DESCRIPTION
CHEMICAL SENSOR, CHEMICAL SENSOR MODULE, CHEMICAL
SUBSTANCE DETECTION APPARATUS, AND CHEMICAL SUBSTANCE
DETECTION METHOD
5
Technical Field
[OOOll T4e present technology relates to a chemical
sensor, a chemical sensor module, a chemical substance
detection apparatus, and a chemical substance detection
10 method for detecting a chemical substance by using
light emission on a detection target object.
Background Art
[00021 A chemical sensor for detecting a chemical
substance by using light emission caused by a chemical
15 binding is being studied. Specifically, a probe
material that is specifically bound to a target
material to be detected is adhered onto a sensor, and a
sample corltaining the target material is supplied to
the sensor. As a result, the target material is bound
20 to the probe material. For example, a fluorescent label
is introduced to a bound body of the target material
and the probe material, and fluorescence is generated
on the bound body by irradiation with excitation light
As a result, the fluorescence is detected by a
25 photoelectric conversion element, and thus it is
possible to confirm the existence of the target
material in the sample.
[0003] In such a chemical sensor, if the excitation
light for exciting the fluorescent label is detected by
the photoelectric conversion element, the excitation
5 light cannot be distinguished from the fluorescence
which should be detected, so it is necessary to
separate thh excitation light from the fluorescence and I
remove the excitation light.
[00041 For example, Patent Document 1 discloses an
10 organic molecule detection semiconductor element
provided with an optical filter and DNA immobilization
film which blocks out excitation light and causes only
fluorescence to pass therethrough. The optical filter
and DNA immobilization film is a multilayer film
15 optical filter formed by laminating a silicon dioxide
film, an aLuminum oxide layer, a magnesium oxide film,
and the like and removes ultraviolet light (excitation
light) by using interference of light.
[00051 Patent Document I: Japanese Patent
20 Application Laid-open No. 2002-202303 (paragraph
[0039], Fig. 1)
Summary of Invention
Problem to be solved by the Invention
[0006] However, the multilayer film optical filter
2 5 as disclosed in Patent Document 1 requires a certain
number of layers in order to sufficiently block out the
excitation light, so there is a fear that crosstalk
(mixture of light with an adjacent photoelectric
conversion element) may be generated due to the large
thickness. Further, because the interference of light
5 is used, it is thought that the excitation light that
enters the multilayer film optical filter in a slanting
direction c2nnot be effectively blocked out.
Furthermore, a great number of processes for forming
the multilayer film are required, and thickness control
10 has to be performed, so it is necessary to study
productivity.
[00071 In view of the circumstances as described
above, an object of the present technology is to
provide a chemical sensor provided with a spectral
15 filter excellent in spectral characteristic, a chemical
sensor module, a chemical substance detection
apparatus, and a chemical substance detection method.
Means for solving the Problem
[ O O O S ] To achieve the above-mentioned object, a
20 chemical sensor according to an embodiment of the
present technology includes a substrate and a plasmon
absorption layer.
In the substrate, a photodetection unit is formed.
The plasmon absorption layer is laminated on the
25 substrate, and the plasmon absorption layer has a metal
nanostructure that generates plasmon absorbency.
jOOO91 With this structure, it is possible to
disperse incident light by the plasmon absorption layer
laminated in the upper layer of the substrate and cause
only light as a detection target to reach the
5 photodetection'unit. By using plasmon absorbency of the
metal nanostructure, it is possible to reduce the
thickness or the plasmon absorption layer that
functions as a spectral filter and prevent fluorescence
emission (autofluorescence) on the plasmon absorption
10 layer. Further, the plasmon absorption layer can be
more easily produced than a multilayer film filter,
which is typical as a spectral filter of a chemical
sensor, so it is possible to increase the productivity
of the chemical sensor.
15 [OOlO] The chemical sensor may further include a
surface layer laminated on the plasmon absorption
layer, the surface layer having a holding surface on
which a detection target object is held.
[OOll] With this structure, by the dispersion by the
20 plasmon absorption layer, it is possible to cause the
photodetection unit to detect light emitted from the
detection target object held on the holding surface of
the surface layer.
[0012] The plasmon absorption layer may block out
2 5 illumination light with which the detection target
object is irradiated and may cause detection target
light generated on the detection target object to pass
therethrough.
[0013] With this structure, by the plasmon
absorption layer, it is possible to perform dispersion
5 for the illumination light and the detection target
light. If the illumination light reaches the
photodetect'ion unit, the illumination light is
superimposed on the detection target light and is
detected by the photodetection unit, resulting in a
10 reduction of the detection accuracy. By blocking out
the illumination light by the plasmon absorption layer,
it is possible to prevent the illumination light from
being detected by the photodetection unit.
[0014] The illumination light may be excitation
15 light, and the detection target light may be
fluorescence.
[0015] With this structure, it is possible to detect
the fluorescence with high accuracy. Generally, the
fluorescence is weak, so it is necessary to perform
2 0 exposure for a long time by the photodetection unit.
Therefore, in order to improve the detection accuracy,
it is necessary to detect only the fluorescence emitted
from the detection target object by the photodetection
unit. The plasmon absorption layer does not generate
25 autofluorescence and is therefore suitable for the
detection of the fluorescence.
[0016j The plasmon absorption layer may contain a
metal nanoparticle.
[0017j By dispersing the metal nanoparticles in
synthetic resin or by laminating only the metal
5 nanoparticles, it is possible to form a metal
nanostructure having the plasmon absorbency. As the
metal nanostructure, there is a metal nanohole in
addition thereto, but photolithography or the like has
to be performed to produce the metal nanohole. In
10 contrast, by using the metal nanoparticle, it is
possible to easily form the metal nanostructure
[0018] The metal nanoparticle is a particle having a
surface formed of one of pure metal containing at least
one of gold, silver, and copper and an alloy thereof.
