JP2010185772A - Sensor element and sensor device including the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sensor element capable of improving the detection sensitivity of objects. <P>SOLUTION: The sensor element includes an oscillator 2. The oscillator 2 includes a substrate 21 and a metal thin film 22. The substrate 21 is made of glass. The metal thin film 22 is made of Pt or Au and has a film thickness of 10-100 nm. The oscillator 2 is resonated by laser beams applied from the side of the substrate 21. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a sensor element and a sensor device including the sensor element, and more particularly to a sensor element using a metal thin film and a sensor device including the sensor element.

  Conventionally, there is known a resonance vibrator mass detection device that detects a detection target by detecting a change in an acoustic amount such as a resonance frequency of a piezoelectric vibrator wirelessly without using an electrode (Patent Document 1).

  The resonance vibrator mass detection apparatus includes a piezoelectric vibrator, a sample supply unit, an electric field supply unit, and a signal analysis unit. The electric field supply means has an input means for inputting a voltage and a receiving means for receiving the vibration of the piezoelectric vibrator.

  The piezoelectric vibrator vibrates due to the piezoelectric effect when an oscillating electric field is applied. The sample supply means supplies a sample material to the surface of the piezoelectric vibrator. The input means of the electric field supply means inputs a voltage and applies the oscillating electric field to the piezoelectric vibrator. The receiving means of the electric field supply means receives the vibration of the piezoelectric vibrator. The signal analysis unit detects a detection target by detecting a change in an acoustic amount such as a resonance frequency caused by the detection target attached to the piezoelectric vibrator based on the vibration of the piezoelectric vibrator received by the receiving unit. .

  The sensitivity of the resonance vibrator mass detection device is inversely proportional to the square of the thickness of the piezoelectric vibrator.

JP 2008-26099 A

  However, in a conventional resonant vibrator mass detection device using a piezoelectric vibrator, it is difficult to reduce the thickness of the piezoelectric vibrator to several tens of μm in order to maintain mechanical strength. There was a problem that the sensitivity of the mass detector was low.

  Accordingly, the present invention has been made to solve such a problem, and an object thereof is to provide a sensor element capable of improving sensitivity.

  Another object of the present invention is to provide a sensor device including a sensor element capable of improving sensitivity.

  According to this invention, the sensor element includes the vibrator and the holding member. The holding member has an opening for holding the vibrator and irradiating the vibrator with laser light. The vibrator includes a first metal thin film or a substrate and a first metal thin film. The first metal thin film is formed on the substrate and has a surface on which a protein supplementing the detection target is fixed, and vibrates when irradiated with laser light.

  Preferably, the first metal thin film is formed in contact with the substrate. Alternatively, a part of the substrate is removed and the part vibrates.

  Preferably, the vibrator further includes a second metal thin film. The second metal thin film is formed on the surface opposite to the surface of the substrate on which the first metal thin film is formed.

  Preferably, the vibrator further includes a second metal thin film. The second metal thin film is formed in a partial region on the surface opposite to the surface of the substrate on which the first metal thin film is formed. The distance between the first metal thin film and the second metal thin film is smaller than the thickness of the substrate.

  Preferably, the second metal thin film is made of a metal different from the first metal thin film.

  Preferably, the substrate is made of an insulator or a semiconductor.

  Preferably, the vibrator further includes a thin film. The thin film is disposed between the substrate and the first metal thin film, and is formed in contact with the substrate and the first metal thin film. The substrate further includes an opening formed in the thickness direction of the substrate and exposing a part of the surface opposite to the contact surface of the thin film with the first metal thin film.

  Preferably, the thin film is made of an insulator or a semiconductor.

  Preferably, the first metal thin film is composed of a plurality of metal thin film pieces.

  Preferably, the first metal thin film is made of a metal resistant to acids.

  Preferably, the sensor element further includes a protein immobilized on the surface of the first metal thin film.

  According to the invention, the sensor device includes a sensor element, first and second light sources, and a detector. The sensor element supplements the detection object. The first light source irradiates the sensor element with excitation light composed of laser light. The second light source irradiates the sensor element with probe light including laser light. The detector receives the reflected light of the probe light from the sensor element, detects the acoustic amount of the sensor element based on the received reflected light, and detects the detection object based on the detected variation in the acoustic amount. A sensor element consists of a sensor element given in any 1 paragraph of Claims 1-11. The first and second light sources irradiate the sensor element with excitation light and probe light from the opposite side of the first metal thin film, respectively.

  The sensor element according to the present invention includes a vibrator held by a support member, and the vibrator includes a first metal thin film formed on a substrate. The first metal thin film vibrates by irradiation with laser light, and if the detection target adheres to the first metal thin film, the acoustic response such as the resonance frequency fluctuates. Therefore, the resonance frequency in the first metal thin film It is possible to detect that the object to be detected has adhered to the first metal thin film by detecting the fluctuation of the acoustic response using the laser beam. In addition, the fluctuation of the acoustic response such as the resonance frequency when the first metal thin film vibrates is inversely proportional to the square of the film thickness of the first metal thin film. In the sensor element according to the present invention, the first metal thin film is Since it is formed on the substrate, the thickness of the first metal thin film can be reduced.

