Abstract: Measuring apparatus includes a first element having its impedance dependant on the state of its surroundings and a second element having a variable impedance connected to the first element. A voltage at the connection point between the first and second elements is converted into a digital value and the impedance of the second element is set based on the converted digital value. The surrounding state (e.g., humidity) is determined based on the converted digital value.

Abstract: This invention relates to an on-line statistical process control device for solder paste and residues. The invention consists of electronics hardware, software, and probing systems. The electrical hardware of the invention provides voltage and current measurements of solder paste materials, the software of the invention controls the hardware, provides real-time complex, nonlinear least squares curve fitting for equivalent circuit analysis, data storage and retrieval of circuit parameters and behavior, and statistical process control tracking and charting. The probing systems of the invention allows for 2, 3, and 4 probe surface and bulk measurements of the solder paste and residues.

Abstract: A method for detecting extent of cross-linking of a high impedance polymer material during a pre-cure state, the method including: placing an insulated ground plane adjacent to the polymer material and substantially parallel to a sensor; applying a test signal through a sensor to the material and through a reference resistance; determining a voltage difference between the test signal applied to the material and the reference resistance as the reference voltage; and correlating the voltage difference as a relative indicator of the extent of cross-linking which has occurred within the polymer material. Also disclosed is a device for implementing the subject method.

Abstract: The presence of air bubbles entrained in a liquid flowing through a tube is detected flowing the liquid through a conduit which comprises a conductivity cell with a continuous path configuration. An electrical current is induced in the liquid in the conductivity cell. The electrical current in the liquid in the conductivity cell is sensed and interpreted, a decrease in the electrical current being indicative of the presence of an air bubble in the liquid. The conductivity cell comprises an upstream connection, a downstream connection, and two branches connecting the upstream connection to the downstream connection with a continuous path configuration from the upstream connection to the downstream connection through one of the two branches and returning to the upstream connection through the other one of the two branches.

Abstract: An odor concentration is measured by energizing an odor sensor connected across a power supply through a load resistance. A total resistance of the odor sensor is represented by and includes a parallel connection of a first resistive component having a value according to surrounding environmental conditions and a second resistive component having a value according to an odor concentration, and a saturation resistive component connected in series with the parallel connection of the first and second resistive components. A CPU is used to measure the odor concentration by obtaining the value of the second resistive component from an output of the odor sensor which is a voltage across the load resistance. Also, the measured odor concentration can be normalized and compared with a given threshold for fire detection.

Abstract: A starch gelatinization measuring system including an ohmic heater to hold and to heat the starch sample to be measured, the ohmic heater having a pair of plate electrodes for heating; a power supply unit electrically connected to the ohmic heater to control the supply of electric current and electric voltage to the plate electrodes of the ohmic heater; a temperature detector controlled to detect the temperature of the starch sample being heated by the ohmic heater; a data logger electrically connected to the power supply unit and the temperature detector to record the data of temperature, electric current, electric voltage during heating; and a computer electrically connected to the data logger to analyze the data provided by the data logger.

Abstract: An apparatus and method for sensing impedances of materials placed in contact therewith. The invention comprises a plurality of drive electrodes and one or more sense electrodes. Both rotating electric fields and differently shaped electric fields are provided for, as are analysis of structure and composition at different orientations and depths.

Abstract: A method and apparatus for detecting the possibility of transfer of material through a protective barrier between a worker and an external object and warning the worker of that possibility is provided. In one embodiment, an electronic leak alarm module is electrically connected to the worker and to the external object. In another embodiment, the module is connected to the worker and a conductive layer on or within the protective barrier.

Abstract: A method for detecting extent of cross-linking of a high impedance polymer material during a pre-cure stage, the method comprising the steps of:a) applying a test signal through a sensor to the polymer material in the pre-cure stage to determine a level of impedance and corresponding sample voltage representative of a degree of cross-linking within the material;b) applying the same test signal through the sensor to a reference material having a fixed resistance to determine a reference voltage;c) determining a voltage difference between the test signal applied to the polymer at pre-cure stage and the test signal applied to the reference material as the reference voltage;d) correlating the voltage difference as a relative indicator of the extent of cross-linking which has occurred within the polymer material, based on comparison of magnitude of the voltage difference with respect to a comparable potential range of impedance for the polymer material from its lower impedance stage at minimal cross-linking to its

Abstract: A method for determining the degree of deterioration of oils or fats for deep-frying or frying foods is disclosed. The specific ohmic resistance of the oils or fats is measured and the extent of the fall of this resistance with increasing deep-frying time or frying time is used as a correlation for the degree of deterioration of the oils or fats.