15 [0019] By using such a particle, it is possible to
cause the plasmon absorbency. The particle having the
surface formed of one of pure metal containing at least
one of gold, silver, and copper and the alloy thereof
includes a particle made of pure metal of gold, silver,
20 or copper, a particle formed of an alloy containing
those, and a core-shell type particle in which a core
made of some materials is covered with a shell formed
of the pure metal of gold, silver, or copper or the
alloy containing those.
25 [0020] The metal nanoparticle may have a particle
diameter of 1 nrn or more and 150 nm or less.
[0021l In the case where the particle diameter of
the metal nanoparticle is less than 1 nm, the
fluorescence may be generated on the plasmon absorption
layer. In the case where the particle diameter thereof
5 exceeds 150 nm, an optical spectrum may be unsuitable
for the spectral filter. Therefore, by settlng the
particle d?lmeter of the metal nanoparticle to fall
within the range of 1 nm or more and 150 nrn or less, it
is possible to make the spectral characteristic of the
10 plasmon absorption layer desirable.
[0022] The chemical sensor may further include a
color filter layer laminated between the substrate and
the plasmon absorption layer, the color filter layer
being made of an organic dye-based material.
15 [0023] Upon receiving irradiation of excitation
light, the color filter layer made of the organic dyebased
materlal generates fluorescence by itself
(autofluorescene), whlch causes a reduction in
detection accuracy of the detection target light.
20 However, with the structure according to the present
technology, the color fllter layer is disposed below
the plasmon absorption layer, with the result that the
excitation light is blocked out by the plasmon
absorption layer to be prevented from reaching the
25 color filter layer, so the autofluorescence is not
generated. At the same time, the color filter has good
controllability of blocking/transmission wavelengths,
so it is possible to interpolate the spectral
characteristic of the plasmon absorption layer by the
color filter layer.
5 [0024] The chemical sensor may further include a
multilayer film filter layer formed by laminating a
plurality o';€k inds of materials.
[0025] With this structure, the multilayer film
filter layer and the plasmon absorption layer can
10 complement the spectral characteristics of each other.
The multilayer film filter layer does not generate
autofluorescence and therefore can be disposed in the
upper layer of the plasmon absorption layer.
i.00261 In the chemical sensor, the holding surface
15 holds a probe material that is specifically bound to a .,
target material to be detected.
LO0271 With this structure, by supplying a sample
containing the target material to the holding surface,
it is possible to cause the target material
20 corresponding to the probe material to be bound to the
probe material. As a result, detection target light is
detected with a bound body of the target material and
the probe material as the detection target object,
thereby making it possible to check the fact the target
25 material is contained in the sample.
[0028] The probe material may be one of DNA, RNA, a
protein, and an antigenic substance.
[0029] With this structure, it is possible to set
those substance as a measurement target.
[0030] To achieve the above object, a chemical
5 sensor module according to an embodiment of the present
technology includes a chemical sensor and an
illuminatio:~ light source.
The chemical sensor includes a substrate on which
a photodetection unit is formed, a plasmon absorption
10 layer laminated on the substrate, and a surface layer
laminated on the plasmon absorption layer, the piasmon
absorption layer having a metal nanostructure that
generates plasmon absorbency, the surface layer having
a holding surface on which a detection target object is
15 held.
The illumination light source irradiates the
holding surface with illumination light.
[0031] To achieve the above object, a chemical
substance detection apparatus according to an
20 embodiment of the present technology includes a
chemical sensor and a signal processing circuit.
The chemical sensor includes a substrate on which
a photodetection unit is formed, a plasmon absorption
layer laminated on the substrate, and a surface layer
25 laminated on the plasmon absorption layer, the plasmon
absorption layer having a metal nanostructure that
generates plasmon absorbency, the surface layer having
a holding surface on whlch a detectlon target object is
held.
The signal processing circuit is connected to the
5 chemical sensor and processes an output signal of the
photodetectlon unit.
[0032] To achieve the above object, a chemical
substance detection method according to an embodiment
of the present technology includes preparing a chemical
10 sensor including a substrate on which a photodetection
unit is formed, a plasmon absorption layer laminated on
the substrate, and a surface layer laminated on the
plasmon absorption layer, the plasmon absorption layer
having a metal nanostructure that generates plasmon
15 absorbency, the surface layer having a holding surface
on which a detection target object is held.
A probe material is caused to be held on the
holding surface.
A sample is brought into contact with the holding
20 surface, and a target material contained in the sample
is caused to bind to the probe material to form a
detection target object.
The holding surface is irradiated with
illumination light.
25 Upon receiving the illumination light, detection
target light generated as a result of binding of the
probe material and the target material on the detection
target object is detected by the photodetection unit.
LO0331 The illumination light may be excitation
light, and the detection target light may be
5 fluorescence.
LOO341 In the step of detecting the fluorescence,
changes in 'fla~~elengatnhd luminance of the fluorescence
caused by an interaction of the target material and the
probe material fluorescently labeled in advance may be
10 detected by the photodetection unit.
[00351 In the step of detecting the fluorescence,
the fluorescence generated by the target material that
is fluorescently labeled in advance and is bound to the
probe material may be detected by the photodetection
15 unit.
[00361 In the step of detecting the fluorescence,
fluorescent labelling is performed for a bound body of
the probe material and the target material, and the
fluorescence may be detected by the photodetection
20 unit.
Effect of the Invention
LOO371 As described above, according to the present
technology, it is possible to provide the chemical
sensor provided with the spectral filter excellent in
2 5 spectral characteristic, the chemical sensor module,
the chemical substance detection apparatus, and the
chemical substance detection method.
Brief Description of Drawings
LO0381 [Fig. 11 A schematic diagram showing the
structure of a chemical substance detection apparatus
5 according to a first embodiment.
[Fig. 21 A schematic diagram showing the structure of
a chemical isensor according to the first embodiment.
