Battery-free sensor nodes for biomedical and wearable applications require ultra-low-power energy harvesting to enable continuous operation without frequent battery replacement. This paper presents a low-power energyharvesting circuit designed in TSMC 180 nm CMOS technology for biomedical sensor nodes. The control loop operates in the subthreshold region and employs a hysteresis-based PWM scheme, where the error amplifier output serves as the reference for a hysteresis comparator that drives the PWM comparator. This configuration allows stable regulation with minimal power consumption while relaxing precision requirements and reducing switching activity. The system is evaluated using a piezoelectric vibration source with an open-circuit voltage of 4 V at 50 Hz. The converter provides a regulated 1.2 V output with 79% efficiency, delivering 63.72 μW from an input power of 80.66 μW. Efficiency decreases by 7% when the load is halved and improves by approximately 5% when doubled. These results demonstrate that the proposed architecture is a promising solution for energy-constrained biomedical sensor nodes and other low-power IoT applications.
A 79% Efficient Piezoelectric Harvester with Hybrid Hysteretic Control for Self-Powered Biomedical Sensor Nodes
Namdari, Ali;Caviglia, Daniele D.
2026-01-01
Abstract
Battery-free sensor nodes for biomedical and wearable applications require ultra-low-power energy harvesting to enable continuous operation without frequent battery replacement. This paper presents a low-power energyharvesting circuit designed in TSMC 180 nm CMOS technology for biomedical sensor nodes. The control loop operates in the subthreshold region and employs a hysteresis-based PWM scheme, where the error amplifier output serves as the reference for a hysteresis comparator that drives the PWM comparator. This configuration allows stable regulation with minimal power consumption while relaxing precision requirements and reducing switching activity. The system is evaluated using a piezoelectric vibration source with an open-circuit voltage of 4 V at 50 Hz. The converter provides a regulated 1.2 V output with 79% efficiency, delivering 63.72 μW from an input power of 80.66 μW. Efficiency decreases by 7% when the load is halved and improves by approximately 5% when doubled. These results demonstrate that the proposed architecture is a promising solution for energy-constrained biomedical sensor nodes and other low-power IoT applications.
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