Abstract: A conducting tip of a hardness tester for metals, alloys and similar conducting materials is set forth. The tester comprises a resistance measuring circuit for measuring the resistance between the indenting tip and the test specimen when a certain load is applied to the indenter, made of a substantially insulating material with a superficial conducting film, the conductivity of which decreases toward the tip vertex. This contains the error induced by differences in temperature affecting the resistivity of the conducting superficial film. A tip of conical form with an angle which does not exceed 110 degrees increases precision, as compared with indenters constructed to the Vickers pyramid standard or to the Rockwell 120 degree cone.

Abstract: A method for detecting extent of cross-linking of a high impedance material during a shelf life, slow state transition or during use, the method including: applying a test signal through a sensor to the material and through a reference material; determining a voltage difference between the test signal applied to the material and the reference material as the reference voltage; and correlating the voltage difference as a relative indicator of the extent of chemical change which has occurred within the material. Also disclosed is a device for implementing the subject method.

Abstract: Inclusions such as encysted parasites and spoilage in food products such as fish fillets are detected by immersing the food products in a bath of an electrolyte, such as a saline solution, having substantially the same electrical conductivity as the uncontaminated food product. An electrical current passed through the electrolyte also passes through the food product. Perturbations in the resulting magnetic field produced by the discontinuities in conductivity at the boundaries of the inclusions or of the spoiled article which have substantially different conductivities from that of the electrolyte and unspoiled food products, provide an indication of the presence of the contamination. Production line inspection rates are achieved by conveying the food products through a container filled with electrolyte and past an array of stationary magnetometers.

Abstract: An object of the present invention is to provide a method of evaluating current-driven conductive material in which a capability of wiring material to withstand electro-migration and that to withstand stress migration can be evaluated independently.In the method according to the present invention wherein reliability of wiring is evaluated with a shorter period of time by repeating an operating cycle comprising the steps of flowing a first current to measure a resistance value, flowing a second current having a larger current value than the first current for a specified period of time to generate changes in the physical properties, and then flowing the first current to measure a resistance value of the wiring, the wiring's capability to withstand electro-migration is measured by making a time for flowing the second current fully smaller than a time for flowing the first current to control temperature rise when the second current is flown to 50.degree. C. or below.

Abstract: A method for measuring the degree of planarity in an integrated circuit includes depositing, onto a dielectric layer to be measured for planarity, a predetermined measure path of a conductive film and measuring the electric resistance of said measure path. The resistance of such a measure path is minimal where the surface on which it has been deposited is perfectly planar, and increases with the surface deviation from perfect planarity. An integrated circuit containing a measurement portion of conductive film and a reference portion of conductive film is described.

Abstract: The present invention relates to a method for testing for leaks in the bodies of sealed containers.

Abstract: A method and an apparatus to electronically identify a page. Each page has a surface conductive trace that is coupled to an electronic circuit to measure the conductivity of the trace. The primary purpose of the conductive trace is to provide an identification for the page.

Abstract: A degradation level of transformer insulating oil can be checked by measuring leakage current of a sensor for measuring the degradation level of the insulating oil, in which DC power is applied to two electrodes of the sensor in the insulating oil for the transformer. In general, free carbons or nonsolute conductive particles are produced in the transformer insulating oil when used over long periods in the power transformer. The porous ceramic of the sensor for measuring degradation level of the insulating oil receives in the pores thereof the conductive impurity particles, and a conductive circuit is formed. Thus, this measurement for degradation level of insulating oil is based on the electric change states for the formation of the conductive circuit. Accordingly, by forming such structures, a method and apparatus for measuring degradation level of insulating oil by measuring leakage current of the sensor are provided.

