Role of parasitics in humidity sensing by porous silicon

Humidity sensing by porous silicon (PS) layer is commonly reported either b y capacitive sensing or by conductive sensing. A critical analysis of both capacitive and conductive sensing by microporous PS layer is presented here . The influences of parasitic capacitances and resistances unavoidably asso ciated with the active porous layer on the measured changes in capacitance and resistance of the humidity sensor with variation of humidity are analys ed. The role of contact geometry, signal frequency and porosity of PS layer are also discussed. It is shown that capacitive sensing is more sensitive in low frequency range owing to the relative contributions of parasitic com ponents. (C) 2001 Elsevier Science B.V. All rights reserved.