Electric‐Field‐Assisted Single‐Step In Situ Fabrication and Focal Length Control of Polymeric Convex Lens on Flexible Substrate

Abstract Here, a simple method for fabricating polymeric convex lens and controlling of its focal length in a single‐step fabrication is presented. The method utilizes electrostatic force to pull the polymer droplet to form the lens, as well as to accelerate the droplet to control the curvature of the lens simultaneously. Lenses with various diameter (ranging from 0.75 to 4.5 mm) and curvature are sequentially fabricated at the preprogrammed position on a dielectric and flexible substrate. Since a transparent dielectric flexible film is employed as a target substrate, not only the electrical short circuit in the process is prevented but also high optical transmittance is secured with superior mechanical bendability which allows transformation of the lens into a positive single‐axis meniscus. To show the functionality, the lenses are integrated into a microscope for a teleconverter, fluidic tubing for a magnifier, laser exposing for a concentrator, and LED bulb encapsulating as a light diffuser. The presented method with extremely simple fabrication step with focal length control is expected to be directly applied to a wide range of applications.