WO2006006587A1 - ガス検知方法およびガスセンサ - Google Patents
ガス検知方法およびガスセンサ Download PDFInfo
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- WO2006006587A1 WO2006006587A1 PCT/JP2005/012817 JP2005012817W WO2006006587A1 WO 2006006587 A1 WO2006006587 A1 WO 2006006587A1 JP 2005012817 W JP2005012817 W JP 2005012817W WO 2006006587 A1 WO2006006587 A1 WO 2006006587A1
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- Prior art keywords
- gas
- electrode
- detected
- electrical characteristics
- acoustic wave
- Prior art date
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- 238000001514 detection method Methods 0.000 title claims abstract description 93
- 238000001179 sorption measurement Methods 0.000 claims abstract description 64
- 230000010355 oscillation Effects 0.000 claims abstract description 45
- 239000010453 quartz Substances 0.000 claims abstract description 17
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N silicon dioxide Inorganic materials O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims abstract description 17
- 239000013078 crystal Substances 0.000 claims description 101
- 238000010897 surface acoustic wave method Methods 0.000 claims description 44
- 239000004065 semiconductor Substances 0.000 claims description 18
- 238000005259 measurement Methods 0.000 claims description 17
- 239000000463 material Substances 0.000 claims description 15
- 230000003287 optical effect Effects 0.000 claims description 14
- 239000010409 thin film Substances 0.000 abstract description 93
- 239000007789 gas Substances 0.000 description 220
- 239000010408 film Substances 0.000 description 37
- 230000007423 decrease Effects 0.000 description 9
- 150000002500 ions Chemical class 0.000 description 9
- 230000031700 light absorption Effects 0.000 description 7
- 239000000126 substance Substances 0.000 description 6
- 238000005530 etching Methods 0.000 description 5
- 238000000034 method Methods 0.000 description 5
- 238000003380 quartz crystal microbalance Methods 0.000 description 5
- XLOMVQKBTHCTTD-UHFFFAOYSA-N Zinc monoxide Chemical compound [Zn]=O XLOMVQKBTHCTTD-UHFFFAOYSA-N 0.000 description 4
- 230000005684 electric field Effects 0.000 description 4
- 230000003321 amplification Effects 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 230000005284 excitation Effects 0.000 description 3
- 238000003199 nucleic acid amplification method Methods 0.000 description 3
- 230000035945 sensitivity Effects 0.000 description 3
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 description 2
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 2
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 2
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 2
- KDLHZDBZIXYQEI-UHFFFAOYSA-N Palladium Chemical compound [Pd] KDLHZDBZIXYQEI-UHFFFAOYSA-N 0.000 description 2
- 239000002131 composite material Substances 0.000 description 2
- 239000000470 constituent Substances 0.000 description 2
- 230000008602 contraction Effects 0.000 description 2
- 230000001590 oxidative effect Effects 0.000 description 2
- IEQIEDJGQAUEQZ-UHFFFAOYSA-N phthalocyanine Chemical compound N1C(N=C2C3=CC=CC=C3C(N=C3C4=CC=CC=C4C(=N4)N3)=N2)=C(C=CC=C2)C2=C1N=C1C2=CC=CC=C2C4=N1 IEQIEDJGQAUEQZ-UHFFFAOYSA-N 0.000 description 2
- 239000011787 zinc oxide Substances 0.000 description 2
- RPAJSBKBKSSMLJ-DFWYDOINSA-N (2s)-2-aminopentanedioic acid;hydrochloride Chemical class Cl.OC(=O)[C@@H](N)CCC(O)=O RPAJSBKBKSSMLJ-DFWYDOINSA-N 0.000 description 1
- ZCYVEMRRCGMTRW-UHFFFAOYSA-N 7553-56-2 Chemical compound [I] ZCYVEMRRCGMTRW-UHFFFAOYSA-N 0.000 description 1
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 description 1
- 239000002253 acid Substances 0.000 description 1
- 230000002378 acidificating effect Effects 0.000 description 1
- HSFWRNGVRCDJHI-UHFFFAOYSA-N alpha-acetylene Natural products C#C HSFWRNGVRCDJHI-UHFFFAOYSA-N 0.000 description 1
- 229910021529 ammonia Inorganic materials 0.000 description 1
- 238000004458 analytical method Methods 0.000 description 1
- 150000001450 anions Chemical class 0.000 description 1
- 229910002092 carbon dioxide Inorganic materials 0.000 description 1
- 239000001569 carbon dioxide Substances 0.000 description 1
- 229910002091 carbon monoxide Inorganic materials 0.000 description 1
- 150000001768 cations Chemical class 0.000 description 1
- 239000000084 colloidal system Substances 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 238000000105 evaporative light scattering detection Methods 0.000 description 1
- 238000009413 insulation Methods 0.000 description 1
- 229910052740 iodine Inorganic materials 0.000 description 1
- 239000011630 iodine Substances 0.000 description 1
