JP2013019748A - Detection device and detection method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a detection device and a detection method that can shorten a detection time by shortening a time needed to coat an optical device with target molecules.SOLUTION: A detection device 100 includes an optical device 20, a chamber 10 whose capacity is variable, a light source 50 which irradiates the optical device with light, an optical detection part 60 which detects light from the optical device, a driving part 80 which drives the chamber to vary the capacity, and a control part 71 which controls the driving part. The optical device emits the light to be reflected by a fluid sample covering the optical device. The control part has a first mode in which the fluid sample is discharged from the chamber, a second mode in which the fluid sample is sucked into the chamber after the first mode, and a third mode in which the chamber is kept airtight after the second mode and the optical detection part performs detection, the capacity of the chamber being V1 in the first and second modes and V2 (V2<V1) in the airtight state in the third mode.

Description

  The present invention relates to a detection apparatus and a detection method that are particularly suitable for detecting trace substances.

In recent years, as one of highly sensitive spectroscopic techniques for detecting a low concentration of sample molecules, SPR (Surface Plasmon Resonance), particularly SERS (Surface) using LSPR (Localized Surface Plasmon Resonance) is used. Enhanced Raman Scattering (surface enhanced Raman scattering) spectroscopy has attracted attention (Patent Document 1). SERS is a phenomenon in which Raman scattered light is enhanced 10 ² to 10 ¹⁴ times on a metal surface having a nanometer scale uneven structure. A sample molecule is irradiated with excitation light having a single wavelength such as a laser. A scattered wavelength (Raman scattered light) slightly deviated from the wavelength of the excitation light by the amount of molecular vibration energy of the sample molecule is spectrally detected to obtain a fingerprint spectrum of the sample molecule. The sample molecule can be identified from the shape of the fingerprint spectrum.

  According to Patent Document 1, a SERS substrate that is stable not only in a solution but also in the atmosphere is proposed. As a result, sample molecules can be detected even in a gaseous state. However, there is no mention of a method for efficiently detecting a gaseous target molecule in a short time. In other words, it was detected after the target molecule was naturally adsorbed. As an efficient method for analyzing gas molecules, there is a technique disclosed in Patent Document 2.

Japanese Patent No. 3714671 Special table 2003-521688 gazette

  However, in Patent Document 2, gas is compressed and supplied to a column (tube), and since it is assumed that gas passes through the column, there is a limit to shortening the detection work time.

  Accordingly, some aspects of the present invention have an object to provide a detection apparatus and a detection method capable of reducing the detection time by reducing the time for which the target molecule covers the optical device.

(1) One aspect of the present invention is
An optical device;
A chamber in which a volume of a space in which the optical device is arranged is variable;
A light source for irradiating the optical device with light;
A light detection unit for detecting light emitted from the optical device;
A drive unit that variably drives the volume of the chamber;
A control unit for controlling the driving unit;
Have
The optical device emits light reflecting a fluid sample covering the optical device;
The control unit includes a first mode for discharging the fluid sample from the chamber, a second mode for sucking the fluid sample into the chamber after the first mode, and the chamber in an airtight state after the second mode. In the first mode and the second mode, the volume of the chamber is set to V1, and in the third mode, the volume of the chamber made airtight is set to V2 (V2 <V1). ).

  According to one aspect of the present invention, the time t at which the optical device reaches a predetermined coverage covered by the fluid sample is inversely proportional to the collision frequency Z of the fluid sample molecules, and the collision frequency Z is the fluid sample in the chamber. We focused on the fact that it is proportional to the partial pressure P. In the third mode, which is detected by the light detection unit in order to increase the partial pressure P of the fluid sample in the chamber, the chamber is hermetically sealed and the volume of the chamber is set when the chamber is opened in the first and second modes. A volume V2 (V2 <V1) smaller than the chamber volume V1 (at the time of suction and discharge of the fluid sample) was set. Thereby, in the third mode, the time t for the optical device to be covered with the fluid sample to reach a predetermined coverage is shortened, and thus the detection time can be shortened.

  (2) In one aspect of the present invention, the optical device generates Raman scattered light of the fluid sample, and the light detection unit detects Raman scattered light of a substance to be inspected that may exist in the fluid sample. can do. Raman scattered light is an example of a signal reflecting a substance to be inspected, and the presence or absence of the substance to be inspected can be determined in a fluid sample.