Abstract: During operation of a fuel cell stack, electrolyte within individual fuel cells migrates between the cathode side and the anode side, and across the separator plate between the cathode side and the anode side electrolyte reservoir plate of a second cell. An electrochemical sensor comprised of wires, a sheath, and a porous conduit having a pore size distribution which is similar to that of the electrolyte reservoir plate in which the electrochemical sensor is located, is capable of determining the electrolyte content during fuel cell operation by measuring the electrical resistance between the wires. The conduit wicks electrolyte into its pores to a content similar to that of the electrolyte reservoir plate. This electrolyte establishes electrical contact between the wires such that the measure of the electrical resistance between the wires is related to the electrolyte content of the electrolyte reservoir plate.

Abstract: Devices and methods for sensing the charge condition of a mixed stream of aggregant and aqueous dispersion of charged particles are based on sensing changes in the potential of an electrode contacting the stream. Sensing the changes in potential permits better control of aggregation in raw water and effluent treatments.

Abstract: A device is provided for measuring dielectric constant and conductance of a material such as massecuite, the device including a pair of electrodes which are switchably connected to a tank circuit which includes a variable frequency oscillator operating at radio frequencies, and two reference frequencies are measured with the electrodes disconnected from the oscillator and two measurement frequencies with the electrodes coupled to the oscillator tank circuit, the differences between the reference and measurement frequencies being used to compute the inductance and dielectric constant or composition of the material. The frequency is modified by not more than about 10 MHz and may be achieved either by switchably introducing additional inductance or capacitance into the tank circuit to modify its frequency or by having the electrodes switchable between a pair or oscillators operating at known radio frequencies.

Abstract: Water quality sensor apparatus comprising a substrate on which a plurality of sensors are supported in spaced apart relationship, each sensor being responsive to a different water characteristic and each sensor comprising a sensor region which, in use, is arranged to be contiguous with water the characteristics of which are to be sensed, which sensor regions are electrically connected to connector means via conductors supported on the substrate, the conductors and the connector means being arranged to be non-contiguous with the water in use of the apparatus.

Abstract: The present invention is directed to an apparatus and method for improving the accuracy of measuring resistivity and/or conductivity of a paste. Exemplary embodiments relate to an apparatus for measuring electrical characteristics of a material. A sample of material is placed in a first charge conducting region with a first cross-sectional area and in a second charge conducting region with a second cross-sectional area, the first cross-sectional area being greater than the second cross-sectional area. Further, the apparatus conducts an electric charge through the first and second charge conducting regions via a conductive terminal located in the first charge conducting region.

Abstract: A system for determining a property, such as conductivity, of a material in which a sensor provides a square wave sensor output signal the value if which is selected to the proper in response to a square wave driver signal. The sensor output signal is compared with a feedback signal to produce an error signal. A forward circuit responds to the error signal and provides an in-phase component thereof which is integrated to provide an integrated DC output signal. A feedback signal provides an in-phase square wave feedback signal the peak-to-peak amplitude of which has a precisely selected relationship with the integrated DC output signal for comparison with the square wave sensor output signal to reduce the error signal to zero. The integrated DC output signal can be digitized and suitably processed to provide a signal which represents the property of the material to a high degree of accuracy.

Abstract: A capacitive proximity monitoring device for corrosive atmosphere environments comprising a capacitance field element or sensing element disposed in such a corrosive atmosphere environment and being made of conductive plastic resistant for such a corrosive atmosphere environment. The field element may be a functional part of a functional device that performs a function with respect to the presence of the liquid being sensed; and in some cases the field element is nonfunctional with respect to the liquid, but functional and sensing the capacitance and determining the presence or absence of liquid.

Abstract: A method and apparatus for detecting the possibility of transfer of material through a protective barrier between a worker and an external object and warning the worker of that possibility is provided. In one embodiment, an electronic leak alarm module is electrically connected to the worker and to the external object. In another embodiment, the module is connected to the worker and a conductive layer on or within the protective barrier.

