Abstract: In a wetness sensor for a window of a motor vehicle, a heating resistor arranged in the window and powered by DC current can be connected to a measuring device for measuring an AC impedance of the heating resistor, in particular the capacitive portion thereof. The impedance varies with the amount of wetness and, thereby, serves as a measure of the wetness. A capacitor is used to bring the sensor near resonance for improved sensitivity.

Abstract: A probe for measuring the moisture content of wood in the center of a stack of wood has a moisture content sensor near a first or forward end thereof. The forward end of the probe is bendable and in one form is articulated. An extendable member also is mounted at the forward end of the probe. The extendable member is pivoted by a slide handle at an opposite end of the probe between reclined and extended positions. The forward end of the probe is inserted into a stack of wood between layers of the stack. The extendable member is extended to press the sensor against wood in the center of the stack. A meter connected to the sensor then registers the moisture content of the wood.

Abstract: A volume sensing device for determining the volume of liquid present in a standard plastic disposable pipette during a pipetting operation, which operation can be an aspiration or dispensing of liquid. The device comprises a cylinder made of hard synthetic material into which a disposable pipette is lowered at a predetermined velocity. The pipette which is being lowered into the cylinder holds an amount of liquid the volume of which the volume sensing device approximately determines. A pair of metal rings are coaxially mounted near the top end of the plastic cylinder. The pair of metal rings are preferably mounted in mating machined recesses of the plastic cylinder. This pair of metal rings is separated from each other by a small gap which forms the dielectric material of a capacitative circuit when the upper ring is connected to one portion of this circuit and the lower ring is connected to an other portion of the capacitative circuit.

Abstract: An impedance detector, in particular for radiosonde operation. The detector comprises a substrate (10 . . . 10E) made of an insulating material, onto which substrate the electrode and contact patterns (11, 11a, 13) necessary for the formation and connecting of the detector impedance have been applied. Between the detector impedance electrodes (11, 13), there is an active film (12), whose impedance values are a function of the physical quantity measured by means of the detector. The substrate of the detector is an oblong core filament (10; 10B; 10C; 10D; 10E) of an insulating material, onto and around which core filament said electrodes (11, 13) and said active insulating film (12) have been applied. Also, a novel process is described for the manufacture of said impedance detector.

Abstract: An impedance detector, in particular for radiosonde operation. The detector comprises a substrate (10 . . . 10E) made of an insulating material, onto which substrate the electrode and contact patterns (11, 11a, 13) necessary for the formation and connecting of the detector impedance have been applied. Between the detector impedance electrodes (11,13), there is an active film (12), whose impedance values are a function of the physical quantity measured by means of the detector. The substrate of the detector is an oblong core filament (10;10B;10C;10D;10E) of an insulating material, onto and around which core filament both electrodes (11,13) and such active insulating film (12) have been applied. Also, a novel process is described for the manufacture of such impedance detector.

Abstract: The present invention is an improved ice sensor which is particularly effective in measuring and quantifying non-uniform, heterogeneous ice typically found on aircraft leading edges and top wing surfaces.In one embodiment, the ice sensor comprises a plurality of surface mounted capacitive sensors, each having a different electrode spacing. These sensors measure ice thickness by measuring the changes in capacitance of the flush electrode elements due to the presence of ice or water. Electronic guarding techniques are employed to minimize baseline and parasitic capacitances so as to decrease the noise level and thus increase the signal to noise ratio. Importantly, the use of guard electrodes for selective capacitive sensors also enables distributed capacitive measurements to be made over large or complex areas, independent of temperature or location, due to the capability of manipulating the electric field lines associated with the capacitive sensors.

Abstract: A continuous liquid level measuring system having a guarded capacitance probe and related drive circuit for providing accurate level measurements, even when measuring the level of ionic and highly viscous fluids. The capacitance probe has two parallel electrodes, each constructed of a half-tube section, that are separated from each other by an insulated guard wire. The probe is excited by a 1 MHz excitation signal applied across the electrodes. The current through the electrodes is a function of the capacitance between the electrodes, which is affected by the relative permitivity of the surrounding liquid. The effects of highly viscous ionic liquids that adhere to the probe are reduced by exciting the guard wire with a guard signal that is 180.degree. out of phase from the probe's excitation signal. The guard signal changes the electric field existing in the space adjacent the junctions of the two electrodes to reduce any liquid coating effects on the level measurement.

