Electrically Programmable Micro-scale Morphing Robots Based on Mechanical Metamaterials

A fundamental problem with robotics at the microscale, is how to design robots that can be printed in 2D via lithography and yet are able to locomote and adopt arbitrary shapes. Auxetic mechanical metamaterials comprised of rigid panels that can locally splay, are an interesting solution to this problem because they can yield reconfigurable curved surfaces and generate different locomotion gaits for robotics applications. Here, we show that such electrically actuated auxetic metamaterials can be utilized to design micro-scale robots. The expansions and contractions in our devices are achieved by splaying neighboring panels. The actuation of the hinges is controlled by applying voltage to a nm thin surface electrochemical actuator. We modeled the target shapes using an inverse design approach in which the shapes are iterated towards target shapes by selecting optimal actuations of the splay hinges. We then show experimentally that we are able to generate a variety of 3D shapes by actuating a subset of the hinges. By integrating photovoltaics and timing circuits, we are working towards manufacturing untethered metamaterial-based micro-scale robots.