[Fig. 31 A schematic diagram showing the structure of
the chemical sensor according to the first embodiment.
10 [Fig. 41 A graph showing an absorption spectrum based
on particle sizes of silver nanoparticles.
[Fig. 51 A graph showing an absorption spectrum based
on particle sizes of gold nanoparticles.
[Fig. 61 An absorption spectrum based on particle
15 sizes of gold nanoparticles (rod shape).
[Fig. 71 A TEM image of the gold nanoparticles (rod
shape) .
[Fig. 81 A table showing necessary thicknesses
depending on filter structures.
2 0 [Fig. 91 A graph showing a fluorescence spectrum of
various filters.
[Fig. 101 A schematic diagram showing the structure of
a chemical sensor module according to the first
embodiment.
2 5 [Fig. 111 A schematic diagram showing the structure of
a chemical sensor module according to a second
embodiment.
[Fig. 121 A schematic diagram showing the structure of
a chemical sensor module according to a third
embodiment.
5 Best Mode(s) for Carrying Out the Invention
100391 (First embodiment)
A chemcical substance detection apparatus according
to a first embodiment of the present technology will be
described.
10 [00401 (Entire structure of chemical substance
detection apparatus)
Fig. 1 is a schematic diagram showing the
structure of a chemical substance detection apparatus 1
according to this embodiment. As shown in the figure,
15 the chemical substance detection apparatus 1 is
constituted of a chemical sensor 3 formed on a
substrate 2 and a peripheral circuit for driving the
chemical sensor 3. The chemical sensor 3 includes a
plurality of photodetection units 21 arranged on the
20 substrate 2.
[0041] The number of photodetection units 21 and the
arrangement thereof are not limited and can be arranged
in a matrix form or a linear form. Here, the
photodetection units 21 are arranged in a matrix
25 pattern on a plane of the substrate 2. A row direction
is set as a vertical direction, and a column direction
is set as a horizontal direction.
[0042] The peripheral circuit is constituted of a
vertical drive circuit 4, a column signal processirg
circult 5, a horizontal drive circuit 6, and a system
5 control circuit 7. Further, the photodetection units 21
are connected to pixel drive lines 8 for each row and
connected to vertical signal lines 9 for each column.
The pixel drive lines 8 are connected to the vertical
drlve circuit 4, and the vertical signal lines 9 are
10 connected to the column signal processing circuit 5.
[0043] The column signal processing circuit 5 is
connected to the horizontal drive circuit 6, and the
system control circuit 7 is connected to the vertical
drive circuit 4, the column signal processing circuit 5,
15 and the horizontal drive circuit 6. It should be noted
that the peripheral circuit can be disposed on a
position of being laminated on a pixel area or an
opposite side to the substrate 2, for example.
[00441 The vertical drive circuit 4 is formed of a
20 shift register, for example. The vertical drlve circuit
4 selects the pixel drive line 8, supplies a pulse for
driving the photodetection unlts 21 to the pixel drive
line 8 selected, and drives the photodetection units 21
on a row basis. In other words, the vertical drive
25 circuit 4 performs selective scanning for the
photodetection units 21 in the vertical direction
sequentially on the row basis. Then, through the
vertical signal line 9 vertically wired with respect to
the pixel drive line 8, the vertical drive circuit 4
supplies, to the column signal processing circuit 5, a
5 pixel signal based on a signal charge generated in
accordance with a received light quantity in the
photodetectlon units 21.
to0451 The column signal processing circuit 5
performs signal processing such as a noise removal for
10 each pixel column with respect to a signal output from
the photodetection units 21 of one row. In other words,
the column signal processing circuit 5 performs signal
processing such as a correlated double sampling (CDS),
a signal amplification, and an analog/digital (AD)
15 conversion for removing a fixed pattern noise specific
to a pixel..
[0046] The horizontal drive circuit 6 is formed of
the shift register, for example, and sequentially
outputs horizontal scanning pulses, thereby selecting
2 0 the column signal processing circuits 5 in order and
causing each column signal processing circuit 5 to
output a pixel signal.
[0047] The system control circuit 7 receives an
input clock and data that specifies an operation mode
2 5 or the like and outputs data relating to inside
information or the like of the chemical sensor 3. That
is, on the basis of a vertical synchronizing signal, a
horizontal synchronizing signal, and a master clock,
the system control circuit 7 generates a clock signal
and a control signal which are references of the
5 operations of the vertical drive circuit 4, the column
signal processing circuit 5, the horizontal drive
circuit 6, ,and the like. Then the system control
circuit 7 inputs those signals to the vertical drive
circuit 4, the column signal processing circuit 5, the
10 horizontal drive circuit 6, and the like.
[0048] , As described above, the vertical drive
circuit 4, the column signal processing circuit 5, the
horizontal drlve circuit 6, the system control circult
7, and a pixel circuit provided to the photodetection
15 units 21 to be described later constitute a drive
circuit that drives the photodetection unlts 21.
[0049] (Structure of chemical sensor)
Fig. 2 1s a schematic diagram showing the
structure of the chemical sensor 3. As shown in the
20 figure, the chemical sensor 3 is formed by laminating a
protection insulating layer 31, a plasmon absorption
layer 32, and a surface protection layer 33 in this
order on the substrate 2 on which the photodetection
units 21 are formed. The chemical sensor 3 is used with
2 5 a detection target object placed on the surface
protection layer 33. Fig. 3 is a schematic diagram
showing the chemical sensor 3 on which detection target
oblects S are placed.
[OOSO] The substrate 2 supports the layers mentioned
above and can be made of monocrystalllne silicon, for
5 example. The substrate 2 has a principal surface on
which the photodetection units 21 are disposed, and on
the princip31 surface, the layers mentioned above are
laminated. On the substrate 2, in addition to the
photodetection units 21, a structure such as an element
10 isolation and a floating diffusion can be formed.
