On 26 May, a research team led by Professor Naoki Shinohara of the Research Institute for Sustainable Humanosphere (RISH) began an experiment to assess the viability of a wireless power transfer (WPT) system for batteryless temperature and humidity sensors. The team is based within the Kyoto University Center for Innovation (COI), and conducting its experiment at the Seika Town Office in Kyoto Prefecture's Soraku District, with government support provided under the National Strategic Special Zones program.
The project's primary objective is to identify the real-life benefits and limitations of this WPT system so that improvements can be made to bring the technology closer to practical use.
The team has also been testing wireless charging of electric bicycles since March, and plans to expand this experiment to include one more bike in the near future.
About the experiment
A great variety of WPT solutions is being explored around the world, accompanied by intense efforts to standardize and commercialize the technologies involved. Most of the methods under development, however, are based on using a magnetic field, which only enables transmission between practically adjacent points.
To solve this problem, Professor Shinohara and colleagues invented a device that is based on converting electricity to microwaves, a type of radio wave, which are then transferred to a target located several meters away. In order to be successful, this method requires both high transmission efficiency and low interference with other microwave-transmitting and -receiving devices, such as mobile phones.
The team decided to apply this technology to develop a wireless charger for batteryless sensors, and partnered with Panasonic Corporation to work on this goal. This collaboration has yielded a high-efficiency power reception antenna and charger.
Panasonic has since obtained an "experimental radio station" license from the Kinki Bureau of Telecommunications, so that it can conduct microwave experiments to learn about the strengths and limitations of these devices under real-use conditions. The team has already obtained data on how the system works in an anechoic environment.
Experiment at the Seika Town Office
In addition to conducting experiments, the team aims to work on the standardization and commercialization of WPT technologies in collaboration with the Wireless Power Transfer Consortium for Practical Applications (WiPoT) and Broadband Wireless Forum (BWF).