  (3) In 1 aspect of this invention, the said optical device can be equipped with the metal nanostructure which has a 1-1000 nm convex part. In this way, an enhanced electric field is formed around the convex portion of the metal nanostructure, and the signal intensity of Raman scattered light enhanced by the enhanced electric field is increased.

  (4) In an aspect of the present invention, the chamber further includes a suction drive unit that sucks the fluid sample, and the control unit sucks the fluid sample on the optical device in the first mode. In the second mode, the suction flow rate of the fluid sample on the optical device can be set to v2 (v2 <v1).

Thus, in the first mode, since the flow velocity v1 is set to be relatively fast, the fluid sample that is covered with or adsorbed to the optical device can be desorbed, and the first mode can be referred to as the desorption mode. . In the second mode, a fluid sample sucked at a relatively slow flow velocity v2 can be coated or adsorbed with an optical device, and the second mode can also be referred to as an adsorption mode. Note that the third mode can be referred to as a detection mode. As described above, when the first mode, the second mode, and the third mode are alternately repeated, the fluid sample once adsorbed to the optical device can be desorbed. it can. In this way, the optical device can be cleaned up after detection, and the next inspection can be repeatedly performed without leaving the influence of the previous detection. Therefore, real-time inspection can be performed by alternately repeating the first, second, and third modes. In addition, since the optical device can be cleaned up after detection, it can be reliably determined whether or not the substance to be inspected in the fluid sample is present at a predetermined concentration or higher.

  (5) In one aspect of the present invention, the modes can be switched in the order of the first mode, the second mode, and the third mode periodically at a predetermined time. Thereby, continuous measurement can be performed and detection can be realized in a short period.

  (6) In one aspect of the present invention, the control unit can switch between the first, second, and third modes based on a signal level from the light detection unit. In the first, second, and third modes, the change in the amount of the fluid sample that is coated or adsorbed on the optical device is different, so the first, second, and third modes are switched based on the signal level from the light detection unit. , Can continuously measure periodically.

  (7) In one aspect of the present invention, the control unit switches from the first mode to the second mode when the signal level is equal to or lower than a first threshold, and the signal level is higher than the first threshold. Switch from the second mode to the third mode when the second threshold is reached or higher, and switch from the third mode to the first mode when the signal level is higher than the third threshold higher than the second threshold. be able to. This is because, in the first, second, and third modes, changes in the amount of the fluid sample that is coated or adsorbed on the optical device are different.

  (8) In one aspect of the present invention, the chamber includes an expansion / contraction part that expands and contracts while a part of the chamber wall is maintained in an airtight state, and the drive unit expands and contracts the expansion / contraction part to change the volume of the chamber. It can be. Examples of this type of stretchable part include bellows and elastic bodies such as rubber.

(9) Another aspect of the present invention is:
A first step of opening a chamber in which the optical device is disposed and discharging a fluid sample from the chamber;
A second step of sucking a fluid sample into the chamber;
A third step in which the chamber into which the fluid sample has been introduced is hermetically sealed, the optical device is irradiated with light, and the light emitted from the optical device is detected;
Have
It relates to a detection method in which the chamber volume is set to V1 in the first step and the second step, and the chamber volume is set to V2 (V2 <V1) in the third step.

  In another aspect of the present invention, the time for the third step can be shortened and the detection time can be shortened in the same manner as in one aspect of the present invention.

It is a figure which shows the outline | summary of the detection apparatus which concerns on one Embodiment of this invention. 2A and 2B are characteristic diagrams showing the chamber volume and the velocity of the fluid sample in the first to third modes. It is a figure for demonstrating the parameter when a chamber volume is changed. It is a characteristic view which shows transition of SERS intensity | strength in the 1st-3rd mode. 5A is an enlarged cross-sectional view of the suction portion and the optical device, and FIGS. 5B and 5C are a cross-sectional view and a plan view showing formation of an enhanced electric field in the optical device. It is a characteristic view which shows the Raman shift of a dimethyl sulfide. It is a characteristic view which shows the exposure time dependence of the coverage which made the chamber volume change the parameter. FIGS. 8A and 8B are schematic explanatory diagrams showing how the SERS signal is generated in the first, second mode, and third mode. It is a block diagram which shows the whole outline | summary of an inspection apparatus. It is a control system block diagram of an inspection apparatus. It is a schematic explanatory drawing of the optical device used for surface enhancement infrared spectroscopy. FIG. 12 is a characteristic diagram of infrared rays incident on the optical device of FIG. 11. It is a characteristic view of the infrared rays reflected by the optical device of FIG.

