Soft lenses with large focal length tuning range based on stacked PVC gel actuators

A novel tunable lens with large focal length change and driven by stacked polyvinyl chloride (PVC) gel actuators is designed and characterized in this study. The lens rigid parts are 3D-printed and commercially available, whereas the PVC gel membrane is in volume production. Under electrical actuation, the lens attains focal length ranges from 30 to 217 mm within 400 V. A manual regulating mechanism is proposed for the finished lens that dexterously adjusts the initial focus and focal length ranges. In the compound actuation mode, large focus variation over 950% is achieved within 250 V. Under 250 V step input, the lens exhibits practical response time around 291 ms. Focal length tuning ability of the lens is also demonstrated by capturing the images of objects placed in different positions. This tunable lens is promising for various smart optics.