Disinfection and Electrostatic Recovery of N95 Respirators by Corona Discharge for Safe Reuse.

With the COVID-19 pandemic surging, the demand for masks is challenging, especially in less-developed areas across the world. Billions of used masks are threatening the environment as a new source of plastic pollution. In this paper, corona discharge (CD) was explored as a safe and reliable method for mask reuse to alleviate the situation. CD can disinfect masks and simultaneously restore electrostatic charges to prevent filtration efficiency deterioration. Electric field, ions, and reactive species generated by CD cause DNA damage and protein denaturation to effectively disinfect N95 respirators. Log reduction of 2-3 against Escherichia coli can be easily reached within 7.5 min. Log reduction of up to 6 can be reached after three cycles of treatment with optimized parameters. CD disinfection is a broad spectrum with log reduction >1 against yeast and >2.5 against spores. N95 respirators can be recharged within 30 s of treatment and the charges can be retained at a higher level than brand-new masks for at least 5 days. The filtration efficiency of masks was maintained at ∼95% after 15 cycles of treatment. CD can provide at least 10 cycles of safe reuse with benefits of high safety, affordability, accessibility, and device scalability/portability.

Corona-Enabled Electrostatic Printing for Ultra-fast Manufacturing of Binder-Free Multifunctional E-Skins.

As essential components in intelligent systems, printed soft electronics (PSEs) are playing crucial roles in public health, national security, and economics. Innovations in printing technologies are required to promote the broad application of high-performance PSEs at a low cost. However, current printing techniques are still facing long-lasting challenges in addressing the conflict between printing speed and performance. To overcome this challenge, we developed a new corona-enabled electrostatic printing (CEP) technique for ultra-fast (milliseconds) roll-to-roll (R2R) manufacturing of binder-free multifunctional e-skins. The printing capability and controllability of CEP were investigated through parametric studies and microstructure observation. The electric field generation, material transfer, and particle amount and size selecting mechanisms were numerically and experimentally studied. CEP-printed graphene e-skins were demonstrated to possess an outstanding strain sensing performance. The binder-free feature of the CEP-assembled networks enables them to provide pressure sensitivity as low as 2.5 Pa and capability to detect acoustic signals of hundreds of hertz in frequency. Furthermore, the CEP technique was utilized to pattern different types of functional materials (e.g., graphene and thermochromic polymers) onto different substrates (e.g., tape and textile). Overall, this study demonstrated that CEP can be a novel contactless and ultra-fast manufacturing platform compatible with the R2R process for fabricating high-performance, scalable, and low-cost soft electronics.