Abstract: An "L" shaped element having horizontal and vertical sections, is submerged in the liquid toner concentrate such that the horizontal section is totally submerged while the vertical section is submerged proportionally to an amount of the liquid toner concentrate. A voltage source is connected to the "L" shaped element. A second element is placed in close proximity to the horizontal section of the "L" shaped element and is also totally submerged in the liquid toner concentrate. Next, a third element is placed in close proximity to the vertical section of the "L" shaped element. The current flowing from the horizontal section of the "L" shaped element through the liquid toner concentrate to the second element is proportional to the concentration of solid. By measuring the current flowing from the vertical section of the "L" shaped element through the liquid toner concentrate to the third element and dividing by the current in the second plate, the volume of the liquid toner concentrate can easily be calculated.

Abstract: A contactless sheet resistance measurement apparatus and a method for measuring the sheet resistance of a desired layer of a first conductivity type, formed upon a substrate of an opposite conductivity type, is disclosed. The apparatus comprises a junction capacitance establishing means, a point location alternating current AC photovoltage generating means for generating a laterally propagated AC photovoltage, an attenuation and phase shift monitoring means for monitoring the .laterally propagated AC photovoltage, and a sheet resistance signal generating means responsive to the-junction capacitance establishing means, the AC photovoltage generating means, and the attenuation and phase shift monitoring means for generating an output signal indicative of a sheet resistance R.sub.S of the desired layer according to a prescribed sheet resistance model.

Abstract: A biosensing meter receives a biomedical sample strip or a check strip, a sample strip including electrically isolated excitation and sense electrodes. The biosensing meter includes first and second contacts that are positioned to be electrically connected by a sense electrode when a sample strip is inserted into the biosensing meter. An operational amplifier circuit has one input connected to the first contact and a second input connected to a reference potential, the one input manifesting the reference potential as a result of a feedback within the operational amplifier. A processor is coupled to the second contact and determines the presence of the reference potential at the second contact when an inserted sense electrode connects the first and second contacts.

Abstract: A method for detecting extent of cross-linking of a high impedance polymer material during a pre-cure state, the method including: applying a test signal through a sensor to the material and through a reference resistance; determining a voltage difference between the test signal applied to the material and the reference resistance as the reference voltage; and correlating the voltage difference as a relative indicator of the extent of cross-linking which has occurred within the polymer material. Also disclosed is a device for implementing the subject method.

Abstract: Phosphorus concentration in molten copper can be determined by measuring temperature and electric resistivity of molten copper.

Abstract: A novel, inexpensive sensor (10) for detecting volatile hydrocarbons and other solvent vapors detects leaks in the fittings and valves of petroleum refineries and chemical manufacturing and processing plants. The sensor comprises (a) a dielectric substrate (12) having a major surface; (b) a pair of interdigitated, electrically conductive electrodes (14a, 14b) disposed on the major surface of the substrate; and (c) a composite coating (16) covering the interdigitated electrodes and comprising (1) a conductive polymer, and (2) a dielectric polymer with an affinity for the solvent vapors to be detected.

Abstract: A probe for real-time in-situ monitoring for hot gas contaminants, such as alkali, uses the detection principles of condensation/vaporization temperatures or corrosion rates with electrical/optical measurements.

Abstract: A system and method of detecting the end of useful life in a gas sensor cell having a cathode, anode, one of which is consumable, and an electrolyte, and a circuit for controlling the flow of gas to the cell and a sensing resistor and circuit connected to said cathode and said anode, the consumable electrode is provided in the form of a plurality of discrete elements which are sequentially connected in circuit with the other electrode, sensing resistor and circuit. A drop in current between respective ones of the consumable electrode is an indication of the approach of the end of the useful life of the gas sensor.

Abstract: An apparatus for identifying and measuring in real time substances overlying a surface comprises a plurality of electrodes, a temperature sensor, an electrode control system connected to the plurality of electrodes for defining an electric field, an amplitude and phase measurement system connected to the plurality of electrodes and to the electrode control system for measuring a plurality of currents responsive to the electric field and converting the currents to a measurement set and computer for storing a map comprising a partition of a vector space of predetermined characteristics of substances into regions of profiles corresponding to the substances which could be overlying the surface. The computer correlates the measurement set with the map thereby identifying and quantifying the substances overlying the surface and generates an output signal corresponding to the identity and quantity of substances overlying the surface.

