U.S. patent application number 11/954951 was filed with the patent office on 2009-02-26 for sensor device.
This patent application is currently assigned to CANON KABUSHIKI KAISHA. Invention is credited to Mitsuro SUGITA.
Application Number | 20090051913 11/954951 |
Document ID | / |
Family ID | 36931996 |
Filed Date | 2009-02-26 |
United States Patent
Application |
20090051913 |
Kind Code |
A1 |
SUGITA; Mitsuro |
February 26, 2009 |
SENSOR DEVICE
Abstract
A sensor device for detecting a substance contained in a fluid
comprises first and second photonic crystal regions, first and
second flow channels, an optical waveguide connected to the first
and second photonic crystal regions and an optical detector for
detecting the lights transmitted through the first photonic crystal
region and the waveguide and transmitted through or reflected by
the second photonic crystal region.
Inventors: |
SUGITA; Mitsuro; (Tokyo,
JP) |
Correspondence
Address: |
FITZPATRICK CELLA HARPER & SCINTO
30 ROCKEFELLER PLAZA
NEW YORK
NY
10112
US
|
Assignee: |
CANON KABUSHIKI KAISHA
Tokyo
JP
|
Family ID: |
36931996 |
Appl. No.: |
11/954951 |
Filed: |
December 12, 2007 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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11276205 |
Feb 17, 2006 |
7391945 |
|
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11954951 |
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Current U.S.
Class: |
356/246 |
Current CPC
Class: |
B82Y 20/00 20130101;
G02B 6/1225 20130101 |
Class at
Publication: |
356/246 |
International
Class: |
G01N 21/05 20060101
G01N021/05 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 25, 2005 |
JP |
2005-051997 (PAT. |
Claims
1-3. (canceled)
4. A sensor device for detecting a substance contained in a fluid,
comprising: a first photonic crystal region having a photonic band
gap; a second photonic crystal region having the same photonic band
gap of the first photonic crystal region; a first flow channel
connected to the first photonic crystal region to allow a reference
fluid to flow; a second flow channel connected to the second
photonic crystal region to allow an objective substance-containing
fluid to flow; an optical waveguide connected to the first photonic
crystal region and the second photonic crystal region to guide
light; an optical source; and an optical detector for detecting the
light which has transmitted through the first photonic crystal
region and the optical waveguide and has transmitted through or
been reflected by the second photonic crystal region, wherein the
first and second photonic crystal regions have the same defect
level within the photonic band gap, and the defect level is within
a wavelength range of the optical source.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a sensor device of a
microanalysis system (.mu.-TAS) for detecting a concentration, a
fine pressure distribution, a fine temperature distribution,
biological information, genetic information, and so forth of a
substance flowing through a flow channel of the system.
[0003] 2. Related Background Art
[0004] Recently, techniques are being developed for microanalysis
in chemistry, biochemistry, and the like fields by use of a much
smaller system. A typical example is a .mu.-TAS system which
employs a micro flow channel, which enables separation/mixing,
reactions, and so forth by a much smaller flow channel.
[0005] With development of biotechnology and bio-industry,
detection elements like DNA chips are being developed and
commercialized for reading bio-genetic information.
[0006] With the development of three-dimensional working
techniques, chemical analysis systems are attracting attention
which are constituted of liquid elements such as a micro flow
channel, a pump, and a valve, and a sensor in integration on a
substrate made of glass, silicon, or the like to conduct chemical
analysis. Such a system is called a miniaturized analysis system,
.mu.-TAS (micro total analysis system), or a lab-on-a-chip. The
miniaturized chemical analysis system enables decrease of a dead
volume in the system, remarkable decrease of a sample quantity,
shortening of analysis time, and saving of power consumption of the
total system. Further, cost-down of the system can be expected by
the miniaturization. Owing to such advantages, the .mu.-TAS is
promising in application in biotechnology fields such as in medical
treatment like home medical care, and a bedside monitor; in
biotechnology fields such as DNA analysis, and proteome
analysis.
[0007] Japanese Patent Application Laid-Open No. H10-337173
discloses a micro-reactor which conducts sequential biochemical
experimental operations of mixing solutions, causing a reaction of
the mixture, analyzing a component, and separating the component by
employing combination of several cells. FIG. 11 shows schematically
a structure of a micro-reactor. In FIG. 11, micro-reactor 1111 has
independent reaction chambers closed by a flat plate on a silicon
substrate. The reactor is constituted of reservoir cell 1112,
mixing cell 1113, reaction cell 1114, detection cell 1115, and
separation cell 1116. With plural reactors formed on a substrate,
plural biochemical reaction can be simultaneously and concurrently
conducted. Further, not only the analysis, but also a substance
synthesis reaction such as protein synthesis can be conducted by
use of the cells.
