The effect of a distributed mass loading on the frequency response of a MEMS mesh resonator

This paper reports on the development of an acoustic-wave biosensor based on integrated MEMS technology that promises high sensitivity and selectively without the need for molecular tagging or external optical equipment. The device works by detecting frequency shifts resulting from the selective binding of target molecules to the surface of a functionalized resonating polymer MEMS-composite membrane. Here, we characterize the frequency response of our metal-oxide MEMS resonators. We show that the structural topology, which includes the amount of void area spacing, total mass of the resonator, and how the mass is distributed on the surface, affects the resonant frequency response in a measurable way. Using a multimodal electrostatic drive, we can either excite or suppress higher order harmonic frequencies. The excitation of higher order harmonics is important for multiple analyte detection or redundancy testing. We use a finite element model to demonstrate how a distributed mass loading affect the frequency responses of our MEMS structures.