Since the Fantom Drives product is a non volatile disk mechanism, a power failure in and of itself should not result in any data loss except any data that was not committed to the disk at the time (any data that was in the computer's memory but not written to the drive due to caching.)
A power outage will result in an unexpected disconnection from the computer, however, which may leave the file system in an inconsistent state- it would be of use to run your computer's disk checking utility on the drive the next time it is connected to a computer.
If the power outage caused damage to the disk or power supply, they will need to be serviced.