Abstract: Methods of concentrating an analyte that is in liquid and method of detecting an analyte in a liquid are disclosed. Methods of screening a liquid for the presence of an analyte are also disclosed. Processes comprising continuously collecting a sample of fluid throughout the process and analyzing the sample are disclosed as are processes comprising treating ultrafilter membranes. Devices and systems for concentrating an analyte that is in liquid and for screening a liquid for an analyte are disclosed as well as devices and systems for concentrating an analyte from a continuous sample are disclosed.

Abstract: The present invention is directed to methods and systems for rapidly identifying microorganisms such as bacteria, viruses, fungi and the like that may be present in an agricultural specimen. The methods of the present invention provide a process for rapidly and accurately identifying infectious or pathogenic microorganisms without the need for culturing. In addition, the methods of the present invention provide processes for assaying harvested agricultural crops for the presence of statistically significant quantities of microorganisms.

Abstract: Methods of concentrating an analyte that is in liquid and method of detecting an analyte in a liquid are disclosed. Methods of screening a liquid for the presence of an analyte are also disclosed. Processes comprising continuously collecting a sample of fluid throughout the process and analyzing the sample are disclosed as are processes comprising treating ultrafilter membranes. Devices and systems for concentrating an analyte that is in liquid and for screening a liquid for an analyte are disclosed as well as devices and systems for concentrating an analyte from a continuous sample are disclosed.

Abstract: A method for fabricating an adhesion-resistant microelectromechanical device is disclosed wherein amorphous hydrogenated carbon is used as a coating or structural material to prevent adhesive failures during the formation and operation of a microelectromechanical device.

Abstract: A method for fabricating an adhesion-resistant microelectromechanical device is disclosed wherein amorphous hydrogenated carbon is used as a coating or structural material to prevent adhesive failures during the formation and operation of a microelectromechanical device.

Abstract: An engine component such as an intake or exhaust valve, or any other component near or within the combustion chamber, is coated with an amorphous hydrogenated carbon film coating to prevent the formation of carbonaceous deposits thereon. Methods for forming the film coating are also disclosed.

Abstract: A sensor for determining the stoichiometric air to fuel ratio (A/F) at the intake of an internal combustion engine is based on a capacitive device in the exhaust stream which can be used to measure the change in the workfunction of an appropriate material which occurs at the stoichiometric point and which forms one of the two interacting elements of the capacitor. To measure A/F over an extended range about stoichiometry the material whose workfunction changes is made the working electrode of an oxygen concentration cell using a solid electrolyte. Oxygen pumping to and from that surface can change the magnitude of the workfunction allowing for a feedback control method for keeping the workfunction constant despite changes in the A/F so that the required pump current becomes a measure of the A/F.

Abstract: A sensor for determining the stoichiometric air to fuel ratio (A/F) at the input to the cylinders of an internal combustion engine which is based on measuring the change in the workfunction of a material which occurs when the oxidizing and reducing species in the adjacent gas phase are at or near their stoichiometric ratio. In one method the sensor includes a material which is capable of thermionically emitting alkali metal or other appropriate ions into an exhaust gas atmosphere where they are subsequently collected by a nearby collector electrode and the magnitude of the emission current is measured. The interaction of the emitting surface with the gas phase reversibly changes the workfunction of the emitting surface from large to smaller values as that gas phase is varied through the stoichiometric ratio with respect to the amounts of the oxidizing and reducing species in the gas.

Abstract: A sensor determines a wide range of air-to-fuel ratio values (A/F) about the stoichiometric A/F in a gaseous mixture which has oxidizing and reducing species as might be found in an automotive exhaust. The sensor includes a surface that serves simultaneously as the working electrode of a solid-state oxygen concentration cell and as a surface whose workfunction changes from a higher to a lower value as the oxidizing and reducing species in the adjacent gas phase, and in interaction with the surface, pass from an excess oxidizing to the excess reducing condition about the stoichiometric ratio. In one embodiment, the surface exposed to the gas in question is the emitter electrode of a thermionic diode which emits positively charged alkali ions into the exhaust ambient where they are collected by a nearby collector electrode. Changes in the ratio of the oxidizing and reducing species about the stoichiometric ratio produce corresponding changes in the thermionic emission.

Abstract: A fluid mass flow sensor uses the effect of aerodynamic drag on a vibrating object. The drag damps the resonance oscillations of the vibrator in an amount proportional to the mass flow. An electronic feedback circuit associated with the mass flow sensor has the effect of allowing for fast response time despite the use of a high Q vibrator and allows for electronic calibration of the device.