  Hereinafter, preferred embodiments of the present invention will be described in detail. The present embodiment described below does not unduly limit the contents of the present invention described in the claims, and all the configurations described in the present embodiment are indispensable as means for solving the present invention. Not necessarily.

1. Basic Configuration of Detection Device FIG. 1 shows a configuration example of a detection device according to this embodiment. In FIG. 1, the detection apparatus 100 includes a chamber 10, an optical device 20, a light source 50, a light detection unit 60, a control unit 71, and a drive unit 80. The chamber 10 has a variable volume of a space in which the optical device 20 is disposed. For this reason, the chamber 10 has an expansion / contraction part such as a bellows or an elastic body (for example, rubber material) 11 in which a part of the chamber wall part expands and contracts. The chamber 10 includes an intake valve 12 and an exhaust valve 13, and is set to each of open / airtight states by driving the valves 12 and 13 under the control of the control unit 71. The light source 50 irradiates the optical device 20 with light. The light detection unit 60 detects light emitted from the optical device 20. The drive unit 80 variably drives the bellows 11 based on the control of the control unit 71 to variably drive the volume of the chamber 10. The optical system 30 can be provided between the optical device 20 and the light source 50 and / or the light detection unit 60. Further, a suction drive unit such as a fan 40 can be provided on the exhaust side of the chamber 10.

  The optical device 20 emits light reflecting the adsorbed fluid sample when irradiated with light from the light source 50. In this embodiment, the fluid sample is, for example, the atmosphere, and the substance to be inspected can be a specific gas molecule (sample molecule) in the atmosphere, but is not limited thereto.

  A fan 40 that is a suction drive unit sucks the fluid sample into the chamber 10. The light source 50 irradiates the optical device 20 with light through, for example, the half mirror 320 and the objective lens 330 that constitute the optical system 30. The light detection unit 60 detects light reflecting the fluid sample adsorbed on the optical device 20 via the half mirror 320 and the objective lens 330.

2. Control Mode The control unit 71 has first, second, and third modes shown in FIGS. 2A and 2B as control modes. The first mode is a mode for discharging the fluid sample from the chamber 10 and is also referred to as a first step. The second mode is a suction mode in which a fluid sample is sucked into the chamber 10 after the first mode, and is also referred to as a second step. The third mode is a detection mode in which the chamber 20 is set in an airtight state after the second mode and is detected by the light detection unit 60, and is also referred to as a third step. The control unit 71 can also perform switching control between the first, second, and third modes shown in FIG. 2 based on the signal from the light detection unit 60.

2.1. Variable control of chamber volume The control unit 71 controls the drive unit 80 to expand and contract the bellows 11, so that the volume of the opened chamber 10 is set to V1 in the first and second modes, and airtight in the third mode. The volume of the chamber 10 brought into the state is set to V2 (V2 <V1). By doing so, the time required for the optical device 20 to be coated with the sample fluid at a predetermined coverage or higher in the third mode and the fluid sample to be adsorbed by the optical device 20 is shortened, thereby shortening the detection time. ing. The reason will be described below.

Usually, the collision frequency Z (number / m ² · sec) of gas molecules to the surface is expressed as follows.

Here, P is the partial pressure [Pa] of the gas, m is the mass [kg] of one molecule, and in the formula (1), m = molecular weight M (g / mol) / NA (Avogadro coefficient: 6 × 10 ²³ Pieces / mol). KB is Boltzmann's constant [1.38e ⁻²³ J / mol], and T is absolute temperature [K]. Since the molecular adsorption probability is given by the product of Z and the adsorption probability, one method for efficiently adsorbing molecules to the sensor surface is to increase the collision frequency Z. In this embodiment, the partial pressure P of the molecule is increased by contracting the volume V of the chamber 10 from V1 to V2 in the third mode (third process), and as a result, the increase of the collision frequency Z is promoted. ing.

Next, as shown in FIG. 3, the partial pressure P1 of the molecule can be increased to the partial pressure P2 by contracting the volume V of the chamber 10 from V1 to V2. First, from the respective state equations in the two states shown in FIG.
P1 × V1 = nRT1 (2)
P2 × V2 = nRT2 (3)
Is established.

