The research team have successfully engineered a material for face masks that is capable of continuously replenishing its electrostatic charge as the mask is worn and breathed through. This led to a significant increase in filtering performance in prolonged use of the mask for up to 60 hours - compared to 4 hours for a conventional surgical mask.

The Problem:
Electrostatic charge is vital for face masks (filters) because it can help to trap and filter tiny particles and provide better protection against respiratory issues.
However, the electrostatic charge of these filters tends to decay over time, particularly in humid conditions. This limits the effectiveness and lifespan of these filters.

The Solution: 
A self-charging air filter has been developed that captures airborne particles efficiently and for an extended period. The filter uses the triboelectric effect between an electrospun film of poly(vinylidene fluoride) nanofibers and nylon fabric to continuously replenish its electrostatic charge as the mask is worn and breathed through.

The result: 
As a result of this breakthrough, the filter has an effective lifespan of up to 60 hours, including 30 hours of wear, and a minimum filtration efficiency of 95.8% for 0.3-micrometer particles. This is significantly higher than a commercial surgical mask's filtration efficiency and lifespan. The researchers also discovered a quantitative relationship between filtration efficiency and surface electrostatic potential, which could be used to extend the electrostatic adsorption efficacy of high-performance air-filtering masks significantly.

Other contributors include: Zehua Peng, Jihong Shi, Xiao Xiao , Ying Hong Yong, liang Cheng , Zuankai Wang, Wen Jung Li, Michael K. H. Leung, Xuemu Li, Weiwei Zhang, Jun Chen