MFC as energy harvesting for powering WSNs

WSN environmental monitoring is increasingly adopted, as an alternative to remote sensing for in situ direct measurement, but more frequently as a cooperative method with the latter. The energy autonomy of WSN systems is important to allow their localization imposed only by issues related to optimization problems of in situ measurements and their validation on more extended territorial areas by means of i.e. interpolation and forecasting algorithms. Using terrestrial MFCs to sustainably power these systems can expand the opportunities for their applications. However, both the output voltage and power of an MFC are lower than those required by a commercial WSN node. Consequently, on the one hand the WSN node must be designed/chosen to reduce the DC voltage and current consumption as much as possible, and on the other hand the optimal configuration of the single MFC or of a stack of these must be studied. This work presents the studies currently in progress and some solutions of the research group: the basic design of the dc-dc converter for powering a system that includes all the essential devices of a WSN node, i.e. microcontroller, sensors and transceiver. The activity is in progress. As for the transceiver, at the moment we have oriented to ourselves to the NRF52840 transceiver by Nordic semiconductor company, which uses multiple protocols, suitable for many applications that require until 2Mbs data transmission speeds, and is the most convenient because the power consumption is very low (TX Vdc=3V, Idc=4.8 mA@0dBm, Idc=14.8 mA@+8dBm; Sleep mode Idc=0.03÷1.5 uA), lower than other with slower data rates (e.g. LoRa RFM 95). Regarding DC-DC converter, BQ25570 by Texas Instruments is a nano power boost charger and buck converter suitable for energy harvester powered WSN applications, which provides as great advantage the stable maintenance of the supply voltage. TMFC and PMFC cells will preferably be used for the implementation of the energy harvesting system.