Thermal tuning of mechanical nonlinearity in GaAs doubly-clamped MEMS beam resonators

We report the thermal tuning of the mechanical nonlinearity in GaAs double-clamped MEMS beam resonators for sensitive thermal sensing applications. We have estimated the mechanical nonlinearity in GaAs MEMS beam resonator by measuring its resonance frequency as a function of oscillation amplitude. The MEMS resonator shows a hardening nonlinearity with a small linear oscillation range of ∼30 nm. When electrical heat is applied to the MEMS beam, we have observed a significant reduction in the mechanical nonlinearity of MEMS resonators near the buckling point of the MEMS beam. The decrease in the mechanical nonlinearity originates from the bending of the MEMS beam, which gives a softening nonlinearity term and, hence, compensates the total nonlinearity. With the thermal tuning effect, MEMS resonator can maintain a very large quasi linear oscillation amplitude of ∼300 nm, which is ∼10 times larger than the linear oscillation range without the control of nonlinearity.