When the volume change is performed slowly, the heat is naturally dissipated at the time of volume contraction, and T1≈T2, so when the equations (2) and (3) are transformed,
P2 / P1 = V1 / V2 (4)
It becomes. Here, since V1> V2, P2 / P1 = V1 / V2> 1 and
P2> P1 (5)
It can be seen that That is, by contracting the volume V of the chamber 10 from V1 to V2, the molecular partial pressure P1 can be increased to the partial pressure P2. Thereby, it turns out that the collision frequency Z can be enlarged from Formula (1).

と表される。初期吸着確率s₀は、例えば１００個の分子が表面に衝突し、そのうち５０個の分子が吸着した場合０．５となる。この微分方程式を被覆率（占有率）θについて解くと以下のようになる。

Next, the adsorption phenomenon will be explained kinetically. According to the adsorption model called Langmuir type, the adsorption speed r is time t, for example, the coverage (occupancy) θ of the adsorption site on the metal surface of the optical device 20 and the collision frequency Z.

It is expressed. The initial adsorption probability s ₀ is 0.5, for example, when 100 molecules collide with the surface and 50 molecules are adsorbed. Solving this differential equation with respect to coverage (occupancy) θ yields the following.

となり、時間ｔは衝突頻度Ｚに反比例することが分かる。単純に衝突頻度Ｚが２倍になれば同じ被覆率に到達する時間ｔは半分になることが分かる。衝突頻度Ｚは式（１）により、気体分圧Ｐ［Ｐａ］に比例する。そのため、分圧Ｐを増加させることで、衝突頻度Ｚを増加させ、時間ｔを短縮できることが分かる。 That is, in order to increase the adsorption speed r, it is important to increase the collision frequency Z. The collision frequency Z is the number of collision molecules per unit [per unit / m ² · sec] to a unit surface area of a certain gas molecule, and is represented by the formula (1). When the equation (7) is transformed with respect to time t,

Thus, it can be seen that the time t is inversely proportional to the collision frequency Z. It can be seen that if the collision frequency Z is simply doubled, the time t to reach the same coverage will be halved. The collision frequency Z is proportional to the gas partial pressure P [Pa] according to the equation (1). Therefore, it can be seen that by increasing the partial pressure P, the collision frequency Z can be increased and the time t can be shortened.

2.2. Fluid Sample Aspiration Speed Control FIG. 2B shows a change in the aspiration rate of the fluid sample on the optical device 20 in the first, second, and third modes described above. In the present embodiment, in order to set the first, second, and third modes described above, the control unit 71 controls the drive of the fan 40 that is a suction drive unit, and performs the first, second, and third modes. The suction speed (the amount of gas transport per unit time) of the fluid sample can be controlled. However, in the third mode, the valves 12 and 13 in FIG. 1 are closed by the control unit 71 and the chamber 10 is sealed, so that the suction speed of the fluid sample on the optical device 20 (regardless of the driving of the fan 40 ( Or the amount of gas transport per unit time) is zero.

  In the first mode, the control unit 71 sets the suction flow velocity (gas transport amount per unit time) v of the fluid sample on the optical device 20 to the maximum velocity v1 (ml / min), and the suction flow velocity v2 (ml / min) in the second mode. v2> v1), and in the third mode, the suction speed v3 is zero. For example, it can be set to v2 = 1000 ml / sec. The suction drive unit 40 functions as a negative pressure generating unit that generates a negative pressure in the chamber 10. The suction drive unit (negative pressure generating unit) 40 is not limited to a fan, and any pump that can generate a negative pressure by the suction drive unit 40 such as a tube pump or a diaphragm pump can be used. . The suction speed may be controlled for the fan 40 as described above, or the opening area of the valve or shutter may be changed. It is only necessary that the suction speed of the fluid sample on the optical device 20 can be varied as a result of the control.

  In the present embodiment, in the first mode (desorption mode), the flow velocity v1 is set higher than the flow velocity v2 in the second mode (adsorption mode). Therefore, in the first mode, the fluid sample previously adsorbed to the optical device 20 can be desorbed. In the second mode (adsorption mode), a fluid sample sucked at a relatively slow flow velocity v2 can be adsorbed to the optical device 20. In the third mode (detection mode) in which the chamber 20 is sealed, the flow velocity v3 is zero, but as described above, the volume of the chamber 10 is contracted to increase the coverage. At this time, when the optical device 20 is irradiated with light from the light source 30, light reflecting the fluid sample adsorbed on the optical device 20 is generated. The light detection unit 60 can detect light from the optical device 20.

