Theoretical and numerical studies of new suspended-silicon-nanowire based static sensors

This paper reports our recent theoretical and numerical studies of new suspended-silicon-nanowire based static sensors. These static sensors detect the presence of molecules according to static deflections induced by the adsorption of molecules. As shown in Fig. 1, the static sensor consists of four suspended silicon nanowires (SiNWs) and one silicon microbeam. Each side of the microbeam includes two SiNWs, instead of one, to avoid the possible torsion of the microbeam and make the microbeam remain parallel to the substrate before detection. The microbeam is used as a platform for the adsorption of molecules. The ultra-high sensitivity of this sensor to mass loading is ensured by the extremely low bending stiffness of the four supporting SiNWs, while the position and deflection of a microbeam are easily found by a routinely used instrument due to the relatively large horizontal dimensions of the microbeam. In this work, theoretical formulation for the sensor deflections under pressure and concentration force is derived and compared with numerical results. Both theoretical and numerical results are subsequently used to optimize the design of the static sensors.

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