Abstract: A frequency standard has a cell formed in a cavity of a substrate. The cell contains a metal alkali vapor. The substrate has an optical path that intersects the cell. A light source is supported by the substrate and supplies light through the first optical path to the cell, and a light detector is supported by the substrate and receives light through the second optical path from the cell. The sealed vapor-filled cell is surrounded by a vacuum cavity enclosure. Bridges between the cell and the substrate may be used to thermally isolate the cell in the cavity and allow closed loop temperature control of the cell.

Abstract: A sampling system for detecting an analyte, comprising a diaphragm pump, a buffer chamber, a sensor head and intake port. The pump includes a chamber for receiving fluids via first and second ports. A buffer chamber is located at the second port for holding a quantity of air, and a sensor head is adapted to identify the presence of a desired analyte and produce a signal in response to the quantity identified. Preferably the diaphragm pump has a volume of gas per stroke capacity slightly larger than the volume of the sensor head such that the pump chamber has a greater volume than the buffer chamber and the buffer chamber has about the same volume as the sensor head. A sensor intake port intakes a sample potentially containing the analyte for contact with the sensor head upon operation of the diaphragm pump and out of the sensor head by jet-action caused by rapid movement of the diaphragm pump. A filter may be used for filtering air drawn through the pump chamber.

Abstract: Carbon nanotubes are formed on projections on a substrate. A metal, such as nickel is deposited on the substrate with optional platforms, and heated to form the projections. Carbon nanotubes are formed from the projections by heating in an ethylene, methane or CO atmosphere. A heat sensor is also formed proximate the carbon nanotubes. When exposed to IR radiation, the heat sensor detects changes in temperature representative of the IR radiation. In a gas sensor, a thermally isolated area, such as a pixel is formed on a substrate with an integrated heater. A pair of conductors each have a portion adjacent a portion of the other conductor with projections formed on the adjacent portions of the conductors. Multiple carbon nanotubes are formed between the conductors from one projection to another. IV characteristics of the nanotubes are measured between the conductors in the presence of a gas to be detected.

Abstract: A portable or wearable cytometer that can be used at remote locations, such as in the field or at home. The flow cytometer of the present invention may help improve the healthcare of many weak, sick or elderly people by providing early detection of infection. By detecting the infection early, the infection may be more readily treatable. In military applications, the portable cytometer of the present invention may help save lives by providing early detection of infection due to biological agents.

Abstract: An optical detection system for flow cytometry that uses two or more light sources positioned laterally at different distances from the central axis of the flow stream for providing light through different parts of the flow stream. By using two or more light sources, the particle position can be detected, and the alignment and width of the core stream can be monitored and controlled. In addition, the velocity and size of the particles can be more accurately determined than when only a single light source is used.

Abstract: A sampling system for detecting an analyte, comprising a diaphragm pump, a buffer chamber, a sensor head and intake port. The pump includes a chamber for receiving fluids via first and second ports. A buffer chamber is located at the second port for holding a quantity of air, and a sensor head is adapted to identify the presence of a desired analyte and produce a signal in response to the quantity identified. Preferably the diaphragm pump has a volume of gas per stroke capacity slightly larger than the volume of the sensor head such that the pump chamber has a greater volume than the buffer chamber and the buffer chamber has about the same volume as the sensor head. A sensor intake port intakes a sample potentially containing the analyte for contact with the sensor head upon operation of the diaphragm pump and out of the sensor head by jet-action caused by rapid movement of the diaphragm pump. A filter may be used for filtering air drawn through the pump chamber.

Abstract: A fluid driving system for portable flow cytometers or other portable devices that accepts a less precise and less stable pressure source, and then adjusts the pressure in a closed-loop manner to maintain a constant, desired flow velocity. The fluid driving system may be used in portable or wearable cytometers for use in remote locations, such as at home or in the field.

Abstract: A sensor device for detecting vibration, including a light source for providing a laser light, a first optical fiber connected to the source for transmitting the laser light, an oscillator positioned to receive the transmitted laser light and adapted to reflect the light as a frequency modulated light; a second optical fiber positioned to capture the frequency modulated light to transmit the frequency modulated light; and a frequency modulated discriminator for receiving the frequency modulated light from the second optical fiber and producing a signal responsive of vibration of the oscillator. In a preferred embodiment, the frequency modulated discriminator further includes a frequency meter for determining the average number of cycles per unit time to provide a second signal responsive of the temperature of the oscillator.

Abstract: A diaphragm pump, which is preferably electrostatically actuated, but which may be activated by other forces such as electromagnetic or piezoelectric actuation. The pump is formed by a pump body having a pump chamber formed therein. First and second diaphragms each having a set of valve holes in the diaphragm surface thereof are mounted in the chamber. Also provided are at least one inlet and at least one outlet port for communication with the pump chamber. The ports are positioned for sealing contact with the diaphragms at points that are not aligned with the holes in the diaphragms. A driver electrostatically actuates the diaphragms to cause diaphragm movement to a plurality of diaphragm positions to control flow of fluid through the pump. The first position is when the diaphragms are spaced from one another and from the ports to permit flow of fluid through the pump chamber.

