Flexible Capacitive Kirigami Electrode: Experimental Investigation and Analytical Model

Flexible electronics have recently garnered increasing attention due to their promise for a wide range of applications, from energy storage to flexible screens, over sensors to wearables. The trend in flexible electronics is toward the fabrication of devices composed of fully flexible materials and components. However, flexible devices still present many limitations, primarily due to the negative Poisson ratio of the materials used, which affects the dimensions and characteristics of the materials when bent or stretched. In this work, we propose a novel design for capacitive electrodes aimed to improve the flexibility of devices without affecting the properties of the materials involved: the design is based on Kirigami, the traditional Japanese art of paper cutting which, when applied to engineering, enables the shaping of stretchable and deformable structures by performing simple cuts on traditional substrates and films, thereby ensuring compatibility with existing manufacturing methods. We formulate a novel analytical model to explain in detail the behavior of the Kirigami electrode applied to an arbitrary nonflat surface. The efficacy of the novel design has been verified by means of capacitive measurements in different nonflat configurations: the results obtained confirm both the validity of the analytical model and the robustness of the novel Kirigami approach, with capacitive values increasing up to 115% for the Kirigami electrode compared to the non-Kirigami one.