Monolithic 0.35-μm CMOS Cantilever for Mass Sensing in the Attogram Range with Self-Excitation

A monolithic mass sensor with attogram resolution in air conditions has been fabricated using a conventional 0.35-μm CMOS process. The mass sensor is based on an electrostatically excited resonating sub-micrometer scale cantilever integrated with full custom designed CMOS electronics for sensing purposes and to self-excite the cantilever allowing its use in system-on-chip applications. The devices have been calibrated obtaining an experimental sensitivity of around 6 × 10^-11 g/cm² Hz equivalent to 0.9 ag/Hz for locally deposited mass. The results reported in this paper represent an improvement from previous works in terms of sensitivity, resolution and fabrication process complexity.