Efficient electrothermal actuation of liquid microlens arrays with low voltages

In this paper, we present a self-assembled liquid microlens array with controllable focus by using electrothermal actuation. The glycerol-filled microlens arrays integrated with transparent electric-heating films are fabricated by combining soft lithographic and self-assembly techniques. The transparent electric-heating film can provide fast and effective modulation of the internal temperature, which can alter the surface tension of the microdroplets, thus propelling the microdroplets to change their shapes. The fine control of the focal length is accomplished by electric-regulating the shape of the liquid droplets in the microhole arrays. The tuning and focusing properties of the microlens arrays can be repeated many times without altering the optical characteristics. Such a liquid microlens array can be used potentially in dynamic imaging systems and adaptive optics.