- 238000010030 laminating Methods 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 239000012528 membrane Substances 0.000 description 1
- 238000012544 monitoring process Methods 0.000 description 1
- 229910052757 nitrogen Inorganic materials 0.000 description 1
- 229920000620 organic polymer Polymers 0.000 description 1
- 239000003960 organic solvent Substances 0.000 description 1
- 229910052763 palladium Inorganic materials 0.000 description 1
- 229920001197 polyacetylene Polymers 0.000 description 1
- 239000013076 target substance Substances 0.000 description 1
- XOLBLPGZBRYERU-UHFFFAOYSA-N tin dioxide Chemical compound O=[Sn]=O XOLBLPGZBRYERU-UHFFFAOYSA-N 0.000 description 1
- 229910001887 tin oxide Inorganic materials 0.000 description 1
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N5/00—Analysing materials by weighing, e.g. weighing small particles separated from a gas or liquid
- G01N5/02—Analysing materials by weighing, e.g. weighing small particles separated from a gas or liquid by absorbing or adsorbing components of a material and determining change of weight of the adsorbent, e.g. determining moisture content
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
- G01N27/26—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating electrochemical variables; by using electrolysis or electrophoresis
- G01N27/403—Cells and electrode assemblies
- G01N27/414—Ion-sensitive or chemical field-effect transistors, i.e. ISFETS or CHEMFETS
- G01N27/4141—Ion-sensitive or chemical field-effect transistors, i.e. ISFETS or CHEMFETS specially adapted for gases
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
- G01N21/1702—Systems in which incident light is modified in accordance with the properties of the material investigated with opto-acoustic detection, e.g. for gases or analysing solids
- G01N2021/1704—Systems in which incident light is modified in accordance with the properties of the material investigated with opto-acoustic detection, e.g. for gases or analysing solids in gases
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
- G01N21/1702—Systems in which incident light is modified in accordance with the properties of the material investigated with opto-acoustic detection, e.g. for gases or analysing solids
- G01N2021/1708—Systems in which incident light is modified in accordance with the properties of the material investigated with opto-acoustic detection, e.g. for gases or analysing solids with piezotransducers
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2291/00—Indexing codes associated with group G01N29/00
- G01N2291/02—Indexing codes associated with the analysed material
- G01N2291/028—Material parameters
- G01N2291/02863—Electric or magnetic parameters
Definitions
- the present invention relates to a gas detection method and a gas sensor using a crystal resonator.
- Patent Document 1 As a conventional gas sensor, as disclosed in Patent Document 1, a change in resistivity of a gas-sensitive thin film (comprised of an oxide in Patent Document 1) accompanying the adsorption of a gas to be measured, generation of an electromotive force, Gas sensors that use changes in electrical characteristics such as capacitance are known.
- a sensor that can detect a small amount of NO gas by using a decrease in the oscillation frequency of the crystal resonator or a decrease in the resistivity of the gas sensitive film is also known.
- a trace amount of hydrogen gas can be detected by utilizing the light absorption change of the gas sensitive film according to the hydrogen gas adsorbed on the gas sensitive film. Sensors that can do this are also known.
- Patent Document 4 also proposes a method for producing an element for measuring electrical characteristics on a mass measuring element.
- Patent Document 1 Japanese Patent Laid-Open No. 11-101763
- Patent Document 2 JP-A-7-43285
- Patent Document 3 Japanese Patent Laid-Open No. 2003-329592
- Patent Document 4 Japanese Patent Publication No. 11-507729
- Non-patent document 1 “Colloids and Surfaces A: Physicochemical and Engineering Aspects”, (Ohnda), Elsevier Science BV, 2002, No. 198— No. 200, p. 905-909
- Non-Patent Document 2 “Sensors and Actuators B”, (Netherlands), Elsevier Science BV, 2002, No. 67, p. 312-316
- Non-Patent Document 3 “Analysis Analytical Chemistry, (USA), American Chemical Society, September 15, 2001, No. 73, No. 18, p. 4441-4449 Disclosure of the Invention
- Patent Document 1 has a problem in that it is impossible to directly know how much the substance to be detected is adsorbed on the element and causes a change in electrical characteristics.
