Dynamic thermal radiation modulators via mechanically tunable surface emissivity

Abstract: Inspired by cephalopods, we design a hybrid structure comprised of a rigid film with a low thermal emissivity and a substrate with a high thermal emissivity combined with a stretchable heater. The film’s topography is characterized by distributed strain-dependent micro-cracks, enabling the exposure of the substrate to be tuned by the applied strain. Thus, the effective surface thermal emissivity originating from the combination of the film and the exposed substrate can be instantaneously and reversibly modulated simply via mechanical means. The system exhibits various pronounced advantages, including ease of fabrication, low working temperature, broad emissivity modulation range, observing angle independence, excellent reversibility, instantaneous response, high strain sensitivity, feasibility for patterning and multiplexing, and autonomous actuation. Additionally, the system demonstrates intriguing thermographic-based applications in finger motion sensing, information encryption, multiplexing display, and thermal camouflage. Therefore, this work can facilitate the invention of next-generation thermal modulators with autonomous, on-demand, and board-range control.