  As described above, when the first, second, and third modes are alternately performed, the fluid sample once adsorbed to the optical device 20 can be desorbed before detection. Thus, the optical device 20 can be cleaned up after the inspection, and the next inspection can be repeatedly performed without leaving the influence of the previous inspection.

  Here, the flow rates v1, v2, and v3 in the first to third modes are the flow rates of the fluid sample on the optical device 20 (the amount of gas transport per unit time), and the fan 40 is set so that the flow rates v1 and v2 are obtained. Is driven. At that time, when the first and second modes are alternately repeated, the driving of the fan 450 in the second mode may be stopped. In this case, the flow velocity v2 (v2 ≠ 0) of the fluid sample on the optical device 20 can be ensured using the air volume and inertia in the second mode.

2.3. Switching Control of First to Third Modes Switching of the first, second, and third modes can be performed based on the output of the light detection unit 60. This is because the light detection signal changes between the first, second, and third modes due to the desorption, adsorption, or increase in the coverage of the fluid sample. FIG. 4 shows a change in the SERS intensity of the sample molecule to be examined in the fluid sample, for example, as the output of the light detection unit 60 at time 0 to T2. In the first mode starting from time 0, the sample molecules adsorbed on the optical device 20 are desorbed, so that the SERS intensity decreases in the first mode. Therefore, it is possible to switch from the first mode to the second mode at time T0 when the SERS intensity falls below the first threshold value I1 shown in FIG.

  Next, in the second mode, the number of sample molecules adsorbed on the optical device 20 gradually increases. Therefore, the SERS intensity increases in the second mode. Therefore, it is possible to switch from the second mode to the third mode at time T1 when the SERS intensity exceeds the second threshold value I2 (I2> I1) shown in FIG.

  Next, in the third mode, the coverage increases due to the volume contraction of the chamber 10, and the sample molecules adsorbed on the optical device 20 increase relatively rapidly. Accordingly, the SERS intensity is further increased in the third mode than in the second mode. Therefore, at the time T2 when the SERS intensity exceeds the third threshold value I3 (I3> I2) shown in FIG. 3, the detection mode can be terminated and the 32nd mode can be switched to the first mode.

  The SERS intensity is a value based on the number of photons received by the light receiving element of the light detection unit 60 shown in FIG. For example, the first threshold value I1 = 10 counts (noise level), the second threshold value I2 = 30 counts, and the third threshold value I3 = 1000 counts (peak count) can be set.

  In the present embodiment, the mode can be periodically switched from the first mode → the second mode → the third mode → the first mode →... At a predetermined time. Thereby, continuous measurement can be performed and detection can be realized in a short period. For example, in FIG. 2, T0 = 30 sec, T1 = 40 sec, and T2 = 60 sec. In this case, the presence or absence of the target molecule can be examined with high reliability in a short period of 60 sec.

3. Example of Light Detection Principle and Structure An explanatory diagram of the principle of detection of Raman scattered light is shown as an example of a light detection principle reflecting a fluid sample with reference to FIGS. 5 (A) to 5 (C). As shown in FIG. 5A, incident light (frequency ν) is irradiated to the sample molecule 1 to be inspected that is adsorbed to the optical device 20. In general, most of the incident light is scattered as Rayleigh scattered light, and the frequency ν or wavelength of the Rayleigh scattered light does not change with respect to the incident light. Part of the incident light is scattered as Raman scattered light, and the frequency (ν−ν ′ and ν + ν ′) or wavelength of the Raman scattered light reflects the frequency ν ′ (molecular vibration) of the sample molecule 1. That is, the Raman scattered light is light reflecting the sample molecule 1 to be inspected. A part of the incident light causes the sample molecule 1 to vibrate and loses energy, but the vibration energy of the sample molecule 1 may be added to the vibration energy or light energy of the Raman scattered light. Such a frequency shift (ν ′) is called a Raman shift.

