Wireless-power transmitter with distance sensor for ultra-small wearable devices

A wireless-power-transmission system, which provides a power source to sensors attached to a human body, has been developed. The human body must be protected from strong fields generated by a radio transmitter. A transmitter with a distance sensor dynamically controls the output power from the antenna so that the field strength at the receiving position is within safe levels. To demonstrate the system, the receiving antenna module was attached to an eyelash along with an LED, and it was confirmed that the LED turned on with a stable brightness regardless of the distance from the transmitting antenna.