Paper NS+EN+SS-TuA10
Flexible, Adaptive Optoelectronic Camouflage Skins Using Concepts Inspired by Cephalopods

Tuesday, October 20, 2015, 5:20 pm, Room 212B

Octopus, squid, cuttlefish and other cephalopods exhibit exceptional capabilities for visually adapting to or differentiating from the coloration and texture of their surroundings, for the purpose of concealment, communication, predation and reproduction. Long-standing interest in and emerging understanding of the underlying ultrastructure, physiological control and photonic interactions has recently led to efforts in the construction of artificial systems that have key attributes found in the skins of these organisms. In spite of several promising options in active materials for mimicking biological color tuning, such as cholesteric liquid crystals, electrokinetic and electrofluidic structures, colloidal crystals and plasmonics, existing routes to integrated systems do not include critical capabilities in distributed sensing and actuation.

The results reported here show that advances in heterogeneous integration and high performance flexible/stretchable electronics provide a solution to these critical sub-systems when exploited in thin multilayer, multifunctional assemblies. The findings encompass a complete set of materials, components, and integration schemes that enable adaptive optoelectronic camouflage sheets with designs that capture key features and functional capabilities of the skins of cephalopods. These systems combine semiconductor actuators, switching components and light sensors with inorganic reflectors and organic color-changing materials in a way that allows autonomous matching to background coloration, through the well-known working principle of each device.

Demonstration devices capable of producing black-and-white patterns that spontaneously match those of the surroundings, without user input or external measurement, involve multilayer architectures of ultrathin sheets of monocrystalline silicon in arrays of components for controlled, local Joule heating, photodetection and two levels of matrix addressing, combined with metallic diffuse reflectors and simple thermochromic materials, all on soft, flexible substrates. Systematic experimental, computational and analytical studies of the optical, electrical, thermal, and mechanical properties reveal the fundamental aspects of operation, and also provide quantitative design guidelines that are applicable to future, scaled embodiments.