Wireless energy transfer (WET) has become readily available with new portable electronic devices. Until now, studies on WET have been mainly based on the electromagnetic (EM) induction method using EM waves. However, it is still challenging to utilize current EM wave mediated WET in those areas where it is most needed: underwater, body-implant, and EM-shielded cases.
A new wireless energy transfer technology announced by the Korea Institute of Science and Technology could be a solution. Scientists- led by Dr. Hyun-Cheol Song at the Electronic Materials Research Center- have developed an ultrasonic wireless power transmission technology that can charge the batteries of underwater devices and body-implanted devices.
Instead of EM waves and magnetic fields, scientists used ultrasonic waves as an energy transmission medium. They developed a model that receives and converts ultrasonic waves into electrical energy. The model works on the triboelectric principle that effectively converts small mechanical vibrations into electrical energy.
The efficiency rate of energy transfer can be improved by adding a ferroelectric material to the triboelectric generator. Doing so, energy transfer efficiency was significantly improved from less than 1% to more than 4%.
Moreover, charging more than 8 mW power at a distance of 6 cm was possible, which was sufficient to operate 200 LEDs simultaneously or to communicate Bluetooth sensor data underwater.
Dr. Song explained the significance of the results as follows: “This study demonstrated that electronic devices could be driven by wireless power charging via ultrasonic waves. If the stability and efficiency of the device are further improved in the future, this technology can be applied to supply power wirelessly to implantable sensors or deep-sea sensors, in which replacing batteries is cumbersome.”
- Hyun Soo Kim et al. Ferroelectrically augmented contact electrification enables efficient acoustic energy transfer through liquid and solid media. DOI: 10.1039/D1EE02623B