High-Resolution Intaglio Transfer Printing of Silver Nanowires for Wearable Electrophysiological Sensors

Silver nanowires (NWs) are promising materials for flexible electronics, such as electronic skins due to their excellent electrical, thermal, and mechanical properties. Achieving precise patterning of Ag NWs is essential for the successful integration and miniaturization of the electronic device system, but the high aspect ratio (AR) of NWs and the high porosity of NW networks pose challenges in forming high-resolution patterns. Herein, the intaglio transfer printing technique to create high-resolution patterning of ultralong Ag NWs (AR≈1000) is presented. During the pattern formation process, the external force becomes concentrated specifically at the edge of the intaglio trench, resulting in the breaking of the entangled Ag NW network in the corresponding region. This simple yet effective technique enables precise high-resolution (minimum line width: 7 µm) and complicated Ag NW patterns on flexible substrates. The patterned Ag NWs are conformally attached to the various curvilinear surfaces and show high mechanical stability under continuous bending conditions. Wearable electrophysiological sensors are demonstrated to monitor electromyography and electrocardiogram signals in real-time for continuous healthcare monitoring. This patterning strategy offers an effective approach for achieving high-resolution patterns of highly anisotropic nanomaterials and highlights the potential of patterned Ag NWs in wearable electronics.