Abstract: A microsensor system for determining water vapor content of the ambient atmosphere that uses a thin film suspended ceramic diaphragm structure featuring an embedded, patterned thin film heater, temperature sensor and an external film of an hygroscopic salt stabilized in a water-insoluble, crosslinked polymer matrix and contacting a pair of patterned electrodes which are proximate to the heater. The heater controls a selected electrical parameter of the salt to a fixed, predetermined value, as determined by its electrical characteristics. The dew point of the atmosphere is determined based on the dynamic relation with the salt dehydration temperature.

Abstract: Quantitative dopant profile measurements are performed on a nanometer scale by using a scanning capacitance microsope. A nanometer scale tip of the microscope is positioned at a semiconductor surface, and local capacitance change is measured as a function of sample bias. The method incorporates a feedback system and procedure in which the magnitude of the AC bias voltage applied to the sample is adjusted to maintain a constant capacitance change as the tip is scanned across the sample surface. A one dimensional model is used to extract dopant density profiles from the measurements made by the scanning capacitance microscope.

Abstract: A meter for measuring the moisture content of wood in the center of a stack of wood has a probe with an electromagnetic wave sensor mounted near a forward end and a meter mounted at an opposite end. An extendable member is also mounted at the forward end of the probe. The extendable member is pivoted by a slide handle at the opposite end of the probe between reclined and extended positions. The forward end of the probe is inserted into a stack of wood between layers of the stack. The extendable member is extended to press the sensor against wood in the center of the stack. The meter then registers the moisture content of the wood.

Abstract: A detector circuit in a moisture detector having an oscillator, a detector electrode and a common electrode for measuring the moisture content of wood and structural materials in buildings comprises a clamping diode network which couples an AC signal generated in the oscillator to a detector electrode. The clamping network clamps the AC signal to a reference voltage. The clamping network is balanced by a second clamping diode network which, together with a low pass filter, establishes the reference voltage. A low pass filter connected to the first clamping network produces an output voltage signal related to the impedance between the electrodes. To maintain the circuit's stability, the diodes in the clamping networks are thermally coupled.

Abstract: An improved method and capacitance probe arrangement for determining the fluid phase fractions of fluids having differing permitivity such as those of gas, oil, and water and oil-water emulsion in a fluid stream flowing from an oil well which includes trapping the primarily liquid in a vertically disposed chamber. The liquid is held therein to permit separation of the phase fractions to the extent possible within a reasonable time. A number of measurements are taken of the capacitance at a plurality of discrete vertically spaced locations within the chamber. These capacitance measurements relate directly to the varying permittivity of the phase fractions of the various liquids contained therein which may be gas, oil, and water and a oil-water emulsion. The measurements are processed by a data processor to provide precise information on such phase fractions and emulsion interfaces. A number of embodiments of the novel probe are disclosed for determining capacitance at spaced locations within the chamber.

Abstract: A meter for measuring the moisture content of wood in the center of a stack of wood has a probe with an electromagnetic wave sensor mounted near a forward end and a meter mounted at an opposite end. An extendable member is also mounted at the forward end of the probe. The extendable member is pivoted by a slide handle at the opposite end of the probe between reclined and extended positions. The forward end of the probe is inserted into a stack of wood between layers of the stack. The extendable member is extended to press the sensor against wood in the center of the stack. The meter then registers the moisture content of the wood.

Abstract: Apparatus and method for determining the water content of an oil and water mixture such as is transported by pipelines and which oil and water may vary in density from time to time. A densitometer measures the density of the oil and water mixture in the pipeline and a value for the dielectric constant of the oil is obtained from the density measurement by correlating the density reading with a capacitance or dielectric constant reading from an empirically generated chart. A basal sediment and water instrument measures the dielectric constant of the same mixture. The difference between the two dielectric constants is then obtained. This result is converted directly into a water based percentage by volume of the oil-water mixture being carried by the pipeline.

Abstract: A humidity meter includes a humidity-frequency converter (2) which is essentially a pulse oscillator, the oscillation frequency of which depends upon the impedance of a humidity sensor (1), a differentiation circuit (3) and a wave-form shaping circuit (4) which essentially operate as a pulse width modulator for adjusting pulse width of an output pulse of the converter (2) for assuring a linear relationship between humidity and the output signal, and an integrator (6) for integrating the output of the pulse width modulator to provide an output signal as a DC level. A feedback path (5) is provided to apply the output signal to the pulse width modulator for assuring a linear output irrespective of the exponential characteristics of the humidity sensor. Said differentiation circuit (3) has a capacitor (31), a first variable impedance element (32) which is controlled by said feedback path , and a second variable impedance element (33) coupled in series with the first variable impedance element (32).

