Towards a vibration energy harvesting WSN demonstration testbed

This work presents the design, implementation, and preliminary validation of a wireless sensor network (WSN) testbed powered by vibration energy harvesting. Developed under the Chist-ERA E-CROPS project, the testbed demonstrates the feasibility of using ambient vibration as a sustainable energy source for low-power sensor nodes, aiming to reduce reliance on battery replacements and promote long-term deployment of WSNs in real-world environments.

The testbed architecture is based on MICAz motes equipped with MTS310CB sensor boards and powered by AA batteries. Power consumption across different node operation modes—such as transmission, reception, sleep, and sensing—is carefully measured and analyzed. A custom-designed current monitoring system using an Atmega128 microcontroller and serial interface is developed to measure instantaneous current flow and visualize energy consumption in real-time on a connected PC.

An electromagnetic vibration energy harvester is designed, built, and characterized for integration into the testbed. The harvester features a cylindrical structure with a suspended magnet and coil configuration optimized for low-frequency vibrations (around 10 Hz), such as those produced by household appliances, human movement, or machinery. The device incorporates a 2-stage Dickson rectifier to efficiently convert AC output to DC and is experimentally demonstrated to recharge AA batteries over time. Under controlled vibration conditions, the harvester produced up to 5.1 V DC, sufficient for charging a sensor node battery.

The study also explores the role of communication protocols in energy consumption. The Collection Tree Protocol (CTP) is initially employed for data routing, while work is ongoing to implement HEED—a clustering-based protocol—for enhanced energy efficiency in larger-scale deployments.

Comprehensive tests under various conditions—including high-power and low-power operation modes—illustrate the effect of hardware settings and environmental factors on battery drain. Results show that careful tuning of duty cycles, disabling of non-essential components, and optimization of RF output power significantly extend node lifetime. When combined with the harvester, these optimizations pave the way for near energy-neutral operation of WSNs.

Overall, this research demonstrates a functional and scalable prototype for vibration-powered WSNs. It contributes practical insights into energy profiling, harvesting integration, and protocol optimization. Future work will expand the testbed to 15 nodes and explore adaptive energy-aware sensing policies for long-term autonomous operation in smart monitoring scenarios.

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