Energy Harvesting in Micro-Robots for Self-Sustainability

Abstract

Energy harvesting has emerged as a transformative approach for powering micro‑robotic systems autonomously, obviating the need for bulky batteries and frequent recharging. By converting ambient mechanical, solar, or electromagnetic energy into electrical power, micro‑robots can maintain continuous operation in diverse environments. This study provides an in‑depth comparison of three energy‑harvesting modalities—piezoelectric, photovoltaic, and radio‑frequency (RF)—implemented on identically sized micro‑robot prototypes. We designed and fabricated three sets of 20 × 20 × 10 mm³ micro‑robots, each equipped with either a PZT cantilever, a monocrystalline silicon solar cell, or a dual‑band RF rectenna. Under controlled laboratory conditions—120 Hz, 1 g vibration for piezoelectric trials; 500 lux illumination for photovoltaic trials; and a calibrated 2 W ERP RF field inside a shielded chamber—each harvester’s output was recorded over ten 60‑second runs. Using a precision data‑logging system sampling at 1 kHz, we integrated harvested charge to compute energy yields per trial. A one‑way ANOVA (α=0.05) tested differences among modalities, revealing significant performance disparities: piezoelectric (mean = 120 µJ, SD = 15), photovoltaic (mean = 85 µJ, SD = 12), and RF (mean = 60 µJ, SD = 10). Post‑hoc Tukey tests confirmed that all pairwise differences were statistically significant (p<0.01). These results underscore the critical role of environmental compatibility in harvester selection and motivate hybrid configurations to balance strengths and weaknesses. We discuss implications for micro‑robot design, propose guidelines for selecting and integrating harvesters based on mission profiles, and outline future research paths, including long‑duration field deployments and multimodal integration to achieve true self‑sustainability.