Toward carbon-zero internet of things: Soil-powered renewable energy for perpetual sensing and communication

The widespread deployment of Internet of Things (IoT) devices has led to an increasing demand for sustainable and cost-effective power resources. Soil microbial fuel cells (SMFCs) have emerged as a promising solution, offering great biocompatibility and operational viability. This study presents a thorough investigation of the critical design parameters that influence the performance of SMFCs, with a particular focus on electrode material selection and electrode spatial configurations. Six common metallic materials, including brass, copper, stainless steel, aluminum alloy, iron, and zinc, are evaluated for their effectiveness as electrode materials, with zinc-stainless steel being found to be the optimal combination based on voltage and current outputs. The spatial arrangement of the electrodes is also shown to impact performance, with the series connection mode providing higher voltage output and larger internal resistance, while the parallel mode results in higher power output and lower internal resistance. To showcase the practical potential of SMFCs, a nine-cell series array was utilized to power a customized low-power IoT node, enabling the successful transmission of temperature data to the cloud without the need for a traditional battery. This work highlights the viability of SMFCs as a renewable, battery-free solution for IoT devices, with potential applications in agriculture, environmental monitoring, and smart campuses.