Modelling the Interaction of Non-Slender MEMS Resonators with Fluidic and Elastic Environments

Abstract

Resonators with slender geometries are ubiquitous in microelectromechanical systems (MEMS). They are key components in various applications like atomic force microscopy or mass sensing and serve as building blocks for complex devices. However, the focus on slender resonator geometries severely limits the freedom of design and the ability to tune the interaction between the resonator and its environment. Going beyond slender structures is often not prohibited by fabrication limitations but rather by difficulties in modelling. In this talk, we present methods for overcoming these challenges and discuss how non-slender resonators interact with elastic and fluidic environments [1]. We show that the fluid-structure interaction changes significantly when transforming from a slender beam to a wide plate resonator geometry [2]. By utilizing vibrational modes not present in slender beam resonators, quality factors in fluids can be increased significantly compared to slender resonators [3]. An elastic environment of a MEMS resonator is represented by the substrate to which the resonator is anchored. The vibrational modes of non-slender MEMS resonators exhibit complex elastic interactions with this anchoring region resulting in a strong dependence of anchor losses on the vibrational mode. What is more, modal interactions change the anchor-loss-related quality factors over orders of magnitude. Our results demonstrate that non-slender resonator geometries have several advantages over conventional slender geometries and the methods presented here allow to tune the interaction with different types of resonator environments.