Model-guided Control of Nanofiber Orientation in Nanomanufacturing of Next-gen Air Filters

KEVIN K. CROWN, Yury Salkovskiy, Yuris Dzenis, National Strategic Research Institute

     Abstract Number: 402
     Working Group: Control and Mitigation Technology

Abstract
While no filter medium has shown to be 100% effective, filtration is the primary defense against the inhalation of hazardous biological or chemical particles. Submicron particles pose the largest health risk since they are best able to penetrate filter media and enter deeply into the respiratory tract, increasing the certainty of illness from the exposure. Since the filter media currently used in conventional air purifying respirators (APRs) have a limited wearing time due to high breathing resistance and often have insufficient filtering efficacy, an improved filter medium with high filtration efficacy and low breathing resistance is needed. Randomly woven nanofibers of 100-150 nm diameter have high specific filtration surface area, porosity, and interfiber distances which yield high particulate filtration efficacy, but also have a high pressure drop which makes them difficult to breathe through for any length of time in an APR. We believe that by aligning the nanofibers during the electrospinning process, filtration of the most penetrating particles will be much improved, a decreased pressure drop will be realized, and the aligned nanofibers will impart an increased mechanical strength in the direction of the nanofiber orientation that will increase their durability. After working to develop such an electrospinning method, we have tested filters with better aligned nanofibers for filtration efficiency against aerosolized MS2, a 23-28 nm bacteriophage virus, and aerosolized submicron beads and have shown promising results in filtration when compared to that of commercially available filter media.