- the conventional gas sensor disclosed in Patent Document 2 detects a very small amount of gas adsorbed on the gas-sensitive thin film by utilizing the so-called QCM (Quartz Crystal Microbalance) of the crystal resonator.
- QCM Quadrat Crystal Microbalance
- the conventional gas sensor disclosed in Patent Document 3 has a problem that it is impossible to directly know how much the detection target substance is adsorbed on the element and causes a change in light absorption characteristics. It was.
- the present invention uses a quartz crystal resonator or a surface acoustic wave device to accurately determine the amount of change in the adsorption mass of the gas to be detected and the amount of change in the electrical characteristics or the optical and electrical characteristics associated therewith.
- An object of the present invention is to provide a gas detection method and a gas sensor that can be detected at the same time.
- a gas-sensitive film whose electrical characteristics change according to the amount of adsorption of the gas to be detected on the crystal resonator or the surface acoustic wave element, and the electrical characteristics are detected.
- a gas adsorbing portion formed by laminating a characteristic detection electrode is disposed, and one of the characteristic detection electrodes located in the uppermost layer is configured to allow the gas to be detected to pass therethrough.
- the adsorption mass is detected by the electrical characteristics between the electrodes and the crystal resonator or the surface elastic wave element.
- both the electric characteristics of the gas sensitive film and the detected adsorption mass of the crystal resonator or the surface acoustic wave device change as the gas sensitive film adsorbs the gas to be detected.
- By observing the electrical characteristics between the characteristic detection electrodes and the adsorbed mass by using it is possible to easily detect and identify the gas to be detected.
- the structure is simplified and steps such as etching are not required. Therefore, it can be manufactured at low cost.
- by configuring one of the characteristic detection electrodes located in the uppermost layer so that the gas to be detected can pass through it is possible to secure a contact area between the gas sensitive film and the gas to be detected. Even if the electrode is covered with the characteristic detection electrode, the gas to be detected can be detected well.
- an insulating film that insulates the crystal oscillation electrode and the characteristic detection electrode is provided between the crystal resonator and the gas adsorbing portion.
- a source electrode, a drain electrode, and a gas-sensitive film formed of a semiconductor material whose electric characteristics change according to the amount of gas to be detected on the crystal resonator or the surface acoustic wave element.
- a semiconductor element comprising a gate electrode and a gate insulating film that insulates the gate electrode from the source electrode and the drain electrode, and applying a voltage to the gate electrode while applying electrical characteristics between the source and drain.
- the adsorption mass is detected by the crystal resonator or the surface acoustic wave element.
- a gas-sensitive film whose electric characteristics change according to the amount of gas to be detected on the quartz resonator or the surface acoustic wave device, and a piezoelectric body of the quartz resonator or the surface acoustic wave device.
- a gas adsorbing portion composed of a characteristic detecting electrode that abuts and detects the electric characteristic is arranged, and an adsorbing mass is detected by the electric characteristic between the characteristic detecting electrodes and the crystal resonator or the surface acoustic wave element.
- the characteristic detection electrode is provided so as to come into contact with the piezoelectric body, so that the characteristic detection electrode and one of the crystal oscillation electrodes are located in the same layer and can be thinned.
- the electrical characteristics of the gas sensitive film can be measured using the characteristic detection electrode. Furthermore, if the gas-sensitive thin film is deformed by gas adsorption, the electromotive force generated by applying stress to the piezoelectric body due to the shape change can be measured.
- a gas sensitive film whose photoelectric characteristics change according to the amount of adsorption of the gas to be detected, and a characteristic detection electrode for detecting the electrical characteristics are arranged.
- light absorption / reflection / fluorescence characteristics of the gas-sensitive film, electrical characteristics between the characteristic detection electrodes, and a detected adsorption mass of the crystal resonator or the surface acoustic wave element are observed.
- the gas-sensitive film adsorbs the gas to be detected, so that the optical and electrical characteristics of the gas-sensitive film and the detected adsorption mass of the crystal resonator or the surface acoustic wave device are as follows. By observing the optical and electrical characteristics between the characteristic detection electrodes and the adsorbed mass by utilizing both of them, it is possible to easily detect and identify the gas to be detected.
- a gas detection method and a gas sensor according to the present invention includes a gas sensitive film having a characteristic detection electrode on a crystal resonator or a surface acoustic wave device, and the substance is formed by the crystal resonator or the surface acoustic wave device.
- the amount of adsorption can be detected, and the change in electrical characteristics with respect to the adsorption can be observed with a single element.
