Development of High-Resolution Stretchable Electrodes and Its Applications Using Gold Nanosheets (AuNSs)

With an increase of the interest in wearable devices and healthcare monitoring systems, research on the development of stretchable electrodes has been conducted to develop wearable applications with sufficient reliability and lifetime. To develop the stretchable devices with superior reliability, it is essential to acquire highly durable and high-performance stretchable electrodes that can sustain the mechanical strain without any electrical performance degradation. Furthermore, the stretchable electrodes necessitate high-resolution patterning capability to achieve a high degree of integration when designing the stretchable circuits or sensors. In this work, gold nanosheets (AuNSs) stretchable electrodes with high-resolution patterns were carried out by adjusting the structure of the AuNSs through the parameter analysis during the synthesizing process. Specifically, a polydimethylsiloxane (PDMS) elastomer was used as a matrix to embed the AuNSs and develop the stretchable electrodes in a nanocomposite format that can exhibit a high mechanical durability and excellent electrical performances. Application of hot-pressing to the AuNSs facilitated a firm contact between the AuNSs and hence they remained intact when stretched. With optimized hot-pressing conditions, superior properties of the AuNSs stretchable electrodes, including lower surface roughness, high mechanical durability, excellent electrical conductivity, and high stretchability, can be achieved. Based on the manufactured stretchable electrodes, the electrical performances with respect to the mechanical strain of a high-resolution stretchable electrodes were examined by measuring the electrical conductivity of the electrodes under different levels of the mechanical strain up to 100%. The resulted AuNSs stretchable electrodes showed the sheet resistance lower than 10 Ω/sq. Regardless of the mechanical strain. Also, the stretchable electrodes maintained their electrical performances without any further degradation even after 100,000 of stretch-release cycles. In addition, the dynamic electrical performance of the elastomeric transistor was investigated by determining the drain current (−ID) in real-time corresponding to various types of mechanical stimuli, such as stretching, twisting, and poking. When continuous and sequential mechanical stimulation was received, the ON and OFF currents of the transistor measured for 60 seconds were confirmed. The overall experimental results is expected to contribute to accelerating the growth of wearable applications including displays with various form-factors, healthcare monitoring sensors, and soft robots.<br/><br/><b>Acknowledgements</b><br/>We would like to acknowledge the financial support from the National Research Foundation of Korea (NRF) grant funded by the Korean government (NRF-2022R1C1C1011130).