[0008] Such a .mu.-TAS system or a bio-chip requires a final
detection step after the reaction or other operation steps. In the
detection step, a light beam is useful as the precise detecting
means less affective to the objective substance owing to
non-contacting and non-reactive properties of the light.
[0009] In an example of the detection procedure, an objective
substance is labeled with a fluorophor, an exciting light beam is
projected to the objective substance, and the fluorescence is
detected. In another example of the detection procedure, a light
beam is projected to the objective substance, and light
transmittance is measured. In still another example of the
detection procedure, the light beam is projected to an objective
substance through a prism brought close to the objective substance
and the loss of the total reflection light is measured.
[0010] In the fluorescence labeling method, a desirable label,
namely a label sufficiently sensitive for the detection, is not
necessarily applicable owing to compatibility between the objective
substance and the labeling substance. Further, in this method, the
fluorescence as the signal component is interfered less by the
intense exciting light as a noise because of the wavelength
difference between the exciting light and the fluorescence
advantageously, but the generation efficiency of the fluorescence
as the signal component cannot readily be raised, which renders
difficult to improve the total SN ratio.
[0011] In the light transmission measurement method or the light
absorbance measurement method utilizing the transmitted light, when
the objective substance is contained in a high concentration in the
measurement fluid to exhibit a low transmittance, the signal is
weak to result in a lower SN ratio. On the other hand, in this
method, when the concentration of the objective substance is
lowered to solve the above disadvantage, the original signal
becomes weak to lower the SN ratio, also. Furthermore, even though
the influence of the light is not remarkable, the light penetrating
through the objective fluid may cause heat generation or a
photoreaction, so that the intensity of the light should be
limited.
[0012] In the total reflection loss measurement method, more
intense light can be used than in the light transmission
measurement method. However, the wavelength of the light for
detection of a change or loss and the wavelength of the irradiated
light are the same, which requires extremely large dynamic range of
the detector, disadvantageously. Therefore, with this measurement
method, a slight loss by a slight degree of reaction in the micro
flow channel cannot be measured with a high accuracy.
[0013] On the other hand, a sensor device employing a photonic
crystal, which has a high sensitivity, tends to detect an external
disturbance as a noise component.
[0014] The external disturbance includes a fluctuation of a
concentration, a temperature, and a density. The photonic crystal
region itself and the substrate connected thermally to the photonic
crystal region change in the temperature in various manners
depending on the measurement operation environment. This is
different from a high-cost or large-sized constitution which is
equipped with a temperature-controlling feedback system, namely a
temperature sensor, a heater/cooler element, a control circuit, or
a power source. The constitution of small integration or a low cost
cannot be equipped with such a temperature control means.
[0015] In particular, in a detection device in which a
concentration of a biological substance as the objective substance
in a solution flowing through a flow channel is measured, the
measurement is conducted in a sequence of operation steps: (1)
firstly a buffer solution containing no biological substance is
allowed to flow through the flow channel, (2) secondly a buffer
solution containing a biological substance is allowed to flow
through the flow channel, and (3) finally a buffer solution
containing no biological substance is allowed to flow through the
flow channel to detect the difference from the initial level. In
such an operation sequence, fluctuation of the concentration,
temperature, or density of the buffer solution directly causes
fluctuation of the baseline to produce a noise component. To
decrease the temperature fluctuation, a means should be equipped
for keeping the temperature constant in the aforementioned
measurement region, and further a means should be equipped for
keeping constant the temperature of the buffer solution before
entering the measurement region. This causes a cost increase and a
larger size of the device.
SUMMARY OF THE INVENTION
[0016] The present invention intends to provide a sensor device
which is less affected by external disturbance
[0017] The present invention provides a device for detecting a
substance contained in a fluid, comprising a first photonic crystal
region; a second photonic crystal region; a first flow channel
connected to the first photonic crystal region to allow a reference
fluid to flow; a second flow channel connected to the second
photonic crystal region to allow an objective substance-containing
fluid to flow; an optical waveguide connected to the first photonic
crystal region and the second photonic crystal region to guide the
light; and an optical detector for detecting the light which has
transmitted through the first photonic crystal region and the
waveguide and has transmitted or been reflected by the second
photonic crystal region.
