Computational Model and Design of the Soft Tunable Lens Actuated by Dielectric Elastomer

Abstract

Inspired by the accommodation mechanism of the human eye, several soft tunable lenses have been fabricated and demonstrated the capability of controllable focus tuning. This paper presents a computational model of a dielectric elastomer-based soft tunable lens with a compact structure that is composed of a lens frame, two soft films, and the optically transparent fluid enclosed inside. The two soft films, respectively, serve as the active film and passive film. The active film is a dielectric elastomer film and can be coated with the annular electrode or circular electrode. The deformation of the lenses with both electrode configurations can all be formulated by a boundary value problem with different boundary conditions and be solved as the initial value problem using the shooting method. Two common failure modes of loss of tension and electrical breakdown are considered in the calculation of the lens. The computational results can well fit the experimental data. The focus tuning performances as well as the distributions of stretches, stresses, and electric field in the active films of the lenses with two different electrode configurations are compared. The influences of several parameters on the performances of the lenses are discussed, such that the tunable lens can be designed to have maximum focal length change or to be optimized based on different application requirements.