[0051] The photodetection unit 2i can be a
photoelectric conversion element (photodiode) that
converts light into current. The photodetection unit 21
can be an impurity region formed by introducing
15 impurities onto the substrate 2 as a semiconductor
substrate. The photodetection unit 21 can be connected
to a pixel circuit formed of a gate insulating film or
a gate electrode (not shown), and the pixel circuit can
be provided on a surface opposite to the principal
20 surface of the substrate 2.
LOO521 The protection insulating layer 31 is a layer
for protecting and insulating the photodetection units
21 and is made of a material that causes at least a
wavelength range of light which is generated on the
2 5 detection target objects S (hereinafter, referred to as
detection target light) to pass therethrough. The
protection insulating layer 31 may not be provided
depending on the structure of the photodetection unit
21.
roo531 The plasmon absorption layer 32 has a metal
5 nanostructure to be described later and is a layer for
performing dispersion for Light (hereinafter, referred
to as illumination light) with which the detection
target objects S are irradiated to generate the
detection target light and the detection target light.
10 The thickness of the plasmon absorption layer 32 can be
sufficiently small as compared to the case of a
multilayer film filter or the like on the basis of a
spectral principle thereof.
[00541 The surface protection layer 33 is a layer
15 for covering and protecting the plasmon absorption
layer 32 and holding the detection target objects S.
Hereinafter, a surface of the surface protection layer
33 on which the detection target objects S are held is
referred to as a holding surface 33a. The surface
20 protection layer 33 is made of a material that causes
at least a wavelength range of the detection target
light to pass therethrough, such as a silicon dioxide
film and a silicon nitride film. Further, for the
holding surface 33a, a surface treatment for causing
25 the detection target objects S to adhere to the surface
protection layer 33, such as a hydrophilic treatment,
may be performed. By such a surface treatment, it is
possible to separate an area to which the detection
target objects S are adhered (adhesion area) and an
area to which the detection target objects S are not
5 adhered (non-adhesion area).
(00551 (Chemical substance detection method by using
chemical sepsor)
A chemical substance detection method by using the
chemical sensor 3 described above will be described. It
10 should be noted that the chemical substance detection
method to be described below is an example, and the
chemical substance detection method by using the
chemical sensor 3 is not limited to the method
described below.
15 [0056] In the chemical substance detection method
using the chemical sensor 3, a probe material capable
of being specifically bound to a chemical substance
intended to be detected (hereinafter, referred to as
target material) can be used.
2 0 LOO571 Specifically, first, the probe material is
adhered to the holding surface 33a. For example, in the
case where the surface treatment is performed for the
holding surface 33a, a solution containing the probe
material is dropped on the adhesion area, thereby
2 5 making it possible to cause the probe material to
adhere to the adhesion area. Further, in the case where
the holding surface 33a is separated into the adhesion
area and the non-adhesion area, probe materials of
different kinds may be adhered for each adhesion area.
[0058] In this state, a sample solution is supplied
5 onto the holding surface 33a. In the case where the
sample solution contains the target material, the
target mateirial is bound to the probe material
corresponding thereto. The holding surface 33a is
washed, thereby removing an extra target material.
10 After that, by introducing a fluorescent label which
can be introduced only to a bound body of the probe
material and the target material, only the bound body
of the probe material and the target material is
fluorescently labeled, and the probe material that is
15 not bound to the target material is not fluorescently
labeled. It should be noted that in this example, the
bound body of the probe material and the target
material corresponds to the detection target objcct S.
[0059] In this state, the chemical sensor 3 is
2 0 irradiated with excitation light from the surface
protection layer 33 side. The fluorescent label
contained in the detection target object S is excited
by the excitation light, and fluorescence is generated
The florescence is transmitted through the surface
25 protection layer 33, the plasmon absorption layer 32,
and the protection insulating layer 31, reaches the
photodetection units 21, and is detected. The
excitation light is blocked out by the plasmon
absorption layer 32 and is thus prevented from reaching
the photodetection units 21.
5 [00601 In the detection of the target material, for
example, in the case where DNA (deoxyribonucleic acid)
is used as ?he probe material, a 5'-fluorescein-labeled
DNA can be used. If the sample contains DNA having a
sequence complementary to the 5'-fluorescein-labeled
10 DNA, a hybridization reaction occurs, resulting in a
change of the probe material from single-stranded DNA
(ss-DNA) to double-stranded DNA (ds-DNA). The change
causes a permittivity of the surrounding of a
fluorescent molecule to change, and thus the change in
15 emission wavelength and intensity of the fluorescence
is caused. The change is detected by the photodetection
units 21.
[0061] Further, in the case where the DNA is used as
the probe material, DNA which is not fluorescently
20 labeled is used as the probe material, and the 5'-
fluorescein-labeled DNA is used for the sample, for
example. In this case, if the sample contains DNA
having a sequence complementary to the DNA as the probe
material, the hybridization reaction occurs, resulting
25 in a change into ds-DNA with the fluorescent label. The
emission of the fluorescence from the fluorescent label
is detected by the photodetection units 21.
100621 Alternatively, in the case where the DNA is
used as the probe material, DNA which is not
fluorescently labeled is used for the probe material,
5 and a fluorescence pigment is not also introduced into
the sample side. In this case, if the sample contains
DNA having 3 sequence complementary to the DNA as the
probe material, the hybridization reaction occurs,
resulting in a change into ds-DNA. Then, a treatment of
10 fluorescent labeling by selectively dying only the ds-
DNA is performed by using Pico-Green 2-stranded DNA
quantification reagent produced by Molecular Probes,
for example, thereby introducing the fluorescent label
into the ds-DNA part. The emission of the fluorescence
15 from the fluorescent label is detected by the
photodetection units 21.
