EP0309085A2
Expired / Lapsed
EP
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A detector device
Assignee: Imed Corp
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Filing: 1988-08-08
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Granted: —
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Expires: 2008-08-08
Abstract
Abstract A device and method for distinguishing between different fluids on the basis of their dielectric properties. In a preferred embodiment, the device comprises two substantially parallel conductive surfaces which are positioned on opposite sides of a fluid conduit so as to form a substantially parallel plate capacitor. The first conductive surface is electrically connected through an inductor to a voltage source, and such first conductive surface is also electrically connected to the source electrode of a field-effect transistor. A resonator device is electrically connected between the second conductive surface and the gate electrode of the field-effect transistor. The gate electrode of the field-effect transistor is further electrically connected through a fixed resistance to ground, and the drain electrode of the field-effect transistor is electrically connected directly to ground. The inductance of the inductor is selected such that the resonant frequency of the inductor and the capacitor is substantially the same as the operating frequency of the resonator device when a desired column of fluid is positioned between the two conductive surfaces. In this state, the output voltage of the detector device will oscillate. However, when a column of fluid having significantly different dielectric properties is positioned between the two conductive surfaces, the resonant frequency of the inductor and the capacitor will change, and the output voltage of the detector device will stop oscillating.
Inventors
- 👤 Robert Meijer
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-07 14:09
CPC Classifications
G; G01; G01N; G01N27/00; G01N27/02; G01N27/22; G01N27/221; G01R; G01R27/00; G01R27/02; G01R27/26; G01R27/2617; G01R27/2635; G01R27/2641; Y; Y10; Y10S; Y10S128/00; Y10S128/13
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
70 words
A detector device for distinguishing between fluids having different dielectric properties characterised by a first conductive surface and a second conductive surface having a pathway for fluid therebetween, a voltage source, an inductor electrically connected between the first conductive surface and the voltage source, a resonator device electrically connected to the second conductive surface, and a transconductance amplifier means electrically connected between the resonator device and the first conductive surface.
Claim 2
Dependent Claim
70 words
A detector device for distinguishing between fluids having different dielectric properties characterised by a first conductive surface and a second conductive surface having a pathway for fluid therebetween, a voltage source, an inductor electrically connected between the first conductive surface and the voltage source, a resonator device electrically connected to the second conductive surface, and a transconductance amplifier means electrically connected between the resonator device and the first conductive surface.
Claim 3
Dependent Claim
53 words
A detector device according to Claim 1 wherein the second conductive surface is positioned in proximity to the first conductive surface, thereby forming a capacitor in combination with the first conductive surface, the first and second conductive surfaces being further positioned so as to be capable of receiving a column of fluid therebetween.
Claim 4
Dependent Claim
60 words
A detector device according to Claim 1 or 2 wherein the resonator device has a substantially fixed oscillating frequency and wherein the resonant frequency of the capacitor and the inductor is substantially equal to the oscillating frequency of the resonator device when a column of a desired fluid is positioned between the first and second conductive surfaces of the capacitor.
Claim 5
Dependent Claim
56 words
A detector device according to any preceding claim further comprising: a housing having a channel formed therein which is adapted to receive a substantially non-conductive fluid conduit; and wherein the first and second conductive surfaces are positioned adjacent the channel and the inductor, the resonator device, and the transconductance amplifier means are positioned within the housing.
Claim 6
Dependent Claim
187 words
A detector according to Claim 1 comprising a housing having a channel formed therein which is adapted to receive a substantially non-conductive fluid conduit and wherein the first conductive surface is positioned adjacent the channel in the housing; the second conductive surface is positioned adjacent the channel in the housing, the second conductive surface forming a capacitor in combination with the first conductive surface, the first and second conductive surfaces being further positioned such that a portion of a fluid conduit which is received in the channel of the housing lies substantially between the first and second conductive surfaces; the resonator device is positioned within the housing and the resonator device has a substantially fixed oscillating frequency; the inductor is positioned within the housing and the inductance of the inductor being selected such that the resonant frequency of the inductor and the capacitor is substantially equal to the oscillating frequency of the resonator device when the portion of a fluid conduit which lies substantially between the first and second conductive surfaces is substantially filled with a desired fluid; and the transconductance amplifier means positioned within the housing.
Claim 7
Dependent Claim
18 words
A detector device according to any preceding claim wherein the first and second conductive surfaces are substantially planar.
Claim 8
Dependent Claim
21 words
A detector device according to any preceding claim wherein the first and second conductive surfaces are substantially parallel to one another.
Claim 9
Dependent Claim
16 words
A detector device according to any preceding claim wherein the inductor is a variable inductance device.
Claim 10
Dependent Claim
17 words
A detector device according to any preceding claim wherein the transconductance amplifier means comprises a field-effect transistor.
Claim 11
Dependent Claim
48 words
A detector device according to any preceding claim wherein the dimensions of the first and second conductive surfaces are selected such that the space between the first and second conductive surfaces is approximately just large enough to receive the smallest volume of fluid it is desired to detect.
Claim 12
Independent Claim
235 words
A method for distinguishing between fluids having different dielectric properties, the method comprising the steps of forming a detector system comprising the steps of; positioning a first conductive surface in proximity to a second conductive surface such that a column of fluid can be received therebetween and such that the first and second conductive surfaces form a capacitor, electrically connecting the second conductive surface to a resonator device having a substantially fixed oscillating frequency; electrically connecting an inductor between the first conductive surface and a voltage source, the inductance of the inductor being selected such that the resonant frequency of the inductor and the capacitor is substantially equal to the oscillating frequency of the resonator device when a column of a first fluid is positioned between the first and second conductive surfaces of the capacitor, the resonant frequency of the inductor and the capacitor being significantly different from the oscillating frequency of the resonator device when a column of a second fluid is positioned between the first and second conductive surfaces of the capacitor; and providing a transconductance amplifier means electrically connected between the resonator device and the first conductive surface; detecting an oscillating output voltage from the detector system when a column of the first fluid is positioned between the first and second conductive surfaces; and detecting a substantially constant output voltage from the detector system when a column of the second conductive surfaces.
Claim 13
Independent Claim
235 words
A method for distinguishing between fluids having different dielectric properties, the method comprising the steps of forming a detector system comprising the steps of; positioning a first conductive surface in proximity to a second conductive surface such that a column of fluid can be received therebetween and such that the first and second conductive surfaces form a capacitor, electrically connecting the second conductive surface to a resonator device having a substantially fixed oscillating frequency; electrically connecting an inductor between the first conductive surface and a voltage source, the inductance of the inductor being selected such that the resonant frequency of the inductor and the capacitor is substantially equal to the oscillating frequency of the resonator device when a column of a first fluid is positioned between the first and second conductive surfaces of the capacitor, the resonant frequency of the inductor and the capacitor being significantly different from the oscillating frequency of the resonator device when a column of a second fluid is positioned between the first and second conductive surfaces of the capacitor; and providing a transconductance amplifier means electrically connected between the resonator device and the first conductive surface; detecting an oscillating output voltage from the detector system when a column of the first fluid is positioned between the first and second conductive surfaces; and detecting a substantially constant output voltage from the detector system when a column of the second conductive surfaces.
Claim 14
Dependent Claim
55 words
A method according to Claim 11 wherein the detector system forming step further comprises the step of selecting the dimensions of the first and second conductive surfaces such that the space between the first and second conductive surfaces is approximately just large enough to receive the smallest volume of fluid it is desired to detect.
References Cited (Backward Citations)
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