Polymeric substrate microcrystalline-silicon strain sensor

Metallic foil and semiconductor piezoresistors are frequently used as strain sensors in shape or strain monitoring applications. The sensors are typically connected in a Wheatstone bridge configuration and mounted on the surface or body to be tested. Semiconductor sensors, for example crystalline silicon, can provide good strain sensitivity with significantly reduced sensor area and also reduced bridge power compared to metal resistor bridges. a-Si:H strain sensors fabricated on glass substrates have recently been demonstrated (G. de Cesare et al, Thin Solid Films, vol. 427, p. 191, 2003). We report here the first microcrystalline-silicon (μC-Si) strain sensors fabricated directly on flexible polyimide substrates with similar gage factor but very low power and higher yield compared to metallic strain sensor.