Electrostatic actuation to counterbalance the manufacturing defects in a MEMS mass detection sensor using mode localization

International audienceThe paper focuses on a MEMS mass detection sensor using mode localization and electrostatic actuation to counterbalance the manufacturing defects. The sensor is composed of two cantilevers with different lengths, connected together with a weak mechanical spring. A DC voltage is applied on the shortest beam so that the system is balanced when no mass is added, allowing the manufacturing defects to be compensated.Harmonic simulations were carried out using COMSOL Multiphysics®. It shows for example that for 100μm/90μm long, 20μm width and 2μm thick cantilevers, a DC voltage of 60.4V is necessary to balance the system. In these conditions and with a quality factor of 1500, a 17.5pg added mass will create a relative change of 22% in the modal amplitude of the first mode of the longest cantilever while the relative shift in the resonant frequency is only 0.24%