Abstract: In a method and system to produce biodiesel using an improved catalytic transesterification process, a first reactant and a second reactant are dispersed to form a laminar slug flow pattern within a microchannel of a microreactor, the first reactant and the second reactant being immiscible. The first reactant and the second reactant are mixed, thereby triggering a reaction between them to produce the biodiesel and glycerol, the mixing being convection-enhanced by shear stress induced circulation occurring within each slug of the reactants. The reaction takes place under a pressure that is less than 5 psi and under a temperature that is less than 70 degrees Celsius. Separation of the glycerol from the biodiesel occurs simultaneously with the mixing. Several microreactors are coupled in parallel to improve throughput of the biodiesel.

Abstract: A system and method is disclosed for focusing an elastically deformable lens by making small changes in the equatorial diameter of the lens. A plurality of micro-electro mechanical system (MEMS) microengine assemblies are coupled to the periphery of the lens. The lens is focused by exerting and relaxing radial tension in a plane generally perpendicular to the optical axis of the lens. Each microengine assembly utilizes thermal beam actuator arrays in combination with mechanical links to move a slider unit that is coupled to an aperture in the periphery of the lens. The movement of the slider unit alters the diameter of the lens to change the focus of the lens. The lens diameter may be changed by amounts as small as one micron.

Abstract: A system and method is disclosed for providing a micro-electro-mechanical (MEMS) microengine assembly. In an advantageous embodiment the microengine assembly of the present invention is coupled to the edge of an object. The microengine assembly moves the object by exerting force on the object. The microengine assembly utilizes thermal beam actuator arrays in combination with mechanical links to move a slider unit that is coupled to the object through an aperture in the object. The slider unit is capable of moving the object in a forward direction and in a backward direction by distances as small as one micron (1 &mgr;m).

Abstract: A system and method for providing an improved micro-electro-mechanical (MEMS) electrothermal actuator is disclosed. In prior art electrothermal actuators an electric current passes through a narrow arm and returns through a wide arm. The larger current density in the narrow arm heats the narrow arm so that it expands more than the wide arm. The differential expansion of the hot narrow arm and the cold wide arm deflects the end of the cold wide arm. The present invention provides an additional hot arm to provide a return path for the electric current so that the cold arm does not conduct electric current. The present invention optimizes power consumption, tip deflection and generated force. A bidirectional thermal beam actuator is also disclosed.

Abstract: A system and method is disclosed for focusing an elastically deformable lens by making small changes in the equatorial diameter of the lens. A plurality of micro-electro mechanical system (MEMS) microengine assemblies are coupled to the periphery of the lens. The lens is focused by exerting and relaxing radial tension in a plane generally perpendicular to the optical axis of the lens. Each microengine assembly utilizes thermal beam actuator arrays in combination with mechanical links to move a slider unit that is coupled to an aperture in the periphery of the lens. The movement of the slider unit alters the diameter of the lens to change the focus of the lens. The lens diameter may be changed by amounts as small as one micron.

Abstract: A two-dimensional, electrically-multiplexed robotic tactile sensor realized by capacitively coupling a piezoelectric film such as a polyvinylidene fluoride (PVDF) polymer film to a monolithic silicon integrated circuit. The disclosed integrated circuit incorporates 64 identical sensor electrodes arranged in a symmetrical 8.times.8 matrix and physically adjacent electronic amplification for each sensor electrode signal. The response of a typical tactile sensor is linear for loads spanning the range of 0.8 to 135 grams of force and provides a response bandwidth of 20-25 Hz. Stability and response reproducibility limitations often associated with piezoelectric-based tactile sensors are resolved by a pre-charge voltage bias sequence for the PVDF film which initializes the pre-and post-load sensor responses. Recognition of sharp-edge, square, trapezoid, isosceles triangle, circle, toroid, slotted screw, and cross-slotted screw shapes using the sensor is also disclosed.

Abstract: A sensor having an interdigitated gate electrode field effect transistor (IGEFET) coupled to an electron beam evaporated copper phthalocyanine thin film is used to selectively detect parts-per-billion concentration levels of atmosphere contaminants such as nitrogen dioxide (NO.sub.2) and diisopropyl methylphosphonate (DIMP). The sensor is excited with a voltage pulse, and its time- and frequency-domain response are examined. The envelopes of the magnitude of the normalized difference frequency spectrums reveal features which unambiguously distinguish the NO.sub.2 and DIMP exposures.

