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Gaseous ammonia (NH3) under high concentration (e.g., larger than 25 ppm) is usually harmful to human organs. Instead, lower - concentration NH3 that is generated from human metabolism may serve as a biomarker for exhaled diagnosis of kidney disease. Ideally, wearable NH3 sensors integrated over cloths are highly desired for real-time monitoring. Here, twistable and tailorable nanocomposites (NCPs) textile has been developed for yielding wearable NH3 sensing, by which graphene oxide was firstly mixed with aniline monomer, and subsequently this mixture was in-situ polymerized by vanadium pentoxide to obtain a ternary NCPs of vanadium oxide, polyaniline and graphene oxide (V2O5/PANI/GO NCPs). Benefiting from the incorporation of PANI, V2O5 and GO, the V2O5/PANI/GO NCPs textile shows enhanced response (Rg/Ra −1 = 31.2 ± 1.8% @10 ppm NH3, room temperature), high stability that maintains 91.5% response after 56 days and excellent interfering selectivity. Remarkably, the V2O5/PANI/GO NCPs textile displays excellent twistability and tailorability. This strategy to V2O5/PANI/GO NCPs textile might be extended to nanosensing materials that could be integrated onto other textiles.

A Pd/Ni nanowires (NWs) film-coated surface acoustic wave (SAW) device is proposed for sensing hydrogen with fast response. The gas adsorption in Pd/Ni NW film modulates the conductivity, and perturbs the SAW velocity, and the corresponding changes in phase can be collected as the sensing signal. 200 MHz SAW device with delay line pattern is prepared by using the lithographic technique on Y35oX quartz substrate. The larger specific surface of Pd/Ni NW contributes well to improvement of the response time. By using anode-aluminum-oxide (AAO) template-confined electrodeposition, the Pd/Ni NWs have been prepared, then dissolved in ethanol and finally deposited on the surface of the SAW device by drop coating method to build the SAW hydrogen sensor. The developed SAW sensor is integrated in a phase discriminating circuit, and experimentally characterized. Fast response less than 2 s, high sensitivity of 1.65 mV/% (0.3–3.5 v/v % in nitrogen gas), and low detection limit of 7 ppm have been achieved at room temperature (25 ℃). Further, the developed sensors show excellent selectivity and stability. Also, the film thickness - and humidity - dependent sensing performance was studied.