Flexible and conductive Polypyrrole/Ag/cellulose paper bar with sensitive response to multiple stimulus of pH, mist, breath and finger press

Cellulose paper is a flexible, biocompatible and portable substrate that possess high potential in smart sensing and electronic application field. The performance of cellulose paper can be regulated to meet special re-quirements by assembling it with functional material. In this work, we show an efficient way to couple cellulose paper with Polypyrrole (PPy) and Ag within 5 s, driven by capillary forces of cellulose paper for liquids. The prepared PPy/Ag/cellulose paper bar exhibited sensitive feedback to multiple inducement of pH, gas (mist and human breath), and mechanical behavior (finger press). These response is attributed to the variation of bipolaron density and the modulation of electrons transfer efficiency in PPy/Ag/cellulose paper bar.