Graphene Oxide based Rechargeable Respiratory Masks

Respiratory masks having similar standards of ‘N95’, defined by U.S. National Institute for Occupational Safety and Health, will be highly sought after, post this COVID-19 related pandemic condition. Here such a low cost (~$1/mask) mask design having electrostatic rechargeability and also having the filtration efficiency of >95% and quality factor of ~20 kPa-1 is demonstrated for its filtration efficacy towards particles of size < 0.5 μm. A tri-layer mask named ‘PPDFGO tri’ is designed here - containing nylon, modified polypropylene (PPY), and cotton non- woven fabrics as three layers. The melt-spun PPY, available in a conventional N95 mask, modified with graphene oxide (GO) and polyvinylidene fluoride (PVDF) mixture containing paste using a simple solution casting method acts as active filtration layer, and this tri-layer filtration system is shown for its efficacy towards triboelectric rechargeability using small mechanical agitations. These triboelectric nanogenerator (TENG) assisted masks have high electrostatic charge retention capacity (~1 nC/cm2 after 5 days in ambient condition) and high rechargeability even in the very humid condition (>80% RH). A simple but robust permeability measurement set up is also constructed to test these TENG based membranes, where a flow rate of 30-35 L/min is maintained during the testing. Such a simple modification in the existing mask designs enabling their rechargeability via external mechanical disturbances, with enhanced usability for single use as well as for reuse with decontantamination, will be highly beneficial in the modern era of indispensable personal protective equipment.