- the above-described method reduces the amount of change in adsorption mass and the amount of change in electrical characteristics. It can be detected accurately.
- a gas-sensitive thin film having a gap electrode or a sandwich electrode is disposed on a quartz resonator or a surface acoustic wave device, and the oscillation characteristics of the quartz resonator or the surface acoustic wave in the surface acoustic wave device is measured. It observes the propagation characteristics, the electrical characteristics of the gas-sensitive thin film with gap electrodes or sandwich electrodes, and the optical characteristics of the gas-sensitive thin film at the same time.
- FIG. 1 shows an arrangement example of a gas sensor in the present embodiment.
- a crystal resonator 10 including a crystal 1 and a pair of crystal oscillation electrodes 2 and 3 and an insulating film on the crystal oscillation electrode 3 are shown. 4 and a gas adsorbing portion 11 including a pair of characteristic detection electrodes 5 and 6 and a gas sensitive thin film 7 disposed on the insulating film 4.
- the insulating film 4 insulates the crystal oscillation electrode 3 from the characteristic detection electrode 5.
- the materials of the crystal oscillation electrodes 2 and 3 and the characteristic detection electrodes 5 and 6 may be the same or different. Further, the crystal oscillation electrode 3 and the characteristic detection electrode 5 without the insulating film 4 may be integrated.
- the gas adsorption unit 11 is provided so that the characteristic detection electrodes 5 and 6 sandwich the gas sensitive thin film 7 from above and below, and is arranged as a so-called sandwich electrode. .
- the distance between the electrodes can be easily reduced, and the drive voltage can be reduced.
- the electrode area increases, a large current can be easily passed.
- the characteristic detection electrode 6 positioned in the uppermost layer needs to be configured so that the gas to be detected can pass, such as a mesh shape. In this way, the contact area between the gas-sensitive thin film 7 and the gas to be detected can be secured. Therefore, even if the upper surface of the gas-sensitive thin film 7 is covered with the characteristic detection electrode 6, the gas to be detected can be detected well. be able to.
- the gas sensitive thin film 7 is made of, for example, an organic semiconductor such as phthalocyanine or SnO (tin oxide).
- the electrical characteristics mean various electrical characteristics such as current-voltage characteristics, resistance value, electromotive force, capacitance, etc., and change depending on the material and combination of materials used for the gas sensitive thin film 7.
- the electrical characteristics to be determined are determined. For example, when SnO is used for the gas sensitive thin film 7, the electric current is applied from the surface of the gas sensitive thin film 7.
- the resistance value increases, and when the reducing gas that gives electrons to the surface of the gas sensitive thin film 7 is adsorbed, the resistance value decreases.
- the gas sensitive thin film 7 surface force adsorbs an acidic gas that takes electrons away, and the resistance value decreases, and the gas sensitive thin film 7 has an electron on the surface.
- the reducing gas that gives is adsorbed, the resistance value increases.
- an oxide semiconductor or an organic / inorganic composite thin film can be used if strength is obtained.
- the characteristic detection electrodes 5 and 6 When a current is passed between the characteristic detection electrodes 5 and 6, the current flowing between the characteristic detection electrodes 5 and 6 increases or decreases according to the change in the resistance value of the gas sensitive thin film 7 due to the adsorption of the gas to be detected. Therefore, the current-voltage characteristic of the gas sensitive thin film 7 can be observed by measuring the current value. In addition, by using the characteristic detection electrodes 5 and 6, electric characteristics such as electromotive force, short-circuit current, and capacitance can be observed.
- Ionized gas molecules can be moved by the applied electric field. That is, if the electrode 6 is positively biased with respect to the electrode 5, the cation can be moved to the electrode 5 side and the anion can be moved to the electrode 6 side. When the polarity of the applied electric field is reversed, the movement of these ions is reversed. This makes it possible to control the distribution of adsorbed gas molecules inside the thin film.
- adsorption to the surface and movement into the thin film may contribute to the adsorption phenomenon.
- the movement of adsorbed molecules into the thin film can be controlled.
- mobile ions existing inside the thin film move by voltage and cause changes in the thin film structure such as expansion and contraction, observe the difference in the gas adsorption phenomenon associated with the change in the thin film structure. You can also.
- the gas sensor element of the present embodiment is an integral element, both the adsorption mass and the change in the electric characteristics can be reliably monitored.
- the element is an integrated element, even if the organic semiconductor film is covered with the upper electrode in the sandwich element, the amount of adsorption can be determined more accurately than in the case where the element is manufactured separately.
