The inventor of N95 masks, which integrate virus-blocking technology into their design, has come out of retirement to find ways to disinfect the masks for reuse, amid the coronavirus pandemic.In 1992 material scientist and engineer Peter Tsai invented the filters on the masks which block out viral particles. "My invention was just to improve the filter. It's not a special invention," he modestly told NPC.However, the masks are currently single use, leading to a shortage of supplies in hospitals as medics treat COVID-19 patients. Consequently, Tsai is looking into ways to upgrade the design.With N95 masks in short supply, some medical personnel have resorted to using alcohol or bleach to try to sterilize the masks, but this can lead to degradation of the components. Tsai said that his phone line and email inbox have been flooded with requests for a safe method to sterilise them, prompting him to come out of retirement to see what he can do."I just want to help people, and just do my job," Tsai said.Tsai retired from the University of Tennessee last year, but since mid-March has been assisting N95DECON, a collective of volunteer researchers and organizations drawn from across the US who are experimenting with various ideas, including using heat, ultraviolet light, and hydrogen peroxide to sterilize the masks.His former colleagues have praised his efforts. Maha Krishnamoorthi, vice president of the University of Tennessee Research Foundation, told NPR that she told Tsai "You seem to be the man of the hour," adding: "And he said, 'No — I'm man of the minute.'"But Tsai says praise should go instead to the medics."The front-line hospital workers — they are heroes. I'm just trying to help them to wear the mask," he said.