data of the monitoring
unit 16 may belong to the status information.
[0047] A monitoring of the charging state of the energy storage
unit 8 and the supply state of the components 4, 6, 10 and 13 of
the implanted sensor 2 takes place during the A/D conversion and an
intermediate storage of the converted data by means of the
monitoring unit 16. The monitoring unit 16 monitors a charging
state of the energy storage unit 8 before, during and after the
measurement. During the measurement with the HF field switched off,
the voltage of the energy storage unit 8 drops continuously by
several 10 mV. The monitoring unit 16 ensures that the operating
voltage of the implanted sensor 2 before, during and after the
measurement is within a range specified for the components of the
implanted sensor 2. The monitoring data are transmitted in the
read-out step 34 to the external data processing unit. As an
alternative or in addition, the microcontroller 10 can carry out an
evaluation of the monitoring data. The implanted sensor 2 may have
an additional voltage stabilisation mechanism, which stabilises the
voltage of the capacitor used as the energy storage unit 8 and
therefore allows a still more precise measurement.
[0048] After the read-out step 34, in a calculation step 35, a
calculation takes place of a measurement value from the digitally
converted measurement data value, optionally to predetermined
calibration values and further information which the external data
processing unit 3 either itself stores or which the external data
processing unit 3 has received from the implanted sensor 2.
[0049] The control unit 19, as the master unit, controls the entire
work sequence of the transmission device 1. The control unit 19
establishes a beginning and duration of a high-frequency field-free
phase, within which a measurement and a measured data conversion
takes place in the implanted sensor 2. As its slave, the
microcontroller 10 controls the implanted sensor 2.
[0050] The data communication via the connecting section 21 is
additionally secured against interferences by means of a cyclic
redundancy check (CRC). This cyclic redundancy check takes place in
the control unit 19 and/or in the implanted sensor 2.
[0051] If a plurality of measurement data recorders in the manner
of the measurement data recorder 4 is used, these can be
sequentially activated for measurement. Between these individual
measurement data recorder activations, analogously to that which
was outlined above in conjunction with the method sequence, an
intermediate charging of the energy storage unit 8 can take
place.
[0052] Circuit parts of the implanted sensor 2 may be partially or
in total implanted in an ASIC or in a microsystem.
[0053] An operating voltage, which is provided by the transmitter
unit 13 by means of the energy storage unit 8 to the further
components of the implanted sensor 2, is about 2 V. A current
consumption of all the circuit parts of the implanted sensor 2 is
less than 10 mA.
[0054] During the measurement and transmission process between the
step 20 and the step 35, the sequences, on the one hand, in the
implanted sensor 2 and, on the other hand, in the external data
processing unit 3 are synchronised. By taking into account
corresponding time reserves in the timing or by the use of
timeouts, the synchronisation is also provided when the HF field is
switched off. A quartz oscillator is used as a time basis for the
external data processing unit 3. An RC oscillator or a quartz
oscillator is used as the time basis for the implanted sensor
2.
* * * * *