- the gas sensor element is exposed to the gas to be detected, and changes in the oscillation frequency of the crystal resonator 10 are observed during that time. At the same time, the current-voltage characteristics or electrical characteristics such as electromotive force, short-circuit current, and capacitance between the electrodes 5 and 6 are observed.
- the gas to be detected is adsorbed on the element and thus on the surface of the gas sensitive thin film 7, the electric characteristics of the gas sensitive thin film 7 change as described above.
- the mass of the gas sensor element is increased by the adsorption amount of the gas to be detected.
- the crystal unit 10 has a specific generation according to the mass of the adhered material adhered to the surface.
- the vibration frequency has a property (QCM)
- QCM the frequency decreases as the amount of gas to be detected increases. That is, the resonance frequency of the crystal resonator 10 changes almost in proportion to the mass of the detected gas adsorbed. Since these electrical characteristics and frequency characteristics show specific values according to the amount and type of adsorption of the gas to be detected, the relationship between the adsorption mass and the change in electrical properties observed in advance for several detection target gases. By comparing these, the detected gas is detected and identified. As described above, the detection gas can be detected and identified from the adsorption amount of the detection gas, that is, the change amount of the electrical characteristic corresponding to the frequency change of the crystal resonator 10. Furthermore, it is possible to change the spatial distribution of ions according to the voltage applied between the electrodes 5 and 6 and measure the adsorption response at that time.
- the gas sensor according to the present invention can detect the adsorption mass of a substance based on the oscillation frequency characteristics of the crystal resonator 10 with one gas sensor element, and can observe the amount of change in electrical characteristics with respect to the adsorption mass. As a result, it is not necessary to use two sensors side by side as in the prior art, and pinpoint and accurate detection is possible with respect to one point (one point) to be detected.
- the structure is simplified and steps such as etching are not required. Therefore, it can be manufactured at low cost.
- the gas sensitive thin film 7 can be secured because the gas sensing thin film 7 and the gas to be sensed can be secured by configuring the characteristic detection electrode 6 located on the uppermost layer so that the gas to be sensed can pass through. 7 Even if the upper surface is covered with the characteristic detection electrode 6, the gas to be detected can be detected well.
- the insulating film 4 that insulates the crystal oscillation electrode 3 from the characteristic detection electrode 5 is provided with a crystal resonator.
- the uppermost electrode 6 may be made of a material whose electrical characteristics change according to gas adsorption, such as palladium. The operation in this case is the same as described above.
- the crystal oscillation electrode 3 is partially removed by etching, etc., and the characteristic detection electrodes 5, 6 and gas A structure in which the sensitive thin film 7 is laminated may be used.
- the quartz crystal resonator 10 that performs mass measurement may be replaced with a surface acoustic wave device as disclosed in JP-A-2002-350445.
- FIG. 2 shows an arrangement example of gas sensors in the present embodiment. That is, the thin film transistor 20 as a semiconductor element composed of the gate electrode 15, the gate insulating film 8, the source electrode 16, the drain electrode 17, and the gas sensitive thin film 7 includes the crystal 1 and the crystal oscillation electrodes 2 and 3. The structure is arranged on the quartz crystal 10 and the insulating film 4. In this gas sensor element, the crystal oscillation electrode 3 and the gate electrode 15 without the insulating film 4 may be integrated. Also, a structure in which a part of the crystal oscillation electrode 3 is removed by etching or the like and a thin film transistor 20 is formed there may be used.
- the thin film transistor 20 includes a gate electrode 15, a gate insulating film 8 that insulates the gate electrode 15 from the source electrode 16 and the drain electrode 17, and a gas sensitive film 7 having the source electrode 16 and the drain electrode 17. Are laminated.
- the characteristic detection electrodes 5 and 6 may be arranged on the lower part of the gas sensitive thin film 7 and the force source electrode 16 and the drain electrode 17 provided on the upper part of the gas sensitive thin film 7.
- the current between the source and drain becomes a current amplified by the amplifying action of the thin film transistor 20, it is greatly amplified even by a small current change. Therefore, even slight adsorption of the gas to be detected can be detected, and the detection sensitivity is improved. Furthermore, the mobility that is the characteristic value of the transistor, the on / off ratio that is the ratio of the drain current when the gate voltage is not applied and the gate voltage that is applied, the threshold voltage V that is the gate voltage for turning on the transistor, Sub-threshold, which is the amount of change in gate voltage when drain current is increased by an order of magnitude By observing changes in transistor operation associated with gas adsorption, such as threshold voltage V
- the gate electrode 15, the source electrode 16, and the drain electrode 17 can be used to observe electrical characteristics such as electromotive force generation and capacitance.
