Silicon carbide resonant tuning fork for microsensing applications in high-temperature and high G-shock environments

We present the fabrication and testing of a silicon carbide balanced mass double-ended tuning fork that survives harsh environments without compromising the device strain sensitivity and resolution bandwidth. The device features a material stack that survives corrosive environments and enables high-temperature operation. To perform high-temperature testing, a specialized setup was constructed that allows the tuning fork to be characterized using traditional silicon electronics. The tuning fork has been operated at 600 degrees C in the presence of dry steam for short durations. This tuning fork has also been tested to 64,000 G using a hard-launch, soft-catch shock implemented with a light gas gun. However, the device still has a strain sensitivity of 66 Hz/mu epsilon and strain resolution of 0.045 mu epsilon in a 10-kHz bandwidth. As such, this balanced-mass double-ended tuning fork can be used to create a variety of different sensors including strain gauges, accelerometers, gyroscopes, and pressure transducers. Given the adaptable fabrication process flow, this device could be useful to microelectromechanical systems (MEMS) designers creating sensors for a variety of different applications. (C) 2009 Society of Photo-Optical Instrumentation Engineers. [DOI: 10.1117/1.3143192]