Paper‐Based Wearable Ammonia Gas Sensor Using Organic–Inorganic Composite PEDOT:PSS with Iron(III) Compounds

Abstract Paper electronics are expected to be a game‐changer in next‐generation flexible electronics that could replace conventional plastic electronics. Paper electronics are disposable and cost‐effective, two distinct advantages for the development of broadly accessible devices, but their poor performance has limited their practical implementation so far. Here, a high‐sensitivity, high‐performance, paper‐based, wearable ammonia sensor comprising composite poly(3,4‐ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) and iron(III) compounds is reported. The sensor achieves 10‐times smaller size than the conventional sensor on Kapton film and high tolerance for humidity without losing practical sensor response. The utility of the device is demonstrated for wearable ammonia sensing in a facial mask and a nasal filter; wireless monitoring of food spoilage; and wireless monitoring of the ammonia level in a diaper. The approach of this study may open the door to advanced healthcare based on ubiquitous wearable sensing.