Response time of liquid lens actuated by dielectric elastomer under different input voltage functions

In this paper, we focus on a study of the response time of a liquid lens actuated by a dielectric elastomer (DE). This paper aims to determine the optimal input voltage function for obtaining a liquid lens actuated by DE with high response speed. First, we fabricate a liquid lens actuated by DE sandwiched between transparent conductive liquids. The liquid lens consists of two supporting frames, transparent conductive liquid, two passive membranes, one DE membrane, and copper foils. When a driving voltage is applied to the copper foils, the shape of the DE membrane changes, which in turn makes the shapes of the two passive membranes altered, then the focal length of the liquid lens is tuned. Second, four different input voltage functions, which including square, ramp, sine, and exponential voltages, are generated by a function generator. The power of the input voltage is amplified by a power amplifier and the amplitude is amplified by a high voltage converter. The amplified input voltage is applied to the copper foils to drive the liquid lens. Last, the time-domain response curves of the liquid lens are obtained by a photodetector. The response times of the liquid lens actuated by DE, including the rise and fall times, are obtained from the time-domain response curves. The experimental results show that the response times are different although the four input voltage functions have the same amplitude and frequency. The study shows potential optical imaging applications that require fast response speed.