Electrically Tunable PDMS Lenses Using Integrated mm-Scale Dielectric Elastomer Actuators

We report on the modelling, fabrication and testing of small arrays of mm-diameter PDMS lenses whose focal length can be electrically tuned. The lenses consist of an array of 1 to 3 mm diameter electroactive polymer actuators bonded to a socket that provides fluidic coupling between devices. The actuator is a membrane with compliant electrodes on both sides, which can be compressed by an electrostatic force obtained by applying a voltage to the electrodes (i.e., it is an dielectric electroactive polymer actuator). Compressing the membrane causes its area to increase, which is used to vary the curvature of the fluidically coupled devices. A key technology is the use of low-energy ion-implantation to fabricate compliant (conducts at strains of more than 100%) and 50% transparent electrodes on 30 μm thick Polydimethysiloxane (PDMS) film. We report tuning the focal length from 4 mm to 8 mm at 1.7 kV, and find an excellent agreement with an analytical model for focal length as a function of voltage, geometry, and material parameters.