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 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.