Microelectromechanical Systems from Aligned Cellulose Nanocrystal Films

Abstract

Microelectromechanical systems (MEMS) have become a ubiquitous part of a multitude of industries including transportation, communication, medical, and consumer products. The majority of commercial MEMS devices are produced from silicon using energy-intensive and harsh chemical processing. We report that actuatable standard MEMS devices such as cantilever beam arrays, doubly clamped beams, residual strain testers, and mechanical strength testers can be produced via low-temperature fabrication of shear-aligned cellulose nanocrystal (CNC) films. The devices had feature sizes as small as 6 μm and anisotropic mechanical properties. For 4 μm thick doubly clamped beams with the CNC aligned parallel to the devices' long axes, the Young's moduli averaged 51 GPa and the fracture strength averaged 1.1 GPa. These mechanical properties are within one-third of typical values for polysilicon devices. This new paradigm of producing MEMS devices from CNC extracted from waste biomass provides the simplicity and tunability of fluid-phase processing while enabling anisotropic mechanical properties on the order of those obtained in standard silicon MEMS.

Keywords: MEMS; anisotropy; cellulose nanocrystals; films; microfabrication.