  Therefore, according to this invention, the sensitivity at the time of detecting a detection target object can be improved.

It is a side view of the sensor element by embodiment of this invention. It is a top view of the supporting member seen from the A direction shown in FIG. It is a top view of the supporting member seen from the B direction shown in FIG. FIG. 4 is a cross-sectional view of the support member between line IV-IV shown in FIG. 3. It is a top view of the supporting member seen from the A direction shown in FIG. FIG. 6 is a cross-sectional view of the support member between line VI and VI shown in FIG. 5. FIG. 2 is a cross-sectional view of the vibrator illustrated in FIG. 1. It is a figure which shows the measurement result of a pulse echo. It is a figure which shows the measurement result of an acoustic phonon resonance vibration. It is a figure which shows a spectrum when the spectrum shown in FIG. 9 is Fourier-transformed. It is a conceptual diagram of the Brillouin vibration method. It is a figure which shows the example of a measurement of Brillouin vibration. It is a figure for demonstrating the detection method of the detection target object using the sensor element shown in FIG. It is a figure which shows the measurement example of the vibration in the metal thin film of the sensor element shown in FIG. It is the schematic of the sensor apparatus by embodiment of this invention. It is sectional drawing which shows another vibrator | oscillator. FIG. 17 is a waveform diagram showing vibrations of the vibrator shown in FIG. It is a top view which shows other vibrators. It is the schematic of the sensor system using the sensor apparatus shown in FIG.

  Embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals and description thereof will not be repeated.

  FIG. 1 is a side view of a sensor element according to an embodiment of the present invention. Referring to FIG. 1, a sensor element 10 according to an embodiment of the present invention includes support members 1 and 3 and a vibrator 2.

  The support member 1 is made of, for example, Teflon (registered trademark), and has flow paths 11 and 12, an opening portion 13, and a holding portion 14.

  Each of the flow paths 11 and 12 penetrates the support member 1. The opening 13 penetrates the support member 1 from the back surface 1 </ b> B of the support member 1 to the holding portion 14. The holding part 14 is provided on the surface 1 </ b> A side of the support member 1.

  The vibrator 2 has a substantially square planar shape and is held by the holding portion 14 of the support member 1.

  The support member 3 is made of, for example, Teflon (registered trademark), and has a liquid reservoir 31 on the surface 3A side.

  The support members 1 and 3 are fixed by screws (not shown) so that the surface 1A of the support member 1 and the surface 3A of the support member 3 are in contact with each other.

  Although not shown in FIG. 1, silicon rubber having a thickness of 1 mm is inserted between the support members 1 and 3 along the holding portion 14. This silicon rubber prevents the solution from leaking to the outside when the solution flows into the liquid reservoir 31.

  FIG. 2 is a plan view of the support member 1 viewed from the direction A shown in FIG. With reference to FIG. 2, the support member 1 has a substantially rectangular planar shape. Each of the flow paths 11 and 12 and the opening 13 provided in the support member 1 is circular. Each of the flow paths 11 and 12 has a diameter of about 2 mm, and the opening 13 has a diameter of about 5 mm.

  FIG. 3 is a plan view of the support member 1 as seen from the direction B shown in FIG. With reference to FIG. 3, the holding portion 14 has a substantially quadrangular planar shape and is disposed in the center portion of the support member 1. The holding unit 14 has approximately the same size as the size of the vibrator 2.

  The opening 13 is disposed at the center of the holding unit 14. Further, the flow channel 11 is disposed on one side of the holding unit 14, and the flow channel 12 is disposed on the other side of the holding unit 14.

  4 is a cross-sectional view of the support member 1 taken along line IV-IV shown in FIG. With reference to FIG. 4, the holding portion 14 is formed of a concave portion formed on the surface 1 </ b> A side of the support member 1. The opening portion 13 communicates with the holding portion 14.

  Since the holding unit 14 has substantially the same size as the vibrator 2, the vibrator 2 is held by the holding unit 14 by inserting the vibrator 2 into the holding unit 14.

  FIG. 5 is a plan view of the support member 3 as viewed from the direction A shown in FIG. FIG. 6 is a cross-sectional view of the supporting member 3 taken along line VI-VI shown in FIG.

  Referring to FIGS. 5 and 6, support member 3 has a recess 32 on the surface 3 </ b> A side. The concave portion 32 is provided in the center portion of the support member 3 and has a size larger than that of the holding portion 14.

  The support member 3 is fixed to the support member 1 such that the surface 3 </ b> A is in contact with the surface 1 </ b> A of the support member 1, whereby the recess 32 forms a liquid reservoir 31 with the vibrator 2.

  FIG. 7 is a cross-sectional view of the vibrator 2 shown in FIG. With reference to FIG. 2, the vibrator 2 includes a substrate 21 and a metal thin film 22.

  The substrate 21 is made of glass, for example. The substrate 21 has a thickness of about 0.5 mm.

  The metal thin film 22 is made of platinum (Pt) or gold (Au) and has a thickness of 10 to 100 nm. The metal thin film 22 is formed on the surface of the substrate 21 by vapor deposition.

  As described above, since the vibrator 2 includes the transparent substrate 21, the metal thin film 22 can be irradiated with laser light from the substrate 21 side.