Abstract: An electrically conductive particle detector that includes a hollow spool or sleeve of insulating material having an open end, a sidewall and a circumferential array of elongated fluid passages that extend radially through the sidewall. A pair of internested helical conductors are mounted in corresponding helical grooves on the interior of the sleeve sidewall, with helical reaches of the conductors spaced from each other by the sleeve. Electrical circuitry is connected to the conductors for detecting impingement of a conductive particle that bridges adjacent reaches of the conductors in fluid that flows through the sleeve. A perforated strainer is carried by the sleeve spaced from the conductors for removing particles in the fluid that flows through the sleeve.

Abstract: An electrical magnetic detector disposed in the passage of a flow of fluid to detect the magnetic particles transported by that flow and to trigger an alarm after detection of a predetermined quantity of magnetic particles. It includes a magnet surrounded by two polar masses separated by an axial air gap. The external surface of the detector has, at least adjacent the air gap (4), peripheral surfaces (5, 6) converging toward the air gap. The detector is useful in the surveillance of wear members to detect the degree of wear thereof.

Abstract: An apparatus is so constructed as to measure a specific substance in a test specimen by the degree of the aggregation of carrier particles in a reaction solution in which the test specimen is mixed with the carrier particles which carry a substance specifically binding to the specific substance. The apparatus includes a substrate having comb-shaped electrodes mounting the reaction solution and amplifier and alternating oscillator for displaying a variable voltage to the comb-shaped electrodes. The test specimen measuring apparatus having the structure accelerates the aggregation of the reaction solution by applying an alternating voltate to the comb-shaped electrodes in a state that the reaction solution is being mounted on the substrate, and detects the spatial spectrum of the comb-shaped electrodes on which the reaction solution is mounted, thus performing the qualitative or quantitative detection of the presence of the substance in the test specimen.

Abstract: A low molecular weight organic liquid detection sensor which is a wire body formed by coating a core material with a conductive layer made of a substantially non-crosslinked material having a Shore A hardness not more than 70 which is mainly composed of thermoplastic elastomer and conductive carbon, the conductive layer varying in its electric resistance upon contact with a low molecular weight organic liquid. The sensor of the invention permits secured mechanical strength, its easy installation in a narrow conduit or over a wide area, and highly sensitive sensing of a low molecular weight organic liquid in the longitudinal direction.

Abstract: An instrument and method for measuring chemical properties, the instrument having electrodes suitable for immersion in a chemical solution. A voltage source and a current-sensing circuit are connected to the electrodes to measure the current produced in the solution in response to a voltage applied to the electrodes to determine a value of the chemical in the solution. The instrument and method further include background compensation for offsetting the value of the analyte by an amount which is reflective of the background value of the solution. The background value is stored in an internal memory of the instrument so that when new experimental measurements are taken, the measurements are immediately offset by the background portion of the new experimental measurements. This allows operation of the instrument at high gain levels, resulting in a broad dynamic range and greater useful precision in the output signal.

Abstract: A sensor (10) is provided, which is based on a conductive polymer (16) as the active material to measure the concentration of alcohol in gasoline. This information is then sent to the engine to immediately adjust the air:fuel ratio, which is critical in these alternate fuel systems for the smooth operation of the engine. The sensor of the invention comprises the conductive polymer and a pair of sensing electrodes (12, 14) associated with the conductive polymer. Most conveniently, the sensing electrodes are arranged in an interdigitated fashion and are coated with the conducting polymer. Certain conducting polymers have been found whose resistance changes as a function of alcohol, e.g., methanol, concentration. Since the resistance of the conducting polymer is related to the alcohol concentration, this information can be processed by a microprocessor, which can then make the necessary adjustments in the air:fuel ratio.

Abstract: Improved circuits for measuring the conductivity of a solution confined between two electrodes in a cell compensate for series capacitance and parallel capacitance between the electrodes. A bipolar square-wave signal is applied to the cell. In one embodiment, the current through the cell is measured by an op-amp in current-to-voltage converter configuration. A feedback resistance employed with the op-amp in a feedback loop is controlled to a low value to ensure that the parallel capacitance is fully charged during an initial portion of each half-cycle of the drive signal. The feedback resistance is then selected so that the gain of the feedback loop is responsive to the range of the resistivity of the solution, and the measurement is made.

