SILICON MICROMACHINING TECHNOLOGY FOR SUBNANOGRAM DISCRETE MASS RESONANT BIOSENSORS

This paper describes a novel sub-nanogram discrete mass sensor with po ssible biological applications including potential biomass monitoring of living cells in culture. The sensing element is a micromachined sil icon dioxide cantilever fabricated using a process compatible with com mercial CMOS microelectronic processes. The 1 mum thick silicon dioxid e device consists of two 8 x 150 mum cantilever arms supporting a 50 x 50 mum payload platform. Actuation of this first generation device is performed using a small vibration table. Resonant amplitude are measu red by detecting the angular shift of a laser beam incident on the dev ice. Finite element analysis is used to model resonant frequencies. mo de shapes, and frequency response. Cantilever resonates in fundamental mode at 15.9 kHz and have an experimental mass sensitivity of 1.9 kHz ng-1.