  When the vibrator 2 is inserted into the holding unit 14, only the substrate 21 of the vibrator 2 is inserted into the holding unit 14. The holding portion 14 of the support member 1 is recessed from the surface 1 </ b> A of the support member 1 by a distance slightly larger than the thickness of the substrate 21. Then, silicon rubber is inserted between the support member 1 and the vibrator 2 and tightened with screws to prevent solution leakage.

  Therefore, in the vibrator 2, only the substrate 21 is in contact with the support member 1, and the metal thin film 22 is not in contact with the support member 1. As a result, when the metal thin film 22 is irradiated with laser light from the substrate 21 side, the metal thin film 22 can vibrate.

  A mechanism in which the metal thin film 22 vibrates by laser light irradiation will be described. In order to vibrate the metal thin film 22 made of Pt or Au, the metal thin film 22 is irradiated with a laser beam for a time on the order of picoseconds.

For example, when the metal thin film 22 is irradiated with laser light for a time of about 100 femto (10 ⁻¹⁵ ) seconds, the temperature of the irradiated portion of the metal thin film 22 rises instantaneously, and thermal stress is generated in the metal thin film 22. .

  Then, this thermal stress becomes a sound source, and a longitudinal wave propagates mainly in the film thickness direction of the metal thin film 22. The longitudinal wave is reflected multiple times in the metal thin film 22, and a standing wave (resonance) mode is generated in the metal thin film 22. As a result, the metal thin film 22 vibrates.

  Next, a method for detecting vibrations generated in the metal thin film 22 will be described. There are three methods for detecting this vibration: a pulse echo method, a resonance method, and a Brillouin vibration method.

(I) Pulse Echo Method First, the pulse echo method will be described. This method is applied to a thin film having a thickness of 50 nm or more.

  The pulse echo method is a method for measuring an echo in which an elastic pulse wave generated in a thin film by irradiating the thin film with pump light is reflected in the thin film and evaluating the attenuation from the amplitude of the echo.

  FIG. 8 is a diagram showing a measurement result of pulse echo. In FIG. 8, the vertical axis represents reflectance, and the horizontal axis represents time. In addition, the measurement result shown in FIG. 8 is a measurement result in Pt which has a film thickness of 70 nm formed on silicon (Si).

  Referring to FIG. 8, the reflectance changes greatly every about 33 ps, and it can be seen that the elastic wave reciprocates once in the thin film at this time interval.

  Then, in the reflectance shown in FIG. 8, the acoustic amount such as the resonance frequency and attenuation is obtained using the time when the reflectance is reduced and the reflectance. Also, the acoustic quantity such as the resonance frequency is obtained by Fourier transforming the reflectance shown in FIG.

(Ii) Resonance Method Next, the resonance method will be described. This method is applied to a thin film whose first thin film is thinner than 50 nm. The present invention is also applied to the case where the first thin film and the substrate, and further, the first thin film, the substrate and the second thin film vibrate. In this case, the total film thickness is about 200 nm.

  The resonance method is to observe the resonance mode generated in the vibrator from the change in reflectance by irradiating the first or second thin film with ultrashort pulsed light having a pulse width of the order of picoseconds. .

  FIG. 9 is a diagram showing measurement results of acoustic phonon resonance vibration. FIG. 10 is a diagram showing a spectrum when the spectrum shown in FIG. 9 is Fourier transformed.

  In FIG. 9, the vertical axis represents reflectance, and the horizontal axis represents time. In FIG. 10, the vertical axis represents amplitude, and the horizontal axis represents frequency.

  9 and 10 show the measurement results of the acoustic phonon vibration generated in the Pt thin film having film thicknesses of 5.6 nm, 13 nm, and 34 nm.

  Referring to FIG. 9, it can be seen that resonance occurs in the Pt thin film after irradiation with pump light (= excitation light). Moreover, if the spectrum shown in FIG. 9 is Fourier-transformed, the spectrum shown in FIG. 10 will be obtained. Therefore, the acoustic quantity such as the resonance frequency of the Pt thin film can be obtained from the spectrum shown in FIG.

  Note that the acoustic quantity such as the resonance frequency of the Pt thin film may be obtained using one time during which a certain reflectance is obtained in the spectrum shown in FIG.

(Iii) Brillouin vibration method Finally, the Brillouin vibration method will be described. This method utilizes the diffraction phenomenon of light by elastic waves, and is a very effective technique for transparent and translucent thin films (oxides and semiconductors).

  FIG. 11 is a conceptual diagram of the Brillouin vibration method. Referring to FIG. 11, a metal thin film made of a thin film such as Al having a thickness of about 10 nm is formed on the surface of the sample, and the metal thin film is irradiated with pump light. Then, longitudinal wave ultrasonic waves are excited in the film thickness direction by the thermal expansion of the thin film.

  The longitudinal wave is a dense wave, and the charge density in the material is also distributed at the same wavelength. That is, since the refractive index also changes at this wavelength, the ultrasonic wave is a so-called diffraction grating when viewed from light. When the probe light is incident on the thin film in this state, a part of the probe light is reflected on the surface, but since the Al thin film (= metal thin film) is thin, most of the probe light is transmitted into the sample. Then, it is diffracted by ultrasonic waves.