Abstract: An interdigitated back-contact vertical-junction solar cell which utilizes an anisotropically etched 110-oriented silicon crystal wafer. The cell structure includes rounded corner top edges of the between cell channel walls in order to improve light capturing ability and also has pn-junctions disposed over all of the cavity internal surfaces. Additional pn-junctions are located on the rear surface of the cell array to assist in generated carrier collection into a rear mounted metallic conductor grid. The disclosed cell has desirable transducer efficiency, without the use of anti-reflection coatings, and previous improved physical robustness, and radiation hardening. Fabrication of the cell array includes an isotropic etch of the cell dividers and the anisotropic etching to form cell cavities.

Abstract: A sensor having an interdigitated gate electrode field effect transistor (IGEFET) coupled to an electron beam evaporated copper phthalocyanine thin film is used to selectively detect parts-per-billion concentration levels of atmosphere contaminants such as nitrogen dioxide (NO.sub.2) and diisopropyl methylphosphonate (DIMP). The sensor is excited with a voltage pulse, and its time- and frequency-domain response are examined. The envelopes of the magnitude of the normalized difference frequency spectrums reveal features which unambiguously distinguish the NO.sub.2 and DIMP exposures.

Abstract: A wafer scale integration arrangement wherein integrated circuit die of varying size, fabrication processes, and function are commonly mounted in the same host wafer using a filled epoxy material of special characteristics. The mounting epoxy material also serves as a substrate for the die interconnecting conductors in regions adjacent the mounted die. The described assembly also includes a newly available photosensitive polyimide material as a planarization and passivation covering for the die and hose wafer and as a mounting surface for an interconnecting metal conductor array. Multiple levels of interconnection metal. Fabrication processes for the die to host wafer attachment and the passivation covering of the assembly are disclosed.

Abstract: A wafer scale integration arrangement wherein integrated circuit die of varying size, fabrication processes, and function are commonly mounted in the same host wafer using a filled epoxy material of special characteristics. The mounting epoxy material also serves as a substrate for the die interconnecting conductors in regions adjacent the mounted die. The described assembly also includes a newly available photosensitive polyimide material as a planarization and passivation covering for the die and host wafer and as a mounting surface for an interconnecting metal conductor array. Multiple levels of interconnection metal. Fabrication processes for the die to host wafer attachment and the passivation covering of the assembly are disclosed.

Abstract: A sensor for a gas detector is provided that detects the presences of the gas when the gas reacts with a distributed Rc notch network to cause a shift in operating frequency and notch depth. A metallic/metallic oxide gas sensitive discontinuous film acts as the distributive resistive element in the RC notch network. The gas changes the conductivity of the film and this causes the network to react. In the preferred embodiment, a copper/cuprous oxide film detects organophosphorus compounds.

Abstract: A solid state thin film detection and measurement apparatus for halogen gas components such as chlorine in a gas mixture is described. The detection cell employs plural response modes to the halogen gas including response to the thermal effect of a halogen and thin film reaction and response to the thermal and ion diffusion effects of the halogen reaction with a halide supporting substrate member. These plural responses are manifested by an electrical resistance change in the thin film element and this change is sensed with a four-lead measurement arrangement. The use of plural measurement cells each of a different composition and computerized multiplexing of thin film resistance signals is included as are identification of possible thin film and substrate compositions.

Abstract: An electrochemical differential resistance measurement arrangement usable for detecting low concentration ionic impurities such as chemical warfare agents in liquids such as water. The disclosure includes details of electrochemical cells used in the liquid resistance measurement arrangement including one cell with fixed electrode positions and a selective ion transmitting membrane one cell with adjustable electrode position, and a combination cell. A differential bridge electrical circuit, together with a preferred form of alternating current energization therefor, an effluent circuit therefor and a balancing method sequence of steps for the bridge, are also included.

Abstract: A personal field chemical warfare nerve agent detector has therein a transducer having two micromechanical cantilever oscillators. One of the cantilever oscillators has deposited, as an end-mass, a chemically selective substance on the cantilever. The nerve agent if present causes the natural resonant frequency to change. The changed resonant frequency is compared to a reference resonant frequency of the other cantilever oscillator without an end-mass. The amount of frequency change indicates the presence of a chemical nerve agent.

Abstract: A device for detecting the degree of contamination of a gas filter system by a contaminating gas. The device comprises a filter chamber having a pair of grids positioned therewithin and coated with a semiconductive polymer whole bulk conductivity changes due to a chemical reaction between the polymer and a contaminating gas. Measurement of the change is then utilized to indicate the degree of contamination in the filter system.