  FIG. 5B is an enlarged view of the optical device 20 of FIGS. 1 and 5A. As shown in FIG. 5A, when incident light is incident from the flat surface of the substrate 200, a material transparent to the incident light is used for the substrate 200. The optical device 20 has a plurality of convex portions 210 made of a dielectric as a first structure on the substrate 200. In this embodiment, a resist is formed on a substrate 200 made of glass such as quartz, quartz, borosilicate glass or silicon as a dielectric transparent to incident light, and the resist is, for example, far ultraviolet ( DUV) patterning using photolithography. By etching the substrate 200 with the patterned resist, for example, a plurality of convex portions 210 are two-dimensionally arranged as shown in FIG. In addition, you may form the board | substrate 200 and the convex part 210 with a different material.

  As the second structure on the plurality of protrusions 210, metal nanoparticles (metal fine particles) 220 such as Au or Ag are formed on the plurality of protrusions 210, for example, by vapor deposition, sputtering, or the like. As a result, the optical device 20 can have a metal nanostructure having a protrusion of 1 to 1000 nm. In addition to processing the upper surface of the substrate 200 to have a convex structure of the size (with a substrate material), the metal nanostructure having a convex portion of 1 to 1000 nm is formed by depositing metal fine particles of the size on the substrate. It can also be formed by a method such as fixing by sputtering or forming a metal film having an island structure on the substrate.

  As shown in FIGS. 5B and 5C, in the region 240 where the incident light is incident on the two-dimensional pattern of the metal nanoparticles 220, an enhanced electric field is formed in the gap G between the adjacent metal nanoparticles 220. 230 is formed. In particular, when the incident light is irradiated onto the metal nanoparticles 220 smaller than the wavelength of the incident light, the electric field of the incident light acts on free electrons existing on the surface of the metal nanoparticles 220 to cause resonance. Thereby, electric dipoles due to free electrons are excited in the metal nanoparticles 220, and an enhanced electric field 230 stronger than the electric field of incident light is formed. This is also called Localized Surface Plasmon Resonance (LSPR). This phenomenon is a phenomenon peculiar to an electric conductor such as the metal nanoparticle 220 having a convex portion of 1 to 1000 nm smaller than the wavelength of incident light.

  5A to 5C, surface enhanced Raman scattering (SERS) occurs when the optical device 20 is irradiated with incident light. That is, when the sample molecule 1 enters the enhanced electric field 230, the Raman scattered light from the sample molecule 1 is enhanced by the enhanced electric field 230, and the signal intensity of the Raman scattered light becomes strong. In such surface-enhanced Raman scattering, the detection sensitivity can be increased even if the amount of sample molecules 1 is very small.

  The phenomenon of “adsorption” of the sample molecule 1 described below is a phenomenon in which the number (partial pressure) of collision molecules with which the sample molecule 1 collides with the metal nanoparticles 220 is dominant. Includes one or both. “Desorption” means releasing adsorption by an external force. The adsorption energy depends on the kinetic energy of the sample molecule 1, and when it exceeds a certain value, it collides and exhibits an “adsorption” phenomenon, and no external force is required for the adsorption. On the other hand, external force is required for detachment. In addition, sucking the fluid sample into the optical device 20 is, in other words, bringing the fluid sample into contact with the optical device 20 by generating a suction flow in the flow path in which the optical device 20 is disposed. .

FIG. 6 shows the results of actual measurement using dimethyl sulfide (DMS) molecules. The SERS spectrum of dimethyl sulfide has a sharp peak at 676 cm ⁻¹ . The DMS molecule is adsorbed in the LSPR enhanced electric field and the SERS signal is detected. In order to obtain a stable SERS signal, when the adsorption coverage is set to 0.5 or more, for example, 0.6 as a threshold value, when there is no volume shrinkage (V2 = V1), as shown in FIG. It takes 6 seconds or more. In order to shorten the detection time, it is important to adsorb efficiently.

  Therefore, the volume V1 in the first and second modes shown in FIG. 8A is contracted to the volume V3 in the third mode as shown in FIG. 8B. This increases the partial pressure of the sample molecule 1 and increases the SERS intensity as shown in FIG. 8 (B). In fact, as shown in FIG. 7, when the volumetric contraction is V2 = V1 / 2, it takes 4 seconds to reach the threshold 0.6, and when the volumetric contraction is V2 = V1 / 4, it reaches less than 2 seconds to reach the threshold 0.6. Shortened to Thus, the characteristics of FIG. 7 reflect the above-described equations (1) to (8).