The diffraction condition is when the wavelength (λ ₀ / n) in the light substance is equal to twice the wavelength (λ _a ) of the ultrasonic wave. Here, n represents the refractive index of the substance with respect to the probe light.

When the ultrasonic wave advances into the thin film, the diffracted light interferes with the reflected light reflected from the surface of the metal thin film, and the reflectance is vibrated. This vibration is called Brillouin vibration. The Brillouin vibration frequency f _BO is expressed by the following equation.

f _BO = 2nv _a / λ ₀ (1)
Incidentally, _{v a} is the velocity of sound in the material.

  FIG. 12 is a diagram illustrating a measurement example of Brillouin vibration. In FIG. 12, the vertical axis represents the reflectance, and the horizontal axis represents time.

The spectrum shown in FIG. 12 shows Brillouin vibration from silicon oxide (SiO ₂ ) formed on the Si substrate.

Referring to FIG. 12, high frequency (˜450 GHz) vibration is observed after low frequency (˜45 GHz) vibration. The former is Brillouin vibration from the SiO ₂ thin film, and the latter is Brillouin vibration from the Si substrate.

Since Si has a higher refractive index and sound speed than SiO ₂ , high-frequency Brillouin oscillation is observed.

  The reason why the vibration in the Si substrate is attenuated is not the attenuation of the ultrasonic wave but the attenuation of light abruptly.

  Then, in the reflectance shown in FIG. 12, an acoustic quantity such as a resonance frequency is obtained using one time during which a certain reflectance is obtained. Further, the resonance frequency is obtained by Fourier transforming the reflectance shown in FIG.

  In the embodiment of the present invention, the acoustic quantity such as the resonance frequency of the vibration generated in the sample is detected using any one of the above-described pulse echo method, resonance method, and Brillouin vibration method. In this case, the pulse echo method is used when the film thickness of the metal thin film 22 is 50 nm or more, the resonance method is used when the film thickness of the metal thin film 22 is less than 50 nm, and the Brillouin vibration method is performed using the metal thin film 22. It is used regardless of the film thickness.

  FIG. 13 is a diagram for explaining a detection target object detection method using the sensor element 10 shown in FIG. 1.

  Referring to FIG. 13, molecule B is fixed on the surface of metal thin film 22 of sensor element 10. Then, the metal thin film 22 is irradiated with laser light (= pump light) from the substrate 21 side of the sensor element 10. As a result, vibration is generated in the metal thin film 22. Then, a laser beam (probe light) is irradiated onto the metal thin film 22 from the substrate 21 side, and an acoustic quantity such as a resonance frequency of vibration generated in the metal thin film 22 is detected using any of the three methods described above.

  Thereafter, when the molecule A is injected into the liquid reservoir 31 via the flow path 11, the molecule A reacts with the molecule B, and a complex (AB) is formed on the surface of the metal thin film 22. Then, the laser beam (= probe light) is irradiated in a state where the composite (AB) is formed on the surface of the metal thin film 22, and the resonance frequency of vibration in the metal thin film 22 using any of the three methods described above. Detect the amount of sound.

  Since the composite (AB) has a mass larger than that of the molecule B, the total mass of the composite (AB) and the metal thin film 22 when the composite (AB) is formed on the surface of the metal thin film 22 is the molecule B. And larger than the total mass of the metal thin film 22.

  As a result, the acoustic quantity such as the resonance frequency when the composite (AB) is formed on the surface of the metal thin film 22 is determined from the acoustic quantity such as the resonance frequency when the molecule B is fixed on the surface of the metal thin film 22. Change.

  Therefore, the fluctuation Af of the acoustic quantity such as the resonance frequency caused by injecting the molecule A into the sensor element 10 is detected, and the molecule A is detected.

  In this case, the speed at which the acoustic quantity such as the resonance frequency changes represents the reaction rate constant between the molecule A and the molecule B.

  FIG. 14 is a diagram showing an actual measurement example of vibration in the metal thin film 22 of the sensor element 10 shown in FIG.

  In FIG. 14, the vertical axis represents amplitude and the horizontal axis represents time. The spectrum shown in FIG. 14 shows the vibration of the metal thin film 22 when S. aureus protein A is immobilized on the metal thin film 22 and human immunoglobulin G (human IgG) is injected.

  Referring to FIG. 14, the vibration in the metal thin film 22 changes greatly after human immunoglobulin G (human IgG) is injected. Since protein A binds to human immunoglobulin G (human IgG) with a relatively high affinity, the IgG molecule binds to the sensor element 10 and a change in acoustic quantity such as amplitude occurs.

  When the amplitude of the vibration shown in FIG. 14 is converted into a frequency change, it corresponds to exceeding 10,000 times the frequency change when the conventional piezoelectric vibrator is used.

  The change Δf in the acoustic amount such as the resonance frequency before and after the detection object adheres is inversely proportional to the square of the film thickness of the vibrator (= metal thin film 22). The thickness of the metal thin film 22 is on the order of nanometers, which is about 1/1000 of the thickness of the conventional piezoelectric vibrator.

  Therefore, the change Δf (= sensitivity) of the acoustic amount such as the resonance frequency in the sensor element 10 is one million times that of the conventional sensor.

