No abstract

Mechanical flexibility introduced in functional electronic devices has allowed electronics to avoid mechanical breakage, conform to nonplanar surfaces, or attach to deformable surfaces, leading to greatly expanded applications, and some research efforts have already led to commercialization. However, most of these devices are passively bendable by external driving forces. Actively bendable flexible thin film devices can be applied to new fields with new functionalities. Here, we report robotic flexible electronics with actively self-bendable flexible films that can serve as a platform for flexible electronics and other applications with the capability of reversible bending and unbending by electrical control. Experimental studies along with mechanical modeling enable the predictable and reversible transformation into different structures by adjusting the design parameters. Demonstrations for self-bendable flexible displays and soft robotic hands prove the feasibility of the concept.

Concentrator photovoltaics are able to maintain power output for extended hours while reducing the quantity of expensive high performance compound semiconductor solar materials. One of the limitations in concentrator photovoltaics is the bulky and heavy form factors of solar tracking systems which usually require dedicated installation locations and resistance to wind loading. This paper describes a planar solar tracker that requires only micro or millimeter scale lateral and vertical displacements of a microlens array to maintain both the optimum lateral locations and focal lengths at various incident angles of light, using dual-axis actuations. Experimental results for lateral solar tracker were obtained under a solar simulator considering the effects of the rotation and revolution of the Earth, and under the Sun on a rooftop with the actual system, to demonstrate the concept and practical performance.