Abstract: A combinational sensor system for measuring multiple measurands includes a flow transducer, a pressure transducer and a humidity transducer. The pressure and humidity transducers are provided with independent access to sensed media and are ratiometric to a supply voltage, whereas the flow sensor is sensitive to openings to the flow path. The combinational sensor system utilizes elastomeric seals that include patterned electrically conductive and non-conductive seals. An ASIC is generally associated with the combinational sensor, and is located on a patterned electrically conductive substrate lead frame or for signal conditioning in order to detect any of the sensed measurands. The transducers can be arranged in a manner that distributes the transducers to optimize the accuracy and response time of the combinational sensor system.

Abstract: A combinational sensor system for measuring multiple measurands includes a flow transducer, a pressure transducer and a humidity transducer. The pressure and humidity transducers are provided with independent access to sensed media and are ratiometric to a supply voltage, whereas the flow sensor is sensitive to openings to the flow path. The combinational sensor system utilizes elastomeric seals that include patterned electrically conductive and non-conductive seals. An ASIC is generally associated with the combinational sensor, and is located on a patterned electrically conductive substrate lead frame or for signal conditioning in order to detect any of the sensed measurands. The transducers can be arranged in a manner that distributes the transducers to optimize the accuracy and response time of the combinational sensor system.

Abstract: A feedback operated DC bridge circuit for monitoring the voltage variations in a voltage divider circuit using a voltage controlled resistance component to reach a null balance across the bridge. Amplification is provided at higher accuracy near the null point when the voltage difference across the bridge is zero. The feedback bridge circuit includes an integrator which directly drives the controlling component to the value of the resistance in an unknown branch to force the null condition. The voltage controlled component (configured as a discrete metal oxide semiconductor device or bipolar junction transistor) and the balancing scheme are suitable for microfabrication and provides noise-rejection enhancement. The interconnected integral feedback of the autonulling DC bridge enables both a neural network for pre-processing sensor input in a spatial domain as well as general analog computation that mimics a first order differential equation in the form of the system state equation.

Abstract: A self-contained autonulling bridge circuit based on phase-sensitive deteon of an impedance to be measured is described. The system utilizes a feedback structure to control a variable impedance in order to establish the null of the bridge. The system utilizes a voltage-variable impedance having both resistance and capacitance and provides the phase sensitive relationship in the control means in order to provide highly accurate measurement of an unknown test impedance. The ability to measure small changes in impedance provides particularly useful application to the area of biological sensor impedance measurement or electrochemical impedance measurement using silicon-based devices.