- the ionized gas molecules can be moved by an electric field generated by a gate voltage. That is, when a positive gate voltage is applied, positive ions can be moved to the outside air and negative ions can be moved to the insulating film. When a negative gate voltage is applied, the movement of these ions is reversed. This makes it possible to control the distribution of adsorbed gas molecules inside the thin film. In addition, adsorption to the surface and movement into the thin film may contribute to the adsorption phenomenon. By applying this voltage, the movement of adsorbed molecules into the thin film can be controlled.
- the difference in transistor characteristics can be observed when gas is adsorbed on the surface of the thin film and when adsorbed gas molecules move into the thin film. Furthermore, when mobile ions existing inside the thin film move due to an electric field and cause changes in the thin film structure such as expansion and contraction, the difference in the gas adsorption response accompanying this change in the thin film structure should be observed. You can also. In these cases, for example, exposure to the gas is performed while applying the gate voltage, and the FET operation is observed after a certain period of time, so that the difference from the case where the gate voltage is impressed is investigated. At this time, if the gas adsorption amount increases, the current value increases, and the capacitance applied voltage characteristics also change due to the charge of the adsorbed gas. In addition, obtain changes in V, V, ⁇ , etc., related to FET operation.
- the change in the amount of gas adsorbed by QCM can be measured simultaneously, and the effect of applying the gate voltage can be measured.
- the measurement as described above since it is an integrated element, it is possible to reliably monitor both the adsorption mass and the change in electrical characteristics.
- the operation of the present embodiment is the same as that of the first embodiment except for the amplification operation of the thin film transistor 20 described above.
- the current flowing between the source and drain becomes an amplified current due to the amplification action of the thin film transistor 20, so that even a minute current change is greatly amplified.
- the Rukoto Therefore, even slight adsorption of the gas to be detected can be detected, and the detection sensitivity is improved.
- the distribution of mobile ions inside the thin film can be controlled by applying a gate voltage.
- the distribution of ionized adsorbed gas within the thin film can be controlled to measure differences in transistor operation, or the adsorption speed and amount can be controlled by changing the thin film structure accompanying the movement of mobile ions. Can do.
- the quartz crystal resonator 10 that performs mass measurement may be replaced with the surface acoustic wave device.
- FIG. 3 shows an example of the arrangement of the gas sensor in the present embodiment.
- the crystal resonator 10 including the crystal 1 and the pair of crystal oscillation electrodes 2 and 3 and the crystal oscillation electrode 3 in the same layer are shown.
- the gas adsorbing section 11 is composed of a pair of characteristic detection electrodes 5 and 6 and a gas-sensitive thin film 7 arranged at positions. In this gas sensor element, the electrode 3 and the electrode 5 may be integrated.
- the crystal oscillation electrode 3 and the characteristic detection electrodes 5, 6 are provided on the same layer. Therefore, in order to form the crystal oscillation electrode 3 and the characteristic detection electrodes 5 and 6, it is only necessary to form one electrode layer and perform etching to form each electrode. In this way, by forming the crystal oscillation electrode 3 and the characteristic detection electrodes 5 and 6 on the same layer, the thickness can be reduced.
- the current flowing between the characteristic detection electrodes 5 and 6 increases or decreases according to the change in the resistance value of the gas sensitive thin film 7 due to the adsorption of the gas to be detected. Therefore, the current-voltage characteristic of the gas sensitive thin film 7 can be observed by measuring the current value. In addition, electrical characteristics such as electromotive force generation and capacitance can be observed by the characteristic detection electrodes 5 and 6. Furthermore, since a current also flows between the crystal oscillation electrode 3 and the characteristic detection electrode 5, the current between the characteristic detection electrodes 5 and 6, the crystal oscillation electrode 3 and the characteristic detection electrode It is also possible to observe both the current flowing between poles 5.
- the operation of the invention in this embodiment is the same as that of the first embodiment except for the crystal oscillation electrode 3 and the characteristic detection electrodes 5 and 6 described above.
- the gas to be detected is placed on the crystal resonator 10 including the crystal 1 that vibrates at a specific frequency and the crystal oscillation electrodes 2 and 3 that apply a voltage to the crystal 1.
- a gas-sensitive thin film 7 whose electrical characteristics change according to the amount of adsorbed gas and a gas-adsorbing part 11 consisting of characteristic detection electrodes 5 and 6 that contact the crystal 1 and detect the electrical characteristics are arranged to detect the characteristics. The electrical characteristics between the electrodes 5 and 6 and the oscillation characteristics of the quartz crystal 10 are observed.