[0018] The sensor device of the present invention in which plural
photonic crystal regions are optically connected enables decrease
of a noise component caused by external disturbance.
[0019] The sensor device of the present invention in which plural
photonic crystal regions are optically connected is useful in
apparatuses employing a micro flow channel, the apparatus including
micro-chemical or micro-biochemical analysis apparatuses such as a
.mu.-TAS system and a bio-analysis chip, and portable inspection
apparatuses.
[0020] The present invention is not limited by the examples
described below, but the sequence of the flows and other matters
may be modified in various manners within the gist of the present
invention.
[0021] As many apparently widely different embodiments of the
present invention can be made without departing from the spirit and
scope thereof, it is to be understood that the invention is not
limited to the specific embodiments thereof except as defined in
the claims.
[0022] Other features and advantages of the present invention will
be apparent from the following description taken in conjunction
with the accompanying drawings in which like reference characters
designate the same or similar parts throughout the figures
thereof.
BRIEF DESCRIPTION OF THE DRAWINGS
[0023] The accompanying drawings, which are incorporated in and
constitute a part of the specification, illustrate embodiments of
the invention and, together with the description, serve to explain
the principles of the invention.
[0024] FIG. 1 illustrates schematically a constitution of the
sensor device of Example 1 of the present invention.
[0025] FIG. 2 illustrates schematically the sensor device of
Example 1 of the present invention.
[0026] FIGS. 3A, 3B, and 3C illustrate schematically the sensor
device of Example 1 of the present invention.
[0027] FIGS. 4A, 4B, 4C, 4D, 4E, and 4F are drawings for explaining
the method for suppressing external disturbance by the sensor
device of Example 1 of the present invention.
[0028] FIGS. 5A, 5B, and 5C illustrate schematically the sensor
device of Example 2 of the present invention.
[0029] FIGS. 6A, 6B, 6C, 6D, 6E, and 6F are drawings for explaining
the method for suppressing external disturbance by the sensor
device of Example 2 of the present invention.
[0030] FIG. 7 illustrates schematically the sensor device of
Example 3 of the present invention.
[0031] FIGS. 8A, 8B, 8C, 8D, 8E, and 8F are drawings for explaining
the method for suppressing external disturbance by the sensor
device of Example 3 of the present invention.
[0032] FIG. 9 illustrates schematically a personal wear type
bio-sensor device.
[0033] FIG. 10 shows a sensing process by an .mu.-TAS bio-sensor
chip.
[0034] FIG. 11 illustrates conception of an .mu.-TAS bio-sensor
chip.
[0035] FIG. 12 illustrates conception of constitution of a sensor
device with many photonic crystals of the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0036] In the present invention, the "photonic crystal" is a
structure having the refractivity changing periodically, including
specifically flat materials in the form of flat plates having holes
periodically arranged therein, laminates thereof, assemblage of
columns, and prisms. In the present invention, in particular,
nearly flat plates having two-dimensional arrangement are
suitable.
[0037] The present invention is explained below specifically by
reference to FIG. 2
[0038] The sensor device of the present invention comprises first
photonic crystal region 205; second photonic crystal region 206;
first and second flow channels 208,209 connected respectively to
first and second photonic crystal regions 205,206; optical
waveguide 102 for introducing light to the first and second
photonic crystal regions; and an optical detector (106 in FIG. 1)
which detects the light having transmitted through the first
photonic crystal region 205 and having transmitted through or
reflected by second photonic crystal region 206.
[0039] Suppression of an external disturbance is shown later in
Example 1 in the case where the first photonic crystal region and
the second photonic crystal region are different from each other in
an optical property (e.g., spectral transmittance).
[0040] Further, suppression of an external disturbance is shown
later in Examples 2 and 3 in the cases where the first photonic
crystal region and the second photonic crystal region have has same
optical property.
[0041] In the present invention, the first photonic crystal and the
second photonic crystal are connected in series, and the incident
light transmits through the first photonic crystal region and
reaches the second photonic crystal region. Even when an external
disturbance causes a change in spectral transmittance in the
respective photonic crystal regions, the change caused is the same
in the respective regions. The present invention utilizes this
effect.
[0042] The present invention offsets an influence of an external
disturbance as mentioned above.
