A survey on power management for long-term measurements using Wireless Sensor Networks

Wireless Sensor Networks (WSN) are often required to monitor structures over a long period of time. This specifies several requirements for the design of WSN hardware, such as the use of low-power chip components, the use of micro-electrical mechanical sensors (MEMS) instead of conventional sensors and the use of a hybrid power supply. On the software side it dictates the utilization of intelligent power saving mechanisms and adequate network algorithms. Only the combination of all these measures provides a practical solution to the desired long-term monitoring. In this paper, a non-comprehensive survey on the measures that can be taken in each of the above-mentioned aspects is given. Different low-power chip components and MEMS are opposed and rated for several physical quantities. Then, some energy-harvesting methods (i.e. thermo-electric, photovoltaic and others) and the resulting hybrid power supplies with a supporting primary battery are presented. On the software side, duty-cycled and event-based measurements are opposed and several radio transmission regimes are presented. The result is a combined low-power approach that prolongs uptime of WSNs. Measurement results of a WSN hardware platform incorporating the Material Testing Institute's data acquisition software are shown, where operating time was extended by using the presented measures.