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WO1996042011A1 - Detecteur integre - Google Patents

Detecteur integre Download PDF

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Publication number
WO1996042011A1
WO1996042011A1 PCT/GB1996/001339 GB9601339W WO9642011A1 WO 1996042011 A1 WO1996042011 A1 WO 1996042011A1 GB 9601339 W GB9601339 W GB 9601339W WO 9642011 A1 WO9642011 A1 WO 9642011A1
Authority
WO
WIPO (PCT)
Prior art keywords
sensing device
gas sensing
mass measurement
conductimetric
organic polymer
Prior art date
Application number
PCT/GB1996/001339
Other languages
English (en)
Inventor
Peter Alfred Payne
Krishna Chandra Persaud
Richard Mark Dowdeswell
Mohammed El Hassan Amrani
Original Assignee
Aromascan Plc
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Aromascan Plc filed Critical Aromascan Plc
Priority to EP96916244A priority Critical patent/EP0830589A1/fr
Priority to JP9502761A priority patent/JPH11507729A/ja
Priority to AU59067/96A priority patent/AU5906796A/en
Publication of WO1996042011A1 publication Critical patent/WO1996042011A1/fr

Links

Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N33/00—Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
    • G01N33/0004—Gaseous mixtures, e.g. polluted air
    • G01N33/0009—General constructional details of gas analysers, e.g. portable test equipment
    • G01N33/0027—General constructional details of gas analysers, e.g. portable test equipment concerning the detector
    • G01N33/0031—General constructional details of gas analysers, e.g. portable test equipment concerning the detector comprising two or more sensors, e.g. a sensor array
    • G01N33/0032—General constructional details of gas analysers, e.g. portable test equipment concerning the detector comprising two or more sensors, e.g. a sensor array using two or more different physical functioning modes
    • 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
    • G01N27/02—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance
    • G01N27/04—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating resistance
    • G01N27/12—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating resistance of a solid body in dependence upon absorption of a fluid; of a solid body in dependence upon reaction with a fluid, for detecting components in the fluid
    • G01N27/125—Composition of the body, e.g. the composition of its sensitive layer
    • G01N27/126—Composition of the body, e.g. the composition of its sensitive layer comprising organic polymers
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N29/00—Investigating or analysing materials by the use of ultrasonic, sonic or infrasonic waves; Visualisation of the interior of objects by transmitting ultrasonic or sonic waves through the object
    • G01N29/02—Analysing fluids
    • G01N29/022—Fluid sensors based on microsensors, e.g. quartz crystal-microbalance [QCM], surface acoustic wave [SAW] devices, tuning forks, cantilevers, flexural plate wave [FPW] devices
    • 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
    • G01N2291/025—Change of phase or condition
    • G01N2291/0256—Adsorption, desorption, surface mass change, e.g. on biosensors
    • 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
    • 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
    • G01N2291/04—Wave modes and trajectories
    • G01N2291/042—Wave modes
    • G01N2291/0423—Surface waves, e.g. Rayleigh waves, Love waves
    • 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
    • G01N2291/04—Wave modes and trajectories
    • G01N2291/042—Wave modes
    • G01N2291/0426—Bulk waves, e.g. quartz crystal microbalance, torsional waves

