With the rapid development of the economy and technology, intelligent wearable devices have gradually entered public life. Flexible sensors, as the main component of wearable devices, have been widely concerned. However, traditional flexible sensors need an external power supply, lacking flexibility and sustainable power supply. In this study, structured poly­(vinylidene fluoride) (PVDF)-based composite nanofiber membranes doped with different mass fractions of MXene and zinc oxide (ZnO) were prepared by electrospinning and were then assembled to flexible self-powered friction piezoelectric sensors. The addition of MXene and ZnO endowed PVDF nanofiber membranes with better piezoelectric properties. The structured PVDF/MXene-PVDF/ZnO (PM/PZ) nanofiber membranes with a double-layer structure, interpenetrating structure, or core–shell structure could further enhance the piezoelectric properties of PVDF-based nanofiber membranes through the synergistic effects of filler doping and structural design. In particular, the output voltage of the self-powered friction piezoelectric sensor made of a core–shell PM/PZ nanofiber membrane showed a good linear relationship with the applied pressure and could produce a good piezoelectric response to the bending deformation caused by human motion.

In the field of water purification, membrane separation technology plays a significant role. Electrospinning has emerged as a primary method to produce nanofiber membranes due to its straightforward, low cost, functional diversity, and process controllability. It is possible to flexibly control the structural characteristics of electrospun nanofiber membranes as well as carry out various membrane material combinations to make full use of their various properties, including high porosity, high selectivity, and microporous permeability to obtain high-performance water treatment membranes. These water separation membranes can satisfy the fast and efficient purification requirements in different water purification applications due to their high filtration efficiency. The current research on water treatment membranes is still focused on creating high-permeability membranes with outstanding selectivity, remarkable antifouling performance, superior physical and chemical performance, and long-term stability. This paper reviewed the preparation methods and properties of electrospun nanofiber membranes for water treatment in various fields, including microfiltration, ultrafiltration, nanofiltration, reverse osmosis, forward osmosis, and other special applications. Lastly, various antifouling technologies and research progress of water treatment membranes were discussed, and the future development direction of electrospun nanofiber membranes for water treatment was also presented.

In the past decades, the rapid development of the Internet of Things (IoT) technology and artificial intelligence (AI) has driven the research boom of physical sensors. Material selection, structure design, and performance research for physical sensors have attracted extensive attention from worldwide researchers in the field of advanced manufacturing. Significant technological progress has been made in the area of physical sensors for applications in various fields such as electronic skin, biomedicine, and tissue engineering. There are many methods (e.g., electrospinning, screen printing, or rotary coating) to prepare physical sensors. Among them, nanofibers or nanofiber membranes prepared by electrospinning have the advantages of a nanosize effect, high specific surface area, and high porosity over other reported materials used for physical sensors. In this review, the working principles of various physical sensors including pressure sensors, strain sensors, temperature sensors, and humidity sensors are first introduced; recent research progress of electrospun nanofiber-based physical sensors is then summarized. Finally, future research trends and associated challenges of large-scale adoption of electrospun physical sensors are proposed.

Electrospinning technology has attracted extensive attention in recent decades and is widely used to prepare nanofiber membranes from hundreds of polymers. Polyvinyl formal acetal (PVFA), as a polymer with excellent properties such as high strength and heat resistance, is not reported on the electrospun water treatment membrane. In this paper, the preparation process of electrospun PVFA nanofiber membrane is optimized, and the effect of sodium chloride (NaCl) addition on the physical and mechanical properties and microfiltration performance of nanofiber membrane is also explored. And the hydrophobic PVFA nanofiber filter layer is then combined with a hydrophilic nonwoven support layer to construct a composite micro/nanofiber membrane with a pore‐size gradient structure and a hydrophilic/hydrophobic asymmetric structure. Finally, unidirectional water transport and water treatment performance are further investigated. The results show that the tensile breaking strength of the composite membrane can reach up to 37.8 MPa, the retention rate for particles with the size of 0.1–0.3 µm is 99.7%, and the water flux is 513.4 L m−2 h−1 under the hydrostatic pressure. Moreover, it still has a retention of more than 98% after three repeated uses. Therefore, the electrospun PVFA composite membrane has a great potential in microfiltration.

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