  FIG. 15 is a schematic diagram of a sensor device according to an embodiment of the present invention. Referring to FIG. 15, sensor device 100 according to the embodiment of the present invention includes a sensor element 10, a laser light source 110, a half-wave plate 111, a polarization beam splitter 112, reflectors 113, 115, 116, 121-123, corner reflector 114, lenses 118, 120, acousto-optic crystal 117, nonlinear optical crystal 119, beam splitter 124, harmonic separator 125, objective lens 126, and detector 127. Prepare.

  The laser light source 110 is made of, for example, a titanium / sapphire pulse laser, generates pulsed light having a wavelength of 800 nm (pulse width: picosecond order), and emits the generated pulsed light to the half-wave plate 111.

  The half-wave plate 111 rotates the polarization plane of the pulsed light received from the laser light source 110 by 90 °, and guides the pulsed light that has rotated the polarization plane to the polarization beam splitter 112.

  The polarization beam splitter 112 transmits the pulsed light received from the half-wave plate 111 to the reflection plate 113 and reflects it toward the lens 118.

  The reflection plate 113 reflects the pulsed light received from the polarization beam splitter 112 to the corner reflector 114.

  The corner reflector 114 guides the pulsed light to the reflecting plate 115 by adjusting the optical path of the pulsed light received from the reflecting plate 113.

  The reflector 115 reflects the pulsed light received from the corner reflector 114 toward the reflector 116.

  The reflecting plate 116 reflects the pulsed light received from the reflecting plate 115 in the direction of the acousto-optic crystal 117.

  The acousto-optic crystal 117 modulates the pulsed light received from the reflecting plate 116 and emits the modulated pulsed light to the harmonic separator 125.

  The lens 118 converts the pulsed light received from the polarization beam splitter 112 into parallel light and emits it to the nonlinear optical crystal 119.

  The nonlinear optical crystal 119 emits the pulsed light received from the lens 118 to the lens 120 as a double wave (wavelength = 400 nm).

  The lens 120 guides the pulsed light received from the nonlinear optical crystal 119 to the reflection plate 121.

  The reflector 121 reflects the pulsed light received from the lens 120 toward the beam splitter 124.

  The reflection plate 122 reflects the light received from the reflection plate 123 toward the detector 127.

  The reflector 123 reflects the light received from the beam splitter 124 toward the reflector 122.

  The beam splitter 124 separates the pulsed light received from the reflecting plate 121 into two pulsed lights, guides one pulsed light to the harmonic separator 125 and guides the other pulsed light to the detector 8127 as reference light. The beam splitter 124 reflects the light received from the harmonic separator 125 in the direction of the reflecting plate 123.

  The harmonic separator 125 guides the pulsed light received from the acousto-optic crystal 117 to the objective lens 126, guides the pulsed light received from the beam splitter 124 to the objective lens 126, and guides the reflected light from the sensor element 10 to the beam splitter 124.

  The objective lens 126 condenses the light received from the harmonic separator 125 and irradiates the condensed light from the substrate 21 side to the vibrator 2 of the sensor element 10.

  The detector 127 receives reference light from the beam splitter 124 and receives reflected light from the sensor element 10 from the reflecting plate 122. Then, the detector 127 subtracts the reference light from the reflected light, inputs the light after the subtraction to the lock-in amplifier, and extracts the modulation frequency component.

  The laser light source 110 has a wavelength of 800 nm through a half-wave plate 111, a polarizing beam splitter 112, a reflector 113, a corner reflector 114, reflectors 115 and 116, an acoustooptic crystal 117, a harmonic separator 125, and an objective lens 126. Is irradiated to the vibrator 2 of the sensor element 10. As a result, vibration is generated in the metal thin film 22 of the vibrator 2. Therefore, the laser beam LS1 is called pump light (= excitation light).

  Further, the laser light source 110 passes through the half-wave plate 111, the polarization beam splitter 112, the lens 118, the nonlinear optical crystal 119, the lens 120, the reflection plate 121, the beam splitter 124, the harmonic separator 125, and the objective lens 126. The vibrator 2 of the sensor element 10 is irradiated with laser light LS2 having a wavelength of 400 nm. Then, the reflected light of the laser light LS2 is guided to the detector 127 via the beam splitter 124 and the reflecting plates 123 and 122. Then, the detector 127 subtracts the reference light from the reflected light of the laser light LS2, and obtains an acoustic quantity such as a resonance frequency of the vibrator 2 of the sensor element 10. Therefore, the laser beam LS2 is called probe light.

  In the sensor device 100, the detector 127 detects the acoustic quantity f0 such as the resonance frequency of the vibrator 2 by the above-described method without flowing the solution containing the detection object from the flow path 11 of the sensor element 10.

  Thereafter, a solution containing the detection object flows from the flow path 11 into the liquid reservoir 31. The detector 127 detects the acoustic amount fm such as the resonance frequency of the vibrator 2 by the above-described method in a state where the solution containing the detection target object is accumulated in the liquid reservoir 31, and the detected acoustic frequency such as the resonance frequency. The detection target is detected by detecting that the amount fm varies from the acoustic amount f0 such as the resonance frequency.

