Abstract

Current micro-electromechanical systems(MEMS)based structures are either mono or bistable, and as such are limited to registering one or two values in mechanical sensors/memories/logical gates. However, with the entrance of AI and Internet-of-Things, sensory input in integrated systems is expected to increase, requiring systems to become more efficient and autonomous. That entails sensing more values in a smaller footprint, as well as possessing basic computational abilities. To mitigate that need, a new type of a microstructure is required, that will introduce new abilities such as multistability, non-volatility, and reconfigurability, along with built-in memory and embedded computational abilities, thus allowing the formation of a new class of smart MEMS from which new sensors can be devised. The first generation of such a structure is composed of an electrostatically actuated double curved beam, connected either by a rigid truss or an elastic spring, essentially composing a simple micro-meta-structure. It is found that weakly coupled and geometrically different sub-structures can manifest global tristablility when introduced to a nonlinear, displacement-dependent, electrostatic actuation whilst exhibiting bistability when under mechanical, displacement-independent, load. The stability analysis and methodology is established first for strongly coupled double beam structures, and is then used for the weakly coupled version. In addition, it was found that electrostatic tristability, which includes statically inaccessible stable branches, can be manifested in different configurations and permutations, while also showing the presence of a global latching point, unattainable the strongly coupled counterpart. It is shown that the energy method can be used to characterise the stability of the proposed metastructure, while also revealing new abilities that can be manifested in a seemingly simple structure. Such findings can promote the usage of such structures in multi-valued MEMS devices, promoting further miniaturisation and decreased footprint.