I’ve had my concerns regarding connecting questionable home-made electronics to my PC through the USB port. How easy is it to kill the port ? I really don’t know. But it was one of the reasons why I wanted to isolate my prototypes from the PC. Another reason was to avoid noise problems while performing high precision measurements.
There might be other solutions out there but I quickly found a PCB created by Tom Keddie and available on Tindie. It’s a design based on ADUM3160. According to the datasheet “The ADuM3160 is a USB port isolator, based on Analog Devices, Inc., iCoupler® technology. Combining high speed CMOS and monolithic air core transformer technology, this isolation component provides outstanding performance characteristics and is easily integrated with low and full speed USB-compatible peripheral devices.“. It has an insulation rating of 2.5 kVrms and data speed rate of 1.5 Mbps to 12 Mbps.