Abstract: A water drop sensor comprises a pair of electrodes disposed in association with a portion of a surface of a vehicle window within a wipe pattern and having edges defining an extended insulating gap between the electrodes. The electrodes define a gap which varies in width over the range of diameters of drops to be sensed. The result is that the sensor shows more sensitivity to larger drops than to smaller drops as compared with a similar sensor having a constant gap width. The variation in gap width may be continuous or stepwise over the total range of drop diameters.

Abstract: A moisture sensitive device includes a polymer capacitive moisture sensitive element and a heater. The polymer capacitive moisture sensitive element is formed by sequentially stacking a lower electrode, a moisture sensitive film made of an organic polymer resin material, and an upper electrode on an insulating substrate. The heater serves to heat the moisture sensitive film to restore the original characteristics thereof.

Abstract: Capacitive humidity sensor comprising a substrate, a moisture-impermeable conducting bottom layer as first capacitor plate, a dielectric layer, and a moisture-permeable conducting top layer as second capacitor plate, and connecting wires associated with the first and second capacitor plates, whereby the change in the dielectric constant, and therefore in the capacitance value, due to absorption of water molecules is measured. The substrate is a flexible copper laminate in which at least the conducting bottom layer is etched, and the conducting top layer comprises a solid printed layer having a conducting grid pattern, which is printed with conducting ink.

Abstract: Disclosed is an oil sensor system having an oil sensor including two spaced apart electrodes, a triangular waveform means, a comparison means and a signal means. The oil system is used in situ (i.e., used directly in the engine) to determine the presence of two-stroke or four-stroke oil, or the occurrence of an engine malfunction, such as a leakage of antifreeze into the oil.

Abstract: A water cut meter includes a test cell through which a petroleum stream will flow. The test cell includes an outer shell, a sensor probe which cooperates with the outer shell to form a sensor capacitor with the flow of the petroleum stream as the dielectric and a reference probe surrounded with pure oil as the dielectric to form a reference capacitor. Processing apparatus includes a comparator network electrically connected to the sensor capacitor and to reference capacitor which compares the capacitance of the sensor capacitor with the capacitance of the reference capacitor. The comparator network provides a signal corresponding to the capacitance difference between the sensor and reference capacitors. An output circuit connected to the comparator network provides an output corresponding to the water cut of the petroleum stream in accordance with the signal from the comparator network.

Abstract: The invention is an apparatus for measuring the volume of water intrusion underwater cables without dissecting the cables. The apparatus comprises a novel arrangement of a capacitive test fixture and an electrical impedance analyzer to provide measurement of the volume of water in a cable based on cable capacitance. The capacitive test fixture measures the electrical capacitance along the cable as the cable is fed through the test fixture.

Abstract: A device, for detecting a sufficient glue coating on a first surface of a paper strip to be adhesively bonded in a cigarette machine, includes a sliding plate having a plate surface engaging a second surface of the paper strip, opposite to the first surface, and over which the paper strip runs in a first direction. A plurality of capacitive sensors, for detecting presence of moisture in the glue coating, on the first surface of the paper strip, are directed toward the second surface of the paper strip, are mounted in recesses in the sliding plate and are arranged in a row extending transversely to the first direction. A control is coupled to the sensors for evaluating signals emitted from the sensors and for emitting a fault signal for controlling the cigarette machine when the moisture sensed in the glue coating is insufficient.

Abstract: A liquid presence detector and method of using the same for a gas fluid conduit is provided by a capacitor that is placed inside the conduit and that is formed of two interwoven wire grids with one of the grids being insulated and the other grid being uninsulated. In one embodiment, the capacitor is generally planar and is oriented generally transverse a longitudinal axis of the conduit with a peripheral portion lying in a generally axial orientation along an inner surface of the conduit. A circuit is provided that measures capacitance between the two wire grids. The conduit is electrically grounded. Liquid particles entrained in the gas fluid or traveling along the conduit wall contact the capacitor and changes the capacitance thereof. In another embodiment, the capacitor is formed as a generally open cylinder positioned coaxially within the conduit.

Abstract: A ceramic bodied sensor having helical metallized electrodes for measuring the capacitance of an oil-water-gas or oil-water mixture flowing through a central bore of the sensor is disclosed. The sensor generally is a hollow cylinder with an inner ceramic layer which is very thin, a thicker outer ceramic layer which forms a strong structural unit, and a pair of isolated metallized electrodes which are generally approximately located between the inner and outer ceramic layers. The inner ceramic layer, outer ceramic layer and metallized electrodes form a dense monolithic ceramic tube. The electrode plates are preferably identical in size and shape and are isolated from one another electrically so that a condenser is formed by the separated plates. The inner ceramic layer is preferably very thin to minimize its capacitance value in comparison to the capacitance value of the water-oil-gas or oil-water mixture flowing through the central bore of the sensor.

