Developing a detachable dry coupled ultrasonic charger

In this project, we collaborated with Sandia National Labs to develop a prototype for a charger that uses ultrasonic waves to transfer power through metals.

Using ultrasonic waves is the only approach to transfer power through metallic walls without introducing any slots that compromises the structural integrity.

To design a detachable charger, we investigated techniques to transfer ultrasonic waves efficiently from the charger to the metal. The main challenge was to find an alternative to using liquids to fill the microscale gaps between the transducer and the metals since these gaps prevent ultrasonic waves from passing from the transducer to the metal.

We developed a setup to provide good contact between the charger and the metal wall. The setup utilizes powerful rare-earth magnet assemblies to provide the force necessry for compressing a soft elastomer for dry coupling.

Several low-attenuation elastomers were tested to maximize the efficiency of the system, and the DC-to-DC performance of the system was evaluated using the setup shown below.

The results show that the system could transfer up to 3 W of power through a dry interface with an overall DC-to-DC efficiency of 50%.

The video below shows a preliminary test designed to demonstrate the ability of the charger to transfer power using ultrasonic waves. The transferred power was used to light an LED array to provide a visual demonstration.

Please feel free to reach out with any questions you might have.