Definitions

  • This invention relates to gas sensors, in particular to gas sensors which combine mass measurement and conductimetric detection facilities, thereby permitting two transduction techniques to be applied to a single sensor.
  • Quartz resonator sensors consist of a piezoelectric quartz crystal oscillator coated with a sensing membrane.
  • SAW devices consist of a piezoelectric substrate (such as quartz) having interdigitated electrodes fabricated thereon, and a thin film coating of a sensitive material.
  • a radio frequency voltage is applied across the electrodes which leads to the formation of a Rayleigh surface acoustic wave, the frequency of which is perturbed by the adsorption of gas due to the attendant increase in mass of the coating.
  • SAW devices can be operated at higher frequencies than quartz resonator devices resulting in improvements in sensitivity.
  • the selectivity of the sensor is determined by the coating material, which is typically a polymer that shows absorptive characteristics that are useful for the range of molecules to be detected.
  • the coating material typically a polymer that shows absorptive characteristics that are useful for the range of molecules to be detected.
  • Other materials have also been employed as coatings for quartz resonators, such as celluloses, gas chromatographic stationary phase materials and both natural and synthetic lipids.
  • Another type of gas sensor which is finding widespread application, involves the bridging of electrodes with semiconducting organic polymers (SOPs).
  • SOPs semiconducting organic polymers
  • the electrical properties of the polymer may be modified by the adsorption of gaseous species and therefore the presence of these species may be detected by monitoring the change in an electrical property accompanying the adsorption process.
  • the electrical property may be the dc resistance of the polymer (see, for example, K.C. Persaud and P. Pelosi, Gas sensors: towards an artificial nose, in "Sensors and Sensory Systems for Advanced Robots", NATO ASI Series: Series F: Computer and Systems Science, ed. P.
  • Sensors of this type offer a number of advantages including enhanced sensitivities compared to quartz resonator and SAW devices and rapid and reversible adsorption kinetics.
  • the "conductimetric" SOP based sensors and “mass measurement” sensors such as quartz resonators and SAWs may be regarded, to some extent, as complementary techniques. This is because the former, although possessing superior sensitivites, are only selective towards gases which adsorb onto the polymer and affect the electrical properties thereof. Such gases are generally polar molecules. The latter is selective toward all molecules which adsorb onto the active surface with an affinity which exceeds the inherent detection limit of the device.
  • the present invention provides an integrated sensor which combines both mass measurement and conductimetric transduction techniques in a single device.
  • the most relevant prior art in this regard appears to be constituted by a series of papers by JM Slater et al (see, for example, J.M. Slater, E.J. Watt, N.J. Freeman, I.P. May and D.J. Weir, Analyst, 117 (1992) 1265 and references therein) wherein a quartz resonator was coated with a SOP and mass measurements were made, augmented by conductimetric interrogation of a separate SOP sensor of the type described above.
  • gas sensing includes the detection of volatile species.
  • a gas sensing device comprising a mass measurement gas sensor coated with at least one layer of semiconducting organic polymer (SOP) and having both mass measurement and conductimetric transduction means.
  • SOP semiconducting organic polymer
  • the mass measurement gas sensor may be a quartz resonator device or a SAW device.
  • the conductimetric transduction means may comprise means for applying a dc electric signal across the layer or layers of SOP, and detection means for detecting changes in resistance.
  • the conductimetric transduction means may comprise means for applying an ac electric signal across the layer or layers of SOP, and detection means for detecting an impedance property.
  • the SOP may be deposited electrochemically, by oxidative chemical vapour deposition, or by spin or spray coating.
  • Figure 1 is a schematic diagram of the apparatus together with a view from above the SAW device.
  • Figure 2 is a view from below the SAW device.
  • Figures 1 and 2 depict a gas sensing device of the present invention comprising a mass measurement sensor 10 coated with a layer of SOP 12, and having both mass measurement transduction means 14 and conductimetric transduction means 16.
  • the mass measurement sensor 10 is a SAW device having interdigitated electrodes 18a, 18b fabricated onto a piezoelectric substrate 20 such as quartz.
  • the mass measurement transduction means 14 includes rf voltage applying means for applying said voltage across the elecrodes 18a, 18b.
  • the applied voltage produces a Rayleigh surface acoustic wave (i.e. a surface oscillation), the frequency of which is perturbed by changes in the mass of the sensor due to adsorption of gas onto the SOP coating.
  • This frequency shift produces a voltage phase shift which may be detected by phase sensitive detection means.
  • Said phase sensitive detection means may be part of the voltage applying means or a separate unit.
  • the sensor 10 may be connected to a reference sensor and the frequency difference measured.
  • the layer of SOP 12 bridges two electrodes 22a, 22b, and the conductimetric transduction means 16 includes means for applying an electric signal across these electrodes.
  • the electric signal may be a dc signal, in which instance the transduction means 16 also includes resistance measuring means (such as described in, for example, BA Gregory; "An Introduction to Electrical Instrumentation and Measurement Systems", 1982, MacMillen).
  • an ac electric signal may be applied, and an impedance property of the SOP layer 12, such as conductance, monitored.
  • a rf impedance analyser could serve as the conductimetric transduction means 16. In either instance the presence of a gas is detected by detecting the variation in the electrical property monitored caused by adsorption of the gas onto the polymer.
  • Data from both transduction techniques may be transmitted, via a suitable interface , to a computer 24 for display and analysis purposes.
  • the advantage of the present invention is that the complementary properties of two gas sensing methods are combined in one device; in particular this feature permits the detection of both polar and non-polar molecules.
  • the conductimetric method has relatively high sensitivity, but is only applicable to molecules which, in addition to being adsorbed onto the polymer, significantly affect the conductivity thereof. Generally speaking, such molecules are polar.
  • the mass measurement method requires only that there is significant adsorption, since the measured properties depend upon the mass of the adsorbed material, and therefore non-polar molecules - which are readily absorbed onto the surface of the SOP - may be detectable.
  • a single sensor may detect polar molecules at high sensitivities and, additionally, that hydrophobic interactions due to the adsorption of certain non-polar molecules will also be detectable by mass measurement techniques, even though the changes in SOP conductance associated therewith are of insufficient magnitude for detection by conventional SOP sensors.
  • the precise identity of molecules detectable by either method depends upon the nature of the SOP used. It should be noted that the results of the two transduction techniques - whether or not there is a significant response- can be used in combination to provide extra information on the nature of the gas detected.
  • the SOP layer may be deposited by any of the numerous techniques described in the literature, such as electrochemical or oxidative chemical vapour deposition, or by spin or spray coating. Numerous SOPs have previously been employed for gas sensing purposes, polypyrrole being perhaps the most commonly encountered example, and the present invention is not limited in scope in this respect.
  • the contact electrodes 22a, 22b may be bonded to the piezoelectric substrate - such is necessary if an electrochemical deposition is contemplated - or may be bonded or attached to the SOP itself.
  • a SOP coated quartz resonator device was produced by modification of a commercially available quartz resonator.
  • the resonator is a quartz wafer having a layer of aluminium of approximate thickness 0.02 ⁇ m deposited on both sides thereof. Aluminium of one face of the resonator was selectively removed by a hand painted etch comprising nitric, acetic and phosphoric acids. Polypyrrole was then deposited by an oxidative chemical vapour method over a substantial portion of the etched resonator surface.
  • the polypyrrole coating 36 extends for approximately 6mm, virtually from one side of the resonator 30 to another, and exhibits a resistance of ca. 10K ⁇ .
  • the resonator was then housed within a PTFE block and connected to a vapour rig of straightforward design.
  • the spring contact electrodes in contact with the aluminium coating 34 were connected to an impedance analyser and the reactance was measured around the resonant frequency (ca. 1845 KHz).
  • Figure 4 shows the effect of exposing the resonator to dry air 1, ethanol vapour 2 and toulene vapour 3 at a flow rate of 200 ml min "1 . Frequency shifts (with respect to the dry air valve) of -33.5 Hz ethanol and -18.5 Hz for toulene are observed.
  • Figure 5 shows the kinetic response of the resonator to a pulse of toulene vapour. A change of 1200% in the reactance (measured around 1844.91 KHz) is observed.
  • the frequency shift measurements are "mass measurements", because the observed perturbation of the resonant frequency is induced by the mass change due to adsorption of molecules with high affinity onto the polymer (although non-specific adsorption onto other regions of the resonator will likely play an as yet unquantified role).
  • Conductimetric measurements were also made by connecting the spring contact electrodes in contact with the polpyrrole coating 36 to a dc resistance measuring meter of conventional type.
  • the dc resistance of the resonator in a dry air atmosphere was 11.8 ⁇ , which rose to 13.1 ⁇ and 12.5 ⁇ on exposure to ethanol and toluene vapour respectively.
  • An improvement on the present arrangement would involve removal of part of the aluminium coating on one face of the resonator followed by patterning with a suitable gold electrode structure.
  • a polymer, or, if desired, an array of polymers could be deposited on and between the electrode structure.
  • Conventional wire bonding techniques could be used to connect to the electrode structure, whilst the spring loaded connection method would be retained for connection to the aluminium coatings.
  • arrays of quartz resonators or SAW devices, or combinations thereof, with different SOPs can be constructed. Patterns of responses from such arrays can be used to identify individual or complex mixtures of chemical species.

