Simulation and analysis of MEMS cantilever designs with fractal surface geometry for TG sensing and frequency switching

Surface geometry plays an important role in case of analyte sensing and RF switching using beams and electrodes. In general, rather than simply supported beam and diaphragm, microcantilever beams are widely preferred in BIO-MEMS and RF-MEMS for biosensing and RF switching, respectively. The lower level detection ability and simple structure make these cantilevers more applicable in many applications. The rectangular cantilever beams are most widely used in TG detection. but due to their constant or planner geometry and non-adhesion of analyte they are less sensitive in case of nano or pico level biosensing. This paper introduces the fractal surface geometry concept for increasing the deflection sensitivity corresponding to lower molecular or analyte loading. The rectangular and stepped cantilever beam structures along with fractal surface are simulated and analysed for TG molecular pressure 294.3 Pa. Both the rectangular and stepped microcantilever beams with fractal surface exhibit better free end or tip deflection (nearly 2×) as compare to the planner surface based beam. The proposed fractal concept also reduces the actuation voltage requirement for perfect switching.