Abstract: An apparatus and method for prevention of migration of mobile ions in a gyroscope. A dielectric barrier material layer is placed between a gyroscope body and one or more gyroscope components. The dielectric barrier material layer reduces the electric field formed in the gyroscope block, and thus reduces ion migration therein. The material may prevent mobile ions from reaching the cathode seal.

Abstract: A micromachined stepper motor having a toothed slider connected at either end to spring flexures. At least one of the spring flexures is positioned between a load, such as a high pass optical filter, and the slider. The slider is positioned within three stators that are sequentially energized such that they move the slider along its longitudinal axis. The springs and guide posts hold the slider in place and establish a rest position when no driving force is applied.

Abstract: A process for forming a UV sensitive gallium nitride layer includes a step of depositing a layer of aluminum nitride on which the gallium nitride layer is deposited. Two tests, sheet resistance and photoluminescent response of the gallium nitride layer, allow one to determine that a particular gallium nitride layer produced by the process will have the required response to UV radiation. Either a careful calibration which determines a required length of the aluminum nitride deposition time, or the introduction of silicon into the gallium nitride layer during its deposition, has been found to result in deposit of a gallium nitride layer which has superior UV sensing characteristics.

Abstract: A photoconductor has an active layer of gallium nitride having approximately 10.sup.15 to 5.times.10.sup.15 net donor sites per cubic centimeter and is sensitive to UV radiation. This photoconductor has at least one of a sheet resistance in the approximate range of 10.sup.4 to 5.times.10.sup.6 ohms/unit area and a relatively low level of photoluminescence in the range from about 430-450 nm when excited with light of energy higher than the bandgap energy of 3.4 eV. These criteria tend to define similar semiconductor materials which can form the active layer of an ultraviolet (UV) photodetector having the improved characteristics of a relatively low dark resistance, high sensitivity over at least a range of UV radiation intensity, and decreasing gain with increasing UV radiation.

Abstract: At least one microbeam situated on a substrate, having a resonant frequency dependent on the strain on the microbeam which may be affected by the bending of the substrate. The beam or beams have sense and drive electrodes proximate to the beam or beams and form capacitors with a beam being the other electrode. The capacitance varies as the beam moves in vibration. The sense electrode is connected to an input of a transistor, such as the gate or base, and the drive electrode is connected to an output of the transistor. The transistor has a load impedance with a capacitive component to aid in the sustaining of vibration of the beam at a resonant frequency. A high ohm resistor is connected between the gate and the drain of the transistor to appropriately bias the gate. The bending of the substrate may be caused by a magnitude of a physical stimulus being measured. However, the bending of the substrate is not utilized nor desired in the filter and temperature sensing configurations of the invention.

Abstract: A temperature and static pressure compensated differential pressure sensor includes a semiconductor substrate in which a flexible, pressure responsive diaphragm is formed. A pressure responsive resonant microbeam is fabricated at the diaphragm periphery. For temperature compensation, a secondary resonant microbeam sensor is fabricated on the substrate at a peripheral location beyond the point of substrate attachment to a pressure tube or other support. For static pressure compensation, another secondary resonant microbeam can be positioned remote from the diaphragm and at a location of maximum substrate response to static pressure. A further resonant microbeam can be mounted at the diaphragm center to augment the signal due to diaphragm deflections. Also disclosed is an accelerometer including a proof mass, a rigid rim surrounding the proof mass, and a series of narrow, flexible bridges supporting the proof mass relative to the rim.

Abstract: Organic vapor species ranging from polar to non-polar are removed from the ambient atmosphere by means of a thin microporous membrane medium in conjunction with a non-volatile collecting fluid having an affinity for the species of interest. The collecting fluid may be regenerated if desired.

Abstract: The instant invention provides a method and system for dehumidifying air by microphorous organic hollow fibers having a hygroscopic liquid disposed in the pores thereof for providing a concentration gradient sufficient to provide a continuous water removal mechanism.

Abstract: A real-time color comparator which performs color comparisons of sample objects to a reference color for the purpose of identification, sorting or matching. Two optical paths are positioned to collect the light from a reference object and a sample object and the light outputs from the two paths are directed onto a spherical dispersive element shown in the form of a concave diffraction grating that decomposes each light signal into its spectral constituents which are imaged on a dual photodetector array. The color signature from the reference and the color signature from the sample are compared.

Abstract: Generic, non-selective sensors identify specific vapors of interest through selectively permeable ILMs which eliminate interfering species.

Abstract: The present invention is an improvement to the method of growing silicon films on a substrate by bringing the substrate in contact with molten silicon. The improved growth technique may be classified as an asymmetric mode of growth of silicon on the substrate and is characterized by the substrate being maintained at a higher temperature than the solidification of silicon in the area of the substrate where the silicon layer growth is taking place, that is in the area of the liquid-solid interface. The higher temperature of the substrate causes the liquid-solid interface to be tilted to be nearly parallel to the substrate surface but inclined at a reentrant angle, so that the leading edge of the crystallization front is away from the substrate. This provides several advantages including increased growth speed, a nonhomogeneous doping of the silicon layer, that is an impurity concentration gradient and results in a high-low junction at the back surface and gives the back surface field effect.