We present the fabrication of a polyimide microcantilever array with integrated gold piezoresistive strain gauges and a thick SU-8 backing for use as a surface stress sensor. The selected polyimide's low Young's modulus (1.8 GPa) theoretically results in a high sensitivity to changes in surface stress. Electroplated gold contact pads, 1.5 µm thick, provide a stable, repeatable surface onto which electrical connections to the fabricated device are made using spring-loaded microprobes. The piezoresistors are found to have a gauge factor of between 4 and 4.5 and a sensitivity to surface stress of 2.1 × 10-4 (N/m)-1. © 2008 Elsevier B.V. All rights reserved.
- Surface stress sensor