Professor Robert Langer and colleagues at the Institute for Soldier Nanotechnologies are working on a unique design of a 'smart surface' that can reversibly switch properties in response to an external stimulus. The new switchable surface essentially consists of a forest of molecules only a nanometer tall, engineered to stand at a precise distance from each other. When a positive electrical potential is applied, the top bends down to reveal another surface. Reverse the electrical potential, and the molecules straighten to their full height. The work paves the way for systems that could, for example, release or absorb cells and chemicals from surfaces on demand. Future work will include developing surfaces that have different switchable properties as well as tailoring the proof-of-concept system for different applications.