Remote infrared radiation detection using piezoresistive microcantilevers

A novel micromechanical infrared (IR) radiation sensor has been developed using commercially available piezoresistive microcantilevers. Microcantilevers coated with a heat absorbing layer undergo bending due to the differential stress between the top layer (coating and the substrate, The bending causes a change in the piezoresistance and is proportional to the amount of heat absorbed. The microcantilever IR sensor exhibits two distinct thermal responses: a fast one (<ms) and a slower one (similar to 10 ms). A noise equivalent power (at a modulation frequency of 30 I-It) was estimated to be similar to 70 nW/Hz(1/2). This value can be further reduced by designing microcantilevers with better thermal isolation that can allow microcantilevers to be used as uncooled IR radiation detectors. (C) 1996 American Institute of Physics.