Mechanical and Electrical Energy Buffer-release Mechanisms for Motion-powered IoT Applications

The increasing number of distributed Internet of Things (IoT) devices makes the power supply a prominent issue, which limits the extent and lifetime of ubiquitous IoT networks. Mechanical energy harvesting (MEH) technology transforms the local mechanical energy into useful electricity. It provides a solution for the realization of self-sustainable motion-powered IoT applications. Given the volatile feature of most ambient vibrations, energy management methods are necessary for matching the unstable energy supply from the MEH sources and the energy demand of timely IoT tasks. This paper summarizes and analyzes two energy buffer-release mechanisms (EBRM) from mechanical and electrical aspects, respectively, for ensuring the robust operation of motion-powered IoT systems. Rather than emphasizing harvesting more energy from vibrations, as most of the previous studies did, we focus on energy neutrality among the mechanical, electrical, and cyber ingredients. A preset energy release threshold realized in either a mechanical or electrical way ensures the completion of every fundamental atomic task. The necessity of EBRM is demonstrated in three controlled experiments. Only those systems with a mechanical or electrical buffer-release mechanism can operate correctly.