Multifunctional Smart Window Based on Dielectric Elastomer Actuator

Abstract

Soft actuators are compliant material-based devices capable of producing large deformations upon external stimuli. Dielectric elastomer actuators (DEAs) are a type of soft actuators that operate on voltage stimuli. Apart from soft robotics, these actuators can serve many novel applications, such as tunable optical gratings, lens, diffusers, smart windows and so on. This article presents our current work on tunable smart windows which can regulate light transmittance and sound absorption. This smart window can promote daylighting while maintaining privacy by electrically switching between being transparent and opaque. As a tunable optical surface scatters, it turns transparent with smooth surfaces like a flat glass; however, it turns opaque (translucent) with the micro-rough surface. The surface roughness is varied, employing surface microwrinkling or unfolding by using dielectric elastomer actuation. In addition, this smart window is equipped with another layer of transparent microperforated dielectric elastomer actuators (DEAs), which act like Helmholtz resonators, serving as a tunable and broader sound absorber. It can electrically tune its absorption spectrum to match the noise frequency for maximum acoustic absorption. The membrane tension and perforation size are tuned using DEA activation to tune its acoustic resonant frequency. Such a novel smart window can be made as cheap as glass due to its simple, all-solid-state construction. In the future, they might be used in smart green building and could potentially enhance urban livability.