3D Printing of a Self-powered Auxetic Photonic Skin

Mechanoluminescence (ML) is a remarkable luminescent phenomenon in which materials emit visible or ultraviolet light in response to mechanical actions like compression, bending, or stretching. Compared to other forms of luminescence, such as photoluminescence (light emission due to photon absorption) or electroluminescence (light emission from an applied electric field), ML stands out for its self-powered feature - the light emission does not require external power sources. The light emission in ML is induced by changes in mechanical stress, allowing it to sense and visualize stress distributions in real-time. This real-time monitoring capability is highly advantageous for dynamic applications and time-sensitive experiments, such as monitoring the motion of the human body during exercise. In this work, we present a self-powered auxetic photonic skin that does not require external power. Periodic cellular reentrant structures were fabricated to achieve uniform and intense ML emission. We systematically characterized the ML performance in terms of phosphor content, strain, stretching frequency, and fatigue resistance.