| Resumen |
Two designs for a mass sensor based on silicon cantilevers are presented. The change of deposited mass on the cantilever is measured through the detection of frequency shifts or the settling time shifts in the cantilever oscillation, which is horizontally produced by an interdigitated comb capacitor structure to increase the electrostatic force. By this operation principle, the constrictions of classical vertical sensors in ultra-planar technologies are eliminated and bigger oscillation amplitudes are possible. Also, the low sensitivity in capacitive detections and the nonlinearity of horizontal sensors is avoided. Therefore, the frequency shift detection is improved, resulting in fewer issues in readout electronics design. The preliminary results are validated with a finite element analysis performed in COMSOL and SPICE simulations in Eldo. Mass-frequency changes of 3.43 pg/Hz and 6.71 pg/Hz are predicted for these designs with natural frequencies of 11.461 kHz and 8.465 kHz respectively. Also, settling time variations of 1.69 ms/ng and 0.7 ms/ng were obtained. |
