A metamaterial perfect absorber-based rectenna engineered by University of South Florida researchers could potentially deliver wireless power to motion sensors, LEDs and other devices with low energy requirements. The metasurface-based component harvests energy from radio waves, such as those associated with cell phone networks or Bluetooth connections.
These materials use small, carefully designed structures to interact with light and radio waves in ways that naturally occurring materials do not. The energy-harvesting rectenna was fabricated on a copper-coated flame retardant-4 circuit board with a metamaterial designed for high absorption of radio waves and that allows a higher voltage to flow across the device’s diode. This improved its efficiency at turning radio waves into power, particularly at low intensity.
(a) The rectenna array with diodes embedded in the gaps. (b) The unit cell. Source: Jiangfeng Zhou et al.
The amount of power harvested by the 16 cm2 device was measured while changing the power and frequency of a radio source between 0.7 GHz and 2.0 GHz. Laboratory tests confirmed that the rectenna could harvest 100 µW of power from radio waves with an intensity of just 0.4 µW/cm2, approximately the level of intensity of radio waves 100 m from a cell phone tower.
The researchers plan to shrink the dimensions of the energy-harvesting system described in Optical Materials Express and to engineer a version that collects energy from multiple types of radio waves simultaneously.
