Embedded microelectromechanical systems (MEMS) for measuring strain in composites

Microelectromechanical strain sensors were fabricated and embedded in laminated composites. These small scale sensors were designed to function as part of a wireless sensing network. The sensing element, signal conditioning, and telemetry circuitry have been developed to be fabricated on a single silicon wafer. In this paper, the sensor design and function are described. The most critical feature for sensor design was the strain transfer between the sensor and composite matrix. Finite element models were developed to investigate various designs prior to manufacture. Two types of sensors were produced, sensors which were integral to the wafer, and sensors which were thin silicon nitrate beams attached to the wafer only at the beam root. An overview of experimental data from an extensive series of tests will be presented.