EP0072744A2
Expired / Lapsed
EP
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Chemical sensor
Assignee: Honeywell International Inc
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Filing: 1982-08-09
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Granted: —
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Expires: 2002-08-09
Abstract
Abstract A chemical sensor for detecting at least one gas component in a gas sample, and comprising at least one vibrating member coated with a reactive material which selectively interacts with said gas component thus increasing the coating's mass and reducing the natural resonance frequency of said vibrating member ; According to this invention, the vibrating member consists of a cantilevered beam (10) suspended from a support (14) and carrying a layer (30) of reactive material, said beam being vibrated at its natural resonance frequency by an oscillator (34) and being further coupled to a sensor means (20) for generating a signal having a frequency component equal to the vibration frequency of said beam. For use in the analyze of gas samples.
Inventors
- 👤 James Michael O'connor
- 👤 Jesse Carl Patton
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-29 13:26
CPC Classifications
G; G01; G01N; G01N29/00; G01N29/02; G01N29/036; G01N2291/00; G01N2291/02; G01N2291/025; G01N2291/0256; G01N2291/04; G01N2291/042; G01N2291/0427
Claims Analysis
Total Claims: 21
Claim 1
Independent Claim
128 words
A chemical sensor for detecting at least one gas component in a gas sample, and comprising at least one vibrating member coated with a reactive material which selectively interacts with said gas component thus causing a change in the coating's mass and consequently in the natural resonance frequency of said vibrating member, characterized in that the vibrating member consists of a beam (10) suspended for vibration from a support structure (14) and carrying on at least one surface thereof a layer (30) of reactive material, said beam being vibrated at its natural resonance frequency by an oscillator (34) and being further associated with sensor means (20) for detecting its vibration to generate a resonance frequency signal having a frequency component equal to the vibration frequency of said beam.
Claim 2
Dependent Claim
128 words
A chemical sensor for detecting at least one gas component in a gas sample, and comprising at least one vibrating member coated with a reactive material which selectively interacts with said gas component thus causing a change in the coating's mass and consequently in the natural resonance frequency of said vibrating member, characterized in that the vibrating member consists of a beam (10) suspended for vibration from a support structure (14) and carrying on at least one surface thereof a layer (30) of reactive material, said beam being vibrated at its natural resonance frequency by an oscillator (34) and being further associated with sensor means (20) for detecting its vibration to generate a resonance frequency signal having a frequency component equal to the vibration frequency of said beam.
Claim 3
Dependent Claim
49 words
A chemical sensor according to claim 1, characterized in that the resonance frequency signal is amplified in the oscillator (34) to generate an output signal which itself is delivered to means (16, 32) for producing a force on the beam (10) to sustain its vibration at its resonance frequency.
Claim 4
Dependent Claim
77 words
A chemical sensor according to claim 2, characterized in that the means for producing a force comprises a first electrode (32) disposed on one surface of the beam (10) and a second electrode (16) fixedly carried by the support structure (14) proximate said first electrode, said output signal being applied between said first and second electrodes to generate an oscillating electrostatic field therebetween which produces an oscillating electrostatic force on the beam (10) sustaining the vibration thereof.
Claim 5
Dependent Claim
35 words
A chemical sensor according to any of claims 1-3, characterized in that the beam (10) is a cantilevered beam having a base end fixedly attached to a supporting substrate (14) and an opposite free end.
Claim 6
Dependent Claim
22 words
A chemical sensor according to claim 4, characterized in that said supporting substrate (14) and cantilevered beam (10) are an integral structure.
Claim 7
Dependent Claim
22 words
A chemical sensor according to claim 5, characterized in that the material of said integral structure (10, 14) is a semiconductor material.
Claim 8
Dependent Claim
36 words
A chemical sensor according to any of claims 1 to 6, characterized in that it further includes heater means (40) disposed on the surface of the beam (10) for heating said layer (30) of reactive material.
