Design of a cantilever-based system for genomic applications

In this work we present the development of system intended for DNA label free detection, based on piezoresistive microcantilever arrays and dedicated readout ASIC. Detector design and microfabrication technologies have been optimised for detection sensitivity, providing an efficient direct electrical measurement of DNA hybridisation. Three technological approaches were investigated and optimised by using analytical and finite element analysis: single crystal Si beams with implanted piezoresistors, SiO2 cantilever with poly-Si piezoresistors and polymeric beams with gold strain gauges. According to results, the most performing technological approach is based on Silicon-On-Insulator (SOI) wafers, allowing the realisation of low thickness beams (340 nm silicon layer) with n-type resistors. Readout ASIC has been implemented in a separate chip using a 0.35 μm CMOS technology to provide a high resolution and low noise readout of the sensors, by also providing the compensation of large offset in the detector response.