Design of non-contact transduction based pressure sensor using Tunneling magnetoresistive (TMR) principle

A pressure sensor with non-contact transduction which measures deflection of diaphragm due to applied pressure, using tunneling magnetoresistive (TMR) principle is aimed to meet the requirements of pressure measurement in harsh environments. In commonly used strain gauge type of pressure sensor, strain depends not only on pressure but also on media temperature which induces more error or burnout strain gauges at high temperature. A novel non-contact measurement principle to detect diaphragm deflection is proposed that allows to overcome these limitations. For this purpose, Samarium Cobalt magnet and TMR sensor are used. As transduction is non-contact, this method is useful to measure pressure of hot gas produced by combustion of short duration. This paper presents the design of pressure sensor using TMR principle and its evaluation supported by the simulated test results. Further scope of work towards improvement of accuracy and confidence on pressure measurement has been concluded to aid sensor design in future.