  FIG. 16 is a cross-sectional view showing another vibrator. In the embodiment of the present invention, the sensor device 10 may include any of the vibrators 2A, 2B, and 2C shown in FIG.

  Referring to FIG. 16A, the vibrator 2 </ b> A is obtained by adding a metal thin film 23 to the vibrator 2 shown in FIG. 7, and the rest is the same as the vibrator 2. The metal thin film 23 is formed on a surface opposite to one main surface of the substrate 21 on which the metal thin film 22 is formed. And the metal thin film 23 consists of Al, for example, and has a film thickness of 10-100 nm. That is, the metal thin film 23 is made of a metal different from the metal thin film 22.

  When the vibrator 2A is used for the sensor element 10, a protein such as an antibody for capturing a detection target is fixed to the surface of the metal thin film 22, and the laser beams LS1 and LS2 are transmitted from the metal thin film 23 side to the vibrator 2A. Irradiated.

  When the laser beam LS1 is irradiated, the above-described longitudinal wave is generated in the thickness direction of the metal thin film 23 in the metal thin film 23, and the generated longitudinal wave propagates to the substrate 21 and the metal thin film 22, and the substrate 21 And the whole metal thin films 22 and 23 vibrate.

  Therefore, the detection target can be detected using the vibrator 2A by detecting the fluctuation Δf of the acoustic amount such as the resonance frequency of the vibrator 2A.

  Thus, in the vibrator 2A, the metal thin film 23 functions as an acoustic source.

  The vibrator 2A is manufactured by forming a metal thin film 22 on one surface of glass by vapor deposition and forming a metal thin film 23 on the other surface of glass by vapor deposition.

  Referring to FIG. 16B, the vibrator 2 </ b> B includes a metal thin film 22, a thin film 24, and a substrate 25.

  The substrate 25 is made of, for example, silicon having a thickness of about 400 μm and has an opening 251. The thin film 24 is made of an insulator or a semiconductor such as silicon nitride (SiN) and silicon carbide (SiC), and has a thickness of 50 to 200 nm. The thin film 24 is formed between the metal thin film 22 and the substrate 25 in contact with the metal thin film 22 and the substrate 25.

  The opening 251 has a cross-sectional shape in which both ends are tapered, has a diameter of about 2 mm on the thin film 24 side, and has a diameter of about 2.5 mm or a square of about 2.5 mm square on the back side of the substrate 25. It has a shape.

  When the vibrator 2B is used in the sensor element 10, a protein such as an antibody for capturing a detection target is fixed to the surface of the metal thin film 22, and the laser beams LS1 and LS2 are transmitted from the opening 251 of the substrate 25 to the thin film 24. Is irradiated.

  When the laser beam LS1 is irradiated, the longitudinal waves described above are generated in the film thickness direction of the thin film 22 in the thin film 22, and the generated longitudinal waves propagate to the metal thin film 24. The whole vibrates.

  Therefore, the detection target can be detected using the vibrator 2B by detecting the fluctuation Δf of the acoustic amount such as the resonance frequency of the vibrator 2B.

  The vibrator 2B forms the thin film 24 on one main surface of the silicon substrate by a plasma CVD (Chemical Vapor Deposition) method or a thermal CVD method, and then forms the metal thin film 22 on the thin film 24 by vapor deposition or sputtering. Further, after that, a part of the silicon substrate is removed by etching from the back surface, and the opening 251 is formed.

  Referring to FIG. 16C, the vibrator 2 </ b> C includes metal thin films 22 and 27 and a substrate 26. The substrate 26 is made of silicon having a thickness of about 400 μm and has a thin film portion 261. The thin film portion 261 has a thickness of about 100 nm.

  The metal thin film 22 is formed on one main surface of the substrate 26. The metal thin film 27 is formed in contact with the thin film portion 261 on the side opposite to one main surface of the substrate 26 on which the metal thin film 22 is formed.

  The metal thin film 27 is made of, for example, Al or chromium (Cr) and has a thickness of about 10 nm. That is, the metal thin film 27 is made of a metal different from the metal thin film 22.

  When the vibrator 2C is used for the sensor element 10, a protein such as an antibody for capturing the detection target is fixed to the surface of the metal thin film 22, and the laser light LS1 and LS2 are irradiated to the metal thin film 27 from the substrate 26 side. Is done.

  When the laser beam LS1 is irradiated, the above-described longitudinal wave is generated in the thickness direction of the metal thin film 27 in the metal thin film 27, and the generated longitudinal wave propagates to the thin film portion 261 and the metal thin film 22 of the substrate 26. Then, the thin film portion 261 and the metal thin film 22 vibrate.

  Therefore, the detection target can be detected using the vibrator 2C by detecting the fluctuation Δf of the acoustic amount such as the resonance frequency of the vibrator 2C.

  Thus, in the vibrator 2C, the metal thin film 27 functions as an acoustic source.

  In the vibrator 2C, the metal thin film 22 is formed on one main surface of the silicon substrate by vapor deposition, and then a part of the silicon substrate is etched from the back surface to form the thin film portion 261. Is formed on the thin film portion 261 by vapor deposition.

  Even when any of the vibrators 2A, 2B, and 2C is used in the sensor element 10, the vibrators 2A, 2B, and 2C are obtained by using any one of the above-described pulse echo method, resonance method, and Brillouin vibration method. The amount of sound such as the resonance frequency is detected.