Abstract: A planar interdigitated dielectric sensor useful for measuring the surface properties of a material is disclosed. The sensor is formed on an insulating substrate. Attached to the surface of the substrate is an excitation electrode and a response electrode disposed in an interdigitated pectinate configuration and a resistance temperature device a (metallic strip). Filling the space between the electrodes and the metallic strip is an insulating material of known dielectric properties. The upper surface of the electrodes and the metallic strip are generally coplanar with respect to the insulating material between the electrodes thus forming a flat upper surface on the sensor. This flat upper surface serves to eliminate air gaps between the sensor surface and sample when analyzing relatively viscous materials.

Abstract: Apparatus monitors the water cut of a petroleum stream flowing in a pipeline by comparing a probe signal to a reference signal. A probe is located in the pipeline and is connected to the reference signal through a series resistance. The probe signal changes as a function of the impedance of the petroleum stream. A circuit measures the changes in the probe signal, compares the changes to the reference signal and derives a water cut value for the petroleum stream based on these measurements.

Abstract: An improved capacitance bridge type liquid level control system for use in refrigeration applications is disclosed which provides improved apparatus for sealing the probe in its mounting and for insulating same against the condenser reservoir stand pipe in which it is mounted. Improved sealing between the probe and probe body is accomplished through an annular PTFE seal which when compressed pushes inwardly to seal a tubular PTFE insulation against annular ridges in the side of the probe rod proper. The improved probe rod shape also maintains a proper stabilized axial alignment between the probe rod and the probe body.

Abstract: The device comprises: a high frequency alternating voltage generator the output of which is connected to a sensor probe 5 which is to be applied to a substrate to be measured, an amplifier the input of which is connected to the sensor probe, and a detector arranged to furnish a D.C. voltage signal based on the output from amplifier. The generator, the amplifier and the detector are located inside a metal envelope enclosure. An electromagnetic radiation shield is disposed inside the envelope to separate the amplifier and the detector from the high frequency generator. In operation, voltage output from the detector is indicative of the electrical impedance of the substrate as sensed at the probe. In the preferred application, the substrate is skin and the measured electrical impedance is indicative of the water content of the skin.

Abstract: A test apparatus for determining a given property, by weight, such as moisture content, of a material such as a grain or the like, comprises a chamber for receiving a sample of material to be tested, having an open top portion through which the material may be introduced therein for testing. An electrical circuit is operatively coupled with the chamber for producing an electrical measurement signal corresponding to the property to be determined and an indicator provides an observable indication of the given property of material in accordance with the corresponding electrical measurement signals. A measurement initiating control in responsive to the accumulation of a predetermined measurement weight of material in the chamber for initiating the operation of the circuit. A further warning control is responsive to the weight of material in the chamber reaching a second, predetermined warning weight slightly less than the predetermined measurement weight for producing a warning signal.

Abstract: This invention relates to the measurement of the moisture content retained in the skin, and enables accurate diagnosis of the skin conditions by a device which can be switched in the connection of measurement electrodes to measure the moisture content either in the surface or in the depth of the keratinous layer of the skin.

Abstract: A multi-line electronic media barrier or safety system for preventing liquid contamination of air lines, including a capacitance proximity sensor for detecting a foreign undesirable medium such as paint in an air line. When foreign media is detected, a main air valve is closed which in turn closes valves connected in the air lines, thereby blocking passage of air or liquid and protecting pneumatic control apparatus. The media barrier is especially designed for use with automated or robotic paint spray devices utilized in industry.

Abstract: This invention relates to a method of annoucing a low level of the remaining liquid in a dropper. According to the present invention, two electrodes are attached to the outer surface of a dropper, and a pulse of a stable level is applied to one of these electrodes. The remaining quantity of the liquid in the dropper can be detected automatically with ease by utilizing the variations of the electrostatic capacity occurring between these two electrodes. An annunciator is activated when it receives a signal representative of a low level of the liquid in the dropper, to inform a nurse of the necessity of replacing the dropper.

Abstract: This invention relates to a method of annoucing a low level of the remaining liquid in a dropper. According to the present invention, two electrodes are attached to the outer surface of a dropper, and a pulse of a stable level is applied to one of these electrodes. The remaining quantity of the liquid in the dropper can be detected automatically with ease by utilizing the variations of the electrostatic capacity occurring between these two electrodes. An annunciator is activated when it receives a signal representative of a low level of the liquid in the dropper, to inform a nurse of the necessity of replacing the dropper.