Media-isolated sensor

Abstract

In pressure-sensing applications it is often desirable to expose the sensor to harsh media. Some applications, for example, gauge measurements, require exposure to harsh media from one side only, but others often require differential measurements between two locations. If the silicon piezoresistive pressure sensor is used in such an application, then the harsh environment could quickly corrode and destroy the unprotected side of the sensor. Historically, protection of silicon piezoresistive sensors from harsh media was provided by enclosing the sensor in an oil-filled compartment with stainless-steel diaphragms. This paper describes another approach to media isolation. An accurate low-cost differential pressure sensor has been developed using standard silicon piezoresistive pressure sensors, and does not require any oil filling for media isolation. It is in mass production for the automotive market now, but can also be used in many other non-automotive applications.