A microcantilever-based alcohol vapor sensor-application and response model

A recently developed microcantilever probe with integrated piezoresistive r eadout has been applied as a gas sensor. Resistors, sensitive to stress cha nges, are integrated on the flexible cantilevers. This makes it possible to monitor the cantilever deflection electrically and with an integrated refe rence cantilever background noise is subtracted directly in the measurement . A polymer coated cantilever has been exposed to vapors of various alcohol s and the resulting cantilever response has been interpreted using a simple evaporation model. The model indicates that the cantilever response is a d irect measure of the molecular concentration of alcohol vapor. On the basis of the model the detection limit of this cantilever-based sensor is determ ined to be below 10 ppm for alcohol vapor measurements. Furthermore, the ti me response of the cantilever can be used to distinguish between different alcohols due to a difference in the evaporation rates. (C) 2000 American In stitute of Physics. [S0003-6951(00)02118-5].