100631 In the above example, the description is
given with the probe material as the DNA, but iL is
possible to use various biomolecules such as RNA (ribo
20 nucleic acid), proteins, and antigenic substances or
various chemical substances as the probe material.
Further, as an example of the illumination light with
which the detection target objects S are irradiated,
the excitation light is given, and as the detection
25 target light emitted from the detection target objects
S, the fluorescence is given, but the illumination
light and the detection target light are not limited
thereto. As long as there is such a relationship that
the detection target objects S are irradiated with any
light, and the detection target objects S emit any
5 light with a different wavelength, the present
technology can be applied.
[00641 (!Tibout dispersing by plasmon absorption
layer)
As described above, the plasmon absorption layer
10 32 blocks out the illumination light and causes only
the detection target light to pass therethrough. That
is, the plasmon absorption layer 32 functions as a
spectral filter. The plasmon absorption layer 32 has a
metal nanostructure, that is, a nand-size structure
15 formed of metal, such as a metal nanoparticle and a
metal nanohole.
[00651 The plasmon absorption layer 32 has plasmon
absorbency. The plasmon refers to a quantum of
collective oscillation of free electrons in metal. In
20 the metal nanostructure, a surface plasmon with
oscillation different from bulk metal is generated. The
interaction between the surface plasmon and light is
referred to as a surface plasmon resonance, and an
optical electric field of a specific wavelength
25 determined depending on a metal type, a nanostructure
shape (particle shape, hole shape, or the like), and a
nanostructure size (particle size, hole diameter, or
the like) and the plasmon are subjected to coupling,
with the result that light absorption is caused.
[0066] Specifically, in this embodiment, it is
5 possible to use a metal nanoparticle having a surface
formed of pure metal containing at least one of gold,
silver, and' copper or an alloy thereof. This includes a
particle made of pure metal of gold, silver, or copper,
a particle formed of an alloy containing at least one
10 of gold, silver, and copper, and a core-shell type
particle formed by covering some metal core or nonmetal
core with a shell made of the pure metal or the
alloy.
[0067] It is desirable that the particle diameter of
15 the metal nanoparticle is 1 nm or more and 150 nm or
less. In the case where the particle diameter of the
metal nanoparticle is less than 1 nm, fluorescence may
be generated in themetal nanoparticle. In addition, in
the case where the particle diameter exceeds 150 nm, an
20 optical spectrum may be unsuitable for the spectral
filter. Specifically, it is thought that designing of
blocking/transmission wavelength becomes difficult, for
example, two or more transmission peaks of the optical
spectrum are generated.
25 [0068] Fig. 4 shows an absorption spectrum based on
particle sizes of silver nanoparticles, and Fig. 5
shows an absorption spectrum based on gold
nanoparticles. It is found that, from Fig. 4, a
wavelength range of maximum absorption is generated at
approximately 400 nm for the silver nanoparticles, and
5 from Fig. 5, a wavelength range of maximum absorption
is generated at approximately 520 nm for the gold
nanoparticl,:~. In both the cases of the silver
nanoparticles and the gold nanoparticles, the
wavelength ranges of absorption are shifted depending
10 on the particle sizes, but a difference in metal type
gives a larger influence.
[0069] Fig. 6 shows an absorption spectrum based on
particle sizes (rod lengths) of rod-shaped gold
nanoparticles. Fig. 7 shows a TEM (transmission
15 electron microscope) image of the rod-shaped gold
nanoparticles (10 nm x 40 nm). As shown in Fig. 6, in
the case of the rod-shaped gold nanoparticles, the
wavelength range of maximum absorption varies from 500
nm to 1400 nm depending on the particle sizes. In this
2 0 way, by appropriately selecting the metal type of the
metal nanoparticles contained in the plasmon absorption
layer 32, the particle shape, and the particle size, it
is possible to set any wavelength range to the
wavelength range of absorption of the plasmon
2 5 absorption layer 32.
[0070] As described above, in this embodiment, by
using the plasmon absorbency of the metal
nanostructure, the absorption wavelength range of the
metal nanostructure is set to the wavelength range of
the illumination light, with the result that the
5 plasmon absorption layer 32 can be used as the spectral
filter.
[0071] The use of the plasmon absorption layer 32 as
the spectral layer provides the following advantages
relative to a typical multilayer film filter or a
10 typical organic dye-based filter (color filter).
[00721 First, it is possible to reduce the thickness
necessary to obtaln sufficient spectral characteristic.
Fig. 8 shows thicknesses necessary to achieve a
transmittance of 0.1% with respect t'o light with a
15 wavelength of 530 nm. As shown in the figure, a
spectral fi:lter (metal nanoparticle containing filter)
that uses the metal nanoparticles has the necessary
thickness smaller than the organic dye-based filter and
the multilayer film filter (Ti02/SiOz). Therefore, the
20 detection target object S and the photodetection unit
21 are closer to each other, so it is possible to
prevent such a phenomenon (crosstalk) that the
detection target light generated on the detection
target object S is detected by the adjacent
25 photodetection unit 21.
[0073] Further, autofluorescence, which is a problem
in the case of the organic dye-based filter, is not
generated. The autofluorescence is a phenomenon that
the spectral filter itself is excited by excitation
light to generate fluorescence. If the autofluorescence
5 is generated, the autofluorescence is mixed in the
fluorescence generated on the detection target object,
resulting i'i a reduction in measurement accuracy of the
photodetection unit.
[00741 Fig. 9 is a graph showing a fluorescence
10 measurement result of the metal nanoparticle containing
filter, the organic dye-based filter, and the silicon
substrate. The silicon substrate is used as reference,
and the metal nanoparticle containing filter is
obtained by coating the silicon substrate with the
15 metal nanoparticles. The wavelength of the excitation
light ranges from 510 nm to 550 nm, and the detection
wavelength of the fluorescence is 600 nm or more. As
shown in the figure, it is found that the
autofluorescence is generated on the organic dye-based
2 0 filter but is not generated on the metal nanoparticle
containing filter. In this way, in the spectral filter
that uses the metal nanoparticles according to the
present technoloqy, the autofluorescence is not
generated, so it is possible to measure the detection
25 target light wlth high accuracy.