[0043] The sensor device of the present invention can be
constituted also as shown below. For example, the sensor device
comprises two or more photonic crystal regions, an optical
waveguide for connecting optically serially the photonic crystal
regions, a light source for emitting a light flux to be transmitted
through or reflected by the photonic crystal regions to give output
light, and an optical detector. From the information derived from
the output light, an environmental condition is detected at or
around the photonic crystal regions.
[0044] The aforementioned plural photonic crystal regions are
preferably constituted of a transmission type of first and second
photonic crystal regions, and the photonic band edge wavelength at
the short wavelength side of the first photonic crystal region and
the photonic band edge wavelength at the long wavelength side of
the second photonic crystal region are preferably close to each
other.
[0045] In the aforementioned plural photonic crystal regions, the
constituting regions are the same or nearly the same photonic
crystal regions, and the respective photonic crystal regions are
preferably of a transmission type and are preferably connected
optically serially.
[0046] The aforementioned plural photonic crystal regions are the
same or nearly the same, and the respective photonic crystal
regions comprises preferably a transmission type region and a
reflection type region, and the photonic crystal regions are
preferably connected optically serially.
[0047] The environmental conditions at or around the photonic
crystal regions to be detected include a temperature, a pressure, a
refractivity change, presence of an objective substance, a
concentration of an objective substance, and a concentration of a
solute in the solution.
EXAMPLES
[0048] The present invention is explained below more specifically
by reference to examples.
Example 1
[0049] Two photonic crystals different in a property are optically
connected serially, and sensing is conducted by utilizing
transmitted light having transmitted through the two photonic
crystals. The entire constitution of the sensor device of this
Example is explained by reference to FIG. 1.
[0050] In FIG. 1, on substrate 101, photonic-crystal optical
element system 103 is placed between light-introduction-side
optical waveguide 102 and output-side optical waveguide 104.
Incident light 105 is introduced from the outside of the element
for measurement of the spectral transmittance of the photonic
crystal optical element system. Optical detector device 106 detects
the light having transmitted through optical waveguide 102,
photonic crystal optical element system 103, and optical waveguide
104.
[0051] The photonic crystal optical element system in combination
with a micro flow channel mentioned below will change its spectral
transmissivity in accordance with an environmental change caused by
contact with an objective fluid or by flow of an objective fluid
nearby. This change is detected by a change of the optical spectrum
shape, or a change in the light transmittance at a fixed
wavelength. When the wavelength is fixed, the wavelength may be
taken in plurality: for example, two wavelengths, or three
wavelengths. The measurement at many wavelengths corresponds to the
aforementioned measurement of optical spectrum shape.
[0052] For optical coupling of the incident light and outgoing
light with the outside of the element, various optical coupling
systems are useful, the useful systems including optical fibers,
sphere-tipped optical fibers, GRIN lens optical fibers,
wedge-shaped optical fibers, fiber bundles, lens coupling systems
including a microscope objective lens, diffraction grating type
coupling elements, and so forth.
[0053] This Example is explained in more detail by reference to
FIG. 2 and FIGS. 3A-3C. In this Example, the photonic crystal
optical element system has two photonic crystals 205,206 and an
optical waveguide between the photonic crystals. The two photonic
crystals are arranged in series, and the detection is conducted by
utilizing spectral transmittance of the light transmitting through
this series. In this Example, first photonic crystal 205 and second
photonic crystal 206 are different in the constitution, and are
different in the spectral transmissivity. Specifically, the
photonic band gap of the first photonic crystal and the photonic
band gap of the second photonic crystal combined thereto are
shifted from each other not to be completely superposed. This
shifted state is described later in connection with the method of
the detection.
[0054] In this Example, the photonic crystals and the optical
waveguide (102-104 in FIG. 1) are formed on an SOI wafer (silicon
on insulator). In FIG. 2, perspective illustration of an example,
optical waveguide core 201 is made of Si (SOI layer); optical guide
cladding 202 is made of SiO.sub.2 (BOX layer); and the substrate
203 is made of Si. SOI layer 201 as the optical waveguide core has
a thickness of about 0.2 .mu.m. Optical waveguide 102 is formed by
a two-trench structure (204 in FIG. 2) to form air interfaces to
confine the light. The interval between the trench pair is the
optical guide breadth, and is about 10 .mu.m in this Example. The
trench breadth is 1 .mu.m in consideration of the light exudation
breadth and the light exudation quantity. The photonic crystal is
constituted of arrangement of cylindrical holes of about 200 nm
diameter and an aspect of about 1 in a triangular lattice state of
about 400 nm period in an area of about 15 .mu.m square. The
wavelength of the detection light is in about 1.5 .mu.m band
region. The micro flow channel has a thickness of about 100 .mu.m,
a breadth of 100 .mu.m. These may be changed suitably in a wide
range from about 10 .mu.m to about 1 mm.