Abstract: A vibration type sensor can make a noncontacting measurement of position or sense the passage of an object past a point. The sensor has a coil of wire placed on a vibrating structure. A power supply causes current to be passed through the coil at the resonant frequency of the vibrating structure. As an object with an attached magnet approaches the coil, a force is exerted on the current carrying coil thereby exciting the structure at its resonant vibrational frequency. A piezoelectric bimorph is attached to the structure so that it flexes with the structure producing an emf output proportional to the vibrational amplitude. As the object moves, the field strength at the coil, the amplitude of the vibration and the induced emf change. The latter quantity is used to sense the motion of the object.

Abstract: A method of controlling the air fuel ratio of an internal combustion engine includes positioning a two cell oxygen pumping device in the exhaust gas of the engine. A pumping current is applied to a pumping cell and an EMF is sensed across a sensor cell. The sensed EMF is compared to reference voltage and an error signal is generated. The air fuel ratio is changed in response to the error signal so as to reduce the absolute magnitude of the error signal.

Abstract: A vibration type sensor can make a noncontacting measurement of position or pick up the passage of an object past a point. The sensor has a coil of wire placed on a vibrating structure. As an object with an attached magnet approaches the coil, an emf is induced in the coil indicating position. Alternatively, the magnet remains fixed with respect to the vibrating coil while a material of high magnetic permeability approaches the coil and magnet combination thereby perturbing the magnetic field and changing the induced emf. This method can be used to obtain a linear variation of sensor output with position or to enable the use of the device as a pickup sensor.

Abstract: A pressure sensor uses two fluidically coupled piezoelectrically driven, vibrating cantilever structures, each tuned to the same fundamental resonance frequency. One cantilever, the driver, is electrically driven at resonance and at constant vibrational amplitude. The other cantilever, the receiver, responds due to the gaseous coupling and generates an output signal proportional to pressure.

Abstract: A planar photoelectrochemical sensing structure includes a thin, porous layer of photoactive semiconductor powder material deposited on an electronically conducting catalyst film which has been fabricated in two regions separated by a narrow stripe. Using incident light absorbed by the semiconductor, the structure is suited to photosensitizing redox reactions of chemical species introduced to the structure in an aqueous gas-phase environment. If photocarriers generated by the incident light are prevented from reaching one of the catalyst regions, for example by use of a light shield, then an EMF develops between the two catalyst regions. The magnitude of the EMF varies with the concentration of one of the gaseous reactants and thus provides a measure of the concentration.

Abstract: A planar photoelectrochemical structure includes a thin, porous layer of semiconductor powder material on a catalytic film. Using incident light absorbed by the semiconductor, the structure is suited to photosensitizing redox reactions of substrates introduced to the structure in an aqueous gas-phase environment. Conducting catalyst films allow significant external electrical interaction with the photoelectrochemical process occurring in the layer.

Abstract: This specification discloses an electrochemical structure having two separate electrochemical cells using liquid electrolytes separated by a material or region which ca take up the electrochemically active species appropriate to the cells in neutral form. Combined with external circuitry, the structure can be made to exhibit transistor action and further can be made to show ac voltage, current and power gain. For example, transistor action occurs with a structure composed of two liquid electrochemical cells using a sulfuric acid electrolyte separated by an enclosed volume. In normal operation, one cell, acting as an emitter, emits hydrogen from a hydrogen ambient into the enclosed volume, which acts as a base region, where it is collected and returned to the ambient by the opposing cell, acting as a collector.

Abstract: This specification discloses an absolute pressure sensor and measuring technique using an electrochemical apparatus as a feedback element in an oscillator circuit. The sensor needs no reference pressure or reference vacuum. Contributing to sustained oscillation is a phase shift caused by the electrochemical apparatus. The period of oscillation of the oscillator circuit is inversely proportional to the diffusion coefficient of oxygen in its carrier gas, which, in turn, is inversely proportional to total absolute pressure. The result is that the period of oscillation of the oscillator circuit is proportional to total absolute pressure.

Abstract: This specification discloses a step function lean burn sensor for determining the partial pressure of oxygen in an exhaust gas. Such a measurement is useful for air fuel ratio control in an internal combustion engine. This device uses the electrical properties of an electrochemical pump cell to determine the step function output. The device utilizes the qualitative nature of the current-voltage characteristic of the pump cell to reduce requirements on cell fabrication.

Abstract: This specification discloses an electrochemical structure having two solid electrochemical cells separated by a material or region which can take up the electrochemically active species appropriate to the cells in neutral form. Combined with external circuitry, the structure can be made to exhibit transistor action and further can be made to show ac voltage, current and power gain. For example, transistor action occurs at elevated temperatures, such as at 800.degree. C., with a structure composed of two ceramic zirconium dioxide electrochemical cells separated by an enclosed volume. In normal operation, one cell, acting as an emitter, emits oxygen from an ambient atmosphere into the volume, which acts as a base region, where it is collected and returned to the ambient by the opposing cell, acting as a collector.