Adaptive liquid lens actuated by dielectric elastomer with transparent conductive droplet

Dielectric elastomer (DE) is a remarkable 'smart' actuator to develop an adaptive liquid lens due to its lightweight, mechanical compliance, simple structure, low power consumption, and low cost. The traditional method to develop an adaptive liquid lens using a DE actuator often confines the liquid in the central region and the remaining part is coated with opaque compliant electrodes. However, this configuration reduces the available optical aperture and increases the overall dimension. A compact adaptive liquid lens actuated by DE with a transparent conductive droplet is proposed in this paper. The droplet not only acts as the material of the adaptive liquid lens because of its high transparency but also works as the compliant electrode of the DE due to its conductibility and flexibility. A mixture liquid of glycerol and sodium chloride droplet is dropped on the top and bottom surfaces of the DE. When the droplet is subjected to a voltage supply, the area of the DE where contacts the transparent conductive droplet expands, which induces an increase in the diameter and a decrease in the thickness of the droplet since the volume of the droplet is constant. Therefore, the focal length of the adaptive liquid lens increases. The effectiveness of the proposed approach has been validated by experiments. The results show that the adaptive liquid lens has a compact structure and transparency of 86.1% at visible wavelength. This method is beneficial for developing a compact adaptive liquid lens.