[0055] The material of the substrate for constituting the photonic
crystals and the optical waveguides may be an SOI wafer, or a like
material such as a silicon nitride film formed by CVD growth on a
glass plate, a relatively high-refractivity Teflon.RTM. resin
formed on low-refractivity mesoporous silica, and so forth. The
material may be selected suitably in view of the light wavelength,
the production cost, environmental resistance, and so forth.
[0056] The substrate supporting the photonic crystal optical
element system and the optical waveguide is covered with a micro
flow channel element 20. The flow channel element is made of an
adsorbent PDMS (polydimethylsiloxane) resin, and adheres to the
clean Si surface by self-adsorption. The micro flow channel element
207 has two flow channels 208,209. First flow channel 208 is placed
on first photonic crystal 205, and second flow channel 209 is
placed on second photonic crystal 206. The fluids are allowed to
flow as shown by arrow mark 301. FIGS. 3A-3C show this state.
[0057] A sensing process by the sensor element constituted of the
aforementioned micro flow channel element and the optical element
is described by reference to FIGS. 4A-4F. This sensing process
offsets external disturbance to achieve the purpose of the present
invention. FIGS. 4A, 4C, and 4E show a spectral transmittance 401
of light passing through the first photonic crystal and a spectral
transmittance 402 of light passing through the second photonic
crystal. FIGS. 4B, 4D, and 4F show respectively a total spectral
transmittance 404 of light passing through the series of the first
and second photonic crystals, and the intensity spectrum 403 of the
light source for the detection.
[0058] The process is described below.
[0059] (FIG. 4A) In this Example, the long wavelength edge
.quadrature.1 of the photonic band gap of the first photonic
crystal and the short wavelength edge .quadrature.2 of the
corresponding photonic band gap of the second photonic crystal are
placed at nearly the same position (wavelength), and at the initial
state, .quadrature.1>.quadrature.2. In the initial state, the
same reference fluid, such as a buffer solution and a control
solution, is allowed to flow through first flow channel 205 and
second flow channel 206 both.
[0060] (FIG. 4B) Incident light 403 is selected to have a spectrum
so as to include the wavelengths of .quadrature.1 and
.quadrature.2, and to cover a wavelength range narrower than the
two photonic band gaps but to be as broad as possible. The incident
light has preferably a flat spectrum within the band gap range.
With the above-mentioned incident light, in the constitution shown
by FIG. 4A, the total spectral transmittance is nearly zero, since
the total spectral transmittance which is a multiplication product
of the two spectral transmittances is low over the entire range of
the incident light wavelength. That is the initial state of this
sensing system.
[0061] (FIG. 4C) Next, a second fluid is allowed to flow through
second flow channel 209. This fluid is, for example, a buffer
solution containing a protein dissolved therein to be determined
for the concentration. This fluid flow causes a change in the
spectral transmittance in the second photonic crystal, the spectral
transmittance wavelength being shifted toward a long wavelength
side as shown in FIG. 4C. Thereby, the relation of
.quadrature.1>.quadrature.2 in the initial state comes to be not
valid.
[0062] (FIG. 4D) Such reversion of .quadrature.1 and .quadrature.2
gives rise to a high-transmittance region in the total spectral
transmittance 404. This high-transmittance region is in the
wavelength range of the introduced light, giving a significant
transmitted light intensity. The difference in the nature of the
fluid flowing through first flow channel 208 from the fluid flowing
through second flow channel 209 causes a change of the transmitted
light intensity, enabling the sensing.
[0063] (FIG. 4E) Next, the operation of this sensing system is
explained in the case where a common external disturbance occurs in
the first and second flow channels and the first and second
photonic crystals. The external disturbance is exemplified by a
temperature change, and a change in the buffer solution. The
distance between the first and second flow channels is about 300
.mu.m which is sufficiently close to each other to undergo the same
temperature change. If necessary, the distance may be shortened as
mentioned before. To offset fluctuation of the buffer solution, the
construction may be modified by employing the same fluid-feed
source, and bringing close the branch of the first and second flow
channels and the protein-mixing portion or the like to the photonic
crystal portions to be affected similarly by the external
disturbance in the two flow channels.
