Piezoresistive Microcantilevers for Biomolecular Force Detection

This paper reports the development of piezoresistive microcantilevers for the detection of biomolecules by the measurement of intermolecular binding forces. The detection of the small forces involved in molecular recognition (<100 pN) requires cantilevers with a high force sensitivity and small spring constant. This can be obtained with cantilevers with submicron thickness and width in the micrometer range. We have fabricated polycrystalline silicon cantilevers in a dedicated technology and also in a commercial CMOS process. The cantilevers have been tested by applying a known displacement with an AFM instrument. For the CMOS-integrated cantilevers, which include on-chip amplifying circuits, a force sensitivity of 11 muV/pN and a force resolution of 27 pN have been measured.