Pressure Transmitter Employing a Diffused Silicon Sensor

The Bailey Meter Company has developed a pressure transmitter which incorporates a solid state sensing element. Pressure across the sensing element, a single crystal silicon wafer, strains a resistor diffused into the silicon by solid state techniques. Due to the piezoresistance effects, the diffused resistor changes value linearly with induced strain. The ohmic change of the piezoresistor is converted directly into millivolts, amplified and converted into a 4 to 20 ma DC output signal which varies linearly with pressure. The transmitter is a true, two-wire system as both excitation power for the transmitter and output signal transmission are accomplished using the same pair of conductors.