The disinfecting process takes about 30 minutes - and users should not wear the mask while it is plugged in. The new mask has a USB port that connects to a power source such as a standard cellphone charger that heats an inner layer of carbon fibres to 70 degrees Celsius (158 Fahrenheit), high enough to kill viruses. The prototype looks like a standard N95 face mask, with a valve at the front and bands to hold it in place around the head. The researchers behind the idea submitted a patent for the mask in the United States in late March and consider commercializing the product with the private sector. It will likely sell at a $1 premium over the price of a typical disposable face mask.