Self sensing cantilevers for the measurement of (biomolecular) forces

We present the fabrication and the testing of self sensing submicron thick piezoresistive cantilevers. Two kind of piezoresistive transducers (piezoresistor and MOSFET transistor) are integrated into the cantilever in the (100) direction, by n-type implantation (As). Cantilevers with both types of transducers are successfully fabricated, showing a yield of 100% and a standard deviation in the electrical characteristics of 6% and 10% for the piezoresistors and MOSFETs, respectively. For the best piezoresistive cantilever design we report an averaged force responsivity of 158 μV/nN, an averaged noise value of 5.87 μV (1 Hz-1 kHz) and finally a minimum detectable force (MDF) of 37 pN. The cantilever will be used as force sensors for label-free detection of bio-molecules by measuring the intermolecular forces between ligands and receptors.