- the characteristic detection electrodes 5 and 6 are provided so as to come into contact with the crystal 1 by rubbing in this way, the characteristic detection electrodes 5 and 6 and one of the crystal oscillation electrodes 3 are in the same layer position.
- the crystal resonator 10 that performs mass measurement may be the surface acoustic wave device.
- FIG. 4 shows an arrangement example of the gas sensor in the present embodiment.
- the surface acoustic wave element 24 including the piezoelectric body 21, the comb-shaped excitation electrode 22, and the comb-shaped reception electrode 23, and the same layer as the excitation electrode 22 are shown.
- the gas adsorbing portion 11 is composed of a pair of characteristic detection electrodes 5 and 6 and a gas sensitive thin film 7 arranged at the position of.
- the operation of the surface acoustic wave element 24 is substantially the same as that disclosed in Japanese Patent Laid-Open No. 2002-350445. A change in the propagation characteristics of the surface acoustic wave due to the substance adsorption is detected by a signal generated at the comb-shaped receiving electrode 23.
- an oscillation circuit is configured by connecting an external circuit, and oscillation characteristics are measured.
- a quartz crystal resonator may be used as the mass measuring means.
- the gas sensitive thin film 7 is made of a material whose optical characteristics and electrical characteristics (photoelectric characteristics) change with gas adsorption. in this case The light characteristics of the light refers to light absorption, reflection, scattering, or fluorescence characteristics.
- a transparent or translucent material can be used for the crystal oscillation electrode and the characteristic detection electrodes 5 and 6 constituting the crystal resonator.
- the current flowing between the characteristic detection electrodes 5 and 6 increases or decreases according to the change in the resistance value of the gas sensitive thin film 7 due to the adsorption of the gas to be detected. Therefore, the current-voltage characteristic of the gas sensitive thin film 7 can be observed by measuring the current value. In addition, electrical characteristics such as electromotive force generation and capacitance can be observed by the characteristic detection electrodes 5 and 6. Furthermore, by installing a photodetector (not shown), light absorption, reflection, scattering, or fluorescence characteristics in the gas-sensitive thin film accompanying adsorption of the gas to be detected can be observed. At the same time, the amount of gas adsorbed is measured by the surface acoustic wave element 24.
- the light absorption / reflection / scattering or fluorescence characteristics of the gas-sensitive thin film 7 are measured in addition to the change in mass and electrical characteristics. . Since the optical characteristics, electrical characteristics, and mass characteristics of the gas-sensitive thin film 7 show unique values depending on the amount and type of adsorption of the gas to be detected, The gas to be detected is detected and identified by comparing the relationship between the optical property and the change in electrical property.
- the surface of the surface acoustic wave element 24 is in contact with the piezoelectric body 21 and the gas sensitive thin film 7 whose optical characteristics and electrical characteristics change according to the amount of gas to be detected.
- a gas adsorbing part 11 composed of characteristic detection electrodes 5 and 6 for detecting the electric characteristics is arranged, and the electric characteristics between the characteristic detection electrodes 5 and 6 and the oscillation characteristics of the surface acoustic wave element 24 are observed. Yes.
- detection and identification of the gas to be detected can be easily performed from the amount of change in the optical characteristics and electrical characteristics corresponding to the change in the amount of adsorption of the gas to be detected detected by the surface acoustic wave element 24. .
- the shape of the gas-sensitive thin film 7 is not particularly limited as long as the electric characteristics or the electric characteristics and the optical characteristics change by adsorbing the gas to be detected.
- gases can be detected by changing the material of the gas-sensitive thin film 7.
- Also have a gap electrode or sandwich electrode The electrical characteristics of the gas-sensitive thin film 7 and the optical characteristics of the gas-sensitive thin film 7, the oscillation characteristics of the crystal resonator 10, or the surface acoustic wave propagation characteristics of the surface acoustic wave element 24 are alternated or only one or only two You may observe it.
- an oxidizing gas such as acid and nitrogen
- a basic gas such as ammonia
- an organic solvent gas such as carbon monoxide, carbon dioxide, etc.
- FIG. 1 is a longitudinal sectional view showing a structure of a gas sensor according to a first embodiment of the present invention.
- FIG. 2 is a longitudinal sectional view showing the structure of a gas sensor in a second embodiment of the present invention.
- FIG. 3 is a longitudinal sectional view showing the structure of a gas sensor according to a third embodiment of the present invention.