[0064] With such a constitution, when the influence of the external
disturbance to the first and second photonic crystals is common,
.quadrature.1 and .quadrature.2 are shifted together by nearly the
same wavelength portion to .quadrature.1' and .quadrature.2' with
the difference kept unchanged. Naturally, the relation of
.quadrature.1'>.quadrature.2' is also kept unchanged.
[0065] (FIG. 4F) As the result, the total spectral transmittance is
low over the wavelength range of the incident light, and the
transmitted light intensity is low.
[0066] As described above, the constitution and the detection
method according to the present invention realizes a sensing system
which does not detect external disturbance but detects only the
difference between the fluids flowing through the first flow
channel and the fluid flowing through the second flow channel.
Example 2
[0067] In this Example, two defect-containing photonic crystals
having the same properties are optically connected in series, and
sensing is conducted the utilizing transmitted light having
transmitted through the two photonic crystals. The sensor device of
this Example has a constitution similar to that shown in FIG. 1 as
a whole. The photonic crystal element system is also similar to
that in Example 1, and is shown in FIGS. 5A-5C. This example is
different from Example 1 in first photonic crystal 205, second
photonic crystal 206, and the incident light 105 for the
detection.
[0068] In this Example, the two same photonic crystals are employed
which have respectively a deficiency of a cylindrical hole and a
defect-resonator 501. Thereby, the spectral transmittance of the
photonic crystal has a sharp transmission peak corresponding to the
defect level in the photonic band gap.
[0069] A sensing process by the sensor element constituted of the
aforementioned micro flow channel element and optical element is
described by reference to FIGS. 6A-6F. This sensing process offsets
external disturbance to achieve the purpose of the present
invention. FIGS. 6A, 6C, and 6E show a spectral transmittance 601
of the light passing through the first photonic crystal and a
spectral transmittance 602 of the light passing through the second
photonic crystal. FIGS. 6B, 6D, and 6F show respectively a total
spectral transmittance 604 of the light passing through the series
of the first and second photonic crystals, and the intensity
spectrum 603 of the light source for the detection.
[0070] The process is described below.
[0071] (FIG. 6A) The first and second photonic crystals are the
same. Therefore, the spectral transmittances 601 are superposed in
the initial state.
[0072] (FIG. 6B) The introduced light has preferably a light
intensity only within the photonic band gap, and has a spectrum as
flat as possible within the range. The total spectral transmittance
604 of the system containing the two photonic crystals is the
square of the spectral transmittance of the single photonic
crystal. Since the defect level is within the incident light
wavelength range, a sufficient intensity of the transmitted light
is obtained. That is the initial state of the sensing system of
this Example.
[0073] (FIG. 6C) Next, a second fluid is allowed to flow through
second flow channel 209 only. This fluid is, for example, a buffer
solution containing a protein dissolved therein to be determined
for the concentration. This fluid flow causes a change in the
spectral transmittance in the second photonic crystal, the spectral
transmittance wavelength being shifted toward a long wavelength
side as shown in FIG. 6C. Thereby, spectral transmittance 602 of
the second photonic crystal, which is entirely superposed on
spectral transmissivity 601 of the first photonic crystal in the
initial state, comes to be shifted. This causes a wavelength shift
of the transmittance peak of the defect level.
[0074] (FIG. 6D) By the wavelength shift of the spectral
transmittance in the second photonic crystal, the high
transmittance peak caused by the defect level comes to disappear
from the total spectral transmittance 604. Consequently, no light
is transmitted in the incident light wavelength range. The
difference in the nature of the fluid flowing through first flow
channel 205 from that flowing through second flow channel 206
causes a change of the transmitted light intensity. Thus the
sensing can be conducted by utilizing this difference in the
properties between the fluids flowing in first flow channel 205 and
second flow channel 206.
[0075] (FIG. 6E) Next, the operation of this sensing system is
explained in the case where a common external disturbance arises in
the first and second flow channels and the first and second
photonic crystals. The external disturbance is exemplified by a
temperature change, and a change in the buffer solution. The
distance between the first and second flow channels is about 300
.mu.m which is sufficiently close to each other to undergo the same
temperature change. If necessary, the distance may be shortened as
mentioned before. To offset fluctuation of the buffer solution, the
construction may be modified by employing the same fluid-feed
source, and bringing close the branch of the first and second flow
channels and the protein mixing portion to the photonic crystal
portions to be affected similarly by the external disturbance in
the two flow channels.