Abstract: A system and method for detecting the presence of contaminants in supercritical fluid. The system is based upon the use of an absorbent module comprising an absorbent which selectively absorbs the contaminant being measured and wherein the electrical properties (i.e. conductance and/or capacitance) of the absorbent varies depending upon the amount of contaminant absorbed. A sample stream of the supercritical fluid is contacted with the absorbent material. By measuring the electrical properties of the absorbent, contaminant levels are measured and monitored.

Abstract: While preparing a photographic emulsion a conductivity reading is continuously or periodically taken from the batch during creation. The conductivity of the batch is compared to a standard plot of conductivity versus time representing an ideal batch preparation process. When conductivity of the batch deviates from the standard plot by more than a pre-determined level, an operator can discard the batch, compensate for the deviations, identify the cause of the deviation for use in correcting existing processes and procedures or optimizing future procedures, or compensate for the deviations.

Abstract: An improved detector assembly with an electromagnetic induction-type conductivity meter is provided with a pair of housing members forming a first liquid sample flow path at a central location, and a second liquid sample flow path on their outer circumference. An excitation coil and a detection coil extend about the first liquid sample path, while the second liquid sample flow path interconnects with the first liquid sample flow path both upstream and downstream of the respective coils. The second liquid sample flow path can substantially extend about the coils so that a relatively large induction current can be generated and measured as representative of the liquid sample.

Abstract: A method and apparatus for detecting changes in the structural strength of bonded joint. Changes in one or more dielectric properties of the bonding adhesive, such as resistance and capacitance, are monitored by a microdielectrometer. A change in a bond dielectric measurement is indicative of a moisture intrusion in the bond and a corresponding weakening of the structural integrity of the bond. A warning or indication of the bond degradation is provided in response to such changes.

Abstract: A sensor for use during the construction of a concrete structure to enable an assessment to be made of whether or not a pour of fresh concrete has settled uniformly throughout the placement area. One of two main electrodes is fitted with an auxiliary electrode in parallel such that the polarity of the electrodes is reversed when they are immersed in water and when they are immersed in fresh concrete. By monitoring this function, it is possible to detect the presence or absence of fresh concrete in accordance with the polarity. In the case of a sensor without an auxiliary electrode, it is still possible to monitor changes in the voltage level when the electrodes are immersed in water and in fresh concrete, thereby providing access to a similar mode of assessment.

Abstract: A combustible gas sensor includes a housing defining an interior containing a reference bead and a measurement bead which are fully exposed by the removal of the shroud or can therefrom. The beads are electrically connected in series and the reference bead is connected in parallel with a resister to define one side of a Wheatstone bridge. A liner consisting of a disk defining an inner face and an outer face overlies the reference and measurement beads. The inner face of the disk is provided with a slot opening at the inner face which is dimensioned to receive the reference and measurement beads therein. The slot provides a confined space for fluid communication between the fully exposed beads. A through running opening is disposed in the disk on each side of the slot adjacent the end of the slot in which the reference bead is disposed. A channel extends from each of the openings and communicates with the slot.

Abstract: In a method of diagnosing deterioration of a paint film, a probe is applied to the surface of a paint film. A voltage having a predetermined waveform is applied by a preamplifier across the probe and a base metal on which the paint film is formed. A current flowing through the paint film is measured by the preamplifier. An analog signal indicative of a measured current value is converted to a corresponding digital signal by an analog-to-digital converter. A personal computer operates to analyze the digital signal in accordance with a predetermined analyzing procedure so that the degree of deterioration of the paint film is determined. The resultant determination is displayed on the display.

Abstract: Process for contactless measurement of the electrical resistance (or of the electrical conductivity) of a preferably flat material (test material) in which an alternating current is capacitively coupled into the test material with the help of two coupling electrodes. The total impedance is measured at at least three different frequencies, and from that measurement, the stray capacitance between the two coupling electrodes, the coupling capacitance between the two coupling electrodes and the test material, as well as the resistance of the test material are determined. In a preferred embodiment the process is used for controlling the windshield wipers of a motor vehicle.