  FIG. 17 is a waveform diagram showing the vibration of the vibrator 2B shown in FIG. In FIG. 17, the vertical axis represents reflectance, and the horizontal axis represents time.

  Referring to FIG. 17, the vibration continues with a substantially constant period. Therefore, even when the thin film 24 is vibrated by irradiating the thin film 24 to the thin film 24 in contact with the substrate 25 having a thickness of about 400 μm like the vibrator 2B, the vibration is attenuated by the substrate 26. But it has been proven to last.

  FIG. 18 is a plan view showing still another vibrator. The sensor element 10 according to the embodiment of the present invention may include a vibrator 20 shown in FIG. 18 instead of the vibrator 2.

  The vibrator 20 includes a substrate 201 and a plurality of vibration members 202. The substrate 201 is made of, for example, glass or a Si substrate.

  The plurality of vibration members 202 are arranged in a grid pattern on one main surface of the substrate 201. Each of the plurality of vibrating members 202 is made of any of the vibrators 2, 2A, 2B, 2C described above, and has a circular shape having a diameter of about 1 mm.

  In the sensor element 10 including the vibrator 20, proteins such as the same antibody may be fixed on the surfaces of the plurality of metal thin films 22 included in the plurality of vibration members 202, and a plurality of different types of antibodies may be used. The protein may be fixed.

  When proteins such as a plurality of types of antibodies are immobilized on the surfaces of the plurality of metal thin films 22, a plurality of types of antigens can be detected simultaneously.

  When the vibrator 20 is used, the laser beams LS1 and LS2 are irradiated to the plurality of vibrating members 202 while being scanned.

  In the vibrator 20, each of the plurality of vibration members 202 is not limited to a circle, and may be a polygon such as a triangle, a quadrangle, and a pentagon.

  FIG. 19 is a schematic diagram of a sensor system using the sensor device 100 shown in FIG. Referring to FIG. 19, the sensor system 1000 includes a sensor element 10, containers 301 to 305 and 340, a liquid feed pump 310, a pipe 320, a thermostatic chamber 330, a laser measurement system 350, a personal computer 360, and the like. Is provided.

  In the sensor system 1000, the sensor element 10 and the laser measurement system 350 constitute the sensor device 100.

  The containers 301 to 305 are connected to the liquid feed pump 310. The liquid feed pump 310 is connected to the flow path 11 of the sensor element 10 by a pipe 320.

  The sensor element 10 is disposed in the thermostatic chamber 330. The flow path 11 is connected to the pipe 320 and the flow path 12 is connected to the container 340.

  The laser measurement system 350 includes a laser light source 110, a half-wave plate 111, a polarization beam splitter 112, reflectors 113, 115, 116, 121 to 123, a corner reflector 114, an acoustooptic crystal 117, and a lens 118 shown in FIG. , 120, a nonlinear optical crystal 119, a beam splitter 124, a harmonic separator 125, an objective lens 126, and a detector 127.

  Each of the containers 301 to 305 holds a solution containing the detection target. In this case, the containers 301 to 305 contain different detection objects.

  The liquid feed pump 310 sucks up the solution from any of the containers 301 to 305 and flows the sucked up solution into the sensor element 10 through the pipe 320.

  The solution that has flowed into the sensor element 10 flows into the liquid reservoir 31 from the flow path 11 and is then discharged from the flow path 12 to the container 340.

  The laser measurement system 350 irradiates the vibrator 2 of the sensor element 10 from the substrate 21 side as pump light (= excitation light) from the substrate 21 side, and uses the laser light LS2 as probe light to the vibrator 2 of the sensor element 10 on the substrate 21. The reference light and the reflected light from the vibrator 2 are detected by irradiating from the side, and based on the detected reference light and reflected light, the fluctuation Δf of the acoustic amount such as the resonance frequency of the vibrator 2 is detected. Detect a detection object.

  Then, the laser measurement system 350 outputs the detected detection object to the personal computer 360.

  The personal computer 360 receives the detection target from the laser measurement system 350 and displays the received detection target.

  Further, the personal computer 360 controls the laser measurement system 350. More specifically, the personal computer 360 drives the laser light source 110 included in the laser measurement system 350 and controls the adjustment of the optical path by the corner reflector 114.

  In the above description, the metal thin film 22 has been described as being made of a noble metal such as Pt and Au. However, in the embodiment of the present invention, the metal thin film 22 is not limited to this, and the metal thin film 22 is made of copper (Cu). In general, it may be made of a metal having resistance to acids.

  In the above description, the sensor element 10 has been described as detecting an antigen in a solution. However, in the embodiment of the present invention, the present invention is not limited to this, and the sensor element 10 may detect gas in the air. Good.

  In this case, the sensor element 10 may not have the support member 3. By removing the support member 3, the detection object in the air can easily adhere to the vibrator 2, and the detection sensitivity in the sensor element 10 can be improved.

  As described above, the sensor element 10 includes the vibrator 2, and the vibrator 2 includes the metal thin film 22 formed on the substrate 21. In the sensor element 10, a detection target is detected by detecting a change in an acoustic amount such as a vibrating resonance frequency generated in the metal thin film 22 by the irradiation of the laser beam LS <b> 1. Further, the fluctuation of the acoustic quantity such as the resonance frequency is inversely proportional to the square of the film thickness of the metal thin film 22.

