Wireless charging is gradually becoming the new standard for gadgets. Perhaps its main drawback is its still limited range of action. Typically, the device being charged needs to be placed directly on top of the charger, which negates its benefits.
The engineers at the Massachusetts Institute of Technology have a solution to this problem. They have developed a new two-dimensional device that can convert Wi-Fi signals into electricity. The system is based on existing devices – rectennas (rectifier antennas). They are capable of intercepting AC electromagnetic waves in the environment, such as Wi-Fi signals, and converting them into DC.
A common disadvantage of rectennas is that they are very tough because they are made of silicon arsenide or gallium arsenide and are best suited for powering small electronic devices. The challenge for MIT scientists was to develop a new rectenna with high flexibility so that it could be used as a basis for a larger device.
The team developed a molybdenum disulfide (MoS2) rectifier. This semiconductor material is only three atoms thick, which gives it extraordinary flexibility while maintaining efficiency. When capturing Wi-Fi signals, the MoS2 rectifier converts them into 10GHz wireless signals with an efficiency of about 30%, much higher than other similar flexible devices.
The new rectenna is not without its drawbacks. It is still almost 2 times less efficient than some rectifiers and generates a small amount of electricity – about 40 microwatts for about 150 microwatts of Wi-Fi power. This is not much, but sufficient to power small wearable electronic and medical devices. As the developers assure, improving the characteristics of the device is just a question. time.