Implementation of Energy-Neutral Operation on Vibration Energy Harvesting WSN

This paper introduces a method for enabling energy-neutral operation in energy-harvesting wireless sensor nodes (WSNs), taking into account the unpredictable and fluctuating nature of environmental energy sources. The approach leverages adaptive duty cycling, dynamically adjusting the node’s activity based on both the current energy availability in the environment and the node’s real-time energy status, managed through a dedicated energy management circuit. The method is implemented on a MicaZ mote, using two types of vibration-based energy harvesters: piezoelectric and electromagnetic. With a fixed duty cycle of 0.21%, the node using a piezoelectric harvester can only operate for 130.5 seconds and then requires 93.5 seconds of downtime for recharging. In contrast, applying the proposed adaptive strategy allows the node to achieve energy-neutral operation by adjusting to a duty cycle of 0.17%. The effectiveness of the approach is further validated using an electromagnetic harvester worn on a runner’s wrist, where the strategy extends the node’s operational lifetime by approximately 64% during periods with no available harvestable energy, before entering sleep mode. These results confirm the efficiency of the proposed energy management scheme in achieving sustainable, energy-neutral sensor operation.

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