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  • Chemical & Material Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Physics & Mathematics (AREA)
  • Health & Medical Sciences (AREA)
  • Analytical Chemistry (AREA)
  • General Health & Medical Sciences (AREA)
  • Pathology (AREA)
  • Immunology (AREA)
  • General Physics & Mathematics (AREA)
  • Biochemistry (AREA)
  • Engineering & Computer Science (AREA)
  • Food Science & Technology (AREA)
  • Combustion & Propulsion (AREA)
  • Medicinal Chemistry (AREA)
  • Acoustics & Sound (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • Investigating Or Analyzing Materials By The Use Of Ultrasonic Waves (AREA)
  • Investigating Or Analyzing Materials By The Use Of Electric Means (AREA)

Abstract

L'invention concerne un dispositif pouvant détecter des gaz, comprenant un détecteur de gaz à mesure de masse, recouvert d'au moins une couche de polymère organique semi-conducteur, possédant à la fois des moyens de mesure de masse et des moyens de transduction conductométrique.
PCT/GB1996/001339 1995-06-09 1996-06-06 Detecteur integre WO1996042011A1 (fr)

Priority Applications (3)

Application Number Priority Date Filing Date Title
EP96916244A EP0830589A1 (fr) 1995-06-09 1996-06-06 Detecteur integre
JP9502761A JPH11507729A (ja) 1995-06-09 1996-06-06 統合センサ
AU59067/96A AU5906796A (en) 1995-06-09 1996-06-06 Integrated sensor

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GBGB9511734.7A GB9511734D0 (en) 1995-06-09 1995-06-09 Intergrated sensor
GB9511734.7 1995-06-09

Publications (1)

Publication Number Publication Date
WO1996042011A1 true WO1996042011A1 (fr) 1996-12-27

