UV light is used at hospitals and other places for sterilization. The Xiaomi Patoneer UVC Sterilization Pen lets you use this technology at home. It has two modes (90s or 60m) and runs on a USB rechargeable 2200mAh battery.
This sterilization pen uses 253.7nm wavelength UV to get the job done. It is waterproof too. The battery life is about 2.5 hours.