Foldable Kirigami Paper Electronics

Significant attention is focused on paper electronics (PEs) for developing flexible and recyclable devices. These devices use paper as the substrate on which electrode materials are successively patterned. Among various conductive materials used for PEs, nanosilver ink is the most commonly used material due to its low cost and easy printing process. However, nanosilver electrodes tend to fracture when a paper substrate is bent or folded, leading to disconnections in printed circuits. To maintain the integrity of the circuit pattern during folding, a novel Kirigami fabrication method for PEs is proposed, in which a paper substrate is prepared by cutting along the edge of the printed electrode prior to use. The Kirigami method is experimentally proven to turn the deformation mode of nanosilver electrodes from bending to twisting, which effectively prevents electrodes from fracture. Experimental measurements reveal that the electrical resistance of the Kirigami electrode increases by merely 30% under full folding. Conductivity is maintained after full folding for 100 cycles. Finally, the Kirigami strategy is applied to different foldable PEs including angle sensors, electrostatic actuators, and locomotion robots. The successful implementation of the Kirigami strategy demonstrates high potential for use in diverse PEs with complicated foldable 3D architectures.