With an aging population and the development of medical technology, the number of patients using implantable electronic devices such as artificial pacemakers and defibrillators is increasing worldwide. Currently, the batteries implanted in the body are replaced by incision surgery, which can lead to health complications. As a result, researchers are currently developing a new wireless energy transfer charging technology that can be used to charge devices implanted in the body without surgery. The same technology can also be used to charge batteries in underwater devices, such as sensors used to monitor the condition of submarine cables.
The Korea Institute of Science and Technology (KIST) announced that a research team led by Dr. Hyun-Cheol Song of the Center for Electronic Materials Research has developed an ultrasonic wireless power transfer technology that can be applied to the above research areas.
Electromagnetic induction and electromagnetic resonance can be used for wireless energy transmission. Electromagnetic induction is currently used in smartphones and wireless headphones; however, its use is limited because electromagnetic waves cannot pass through water or metal, resulting in short transmission distances. In addition, this method cannot be easily used to charge implantable medical devices, as the heat generated when charging is harmful. The electromagnetic resonance method requires that the magnetic field generator and the transmitting device have exactly the same resonance frequency; in addition, there is a risk of interfering with other wireless communication frequencies, such as Wi-Fi and Bluetooth.
Therefore, the KIST team used ultrasonic waves as a medium for energy transmission, rather than electromagnetic waves or magnetic fields. Sonar using ultrasound is often used in underwater environments, while the safety of using ultrasound in humans is also guaranteed in various medical applications, such as the diagnosis of organ or fetal conditions. However, due to the low efficiency of acoustic energy transmission, existing acoustic energy transmission methods are not easy to commercialize.
The research team developed a model that uses the tribological onset principle to receive ultrasonic waves and convert them into electrical energy, a principle that efficiently converts small mechanical vibrations into electrical energy. By adding ferroelectric materials to triboelectric generators, the energy transmission efficiency of ultrasonic waves has been greatly improved from less than 1% to more than 4%. In addition, more than 8 milliwatts can be charged at a distance of 6 centimeters, which is enough to operate 200 LEDs simultaneously or for Bluetooth sensor data communication underwater. In addition, the newly developed device has a high energy conversion efficiency and generates very low heat.
Dr. Song explains the significance of the results as follows: "This study shows that electronic devices can be driven by ultrasonic wireless power charging. If the stability and efficiency of the device are further improved in the future, the technology could be applied to wirelessly power implantable sensors or deep-sea sensors, in which case replacing the battery is cumbersome. ”