[0075] Further, for the multilayer film filter, it
is necessary to laminate a plurality of layers in
accurate thicknesses. In contrast, for the plasmon
absorption layer 32, only one layer is used, and the
thickness thereof may be set less accurately than the
5 multilayer film filter. Therefore, by using the plasmon
absorption layer 32 for the spectral filter, it is
possible tolincrease the productivity of the chemical
sensor 3.
(00761 In addition, on the basis of the spectral
10 principle in which a light interference is used, the
multilayer film filter has a spectral function with
respect to incident light in a direction vertical to
the layer but cannot perform effective dispersion with
respect to incident light in a slanting direction. In
15 contrast, the plasmon absorption layer 32 according to
this embodi,ment has the advantage over the multilayer
film filter in that an incident angle that allows
effective dispersion is wider without a limitation on
the incident angle unlike the multilayer film filter.
20 LOO771 (Chemical sensor module)
The chemical sensor 3 can form a module with an
illumination light source that emits illumination light
to the chemical sensor 3. Fig. 10 is a schematic
diagram showing a chemical sensor module 100. As shown
25 in the figure, the chemical sensor module 100 is
constituted by integrally connecting an illumination
light source 101 to the chemical sensor 3. The
illumination light emitted from the illumination light
source 101 enters the detection target objects S held
on the holding surface 33a and causes the detection
5 target light to generate. It should be noted that the
plasmon absorption layer 32 according to this
embodiment :an effectively disperse the light incident
on the layer in a slanting direction, so such a llght
source can be used as the illumination light source
10 101.
[0078] (Method of manufacturing chemical sensor)
A method of manufacturing the chemical sensor 3
will be described (see, Fig. 1). First, on the
principal surface of the substrate 2, the
15 photodetection units 21 formed of impurity regions, a
gate insulating film (not shown), and a gate electrode
(not shown) by ion implantation through a mask and a
thermal treatment thereafter. Then, on the subsLrate 2
on which the photodetection units 21 are formed, the
20 protection insulating layer 31 is laminated by a CVD
(Chemical Vapor Deposition), a sputtering method, or
the like.
[0079] Then, on the protection insulating layer 31,
the plasmon absorption layer 32 is laminated. In the
25 case of being formed of the metal nanoparticles, the
plasmon absorption layer 32 can be formed by performing
spin coating, mist coating, an inkjet method, or the
like of resin containing the metal nanoparticles or a
metal nanoparticle solution. Further, in the case of
being formed of the metal nanoholes, the plasmon
5 absorption layer 32 can be formed by patterning a metal
film by photolithography or the like.
[00801 Then, on the plasmon absorption layer 32, the
surface protection layer 33 is laminated. The surface
protection layer 33 can be laminated by the CVD method,
10 the sputtering method, or the like. It should be noted
that it is also possible to laminate the plasmon
absorption layer 32 by the inkjet method on a wafer
chip after the protection insulating layer 31 is
laminated, PAD opening is performed, and a post-process
15 is performed.
[0081] As described above, according to this
embodiment, the plasmon absorption layer 32 is used as
the spectral filter, with the result that the eLLective
dispersion can be performed, and the chemical sensor 3
2 0 provided with the optical filter with high productivity
can be provided.
[0082] (Second embodiment)
A chemical substance detection apparatus according
to a second embodiment of the present technology will
25 be described. It should be noted that in this
embodiment, structures which are the same as those in
the first embodiment are denoted by the same reference
symbols, and descriptions thereof will be omitted.
[0083] The chemical substance detection apparatus
according to this embodiment is different from the
5 chemical substance detection apparatus according to the
first embodiment in terms of the structure of a
chemical seQsor. Fig. 11 is a schematic diagram showing
the structure of a chemical sensor 200 according to
this embodiment.
10 [a0841 As shown in Fig. 11, the chemical sensor 200
Includes a color filter layer 34, in addition to the
substrate 2 on which the photodetection units 21 are
formed, the protection insulating layer 31, the plasmon
absorption layer 32, and the surface' protection layer
15 33. The color filter layer 34 is laminated between the
protection ,insulating layer 31 and the plasmon
absorption layer 32, that is, on a lower layer side of
the plasmon absorption layer 32.
[0085] The color filter layer 34 is made of organic
2 0 dye-based resin and disperses incident light by a color
thereof. The color filter layer 34 can be made of a
material having an appropriate spectral characteristic
in accordance with wavelength ranges of the
illumination light and the detection target light.
2 5 LOO861 As described above, the color filter made of
the organic dye-based resin may generate
autofluorescence, which is the fluorescence generated
by receiving excitation light irradiation. However, in
the chemical sensor 200 according to this embodiment,
in the upper layer of the color filter layer 34, the
5 plasmon absorption layer 32 is provided, so the
excitation light is blocked out by the plasmon
absorption 'layer 32, with the result that the
autofluorescence by the color filter layer 34 is
prevented.
10 [0087] On another front, it is easy to control the
absorption and transmission wavelength of the color
filter. Thus, by disposing the color filter layer 34 in
the lower layer of the plasmon absorption layer 32, it
is possible to perform dispersion in accordance with
15 the wavelength ranges of the illumination light and the
detection target light, while preventing the generatlon
of the autofluorescence. In other words, it is
sufficient that the plasmon absorption layer 32 blocks
out only a wavelength range in which the
20 autofluorescence is generated by the color filter 34,
that is, the color filter 34 is used, thereby making it
easy to perform optical design of the plasmon
absorption layer 32.
