November 27, 2007 — Three patents covering high-temperature, harsh-environment silicon carbide pressure sensors have been licensed by NASA’s Glenn Research Center to Endevco Corp., San Juan Capistrano, Calif.

The technologies include a packaging technique and chip fabrication methods that were developed by a team led by Robert Okojie at Glenn for use in aircraft engine combustion chambers. Silicon carbide (SiC) pressure sensors manufactured using these new processes can be used to improve testing of jet engines, in deep well drilling (where pressure and temperature increase as drilling depth increases), and in automobile combustion cylinders.

Silicon carbide is used for these new technologies, rather than the traditional silicon, which eliminates the need for cooling and enables operation in extreme temperatures. Currently, SiC-based pressure sensors built using these NASA technologies are able to operate for 130 hours at 600 degrees Celsius in air, making it durable and reliable for use for the first time in engine ground testing and short duration flight test instrumentation.

Glenn had used an Endevco silicon-based accelerometer in 2000 as a benchmark to validate Glenn’s SiC accelerometer. Test results showed the NASA device operated as well as the Endevco benchmark device. However, NASA’s SiC accelerometer had the added advantage of operating at much higher temperatures. This led to discussions between Endevco and Glenn about licensing opportunities to acquire Glenn’s SiC pressure and accelerometer sensor fabrication and packaging technologies.

According to Okojie, “Operation at high temperatures allows the SiC pressure sensors to be located in closer proximity to the sensed environment than conventional silicon based sensors, which must be isolated or protected in a water-cooled controlled environment. Placing the sensor closer to the harsh environment provides more reliable measurements. Additionally, its lighter weight due to absence of water-cooling plumbing makes the device less complex, relatively inexpensive and reduces tear-down cycle for engine maintenance. Its lightweight and reduced complexity leads to reduced engine weight for flight vehicles, hence improved fuel efficiency.”