1) One day you may be charging your Apple Watch with small electric currents running through your skin. Researchers at the University of Massachusetts Amherst are able to send enough electric current through the skin to recharge ultra-low-power fitness trackers like the Fitbit Flex with their prototype design.
2) The human skin is actually conductible material. The researchers are able to send about 0.5 – 1 milliwatt (mW) of direct current (DC) power through to skin to a device on the wrist. The small electric current is safe by government standards. In fact, it current is about the same you get while standing on a body composition scale, so there are minimal health risks.
3) The researchers have received a $598,720 grant from the National Science Foundation to continue work on developing the hardware and software of their current prototype.
Summary: In the future, you can just be in contact with a power source that can send a very small current along your skin to charge your smartwatch. Your skin will act like a wire, conducting the current. You’ll feel nothing and the low power current is safe.
Journal source: Proceedings of the ACM on Interactive, Mobile, Wearable and Ubiquitous Technologies
ShaZam: Charge-Free Wearable Devices via Intra-Body Power Transfer from Everyday Objects