A new high temperature silicon on sapphire transducer for jet engine control applications

A new pressure transducer has been designed using silicon on sapphire technology. This transducer has been primarily designed for use in jet aircraft monitoring and control applications. The heart of this device is a single crystal sapphire substrate with epitaxially deposited silicon strain gages in intimate contact with the sapphire. The sapphire substrate becomes the pressure sensitive diaphragm and the strain gage resistance change is directly proportional to applied pressure. The transducer exhibits excellent linearity and low hysteresis due to the crystalline nature of the diaphragm. The transducer is fabricated using materials that have excellent thermal expansion match properties and is capable of operating at temperatures up to 500 degrees Fahrenheit. A means of monitoring diaphragm temperature is also included in the design. This paper contains a complete description of the fabrication process and the performance characteristics of this new device.