  Therefore, by reducing the film thickness of the metal thin film 22, the detection sensitivity (= variation in acoustic quantity such as the resonance frequency) in the sensor element 10 can be dramatically improved.

  In the embodiment of the present invention, the metal thin film 22 constitutes a “first metal thin film”, and each of the metal thin films 23 and 27 constitutes a “second metal thin film”.

  Further, in the embodiment of the present invention, the plurality of metal thin films 22 included in the plurality of vibration members 202 constitute “a plurality of metal thin film pieces”.

  Further, in the embodiment of the present invention, the laser light LS1 is divided into the half-wave plate 111, the polarizing beam splitter 112, the reflectors 113, 115, 116, the corner reflector 115, the acoustooptic crystal 117, the harmonic separator 125, and the objective. The laser light source 110 that irradiates the sensor element 10 using the lens 126 constitutes a “first light source”.

  Further, in the embodiment of the present invention, the laser beam LS2 is divided into the half-wave plate 111, the polarization beam splitter 112, the lenses 118 and 120, the nonlinear optical crystal 119, the reflection plate 121, the beam splitter 124, the harmonic separator 125, and The laser light source 110 that irradiates the sensor element 10 using the objective lens 126 constitutes a “second light source”.

  Furthermore, in the embodiment of the present invention, the acoustic quantity refers to the resonance frequency or amplitude of the vibrators 2, 2A, 2B, 2C, and 20.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is shown not by the above description of the embodiments but by the scope of claims for patent, and is intended to include meanings equivalent to the scope of claims for patent and all modifications within the scope.

  The present invention is applied to a sensor element capable of improving sensitivity. The present invention is also applied to a sensor device including a sensor element that can improve sensitivity.

  DESCRIPTION OF SYMBOLS 1,3 Support member, 1A, 3A surface, 1B back surface, 2,2A, 2B, 2C, 20 vibrator | oscillator, 10 sensor element, 11,12 flow path, 13,251 opening part, 14 holding | maintenance part, 21,25 26, 201 Substrate, 22, 23, 27 Metal thin film, 24 Thin film, 31 Liquid reservoir, 32 Recess, 100 Sensor device, 110 Laser light source, 111 Half-wave plate, 112 Polarizing beam splitter, 113, 115, 116 , 121-123 reflector, 114 corner reflector, 117 acousto-optic crystal, 118, 120 lens, 119 nonlinear optical crystal, 124 beam splitter, 125 harmonic separator, 126 objective lens, 202 vibrating member, 261 thin film portion, 301-305, 340 container, 310 liquid feed pump, 320 piping, 330 constant temperature , 350 laser measurement system, 360 personal computer, 1000 sensor system.

Claims (12)

A vibrator,
A holding member that holds the vibrator and has an opening for irradiating the vibrator with laser light;
The vibrator is
A substrate,
A sensor element comprising: a first metal thin film that is formed on the substrate and has a surface on which a protein that supplements a detection target is fixed, and vibrates upon irradiation with the laser beam.   The sensor element according to claim 1, wherein the first metal thin film is formed in contact with the substrate.   The sensor element according to claim 2, wherein the vibrator further includes a second metal thin film formed on a surface opposite to the surface of the substrate on which the first metal thin film is formed. The vibrator further includes a second metal thin film formed in a partial region of the surface opposite to the surface of the substrate on which the first metal thin film is formed,
The sensor element according to claim 2, wherein a distance between the first metal thin film and the second metal thin film is smaller than a thickness of the substrate.   The sensor element according to claim 4, wherein the second metal thin film is made of a metal different from the first metal thin film.   The sensor element according to any one of claims 1 to 5, wherein the substrate is made of an insulator or a semiconductor. The vibrator is
A thin film disposed between the substrate and the first metal thin film and formed in contact with the substrate and the first metal thin film;
2. The sensor according to claim 1, wherein the substrate further includes an opening formed in a thickness direction of the substrate and exposing a part of a surface opposite to a contact surface of the thin film with the first metal thin film. element.   The sensor element according to claim 7, wherein the thin film is made of an insulator or a semiconductor.   The sensor element according to any one of claims 1 to 8, wherein the first metal thin film includes a plurality of metal thin film pieces.   The sensor element according to any one of claims 1 to 9, wherein the first metal thin film is made of a metal having resistance to an acid.   The sensor element according to any one of claims 1 to 10, further comprising the protein fixed to a surface of the first metal thin film. A sensor element for supplementing the detection object;
A first light source that irradiates the sensor element with excitation light comprising laser light;
A second light source for irradiating the sensor element with a probe light comprising a laser beam;
Detection that receives the reflected light of the probe light from the sensor element, detects the acoustic amount of the sensor element based on the received reflected light, and detects the detection object based on the variation of the detected acoustic amount Equipped with
The sensor element comprises the sensor element according to any one of claims 1 to 11,
The sensor device, wherein the first and second light sources irradiate the sensor element with the excitation light and the probe light from the opposite side of the first metal thin film, respectively.

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