4). Specific Configuration of Detection Device FIG. 9 shows a specific configuration example of the detection device of the present embodiment. 9 also includes a processing unit including the chamber 10, the optical device 20, the optical system 30, the suction drive unit 40, the light source 50, the light detection unit 60, and the control unit 71 illustrated in FIG. 70 (omitted in FIG. 9) and a drive unit 80.

  In FIG. 9, the light source 50 is, for example, a laser, and a vertical cavity surface emitting laser can be preferably used from the viewpoint of miniaturization, but is not limited thereto.

  The light from the light source 50 is collimated by the collimator lens 310 constituting the optical system 30. A polarization control element may be provided downstream of the collimator lens 310 and converted to linearly polarized light. However, if, for example, a surface emitting laser is employed as the light source 50 and light having linearly polarized light can be emitted, the polarization control element can be omitted.

  The light collimated by the collimator lens 310 is guided by the half mirror (dichroic mirror) 320 toward the optical device 20, collected by the objective lens 330, and incident on the optical device 20. In the optical device 20, metal nanoparticles 220 shown in FIGS. 5A to 5C are formed. Rayleigh scattered light and Raman scattered light by, for example, surface-enhanced Raman scattering are emitted from the optical device 20. Rayleigh scattered light and Raman scattered light from the optical device 20 pass through the objective lens 330 and are guided toward the light detection unit 60 by the half mirror 320.

  Rayleigh scattered light and Raman scattered light from the optical device 20 are collected by the condenser lens 340 and input to the light detection unit 60. First, the light detection unit 60 reaches the optical filter 610. Raman scattered light is extracted by an optical filter 610 (for example, a notch filter). This Raman scattered light is further received by the light receiving element 630 via the spectroscope 620. The spectroscope 620 is formed of, for example, an etalon using Fabry-Perot resonance, and the pass wavelength band can be made variable. The wavelength of light passing through the spectroscope 620 can be controlled (selected) by the control unit 71. The light receiving element 630 obtains a Raman spectrum peculiar to the sample molecule 1, and the sample molecule 1 can be specified by collating the obtained Raman spectrum with previously stored data.

  The chamber 10 includes a suction channel 14B connected to the suction port 14A and a discharge channel 15B connected to the discharge port 15A. The fluid sample including the sample molecule 1 is introduced into the chamber 10 through the suction port 14A (carrying-in port), and is discharged out of the chamber 10 through the discharge port 15A. A dust filter 14C can be provided on the suction port 14A side. In FIG. 9, the detection device 10 has the fan 40 in the vicinity of the discharge port 15 </ b> A, and when the fan 40 is operated, the pressure (atmospheric pressure) in the chamber 10 decreases. Thereby, the fluid sample is sucked into the chamber 10 together with the sample molecule 1. The fluid sample passes through the suction channel 14B and is discharged from the discharge channel 15B via the channel near the optical device 20. At this time, a part of the sample molecule 1 is adsorbed on the surface (electrical conductor) of the optical device 20.

  The sample molecule 1 that is a test target substance can be assumed to be a rare molecule such as narcotics, alcohol or residual agricultural chemicals, or a pathogen such as a virus. In particular, this embodiment detects these sample molecules 1 in real time. Suitable for doing.

  FIG. 10 is a control system block diagram of the detection apparatus 10 of FIG. As illustrated in FIG. 10, the detection apparatus 100 may further include, for example, an interface 120, a display unit 130, an operation unit 140, and the like. Further, as shown in FIG. 10, the processing unit 70 can include, for example, a CPU (Central Processing Unit) 71, a RAM (Random Access Memory) 72, a ROM (Read Only Memory) 73, and the like as control units. Furthermore, the detection apparatus 10 can include, for example, a bulb driver 16, a light source driver 52, a spectral driver 622, a light receiving circuit 632, and a fan driver 452. The processing unit 70 can send commands to the light detection unit 60 other than the light source 50 shown in FIG. Furthermore, the processing unit 70 can execute spectroscopic analysis using a Raman spectrum, and the processing unit 70 can specify the sample molecule 1 that is a target. Note that the processing unit 70 can transmit the detection result by Raman scattered light, the spectroscopic analysis result by Raman spectrum, and the like to an external device (not shown) connected to the communication connection unit 90, for example.

5. Other Modifications Although the present embodiment has been described in detail as described above, those skilled in the art can easily understand that many modifications that do not substantially depart from the novel matters and effects of the present invention are possible. .

