Smart sensors soak up free electricity from their environment
The limited battery storage capacity combined with their performance degradation over time threatens continuous wireless connectivity, critical to the safe and effective operation of wireless sensor networks (WSNs). Further, with more and more WSNs being deployed, disposal of spent batteries becomes an environmental issue. Within SWAP (Symbiotic wireless autonomous powered system), scientists deployed novel technology that enables wireless sensors to harness energy from their environment – photovoltaic and thermal sources. Such sensors can easily be set up anywhere, are autonomous and have no negative environmental impact. The SWAP team successfully developed an advanced sensor node platform consisting of a high-efficiency radio frequency transceiver, a low-power microcontroller, an energy accumulator and modular harvesting systems. Researchers conducted excellent work on developing the SWAP system, both in the area of hardware design and in communication software. Analysis of state-of-the-art wireless devices, energy-harvesting technology and lossy compression algorithms (in which there is some loss of information) pointed the way to the prototype design. It combines computational capability with reduced power consumption and a communication protocol compliant with Institute of Electrical and Electronics Engineers (IEEE) / Internet Engineering Task Force (IETF) standards. To successfully demonstrate sensor operation without batteries, partners selected a commercial sensor node. The LoadSensing datalogger, shown previously to harvest emissions from a Wi-Fi router, wirelessly transmits real-time data. A video demonstration of the LoadSensing sensor operation can be found on the SWAP website. The SWAP prototype is a step forward compared to the state of the art as it integrates an electromagnetic harvester into a solar harvester. Interchanging harvester systems provides the best solution for many different environments. Project results can thus lead to developing WSNs that can be charged from electromagnetic harvesters and solar harvesters embedded in flexible textile, polyethylene terephthalate or paper substrates.
Keywords
Electricity, renewable energy, energy-harvesting, environmental monitoring, wireless sensor networks
