WO1998057164A1 - Detection du point de condensation - Google Patents

Detection du point de condensation Download PDF

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Publication number
WO1998057164A1
WO1998057164A1 PCT/GB1998/001690 GB9801690W WO9857164A1 WO 1998057164 A1 WO1998057164 A1 WO 1998057164A1 GB 9801690 W GB9801690 W GB 9801690W WO 9857164 A1 WO9857164 A1 WO 9857164A1
Authority
WO
WIPO (PCT)
Prior art keywords
substance
saw
dependent
saw filter
signal
Prior art date
Application number
PCT/GB1998/001690
Other languages
English (en)
Inventor
Roderic Lewis Jones
Victor Petrovich Ostanin
Original Assignee
Cambridge University Technical Services Ltd.
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 Cambridge University Technical Services Ltd. filed Critical Cambridge University Technical Services Ltd.
Priority to AU80274/98A priority Critical patent/AU8027498A/en
Publication of WO1998057164A1 publication Critical patent/WO1998057164A1/fr

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Classifications

    • 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
    • G01N29/22—Details, e.g. general constructional or apparatus details
    • G01N29/32—Arrangements for suppressing undesired influences, e.g. temperature or pressure variations, compensating for signal noise
    • G01N29/326—Arrangements for suppressing undesired influences, e.g. temperature or pressure variations, compensating for signal noise compensating for temperature variations
    • 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
    • G01N2291/01—Indexing codes associated with the measuring variable
    • G01N2291/014—Resonance or resonant frequency
    • 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
    • G01N2291/02845—Humidity, wetness
    • 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

Definitions

  • This invention relates to the detection of condensation point and condensation point temperature.
  • a number of apparatus have been proposed in order to make such measurements.
  • One such apparatus employs a mirror onto which the substance can condense and measures the intensity of light reflected from the surface of the mirror, the reflection intensity being dependent upon whether or not the substance has condensed on the mirror's surface.
  • Such an arrangement does, however, have considerable disadvantages. Not in the least, the surface of the mirror becomes contaminated with dirt, and requires a relatively thick layer of substance to condense on it to observe significant variation, both affect reflectivity and hence measurement accuracy.
  • a sensor employing surface acoustic waves (SAW) .
  • SAW surface acoustic waves
  • Such an arrangement generates a surface acoustic wave and measures the intensity of the wave after it has passed over a surface exposed to an atmosphere to be measured. Condensation of a substance on the surface across which the SAW travels attenuates the SAW and the measured attenuation is used to determine condensation point temperature.
  • Such an arrangement whilst overcoming some of the problems associated with reflecting mirror devices, still has a number of problems associated with it. Firstly, the phase state of the substance which condenses can have a considerable effect on SAW attenuation.
  • the object of the present invention is to overcome the above and other problems.
  • an apparatus for detecting the presence of a condensed substance on a surface comprising: a reference frequency generator for generating an electrical reference frequency signal; a first surface acoustic wave (SAW) filter the frequency characteristics of which are dependent upon the mass of condensate formed on a measuring surface thereof for receiving the reference frequency signal and outputting a signal dependent thereon and dependent upon the mass of the substance on a measuring surface; output signal generating means for receiving the output of the first SAW filter and providing a signal indicative of the mass of the condensation substance dependent upon the first SAW filter attenuation.
  • SAW surface acoustic wave
  • the first SAW filter may be provided by an SAW device having no propagation area.
  • the generator may comprise a second surface acoustic wave (SAW) filter, in which case, the reference signal generator may include an RF amp and the second SAW filter may be isolated from the gas and the substance. If this is the case, the reference frequency generating means and the first SAW filter may be formed on the same substrate optimising phase matching of the filters and assuring good temperature compensation.
  • a temperature control means may be provided to control the temperature of both the reference frequency signal generator and the SAW filter.
  • the output signal generator may be an amplitude detector, eg. a rectifier.
  • the temperature control means may include a cooling and/or heating device, such as a Peltier element in combination with a temperature regulator.
  • a temperature sensor may be employed in combination with the temperature control means and related circuitry to produce an output signal indicative of condensation point temperature. This is because the first SAW filter is being employed as an electrical signal filter, and as such its attenuation characteristics are dependent upon mass of condensate.
  • Figure 1 is a schematic diagram of an apparatus according to the present invention.
  • Figure 2 is a schematic diagram of an apparatus according to the invention further comprising a temperature regulator and cooling/heating device; and, Figure 3 is a graph showing the variation of frequency characteristics of an SAW filter with condensed substance presence.
  • the sensor according to the invention has a second surface acoustic wave filter 1 connected in a loop with an RF amplifier 3.
  • the connection is such that the output of the RF amplifier 3 generates a signal at a frequency which is close to the maximum of the frequency characteristic of the second SAW filter 1.
  • the second SAW filter 1 has a characteristic shown by line 10 of Figure 3 and is sealed from the atmosphere.
  • the output of the RF amplifier 3 is attached to the input of a first SAW filter 2.
  • a surface of the first SAW filter 2 is exposed to the atmosphere containing the substance for which a condensation point is to be detected.
  • the output of the first SAW filter 2 is connected to an amplitude detector 4, which in this example is a rectifier.
  • the first SAW filter 2 may be formed on the same substrate as the second SAW filter 1 or may be formed separately. In either case, it will have a frequency characteristic which is substantially equal to that of the second SAW filter 1, ie, of the type shown by line 10 in Figure 3. If the substance contained in the atmosphere starts to condense on the surface of the first SAW filter 2, its frequency characteristic changes, which its maxima shifting (line 11, Figure 3) . The amount of shift depends upon the mass of substance formed on its surface.
  • Its changing frequency characteristic means that the reference signal provided at the output of the RF amplifier 3 is outside frequency characteristic of the first SAW filter 2, and the amplitude output from the amplitude detector 4 will reduce, providing an indication of condensation point.
  • the value of the output of the amplitude detector 4 will indicate the mass of substance that has been condensed.
  • a temperature controlling element 5 may be positioned in good thermal contact with both the second SAW filter 1 and the first SAW filter 2.
  • This element 5 may be a Peltier element, and may include a temperature sensor 6.
  • the sensor of the invention may then be employed in conjunction with a temperature regulator 7 which controls the element 5 and hence the temperature of the sensor.
  • the output from the amplitude detector 4 is compared to a reference level signal 8 and the subsequent error signal 9 fed to the temperature regulator 7. Varying of the temperature of the sensor by the element 5 made by employing the condensation point output signal can enable the temperature regulator 7 to produce an output indicative of condensation point temperature.
  • the SAW filters 1, 2 have a narrow bandwidth, for example having a 100MHz centre frequency and 30KHz bandwidth, but this is not essential to the invention.

