Design fabrication and test of micromachined silicon capacitive gas sensors with integrated read-out

In 1985 Gerd Binnig and Calvin F. Quate from Stanford and Christoph Gerber from IBM (Zurich) designed the Atomic Force Microscope (AFM) [1], since then a big interest arose around one of its main components: micromachined cantilevers. During all these years, authors have employed these tiny devices to sense multiple physical and chemical, parameters through diverse transduction principles [2]. Micromachined cantilevers offer many different transduction mechanisms [6]: force sensing, bimetallic effect, mass loading, medium viscoelasticity, thermogravimetry, stress sensing, and more. Along with all these transduction mechanisms, a great variety of detection methods can be employed with cantilever-based sensors as for example: optical detection, resonance frequency measurement, piezoelectric integrated resistors, etc. The design and fabrication process of a micromachined Silicon capacitive gas sensor are described in this paper-Design and testing of the interface circuitry are also shown with preliminary results.