Direct Embedment And Alignment Of Silver Nanowires By Inkjet Printing For Stretchable Conductors

Stretchable conductors have attracted tremendous attention owing to their potential applications as electrodes and sensing elements for wearable electronic devices. In this study, we have developed an inkjet printing process to directly embed and align silver nanowires in the polydimethylsiloxane elastomer for stretchable conductors. Instead of printing on top of elastomers, we printed the silver nanowires directly into an uncured liquid elastomer layer to embed the conductive nanowires, therefore eliminating the problems with surface wetting and delamination in conventional approaches, where the conductor is patterned on top of elastomers. This study investigated the process controls to tune the embedment depth and alignment of silver nanowires through inkjet printing. The printing process was captured with a high-speed camera to elucidate the mechanisms that direct the printed features. By controlling the thickness of the liquid elastomer layer and the post-printing treatment of printed lines, stretchable conductors composed of embedded silver nanowires have been fabricated in a single step. Because of the reflow of the viscous liquid elastomer, the printed silver nanowires are aligned along the printing direction, resulting in linewidth of tens of micrometers upon solvent removal. The stretchable conductors showed good mechanical and electrical stability under repeated bending and stretching/releasing cycles. This method of directly embedding silver nanowires into a liquid elastomer offers facile heterogeneous integration for digital patterning of stretchable electronics.