Self-assembled metal-elastomer wrinkles for reversible coloration and curvature sensing [Invited]

Mechanochromic surfaces capable of reversible color modulation under mechanical deformation are highly desirable for real-time curvature sensing. However, an effective stress-sensing material must respond to low deformation with a detectable color change that should be quickly reversible upon force unloading. In this work, a bilayer system comprising silver thin-films on PDMS substrates has been engineered to develop one-dimensional, ordered sinusoidal wrinkles through a single-step controlled self-assembly process involving thermal processing. The wrinkled structures exhibit pronounced, curvature-dependent color changes over a range of colors covering a wide gamut in CIE (Commission Internationale de l’Éclairage) coordinates. They are also robust and repeatable over hundreds of bending cycles. The reversible and reliable mechanochromic response of these metallic wrinkled films enables their potential application as body motion sensors and flexible curvature-responsive reflective display elements.