200 mW-class LED-based optical wireless power transmission for compact IoT

For Internet of Things terminals such as many types of sensors, tags or beacons, wiring and using batteries are less effective power supplying methods due to excessive installation and maintenance costs. Wireless power transmission is a promising candidate, particularly optical wireless power transmission (OWPT), with its attractive advantages of long transmission distance, good directionality and small size. However, previous researches of OWPT are almost all focused on laser as a light source, which is difficult to use in the usual spaces due to possible safety reasons at the current stage. In this research, an LED-based OWPT system that realized large electricity power supply was designed and demonstrated. 223.9 mW of output power from 100 cm distance was achieved with a 1.7 × 1.7 cm2 size GaAs solar cell as a receiver. Around 77% of optical system efficiency was confirmed at a 2.1 × 2.3 cm2 irradiation size. The total power feeding efficiency was 6.3%.