[0076] With such a constitution, when the influence of the external
disturbance is common to the first and second photonic crystals,
the two spectral transmittances shift together by nearly the same
wavelength portion with the defect levels kept superposed.
[0077] (FIG. 6F) As the result, the total spectral transmittance
has a transmission peak within the range of the wavelength range of
the incident light, and the transmitted light is the same as in the
initial state.
[0078] As described above, the constitution and detection method
according to the present invention realizes a sensing system which
does not detect external disturbance but detects only the
difference in the fluids flowing through the first flow channel and
the second follow channel.
Example 3
[0079] In this Example, two photonic crystals having the same
properties are optically connected in series, and the sensing is
conducted the utilizing the light transmitted through a first
photonic crystal region and then reflected by the second photonic
crystal region.
[0080] Optical Waveguide
[0081] The sensor device of this Example has a constitution similar
to that shown in FIG. 1 as a whole. FIG. 7 shows the constitution
in more detail. In FIG. 7, first photonic crystal 205 and second
photonic crystal 206 have the same properties, but the light is
transmitted through the first photonic crystal and is reflected by
the second photonic crystal, being different from the above
Examples 1 and 2. For the optical connection of the transmitted
light and the reflected light, Y-shaped coupling portion 703 is
provided which is branched from optical guide 701 for the
transmitted light into optical guides 705 for the light to be
reflected. Thereby, transmitted light 702 is introduced to the
second photonic crystal and reflected light 704 is guided to
optical detector 106. The Y-shaped coupling portion may be modified
suitably in the shape or other constitutions for adjusting the
coupling ratio or the like. A beam splitter or an optical branch
coupling system other than the Y-shaped one may be employed. Second
micro flow channel 209 is bent to cross minimally over the Y-shaped
coupling portion and the optical waveguide.
[0082] A sensing process is explained which is less affected by
external disturbance. In the process, the sensing is conducted by a
sensor element constituted of the aforementioned micro flow channel
and the optical element to achieve the purpose of the present
invention of offsetting external disturbance. The explanation is
made by reference to FIGS. 8A-8F. FIG. 8A, FIG. 8C, and FIG. 8E are
graphs showing spectral transmittance 801 of the light passing
through the first photonic crystal and spectral reflectance 802 of
the light reflected by the second photonic crystal. FIG. 8B, FIG.
8D, and FIG. 8F are graphs showing total spectral transmittances
805, 806, 807, and 808 of light having transmitted through the
first photonic crystal and reflected by the second photonic crystal
successively in the photonic crystal optical element system, and
the intensity spectrums 803,804 of two light sources employed for
the detection.
[0083] (FIG. 8A) The first photonic crystal and the second photonic
crystal are the same. Therefore, in the initial state, the photonic
band edges of spectral transmittance 801 and of spectral
reflectance 802 overlap at the long wavelength-side edges and the
short wavelength-side edges.
[0084] (FIG. 8B) One kind or two kinds of incident light fluxes are
employed. First incident light 803 covers a broad wavelength range,
containing the long wavelength-side edge of the photonic band gap.
When second light is employed, the wavelength range is preferably
selected not to overlap on the wavelength range of the first light.
The second incident light covers a broad wavelength range,
containing the short wavelength-side edge of the photonic band gap.
Each of the incident light fluxes has preferably a light intensity
spectrum as flat as possible in the light wavelength range.
[0085] Total spectral transmittance 805 is a multiplication product
of the spectral transmittance and the spectral reflectance, and the
transmission is obtained at the two edge portions only. The
transmittance is about 25% at the highest. This highest
transmittance is obtained at the wavelengths where the both of the
transmittance and the reflectance are about 50%. The two
wavelengths are respectively within the wavelength range of the
first incident light or the second incident light. Therefore, for
either of the incident light, an intermediate intensity can be
obtained: about 25% of the maximum transmittance. The above state
is the initial state of the sensing system of this Example.
[0086] (FIG. 8C) Next, a second fluid is allowed to flow in second
flow channel 206. This fluid is, for example, a buffer solution
containing a protein dissolved therein to be determined for the
concentration. This fluid flow causes a change in the spectral
reflectance at the second photonic crystal to shift the spectral
reflectance wavelength toward a long wavelength side as shown in
FIG. 8C. Thereby, spectral reflectance 802 of the second photonic
crystal, which is overlapping at the edges on spectral
transmittance 801 of the first photonic crystal in the initial
state, shifts toward the long wavelength side.
