Designing Perpetual Energy Harvesting Systems explained with RiverMote: A Wireless Sensor Network Platform for River Monitoring

Wireless Sensor Network (WSN) motes are devices of small form factor. They are tailored to cost-effectiveness for monitoring and control applications. Different optimizations exist for the robust lifetime improvement of such devices, but the community still lacks a clear approach of how to achieve a robust system design that is of low cost and implements low-power optimizations. In particular, it is a demanding task to efficiently utilize energy harvesting system (EHS) technology for WSNs. However, that is the only way for implementing battery-free mote devices for achieving perpetual operation of WSNs. We demonstrate the design methodology that let us implement RiverMote. RiverMote is a case study for designing a low cost hardware system architecture combining low-power mote and a highly efficient EHS architecture. First, we provide a detailed explanation for how to deduce the prototype dimensioning parameters given the application requirements of an energy-autarkic river level monitoring system. Then we show how to select proper energy harvesting device (EHD) technologies and design all EHS stages for fitting the application-depending power state model of the integrated mote. Finally, we implement and evaluate tests of all stages for their energy efficiency as well as RiverMote’s self-measurement accuracy which is crucial for robust perpetual designs.