Wet stable transparent flexible sensor: long-term resistance to ultrasonication shock

Flexible transparent sensor is essential to many smart systems towards digital life style. However, the poor stability of flexible sensors based on the new transparent conductive materials especially under wet environment seriously limit the long term reliability and the solution process handling. In this work, wet stable flexible transparent sensor is fabricated with new silver nanowires (AgNWs) composite electrode. Only 15.6 nm thick lactic acid solubilized biocompatible chitosan (Chi-LaA) coating enables AgNWs transparent electrode and the sensor resisting more than 56 h of 40 kHz ultrasonic shock both in acetone and water. By contrast, AgNWs without coating were almost detached from substrate within 1 min in water bath to disable the sensor. More importantly, the significantly improved wet stability via over coating doesn't scarify the conductivity and sensitivity of the sensor. In contrast, the conductivity and transparency of AgNWs transparent electrode for flexible sensor are both enhanced, and the RMS roughness is reduced to below 10 nm from tens of nanometers. The transparent flexible sensors still show good sensitivity to finger touch after hours of ultrasonication.