- FIG. 4 is a longitudinal sectional view showing the structure of a gas sensor according to a fourth embodiment of the present invention.
- FIG. 5 is a perspective view showing the structure of the gas sensor.
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Description
Claims
Priority Applications (2)
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JP2006529055A JP4164580B2 (ja) | 2004-07-12 | 2005-07-12 | ガス検知方法およびガスセンサ |
US11/632,243 US20080022755A1 (en) | 2004-07-12 | 2005-07-12 | Gas Detection Method and Gas Sensor |
Applications Claiming Priority (2)
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JP2004205168 | 2004-07-12 | ||
JP2004-205168 | 2004-07-12 |
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WO2006006587A1 true WO2006006587A1 (ja) | 2006-01-19 |
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PCT/JP2005/012817 WO2006006587A1 (ja) | 2004-07-12 | 2005-07-12 | ガス検知方法およびガスセンサ |
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US (1) | US20080022755A1 (ja) |
JP (1) | JP4164580B2 (ja) |
WO (1) | WO2006006587A1 (ja) |
Cited By (10)
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JP2008083036A (ja) * | 2006-08-28 | 2008-04-10 | Hitachi Chem Co Ltd | センサ基板およびこれを用いた複合センサ |
JP2009098084A (ja) * | 2007-10-19 | 2009-05-07 | Fujitsu Ltd | 雰囲気分析装置及び雰囲気分析方法 |
US7659654B2 (en) | 2007-03-22 | 2010-02-09 | Seiko Epson Corporation | Piezoelectrics oscillator, sensor, and multi-sensor |
JP2011038979A (ja) * | 2009-08-18 | 2011-02-24 | Fujitsu Ltd | イオンセンサ、イオン分析装置、及びイオン分析方法 |
KR101355371B1 (ko) * | 2012-05-29 | 2014-01-27 | 포항공과대학교 산학협력단 | 전기적 특성과 질량변화를 동시에 측정하는 수정 진동자 미세 저울 센서 |
JP2017167122A (ja) * | 2016-03-11 | 2017-09-21 | セイコーインスツル株式会社 | 圧電装置、圧電ユニット、測定装置、及び測定方法 |
CN107290392A (zh) * | 2017-07-31 | 2017-10-24 | 成都信息工程大学 | 一种高稳定性低湿度检测的qcm湿度传感器及其制备方法 |
CN107290241A (zh) * | 2017-07-31 | 2017-10-24 | 成都信息工程大学 | 一种qcm湿度传感器及其制备方法 |
JP2020514687A (ja) * | 2017-01-17 | 2020-05-21 | マトリックス センサーズ, インコーポレイテッドMatrix Sensors, Inc. | 湿度補正付きガスセンサー |
JP2020098113A (ja) * | 2018-12-17 | 2020-06-25 | 株式会社東芝 | 分子検出装置 |
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Publication number | Priority date | Publication date | Assignee | Title |
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JP2008083036A (ja) * | 2006-08-28 | 2008-04-10 | Hitachi Chem Co Ltd | センサ基板およびこれを用いた複合センサ |
US7659654B2 (en) | 2007-03-22 | 2010-02-09 | Seiko Epson Corporation | Piezoelectrics oscillator, sensor, and multi-sensor |
JP2009098084A (ja) * | 2007-10-19 | 2009-05-07 | Fujitsu Ltd | 雰囲気分析装置及び雰囲気分析方法 |
JP2011038979A (ja) * | 2009-08-18 | 2011-02-24 | Fujitsu Ltd | イオンセンサ、イオン分析装置、及びイオン分析方法 |
KR101355371B1 (ko) * | 2012-05-29 | 2014-01-27 | 포항공과대학교 산학협력단 | 전기적 특성과 질량변화를 동시에 측정하는 수정 진동자 미세 저울 센서 |
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CN107290392A (zh) * | 2017-07-31 | 2017-10-24 | 成都信息工程大学 | 一种高稳定性低湿度检测的qcm湿度传感器及其制备方法 |
CN107290241A (zh) * | 2017-07-31 | 2017-10-24 | 成都信息工程大学 | 一种qcm湿度传感器及其制备方法 |
JP2020098113A (ja) * | 2018-12-17 | 2020-06-25 | 株式会社東芝 | 分子検出装置 |
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Also Published As
Publication number | Publication date |
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JP4164580B2 (ja) | 2008-10-15 |
JPWO2006006587A1 (ja) | 2008-07-31 |
US20080022755A1 (en) | 2008-01-31 |
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