Abstract: A sensor system for detecting the presence of at least one specific component in a fluid medium such as an exhaust gas. A sensor is mounted in a sensor body for detecting the presence of at least one specific component and providing a representative signal that is transmitted to a remote receiver for processing. A power source such as a thermopile provides power for the sensor and the transmitter. Preferred are sensors that detect a plurality of different components in the gas and provide a distinct signal for each component. A preferred transmitter is designed to transmit at a low duty cycle so as to conserve power. A preferred sensor is electronic, has the capability for self-diagnostics and self-calibration, and causes a change in current when exposed to the component, such as a functionalized field effect transistor.

Abstract: Methods of and systems for balancing the capacitance of a common series capacitive circuit in a semiconductor-based sensor, such as a humidity sensor, are described. Relative humidity sensors can provide measurements via a series capacitive circuit including a humidity-sensitive dielectric separating a common top plate and first and second bottom plates associated with a first and second capacitor, Cx1 and Cx2. For proper operation, the common top plate should be in capacitive balance. Capacitive balance can be achieved by creating voids within and/or along the common top plate of the sensor. A system for creating voids can include a precision cutting instrument, a measuring device for enabling the measurement of capacitance of at least one of the common series capacitive circuit, Cx1 and Cx2, and power provided from a voltage source.

Abstract: Methods of and systems providing high reliability relative humidity sensors having integrated signal conditioning are described, providing a series capacitive circuit including a humidity-sensitive dielectric, a common top plate and first and second bottom plates associated with a first and second capacitor, respectively. Changes in humidity affect the humidity-sensitive dielectric thereby causing changes in the capacitive value of said series capacitive circuit.

Abstract: A temperature compensation circuit is provided for use in conjunction with a Hall effect element in which the temperature compensating resistors, or epitaxial resistors, are not placed in the signal loop as portions of the feedback loops of amplifiers. The circuit therefore permits a higher degree of linearity and temperature compensation without inducing the problems that are normally caused by varying voltage potentials across the epitaxial resistors. One embodiment of the circuit also provides a means for clamping, or truncating the output voltage of the circuit to a preselected percentage of the supply voltage even though the supply voltage may vary during the operation of the device. The circuit utilizes several external trimmable resistors to perform final adjustment on the circuit in order to permit individual variations from component to component to be compensated.

Abstract: A temperature compensation circuit is provided for use in conjunction with a Hall effect element in which the temperature compensating resistors, or epitaxial resistors, are not placed in the signal loop as portions of the feedback loops of amplifiers. The circuit therefore permits a higher degree of linearity and temperature compensation without inducing the problems that are normally caused by varying voltage potentials across the epitaxial resistors. One embodiment of the circuit also provides a means for clamping, or truncating the output voltage of the circuit to a preselected percentage of the supply voltage even though the supply voltage may vary during the operation of the device. The circuit utilizes several external trimmable resistors to perform final adjustment on the circuit in order to permit individual variations from component to component to be compensated.