Wide Working Range Mechanochromic Sensor based on Multiple Photonic Crystals and Angle Compensators

Flexible and wearable sensors have gained tremendous interest due to increasing demands in diverse applications such as prosthetics, personal healthcare, and e-skin. However, they are mostly based on electronic signals, restricting their potential in visualized mechanical measuring. Herein, inspired by the structural colors of natural species, we developed a novel mechanochromic sensor with a wide working range and angle compensators. Employing the colloidal lithography technique, multiple nanostructures were fabricated on a single stretchable substrate. Thus, broadening the detection range to 150% without sacrificing high sensitivity. We also introduced a novel approach using angle compensators to circumvent the issue of angle-dependent colors. By comparing the colors of rigid and stretchable photonic crystals, the users can facilely estimate the strain regardless of the incident and viewing angles. The fabrication principle in this study is based on a reusable mold, which is cost-effective for large-scale production. Thus, we believe this study will have a broad impact on the development of smart mechanochromic devices for visually measuring the deformation of materials.