Tunable lens driven by dielectric elastomer actuator with ionic electrodes

A tunable lens driven by a dielectric elastomer actuator is developed. A solution of NaCl was used as the deformable lens and one of the electrodes for applying a bias voltage across the actuator. The dielectric elastomer actuator was made of a curved polydimethylsiloxane (PDMS) thin film sandwiched between a gold electrode and the NaCl solution. When a bias voltage was applied, the electrostatic force induced a radial compression, causing a lateral deflection of the PDMS. The radius of the curvature of the NaCl lens was consequently changed. The variation of the focal length under different bias voltages was characterised separately using two different approaches, and consistent results were obtained. The lens diameter was 4 mm. The focus lens can be tuned from 16.1 to 13.1 mm when the bias voltage is increased from 0 to 900 V.