Nanocomposite-Decorated Filter Paper as a Twistable and Water-Tolerant Sensor for Selective Detection of 5 ppb-60 v/v% Ammonia

Ammonia (NH3) sensors proposed for the simultaneous exhalation diagnosis, environmental pollution monitoring,and industrial leakage alarm require highflexibility, selectivity, stability, humidity tolerance, and wide-concentration-range detection;however, technical challenges still remain. Herein, twistable and water-tolerant paper-based sensors integrated over surgical maskshave been developed for NH3detection at room temperature, via decorating specially designed ternary nanocomposites (ternary-NCs) on the commercialfilter paper. The NCs consist of a multiwalled carbon nanotube framework with a polypyrrole nanolayerand are further loaded with Pt nanodots. Benefiting from the synergy effect of ternary components, the ternary-NCs exhibit anultrasensitive response to 5 ppb-60 v/v% NH3and present high selectivity confirmed by the theory calculations. Remarkably, thefilter-paper-based sensors possess outstanding stability against twisting 0-1080 degrees, along with excellent cuttability and foldability.Critically, such paper-based sensors can be integrated over surgical masks for simulated exhaled diagnosis and display superior watertolerance even being immersed in water for 24 h. Practically, the detecting accuracy of thefilter-paper-based sensor toward thesimulated exhaled NH3, environmental NH3pollution, and industrial NH3leakage is validated using ion chromatography.

Automated summary

In this study, twistable and water-tolerant paper-based sensors integrated over surgical masks were developed for NH3 detection. The sensors exhibited high sensitivity, selectivity, stability, and humidity tolerance. They could detect NH3 in a wide concentration range and perform well even when immersed in water. The accuracy of the sensors in detecting exhaled NH3, environmental NH3 pollution, and industrial NH3 leakage was validated using ion chromatography.