Fabrication and Characterization of Electrostatically Actuated Microcantilever Mass Sensors

Microcantilevers have been actively used in probe-based microscopy and gravimetric sensing for biological or chemical analytes. To integrate actuation or detection schemes in the structure, typical fabrication processes include several photolithographic steps along with conventional MEMS fabrication. In this paper, a simple and straightforward way to fabricate and operate silicon microcantilever mass sensors is presented. The fabricated microcantilever sensors which can be electrostatically actuated require only two photolithographic steps. Resonant characteristics of fabricated microcantilevers are measured with a custom optical-lever and results show size-dependent quality factors. Using a 40 μm long, 7 μm wide, and 3 μm thick cantilever, we achieved sub-femtogram mass resolution in a 1 Hz bandwidth