Chemical capacitive sensing using ultrathin flexible nanoporous electrodes

Ultrathin porous nanocrystalline silicon (pnc-Si) membranes metallized with gold are used as flexible conductive electrodes in chemical capacitive vapor sensor. This use of a porous electrode simplifies the conventional parallel-plate design of typical sensors. pnc-Si is a 15 nm thick membrane material with pore sizes ranging from 5 to 50 nm and porosities from <0.1 to 15% fabricated using standard silicon semiconductor processing techniques. We experimentally test the mechanical stability and elasticity of pnc-Si. The very thin porous membrane allows fast analyte vapor permeation to the underlying polymer material that serves as receptor which is tested using an optical profiler. Electrical techniques are used to determine the degree of swelling and the reversibility of the polymer/pnc-Si membrane system when exposed to analyte-containing vapors.