Electrospun transparent nanofibers as a next generation face filtration media: A review

Enhanced Air Filtration Efficiency through Electrospun PVC/PVP/MWCNTs Nanofibers: Design, Optimization, and Performance Evaluation

This study presents a novel approach for creating an effective air filtration medium using electrospun nanofibers comprised of poly(vinyl chloride) (PVC), poly(vinylpyrrolidone) (PVP), and impregnated with multiwall carbon nanotubes (MWCNTs). The membrane production was optimized using an experimental design methodology, resulting in a hydrophobic membrane that exhibits excellent dispersion of MWCNTs. Scanning electron microscopy images illustrate the nanofibers' morphology, featuring an average diameter of approximately 240 nm, minimal bead formation, and optimal MWCNT dispersion. Air filtration tests conducted with NaCl nanoparticles (7-300 nm) demonstrated superior permeability (10-12 m2) and minimal pressure drop (approximately 780 Pa at a 5 LPM airflow rate) compared to other electrospun materials. Both MWCNT-impregnated samples and individual PVC/PVP nanofibers exhibited filtration efficiencies nearing 96%. These results underscore the potential of this developed material for air filtration, particularly in indoor environments, where MWCNTs effectively adsorb and maintain low levels of gaseous and particulate pollutants. This study emphasizes the design, optimization, and comprehensive performance evaluation of PVC/PVP/MWCNT nanofibers, showcasing significant advancements in filtration efficiency with high flux. The findings suggest promising applications for this composite material in advanced air purification systems.

The Potential of Electrospinning to Enable the Realization of Energy-Autonomous Wearable Sensing Systems

The market for wearable electronic devices is experiencing significant growth and increasing potential for the future. Researchers worldwide are actively working to improve these devices, particularly in developing wearable electronics with balanced functionality and wearability for commercialization. Electrospinning, a technology that creates nano/microfiber-based membranes with high surface area, porosity, and favorable mechanical properties for human in vitro and in vivo applications using a broad range of materials, is proving to be a promising approach. Wearable electronic devices can use mechanical, thermal, evaporative and solar energy harvesting technologies to generate power for future energy needs, providing more options than traditional sources. This review offers a comprehensive analysis of how electrospinning technology can be used in energy-autonomous wearable wireless sensing systems. It provides an overview of the electrospinning technology, fundamental mechanisms, and applications in energy scavenging, human physiological signal sensing, energy storage, and antenna for data transmission. The review discusses combining wearable electronic technology and textile engineering to create superior wearable devices and increase future collaboration opportunities. Additionally, the challenges related to conducting appropriate testing for market-ready products using these devices are also discussed.

Influence of different treatment conditions on the filtration performance of conventional electret melt blown non-woven and novel nano FFP2 masks

To allow an efficient protection against viruses like the severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2), it is important to avoid their spreading by using filtering face pieces (FFP), which are categorized by different standards according to their filtration efficiency. In this study, we subjected six brands of FFP2 standard masks to three different conditions and subsequently analysed them for their filtration performance to evaluate potentials for reusability. The conditions comprised changes of temperature and air humidity, an exposure to isopropyl alcohol (IPA) and an autoclave sterilization. While four of six masks consisted of electrostatically treated melt blown non-wovens, two masks were fabricated using a nanofibrous multilayer system. Due to the absence of prior electrostatic treatment, the nano-masks did not show a significant change in filtration efficiency when discharged by IPA, unlike the melt blown nonwoven masks showing a significant decrease of filtration efficiency down to around 50% at a particle size of 0.3 μm. However, most melt blown masks maintained a sufficient filtration efficiency after all other treatments with even better results than the nanofibrous masks. This was particularly the case for the capacity to filter smallest particles/droplets with a size of around 0.1 μm, which is below the range of typical filtering standards and important for the retention of virally contaminated nano-aerosols or unattached viruses. After temperature/humidity variation and autoclave sterilization, melt blown masks were able to retain a filtration efficiency up to over 90% at 0.1 μm contrary to nano-masks showing a decrease down to around 70%. Based on their better filtration performance, lower price and potential reusability, we conclude that electret melt blown masks are the preferable type of FFP2 masks.

Optical Properties of Electrospun Nanofiber Mats

Electrospun nanofiber mats are usually applied in fields where their high specific surface area and small pore sizes are important, such as biotechnology or filtration. Optically, they are mostly white due to scattering from the irregularly distributed, thin nanofibers. Nevertheless, their optical properties can be modified and become highly important for different applications, e.g., in sensing devices or solar cells, and sometimes for investigating their electronic or mechanical properties. This review gives an overview of typical optical properties of electrospun nanofiber mats, such as absorption and transmission, fluorescence and phosphorescence, scattering, polarized emission, dyeing and bathochromic shift as well as the correlation with dielectric constants and the extinction coefficient, showing which effects may occur and can be measured by which instruments or used for different applications.