Landscapes

  • Physics & Mathematics (AREA)
  • Health & Medical Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Chemical & Material Sciences (AREA)
  • Analytical Chemistry (AREA)
  • Biochemistry (AREA)
  • General Health & Medical Sciences (AREA)
  • General Physics & Mathematics (AREA)
  • Immunology (AREA)
  • Pathology (AREA)
  • Acoustics & Sound (AREA)
  • Investigating Or Analyzing Materials By The Use Of Ultrasonic Waves (AREA)

Abstract

Un appareil servant à détecter la présence d'une substance condensée sur une surface comprend un générateur de fréquence de référence qui génère un signal électrique à la fréquence de référence. Un premier filtre à ondes de surface dont les caractéristiques de fréquence dépendent de la masse de condensat formé sur une surface de mesure reçoit le signal de fréquence de référence et produit un signal fonction de ce dernier et de la masse de la substance située sur la surface de mesure. Un dispositif générant un signal de sortie reçoit la sortie du premier filtre à ondes de surface et produit un signal indiquant la masse de la substance de condensation fonction de l'atténuation du premier filtre à onde de surface.
PCT/GB1998/001690 1997-06-12 1998-06-10 Detection du point de condensation WO1998057164A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AU80274/98A AU8027498A (en) 1997-06-12 1998-06-10 Condensation point detection

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB9712299.8 1997-06-12
GBGB9712299.8A GB9712299D0 (en) 1997-06-12 1997-06-12 Condensation point detection

Publications (1)

Publication Number Publication Date
WO1998057164A1 true WO1998057164A1 (fr) 1998-12-17

Family

ID=10814084

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/GB1998/001690 WO1998057164A1 (fr) 1997-06-12 1998-06-10 Detection du point de condensation

Country Status (3)

Country Link
AU (1) AU8027498A (fr)
GB (1) GB9712299D0 (fr)
WO (1) WO1998057164A1 (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2006132926A1 (fr) * 2005-06-03 2006-12-14 Honeywell International Inc. Capteur de flux à ondes acoustiques pour des applications à forte condensation

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1983001511A1 (fr) * 1981-10-13 1983-04-28 Univ Maine Detecteur de gaz a oscillateur a onde acoustique de surface
EP0416160A1 (fr) * 1988-03-14 1991-03-13 Siemens Aktiengesellschaft Dispositif de mesure de la pression partielle de gaz ou de vapeurs
EP0477648A1 (fr) * 1990-09-28 1992-04-01 BASF Aktiengesellschaft Detecteur de gaz à ondes de surface

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1983001511A1 (fr) * 1981-10-13 1983-04-28 Univ Maine Detecteur de gaz a oscillateur a onde acoustique de surface
EP0416160A1 (fr) * 1988-03-14 1991-03-13 Siemens Aktiengesellschaft Dispositif de mesure de la pression partielle de gaz ou de vapeurs
EP0477648A1 (fr) * 1990-09-28 1992-04-01 BASF Aktiengesellschaft Detecteur de gaz à ondes de surface

Non-Patent Citations (2)

* Cited by examiner, † Cited by third party
Title
ENGUANG D ET AL: "ORGANIC VAPOR SENSORS BASED ON SAW RESONATOR AND ORGANIC FILMS", IEEE TRANSACTIONS ON ULTRASONICS, FERROELECTRICS AND FREQUENCY CONTROL, vol. 44, no. 2, March 1997 (1997-03-01), pages 309 - 314, XP000690803 *
SCHWEYER M G ET AL: "AN ACOUSTIC PLATE MODE SENSOR FOR AQUEOUS MERCURY", SENSORS AND ACTUATORS B, vol. 35, no. 1/03, September 1996 (1996-09-01), pages 170 - 175, XP000641394 *

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2006132926A1 (fr) * 2005-06-03 2006-12-14 Honeywell International Inc. Capteur de flux à ondes acoustiques pour des applications à forte condensation
US7373838B2 (en) 2005-06-03 2008-05-20 Honeywell International Inc. Acoustic wave flow sensor for high-condensation applications

Also Published As

Publication number Publication date
AU8027498A (en) 1998-12-30
GB9712299D0 (en) 1997-08-13

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