Strain-induced alignment of printed silver nanowires for stretchable electrodes

Abstract

Silver nanowires (Ag NWs) have been in the spotlight as a nanomaterials for roll-to-roll printed stretchable electrode because of excellent mechanical properties. Electrical conductivity of Ag NWs was affected by the nanowire orientation. Here, we printed Ag NWs ink with the drop-on-demand dispenser and stretched the Ag NWs electrode on silicone rubber and thermoplastic polyurethane (TPU) up to 140% in length. The averaged resistance at released state of 50 test samples of Ag NWs electrodes on silicone rubber film after 10% stretching test was approximately 14% lower than before stretching test. During the stretching test, both electrodes and film were stretched and strain was induced. However, the resistance at released state of Ag NWs electrodes on TPU film was increased as strain increased. The Ag NWs alignment to the stretching direction was observed on silicone rubber film by FESEM images, but alignment of Ag NWs on TPU film by stretching did not occur. Because the adhesion class (ASTM D 3359) of Ag NWs electrodes with the silicone rubber film is 1B and TPU film is 5B, Ag NWs could slide and rotate on silicone rubber film as applying the strain. We confirmed that alignment of Ag NWs on the silicone rubber film by stretching resulted in reduction of electrical resistance.