Fig. 5: Principles and optimization of a low-power wireless sensor node and field tests of TESS.
a Graphical representation of the TESS, highlighting the low-power wireless sensor node and its different parts and functions. b Photograph of the on-site experiments, illustrating the TESS along with the environmental parameters and accessories used for data acquisition. c Charge/Discharge cycle of the storage capacitor Cstore (22 mF) in the mine for a TESS supplemented by 10 arrays of Mixed-Mode TENG units, each containing 4 horizontal Mixed-Mode TENGs. d Comparison of wind speed values obtained from the TESS using a 10 mF storage capacitor Cstore and a commercial wind-speed sensor. e Comparison of the cycle durations, indicating the time interval between each signal, over a period of 3 months. Morphology of the (f) FEP tribolayer and (g) the copper electrodes of the Mixed-Mode TENGs at the end of the experiment.