Family

ID=10775807

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/GB1996/001339 WO1996042011A1 (fr) 1995-06-09 1996-06-06 Detecteur integre

Country Status (5)

Country Link
EP (1) EP0830589A1 (fr)
JP (1) JPH11507729A (fr)
AU (1) AU5906796A (fr)
GB (1) GB9511734D0 (fr)
WO (1) WO1996042011A1 (fr)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1998037412A1 (fr) * 1997-02-19 1998-08-27 Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V. Dispositif pour la detection de parametres de materiau de milieux liquides
WO2000016096A1 (fr) * 1998-09-14 2000-03-23 THE MINISTER OF AGRICULTURE, FISHERIES & FOOD IN HER BRITANNIC MAJESTY'S GOVERNMENT OF THE UNITED KINGDOM OF GREAT BRITAIN AND NORTHERN IRELAND Ministry of Agriculture, Fisheries & Food Systeme artificiel de detection olfactive
US6341629B1 (en) 1996-11-01 2002-01-29 Bp Oil International Limited Testing device and method of use
US6881585B1 (en) 2000-03-06 2005-04-19 General Electric Company Method and apparatus for rapid screening of volatiles
KR101355371B1 (ko) * 2012-05-29 2014-01-27 포항공과대학교 산학협력단 전기적 특성과 질량변화를 동시에 측정하는 수정 진동자 미세 저울 센서

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2005052570A1 (fr) * 2003-11-13 2005-06-09 Technische Universität Clausthal Capteur, systeme de capteur et procede de mesure
WO2006006587A1 (fr) * 2004-07-12 2006-01-19 Niigata University Capteur et méthode de détection de gaz

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4674320A (en) * 1985-09-30 1987-06-23 The United States Of America As Represented By The United States Department Of Energy Chemoresistive gas sensor
US4681855A (en) * 1985-08-05 1987-07-21 The United States Of America As Represented By The Secretary Of Commerce Humidity sensing and measurement employing halogenated organic polymer membranes
WO1993003355A1 (fr) * 1991-07-29 1993-02-18 Neotronics Limited Dispositif de detection de produits volatils
JPH05223720A (ja) * 1992-02-17 1993-08-31 Nippon Telegr & Teleph Corp <Ntt> におい質センシング方法

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4681855A (en) * 1985-08-05 1987-07-21 The United States Of America As Represented By The Secretary Of Commerce Humidity sensing and measurement employing halogenated organic polymer membranes
US4674320A (en) * 1985-09-30 1987-06-23 The United States Of America As Represented By The United States Department Of Energy Chemoresistive gas sensor
WO1993003355A1 (fr) * 1991-07-29 1993-02-18 Neotronics Limited Dispositif de detection de produits volatils
JPH05223720A (ja) * 1992-02-17 1993-08-31 Nippon Telegr & Teleph Corp <Ntt> におい質センシング方法

Non-Patent Citations (3)

* Cited by examiner, † Cited by third party
Title
J.M. SLATER, ET AL.: "GAS AND VAPOUR DETECTION WITH POLY(PYRROLE) GAS SENSORS", ANALYST, vol. 117, August 1992 (1992-08-01), LONDON, GB, pages 1265 - 1270, XP000604336 *
PATENT ABSTRACTS OF JAPAN vol. 17, no. 666 (P - 1656) 8 December 1993 (1993-12-08) *
T. NOMURA ET AL.: "MEASUREMENT OF HUMIDITY USING SURFACE ACOUSTIC WAVE DEVICE", JAPANESE JOURNAL OF APPLIED PHYSICS, vol. 31, September 1992 (1992-09-01), TOKYO JP, pages 3070 - 3072, XP000355711 *

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6341629B1 (en) 1996-11-01 2002-01-29 Bp Oil International Limited Testing device and method of use
WO1998037412A1 (fr) * 1997-02-19 1998-08-27 Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V. Dispositif pour la detection de parametres de materiau de milieux liquides
WO2000016096A1 (fr) * 1998-09-14 2000-03-23 THE MINISTER OF AGRICULTURE, FISHERIES & FOOD IN HER BRITANNIC MAJESTY'S GOVERNMENT OF THE UNITED KINGDOM OF GREAT BRITAIN AND NORTHERN IRELAND Ministry of Agriculture, Fisheries & Food Systeme artificiel de detection olfactive
US6881585B1 (en) 2000-03-06 2005-04-19 General Electric Company Method and apparatus for rapid screening of volatiles
KR101355371B1 (ko) * 2012-05-29 2014-01-27 포항공과대학교 산학협력단 전기적 특성과 질량변화를 동시에 측정하는 수정 진동자 미세 저울 센서

Also Published As

Publication number Publication date
GB9511734D0 (en) 1995-08-02
EP0830589A1 (fr) 1998-03-25
JPH11507729A (ja) 1999-07-06
AU5906796A (en) 1997-01-09

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