Measurement and monitoring of the natural or human-made environment has become a necessity in order to increase safety and improve the standard of living. The sensors require power and the most common ways of supplying it are by batteries or through cable. These means of providing power are not always applicable and alternative means such as by wireless power transfer (WPT) or by harvesting available ambient energy are sought for. The latter solution require sufficient light, temperature gradients, chemical constituents or vibrations at the sensor node which may not be the case. Also some of these have little versatility and require a high degree of tailoring to each application.
The other option of WPT has the potential to circumvent these obstacles. While there are several ways to transfer wireless power, the transfer of energy by means of sound is particularly interesting because the sound has least attenuation in the water, human tissue and sealed metal structures compared to the other, electromagnetic methods.
This project will develop technologies for acoustic WPT based on piezoelectric ultrasound transducers. Piezoelectricity is the phenomenon that some materials experience an electrical polarization change when a mechanical stress is applied. We investigate ways to make acoustic power transfer through a metal wall robust towards variable operating conditions, how to make acoustic power transfer systems work over distance in structures with reflections and multiple paths, and how the receiver- or sensor-end transducer can be miniaturized. The project will also develop research-based teaching material for use in engineering education and courses to be offered to industry.