Claim 9
Dependent Claim
50 words
A chemical sensor according to any of claims 4 to 7, characterized in that said supporting substrate (14) has a thickness greater than the thickness of the beam (10) and has an aperture (12) passing therethrough, and in that the cantilevered beam is suspended over one end of said aperture.
Claim 10
Dependent Claim
26 words
A chemical sensor according to claim 8, characterized in that said second electrode (16) is a metal plate covering the opposite end of said aperture (12).
Claim 11
Dependent Claim
33 words
A chemical sensor according to any of claims 5 to 9, characterized in that said sensor means (20) and oscillator (34) are formed directly on the surface of said integral structure (10, 14).
Claim 12
Dependent Claim
32 words
A chemical sensor according to claim 10, characterized in that said sensor means (20) is a piezoresistive bridge formed at the base end of the beam (10) adjacent to.said integral structure (14).
Claim 13
Dependent Claim
44 words
A chemical sensor according to claim 10, characterized in that said sensor means (20) is a dual element voltage divider (50, 52) having at least one piezoresistive element (50) disposed at the base end of the beam (10) adjacent to said integral structure (14).
Claim 14
Dependent Claim
89 words
A chemical sensor according to any of claims 1 to 12, characterized in that it includes two beams (110, 112) having the same initial resonance frequency and each associated with a respective oscillator (134, 144) and a respective sensor means (120, 122), at least one (110) of said beams carrying a layer (30) of reactive material, and a mixer circuit (150) responsive to the resonance frequencies of said two beams (110, 112) to generate an output signal having a frequency component equal to the difference between their resonance frequencies.
Claim 15
Dependent Claim
21 words
A chemical sensor according to claim 13, characterized in that said two beams (110, 112) carry layers of different reactive materials.
Claim 16
Dependent Claim
60 words
A chemical sensor according to claim 14, characterized in that the layer of reactive material carried one one of said two beams (110, 112) interacts with a first and a second component of the gas sample to be analyzed, and the layer of reactive material carried on the other beam interacts with only said first component of the gas sample.
Claim 17
Dependent Claim
65 words
A chemical sensor according to any of claims 1 to 12, characterized in that it includes a plurality of beams (110, 112, 114, 116, 118) carrying layers of reactive materials which interact with different components of the gas sample to be analyzed, each beam being associated with a respective oscillator (134, 144, 154, 164, 174) and a respective sensor means (120, 122, 124, 126, 128).
Claim 18
Dependent Claim
39 words
A chemical sensor according to claim 16, characterized in that it further includes a reference beam (112) carrying no layer of reactive material, said reference beam being associated with a reference oscillator (144) and a reference sensor means (122).
Claim 19
Dependent Claim
73 words
A chemical sensor according to claim 17, characterized in that it further includes mixer circuits (150, 160, 170, 180) responsive to the resonance frequencies of each of said beams (110, 114, 116, 118) and said reference beam (112) to generate an output signal for each beam, each output signal having a frequency component equal to the difference between the resonance frequency of its associated beam and the resonance frequency of the reference beam.
Claim 20
Dependent Claim
99 words
A chemical sensor according to claim 18, characterized in that at least one (118) of said beams carries a layer of reactive material interacting with two different components of the gas sample to be analyzed and a second (116) of said beams carries a layer of reactive material responsive to only one of said two different components, and in that the .sensor further includes a mixer circuit (180) for generating an output signal in response to the resonance frequencies of said one and second beams (118, 116) having a frequency component equal to the difference between their resonance frequencies.
Claim 21
Dependent Claim
63 words
A chemical sensor according to claim 18 or 19, characterized in that said associated oscillator and sensor means and said reference oscillator and sensor means each generate an output signal indicative of the resonance frequencies of their associated beams and the reference beam respectively, and in that said mixer circuits are responsive to the output signals generated by said oscillator and sensor means.
References Cited (Backward Citations)
No citation records indexed.
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