The present invention is not limited to detecting SERS intensity. For example, surface enhanced infrared spectroscopy (SEIRAS) can be used. In this case, the optical device 20 shown in FIG. 1 or FIG. 9 is replaced with the optical device 170 shown in FIG. In this optical device 170, for example, a metal thin film 172 is formed on the bottom surface of a right-angle prism 171. The right-angle prism 171 is made of a material that transmits infrared rays, such as CaF ₂ . The material of the metal thin film 172 may be a metal thin film such as Ag or Cu.

  A P-polarized infrared ray IR1 having the characteristics shown in FIG. 12 is reflected by, for example, the first reflecting mirror 180 and is incident on the optical device 170 at an angle θ with respect to the normal L of the metal thin film 172. In the reflected infrared IR2 obtained by totally reflecting the incident infrared IR1 with the metal thin film 172, there is an evanescent wave reflected at a position slightly recessed from the interface to the sample side, so that the spectrum of the sample molecule or the standard molecule is obtained. It can be measured. The characteristic of this reflected infrared ray IR2 is shown in FIG. The reflected infrared ray IR2 is reflected by the second reflecting mirror 181 and is incident on the light detection unit 60 shown in FIG.

  DESCRIPTION OF SYMBOLS 10 Chamber, 11 Expansion-contraction part, 12, 13 Valve, 20,170 Optical device, 30 Optical system, 40 Suction drive part (fan), 50 Light source, 60 Light detection part, 70 Processing part, 71 CPU (control part), 80 Drive unit, 100 detection device, V1, V2 chamber volume, v1, v2 flow velocity (transportation amount), I1 first threshold, I2 second threshold, I3 third threshold

Claims (9)

An optical device;
A chamber in which a volume of a space in which the optical device is arranged is variable;
A light source for irradiating the optical device with light;
A light detection unit for detecting light emitted from the optical device;
A drive unit that variably drives the volume of the chamber;
A control unit for controlling the driving unit;
Have
The optical device emits light reflecting a fluid sample covering the optical device;
The control unit includes a first mode for discharging the fluid sample from the chamber, a second mode for sucking the fluid sample into the chamber after the first mode, and the chamber in an airtight state after the second mode. In the first mode and the second mode, the volume of the chamber is set to V1, and in the third mode, the volume of the chamber made airtight is set to V2 (V2 <V1). ). In claim 1,
The optical device generates Raman scattered light of the fluid sample;
The light detection unit detects Raman scattered light of a substance to be inspected that may exist in the fluid sample. In claim 2,
The said optical device is equipped with the metal nanostructure which has a convex part of 1-1000 nm, The detection apparatus characterized by the above-mentioned. In any one of Claims 1 thru | or 3,
The chamber further has a suction drive unit for sucking the fluid sample,
In the first mode, the control unit sets the suction flow rate of the fluid sample on the optical device to v1, and in the second mode, sets the suction flow rate of the fluid sample on the optical device to v2 (v2 <v v1) is set as a detection device. In claim 4,
The control unit switches the mode in order of the first mode, the second mode, and the third mode periodically at predetermined time intervals. In claim 4,
The control unit switches the first, second, and third modes based on a signal level from the light detection unit. In claim 6,
The control unit switches from the first mode to the second mode when the signal level becomes equal to or lower than a first threshold, and when the signal level becomes equal to or higher than a second threshold higher than the first threshold. 2. A detection apparatus, wherein the mode is switched from the second mode to the third mode, and the mode is switched from the third mode to the first mode when the signal level becomes a third threshold value higher than the second threshold value. In any one of Claims 1 thru | or 7,
The chamber includes an expansion / contraction part in which a part of the chamber wall extends and contracts while maintaining an airtight state,
The detection device characterized in that the drive unit expands and contracts the expansion and contraction unit to make the volume of the chamber variable. A first step of opening a chamber in which an optical device is disposed and sucking and discharging a fluid sample from the chamber;
A second step in which the chamber into which the fluid sample is introduced is hermetically sealed, the optical device is irradiated with light, and the light emitted from the optical device is detected;
Have
In the first step of the first period, the volume of the chamber is set to V1, and in the second step, the volume of the chamber is set to V2 (V2 <V1), and the first and second steps are based on a signal from the light detection unit. A detection method characterized by switching.

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