[0088] (Thlrd embodiment)
25 A chemical substance detection apparatus according
to a third embodiment of the present technology will be
described. It should be noted that in this embodiment,
structures which are the same as those in the first
embodiment are denoted by the same reference symbols,
and descriptions thereof will be omitted.
5 [0089] The chemical substance detection apparatus
according to this embodiment is different from the
chemical su"stance detection apparatus according to the
first embodiment in terms of the structure of a
chemical sensor. Fig. 12 is a schematic diagram showing
10 the structure of a chemical sensor 300 according to
this embodiment.
[0090] As shown in Fig. 12, the chemical sensor 300
includes a multilayer film filter layer 35, in addition
to the substrate 2 on which the photodetection units 21
15 are formed, the protection insulating layer 31, the
plasmon absorption layer 32, and the surface protection
layer 33. The multilayer film filter layer 35 is
laminated between the protection insulating layer 31
and the plasmon absorption layer 32. In addition,
20 although not shown, the multilayer film filter layer 35
may be laminated between the plasmon absorption layer
32 and the protection insulating layer 31.
[0091] The multilayer film filter layer 35 is formed
by alternately laminating a plurality of materials such
2 5 as Tic2 and Si02 and disperses incident light by a light
interference. The multilayer film filter layer 35 can
be made of a material having an appropriate spectral
characteristic in accordance with the wavelength ranges
of the illumination light and the detection target
light.
5 [0092] In the multilayer film filter layer 35,
unlike the color filter, the autofluorescence is not
generated, jio the multilayer film filter layer 35 can
be formed in the upper layer of the plasmon absorption
layer 32, instead of being formed in the lower layer of
10 the plasmon absorption layer 32. By using the
multilayer film filter layer 35, it is possible to
mutually interpolate the spectral characteristics of
the plasmon absorption layer 32 and the multilayer film
filter layer 35 and reduce the number of required
15 layers of the multilayer film filter layer 35.
[0093] The present technology is not limited to the
above embodiments and can be modified without departing
from the gist of the present technology.
[0094] The plasmon absorption layer described in the
20 above embodiments, that is, the spectral filter using
the plasmon absorbency by the metal nanostructures can
be used for another device other than the chemical
sensor. For example, the plasmon absorption layer can
be used as a spectral filter of a health-care sensor
25 that irradiates a finger of a test subject with
infrared rays and detect a displacement in reflection,
absorption, or the like thereof.
[0095] It should be noted that the present
technology can take the following configuration.
[00961 (1) A chemical sensor, including:
5 a substrate on which a photodetection unit is
formed; and
a plasnon absorption layer laminated on the
substrate, the plasmon absorption layer having a metal
nanostructure that generates plasmon absorbency.
10 [00971 (2) The chemical sensor according to Item
(I), further including
a surface layer laminated on the plasmon
absorption layer, the surface layer having a holding
surface on which a detection target object is held.
15 [0098] (3) The chemical sensor according to Item (1)
or (2), in xhich
the plasmon absorption layer blocks out
illumination light with which the detection taryet
object is irradiated and causes detection target light
20 generated on the detection target object to pass
therethrough.
[0099] (4) The chemical sensor according to any one
of Items (1) to (3), in which
the illumination light is excitation light, and
25 the detection target light is fluorescence.
[OlOO] ( 5 ) The chemical sensor according to any one
of Items (1) to (4), in which
the plasmon absorption layer contains a metal
nanoparticle.
[OlOl] (6) The chemical sensor according to any one
5 of Items (1) to (5), in which
the metal nanoparticle is a particle having a
surface formed of one of pure metal containing at least
one of gold, silver, and copper and an alloy thereof.
[01021 (7) The chemical sensor according to any one
10 of Items (1) to (6), in which
the metal nanoparticle has a particle diameter of
1 nm or more and 150 nm or less.
[01031 (8) The chemical sensor according to any one
of Items (1) to (7), further including
15 a color filter layer laminated between the
substrate and the plasmon absorption layer, the color
filter layer being made of an organic dye-based
material.
[01041 (9) The chemical sensor according to any one
2 0 of Items (1) to (8), further including
a multilayer film filter layer formed by
laminating a plurality of kinds of materials.
[OlOS] (10) The chemical sensor according to any one
of Items (1) to (9), in which
25 the holding surface holds a probe material that is
specifically bound to a target material to be detected.
[01061 (11) The chemical sensor according to any one
of Items (1) to (lo), in which
the probe material is one of DNA, RNA, a protein,
and an antigenic substance.
5 [0107] (12) A chemical sensor module, including:
a chemical sensor including a substrate on which a
photodetection unit is formed, a plasmon absorption
layer laminated on the substrate, and a surface layer
laminated on the plasmon absorption layer, the plasmon
10 absorption layer having a metal nanostructure that
generates plasmon absorbency, the surface layer having
a holding surface on which a detection target object is
held; and
an illumination light source that irradiates the
15 holding surface with illumination light.
[0108] (13) A chemical substance detection
apparatus, including:
a chemical sensor including a substrate or1 whlch a
photodetection unit is formed, a plasmon absorption
20 layer laminated on the substrate, and a surface layer
laminated on the plasmon absorption layer, the plasmon
absorption layer having a metal nanostructure that
generates plasmon absorbency, the surface layer having
a holding surface on which a detection target object is
2 5 held; and
a signal processing circuit that is connected to
the chemical sensor and processes an output signal of
the photodetection unit.
[01091 (14) A chemical substance detection method,
including:
5 preparing a chemical sensor including a substrate
on which a photodetection unit is formed, a piamon
absorption 1,ayer laminated on the substrate, and a
@
surface layer laminated on the plasmon absorption
layer, the plasmon absorption layer having a metal
10 nanostructure that generates plasmon absorbency, the
surface layer having a holding surface on which a
detection target object is held;
causing a probe material to be held on the holding
surface;
15 bringing a sample into contact with the holding
surface and causing a target material contained in the
sample to bind to the probe material to form a
detection target object;
irradiating the holding surface with illumination
20 light; and
detecting, by the photodetection unit, detection
target light generated as a result of bindlng of the
probe material and the target material on the detection
target object upon receiving the illumination light.
