Micromachined silicon microcantilevers for gas sensing applications with capacitive read-out

The design and fabrication of a simple and low-cost micromachined silicon capacitive device is reported. Application to the detection of volatile organic compounds (VOCs) based on capacitive variations due to induced differential surface stress is presented. Good results in terms of sensitivity, reproducibility and response and recuperation times have been obtained with this type of devices. Limits of detection (LoDs) for the measured gases are below 50 ppm for toluene and 10 ppm for octane. The responses to the tested gases are different thus we would be able to discriminate a mixture of them.