[0087] (FIG. 8D) By the wavelength shift by the second photonic
crystal, regarding total spectral transmittance 805, the
transmittance at the transmission peak becomes larger at the long
wavelength side, and the transmission peak at the short wavelength
side disappears. Therefore, the total transmittance intensity of
the first incident light increases, whereas the total transmittance
intensity of the second incident light becomes zero. Therefore,
sensing can be conducted by utilizing the change in the total
transmittance by difference in properties between the fluids
flowing first flow channel 205 and second flow channel 206.
[0088] (FIG. 8E) Next, the operation of this sensing system is
explained in the case where a common external disturbance arises in
the first and second flow channels and the first and second
photonic crystals. The external disturbance is exemplified by a
temperature change, and a change in the buffer solution. The
distance between the first and second flow channels is about 300
.mu.m which is sufficiently close to each other to undergo the same
temperature change. If necessary, the distance may be shortened as
mentioned before. To meet fluctuation of the buffer solution, the
construction may be modified by employing the same fluid-feed
source, and bringing close the branch of the first and second flow
channels and the protein mixing portion to the photonic crystal
portions to be affected similarly by the external disturbance in
the two flow channels.
[0089] With such a constitution, when the influence of the external
disturbance to the first and second photonic crystals is common,
the two spectral transmissivities shift by nearly the same
wavelength portion with the edges at the long wavelength-side and
the short wavelength-side of the photonic band gaps kept
overlapped.
[0090] (FIG. 8F) As the result, the total spectral transmittance
has a transmission peak within the wavelength ranges of the first
and second incident light intensities, at an intermediate
transmittance, and the transmitted light is the same as in the
initial state.
[0091] As described above, the constitution and detection method
according to the present invention realizes a sensing system which
does not detect external disturbance but detects only the
difference in the fluids flowing through the first flow channel and
the second follow channel.
[0092] The embodiment of this Example can be realized either with
one incident light flux, or an additional second incident light
flux. The use of the two light fluxes is advantageous: when the
change caused by the second photonic crystal is a shift toward a
short wavelength side, the total transmittance of the first
incident light becomes zero, and the total transmittance of the
second incident light is decreased; and from the decrease, the
change can be detected. Thus the amount of the change toward a
positive side as well as a negative side can be detected.
Example 4
[0093] Example 4 of the present invention is explained by reference
to FIG. 9 and FIG. 10. FIG. 9 illustrates schematically a sensor
device incorporating a sensor and flow channel element of the
present invention in a shape of a wrist watch for wearing at a
wrist or arm of a human body.
[0094] This sensor device is worn on a wrist or arm with a belt 902
to detect necessary information by taking blood or a like method as
shown in the step in FIG. 10 by sensor section 901, showing the
detection result in display panel 903.
[0095] FIG. 10 shows briefly a typical process for obtaining
necessary information. The process shown in FIG. 10 includes
blood-taking step 1001 in which a small amount of blood is taken
from a human body by a blood-taking needle not shown in FIG. 9;
component separation/reaction step 1002 in which an objective
component is separated from the blood components and a reaction
necessary for the separation is caused;
component-concentration/reaction step 1003 for higher detection
sensitivity; detection step 1004 in which the detection is
conducted at a high sensitivity by bringing the fine resonator LD
of the present invention into contact with flow channel for flow of
the fluid containing the concentrated objective, and the detection
result is converted by calculation to intended style; and
result-displaying step 1005 which displays the result at displaying
panel 903.
[0096] As shown in FIG. 9 and FIG. 10, the sensor device of the
present invention incorporating the micro resonator LD and the flow
channel can be used for constituting a portable detection-testing
device. Naturally, the body-worn sensor device of the present
invention may be equipped with communication facility to a server
apparatus, clock facility, photographing facility, or the like
facility for a portable terminal.
Example 5
[0097] The constitution of Example 3 is expanded to employ three or
more photonic crystal regions 1201 connected suitably to each other
as shown in FIG. 12. Further, a plurality of the serial
constitutions may be arranged in parallel for statistical treatment
of the sensing data.
[0098] This application claims priority from Japanese Patent
Application No. 2005-051997 filed on Feb. 25, 2005, which is hereby
incorporated by reference herein.
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