25 [OllO] (15) The chemical substance detection method
according to Item (141, in which
the illumination light is excitation light, and
the detection target light is fluorescence.
[Ollll (16) The chemical substance detection method
according to Item (14) or (15), in which
5 in the step of detecting the fluorescence, changes
in wavelength and luminance of the fluorescence caused
by an inter3ction of the target material and the probe
material fluorescently labeled in advance are detected
by the photodetection unit.
10 [0112] (17) The chemical substance detection method
according to any one of Items (14) to (16), in which
in the step of detecting the fluorescence, the
fluorescence generated by the target material that is
fluorescently labeled in advance and is bound to the
15 probe material is detected by the photodetectlon unit.
[0113] (18) The chemical substance detection method
according to any one of Items (14) to (17), in which
in the step of detecting the fluorescence,
fluorescent labelling is performed for a bound body of
20 the probe material and the target material, and the
fluorescence is detected by the photodetection unit
Description of Symbols
[0114]
1 chemical substance detection apparatus
2 5 2 substrate
3 chemical sensor
photodetection unit
protection insulating layer
plasmon absorption layer
surface protection layer
holding surface
color filter layer
multilqyer film filter layer
chemical sensor module
illumination light
10 200 chemical sensor
300 chemical sensor
Claims
[I] A chemical sensor, comprising:
a substrate on which a photodetection unit is
formed; and
5 a plasmon absorption layer laminated on the
substrate, the plasmon absorption layer having a metal
nanostructu:re that generates plasmon absorbency.
[2] The chemical sensor according to claim 1, further
comprising
a surface layer laminated on the plasmon
absorption layer, the surface layer having a holding
surface on which a detection target object is held.
[3] The chemical sensor according to claim 2, wherein
the plasmon absorption layer blocks out
15 illumination light with which the detection target
object is irradiated and causes detection target light
generated on the detection target object to pass
therethrough.
141 The chemical sensor according to claim 3, wherein
20 the illumination light is excitation light, and
the detection target light is fluorescence.
[5] The chemical sensor according to claim 1, wherein
the plasmon absorption layer contains a metal
nanoparticle.
2 5 [ 6 ] The chemical sensor according to claim 5, wherein
the metal nanoparticle is a particle having a
surface formed of one of pure metal containing at least
one of gold, silver, and copper and an alloy thereof.
[71 The chemical sensor according to claim 6, wherein
the metal nanoparticle has a particle diameter of
5 1 nm or more and 150 nm or less.
[ 8 ] The chemical sensor according to claim 1, further
a color filter layer laminated between the
substrate and the plasmon absorption layer, the color
10 filter layer being made of an organic dye-based
material.
[9] The chemical sensor according to claim 1, further
comprising
a multilayer film filter layer 'formed by
15 laminating a plurality of kinds of materials.
[lo] The chemical sensor according to claim 2, wherein
the holding surface holds a probe material that is
specifically bound to a target material to be detected.
[ll] The chemical sensor according to claim 10, wherein
20 the probe material is one of DNA, RNA, a protein,
and an antigenic substance.
[I21 A chemical sensor module, comprising:
a chemical sensor including a substrate on which a
photodetection unit is formed, a plasmon absorption
25 layer laminated on the substrate, and a surface layer
laminated on the plasmon absorption layer, the plasmon
absorption layer having a metal nanostructure that
generates plasmon absorbency, the surface layer having
a holding surface on which a detection target object is
held; and
5 an illumination light source that irradiates the
holding surface with illumination light.
[13] A cheqical substance detection apparatus,
comprising:
a chemical sensor including a substrate on which a
10 photodetection unit is formed, a plasmon absorption
layer laminated on the substrate, and a surface layer
laminated on the plasmon absorption layer, the plasmon
absorption layer having a metal nanostructure that
generates plasmon absorbency, the surface layer having
15 a holding surface on which a detection target object is
held; and
a signal processing circuit that is connected to
the chemical sensor and processes an output signal of
the photodetection unit.
2 0 [ I 4 1 A chemical substance detection method, comprising:
preparing a chemical sensor including a substrate
on which a photodetection unit is formed, a plasmon
absorption layer laminated on the substrate, and a
surface layer laminated on the plasmon absorption
2 5 layer, the plasmon absorption layer having a metal
nanostructure that generates plasmon absorbency, the
surface layer having a holding surface on which a
detection target object is held;
causing a probe material to be held on the holding
surface;
5 bringing a sample into contact with the holding
surface and causing a target material contained in the
sample to b,,ind to the probe material to form a
i
detection target object;
irradiating the holding surface with illumination
10 light; and
detecting, by the photodetection unit, detection
target light generated as a result of binding of the
probe material and the target material on the detection
target object upon receiving the illumination light.
15 [15] The chemical substance detection method according
to claim 14:, wherein
the illumination light is excitation light, and
the detection target light is fluorescence.
[16] The chemical substance detection method according
20 to claim 15, wherein
in the step of detecting the fluorescence, changes
in wavelength and luminance of the fluorescence caused
by an interaction of the target material and the probe
material fluorescently labeled in advance are detected
25 by the photodetection unit.
[17] The chemical substance detection method according
to claim 15, wherein
in the step of detecting the fluorescence, the
fluorescence generated by the target material that is
fluorescently labeled in advance and is bound to the
5 probe material is detected by the photodetection unit.
[I81 The chemical substance detection method according
to claim 15 wherein
in the step of detecting the fluorescence,
fluorescent labelling is performed fdr a bound body of
the probe material and the target material, and the
fluorescence is detected by the photodetection unit.