Stable output performance generated from a magneto-mechano-electric generator having self-resonance tunability with a movable proof mass

Abstract

A magneto-mechano-electric (MME) generator that converts an ambient magnetic field to useable electricity has the potential as an autonomous power source for sensor networks without or supporting driving batteries. However, the output of a typical MME generator decreases when temperature changes lead to resonant frequency drift of the generator. Herein, a broadband MME generator having self-resonance tunability with a movable proof mass was described for continuously generating stable output energy over a range of surrounding temperatures. The designed MME generator with a movable proof mass presented a wide bandwidth of 14.7 Hz, which was 865 % compared to that of a typical MME generator with a fixed proof mass (1.7 Hz). Owing to the self-resonance tunability, the broadband MME generator presented a lower output degradation (0.7 vs. 2.1 mW for a typical MME generator), even when the temperature changed from −30 °C to 60 °C. Under temperature variation, the broadband MME generator generated stable output energy that was sufficient to continuously operate the IoT sensors and maintain the brightness of 120 white LEDs with high intensity. Thus, the MME generator with self-resonance tunability is anticipated to provide a stable energy source, even under harsh environments that induce variable resonant frequency.