Topology‑Programmed Silver Nanowire Electrodes via Direct Ink Writing for Stretchable Electronics

Abstract

Topology engineering is an effective strategy for improving the electromechanical stability of printed stretchable electrodes. Here, we report a direct ink writing approach to fabricate silver nanowire (AgNW) electrodes with various topological patterns on polyurethane substrates. Aqueous AgNW inks are formulated using sodium alginate (SA) as a rheology modifier and Triton X-100 as a wetting agent, enabling smooth printing through a 50 μm nozzle. A CaCl₂/ethanol spray post‑treatment effectively reduces line resistance by improving AgNW junctions via capillary‑driven cold welding and forming a Ca²⁺‑crosslinked SA network, while also enhancing adhesion stability (only ∼15% resistance increase after 200 tape‑peeling cycles). Among the evaluated patterns, the Peano topology exhibits the lowest stretch sensitivity (S = 5.6), outperforming arc and spiderweb patterns. Within Peano variants, the half‑and‑half layout demonstrates the best directional consistency under orthogonal stretching, with similar and relatively low S values along both x and y directions, although a larger resistance change is observed at 45° stretching. This work provides a rational basis for designing topology‑patterned stretchable electrodes with balanced multidirectional performance.