Over the past dozen or so years, our lives have been changed greatly by the spread of smartphones and other technologies. A major contributor to this has been compact sensors that use micro electro-mechanical system (MEMS) technology. In the years to come, moreover, Internet of things (IoT) technologies using compact sensors will be needed to grasp the status of all kinds of things out in the world and connect them to the Internet. This will not only further enrich our lives through synergies with big data and AI technologies, it is also expected to facilitate the sustainability of limited resources and help solve food- and medical-related problems. Expectations are high for compact sensors, but they have not yet spread much beyond smartphones. One reason is the power supply problem. The power supplies of compact sensors need to provide power without the need for recharging or replacement like with batteries and without being affected by the weather or time of day.
We therefore focused on the environmental vibrations that are everywhere around us, which, being so small, had been difficult to generate electricity from, and developed an original solid ionic electret MEMS technology, which we then used to successfully generate enough power to drive a compact sensor. Our research established clear design criteria for actual vibration-generated power devices, criteria that had not been previously articulated. Based on this, we developed a high-density ionic electret molding technology and a vacuum package technology that fully minimizes mechanical loss, and thereby succeeded in recovering power at a rate of 92%, which is just about the theoretical limit. Going forward, we plan to create a practical product that will make this technology easy to use for everyone and in this way further contribute to the IoT society.
Prototype for verification of principle