Making Electricity From Microwaves

A research team in Japan has developed a highly sensitive diode capable of converting microwaves to electricity.

AsianScientist (Oct. 29, 2019) – Researchers in Japan have developed a device which can convert low-power microwaves into electrical energy. Their findings were presented at the European Solid-State Device Research Conference.

For Internet of Things (IoT) devices to become widely used, energy-harvesting technologies to power them over prolonged periods of time are required. Since radio waves, also known as microwaves, are frequently emitted from base stations for use in communications, scientists are finding ways to tap on microwaves to generate electricity.

Equipment for producing electricity from ambient radio waves consists of an antenna for collecting radio waves and a rectifying element, or diode. In the present study, researchers led by Professor Michihiko Suhara of the Tokyo Metropolitan University, Japan, developed what they call a miniaturized backward diode.

The researchers fabricated the diode by processing a thin film of a semiconducting material into a disk shape via etching. By adjusting the ratio of the constituent elements of the connected semiconductor materials and the density of the added impurities, they also succeeded in growing nanocrystals consisting of indium arsenide and gallium arsenide antimonide. The result was a nanowire backward diode with a diameter of 150 nanometers.

The team subsequently tested their diode’s ability to harvest energy from microwaves with the frequency of 2.4GHz, which is currently used for 4G LTE and Wi-Fi communication in mobile phones. They found that their diode’s sensitivity was 700kV/W, roughly 11 times that of conventional diodes.

With this technology, microwaves with a power level of as low as 100 nanowatts can be converted to electricity. Going forward, the researchers intend to optimize the design of the diode and the radio wave-collecting antenna while ensuring a constant voltage output.


Source: Japan Science and Technology Agency; Photo: Pixabay.
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