Array of lenses with individually tunable focal-length based on transparent ion-implanted EAPs

We report on the fabrication and characterization of 2x2 arrays of mm-diameter PDMS lenses whose focal length can be electrically tuned. Dielectric elastomer actuators generally rely on carbon powder or carbon grease electrodes, which are not transparent, precluding the polymer actuator from also being a lens. However compliant electrodes fabricated by low-energy ion implantation are over 50% transparent in the visible, enabling the polymer lens to simultaneously be an actuator. We have developed a chip-scale process to microfabricate lens arrays, consisting of a molded socket bonded to a Pyrex chip supporting 4 membrane actuators. The actuators are interconnected via an incompressible fluid. The Pyrex chip has four through-holes, 1 to 3 mm in diameter, on which a 30 μm thick Polydimethysiloxane (PDMS) layer is bonded. The PDMS layer is implanted on both sides with 5 keV gold ions to define the transparent electrodes for EAP actuation. Applying a voltage to one of the lens/actuators leads to an area expansion and hence to a change in radius of curvature, varying the focal length. We report tuning the focal length from 4 mm to 8 mm at 1.7 kV, and present changes in optical transmission and membrane stiffness following gamma and proton irradiation.