Highly stretchable and conductive kirigami-like double-layer electrodes for motion-insensitive wearable electronics

Abstract

The development of motion-insensitive electronic devices capable of maintaining consistent performance during bending, twisting, and stretching movements of the human skin is crucial for realizing wearable sensor systems. Various approaches for creating stretchable electrodes for wearable device fabrication have been exploited; however, the simultaneous achievement of high stretchability and conductivity in an electrode remains challenging. In this study, we propose styrene-ethylene-butylene-styrene-based highly stretchable and conductive double-layer electrodes that have a kirigami structure that promotes conductivity preservation. Ag nanowires (NWs) and an Au double-layer film exhibited a low sheet resistance of 7.6 Ω/sq and maintained conductivity even at a maximum tensile strain of 350 %. The electrodes demonstrated consistent current responses after 1000 cycles of testing and maintained reliable electronic device performance under motion-induced conditions such as bending, twisting, and stretching. Electrocardiogram (ECG) sensing was conducted to monitor the heart rate of the mouse with strain applied to the electrode. Morphological analysis revealed that the Au film dispersed the stress uniformly across the entire film during stretching, and the Ag NWs suppressed microcrack propagation, demonstrating the contribution of the kirigami structure and the resulting stretching mechanism toward the significant enhancement of stretchability. The highly conductive and stretchable electrodes developed in this study promote the development of high-performance wearable electronics that can function under highly flexible conditions.