THE OBJECTIVE OF THIS PROPOSAL IS THE DEVELOPMENT OF A HIGH ACCURACY (+/-0.

THE OBJECTIVE OF THIS PROPOSAL IS THE DEVELOPMENT OF A HIGH ACCURACY (+/-0.02% OF READING) VARIABLE CAPACITANCE PRESSURE TRANSDUCER WHICH IS IMMUNE TO FLOODING, THIS BEING A MAJOR PROBLEM IN EXISTING EQUIPMENT. THIS IMMUNITY IS PROVIDED BY SURROUNDING THE ACTUAL PRESSURE CELL WITH OIL AND SEGREGATING IT FROM THE PRESSURE MEDIA BY A DIAPHRAGM. THE DESIGN OF THE SENSOR AND ITS ELECTRONICS ALLOW ACCURATE MEASUREMENT OF PRESSURE BY MEASURING SMALL CHANGES IN SENSOR CAPACITANCE. THESE CHANGES REQUIRE LITTLE PHYSICAL DEFLECTION OF THE MEASUREMENT CELL, RESULTING IN MINIMAL EFFECTS FROM THE DIAPHRAGM AND THE HYSTERESIS OF THE CELL MATERIAL. ACCURATE CAPACITANCE MEASUREMENTIS ACHIEVED BY THE USE OF THE GUARDED ELECTRODE TECHNIQUE, COUPLED WITH NEIL BROWN INSTRUMENT SYSTEMS, INC. PROPRIETARY AC RATIOMETRIC ANALOG-TO-DIGITAL CONVERSION TECHNIQUES. TOGETHER THESE ESSENTIALLY ELIMINATE THE EFFECTS OF STRAY CIRCUIT CAPACITANCE USUALLY FOUND IN OTHER CAPACITANCE PRESSURE SENSORS. THE EFFORT OF THIS RESEARCH AND DEVELOPMENT IS IN DESIGNING TRANS DUCERS WITH PROPER PHYSICAL AND ELECTRICAL CHARACTERISTICS; DETERMINING FABRICATION TECHNIQUES TO REPEATEDLY PRODUCE TRANSDUCERS THAT MEET THE DESIGN, AND TO CHARACTERIZE THE TRANSDUCERS PHYSICAL, ELECTRICAL AND THERMAL PROPERTIES. THESE CHARACTERISTICS CAN THEN BE ACCOUNTED FOR IN THE ELECTRONICS TO PROVIDE ACCURATE DIRECT PRESSURE MEASUREMENT.