A thermal micro pressure sensor: its characteristics and application to pressure measurement in a minute package

Abstract

A thermal micro pressure sensor suitable for measurement in the range of 7×10^-3 to 1×10⁵Pa was realized by forming a titanium (Ti) thin-film resistor on a floating NSG (non-doped silica glass) membrane, with the sensing area being as small as 60μm×60μm. The sensor performance was raised by increasing the gaseous ratio to the total thermal conduction, compensating the effect of ambient-temperature drift, and utilizing an optimized novel constant-bias Wheatstone bridge circuit. The sensor was successfully applied to monitoring the pressure in a sealed minute metal package with a capacity of about 0.5ml.