A novel gradient structured nanofiber and silver nanowire composite membrane for multifunctional air Filters, oil water Separation, and health monitoring flexible wearable devices

Particular matter (PM), oily wastewater, and microorganisms (e.g., bacteria) have caused serious environ-mental, health, and safety issues. However, the development of multifunctional filtration materials to address these problems remains a great challenge. Here, we present a series of gradient structured air fil-ters by simply spray coating poly(vinyl alcohol -co-ethylene) (PVA-co-PE) nanofibers on nylon mesh, fol-lowed by silver nanowires (AgNWs). Interestingly, it is found that the ANF-6 air filter is an anisotropic Janus membrane with asymmetric wettability and translucency. The as-prepared ANF-6 air filter exhibits excellent water vapor transmission rate (4447.92 +/- 184.78 g/(m2. d)), PM filtration (96.42 +/- 0.64 % for PM0.3), photothermal (79.6 degrees C under 1sun in 150 s), thermal insulation, antibacterial, and oil water sep-aration. Additionally, the obtained ANF-6 air filter was impregnated with carbon black (CB) dispersion and served as flexible pressure sensors to monitor human respiration rate (17 times/min) and wrist pulse rate (80 times/min). The gradient structured PVA-co-PE nanofibers and AgNWs network provides excel-lent air filtration, oil water separation, and sensitivity performance for the sensors. These results provide a new scheme for designing multifunctional filtration materials and wearable pressure sensors in the application of air filtration, oil water separation, and wearable electronics for monitoring human health.(c) 2022 Elsevier Inc. All rights reserved.

Automated summary

In this study, gradient structured air filters were prepared by spray-coating PVA-co-PE nanofibers and silver nanowires on nylon mesh. The ANF-6 air filter showed asymmetric wettability and translucency, and exhibited excellent water vapor transmission rate, PM filtration, photothermal performance, thermal insulation, antibacterial properties, and oil-water separation. Additionally, the ANF-6 air filter impregnated with carbon black dispersion served as flexible pressure sensors to monitor human respiration rate and wrist pulse rate.