Powering the IoT

industry, where sensors in hard hats are being used to improve safety and efficiency on construction sites.

Pioneers of vibration energy harvesting

Energy harvesting has been a focus at Southampton since the 1990s, when our researchers developed novel microgenerators able to convert the vibrations from industrial machinery into energy for wireless sensors. This technology was commercialised through the formation of spin-out company Perpetuum in 2004, which produces smart sensors deployed in the rail industry for real-time condition monitoring of train axle bearings, wheels and track. Perpetuum’s systems enable rail companies to plan maintenance according to need, reducing costs without compromising the safety and reliability of their fleet. The company has been hugely successful, expanding to employ more than 80 engineers, and was recently acquired by Hitachi Rail.

Flexible and wearable IoT devices While there are numerous wearable IoT devices already on the market, such as activity trackers and smart watches, research at Southampton is taking wearable tech to the next level in the form of smart clothing. Work is underway on energy harvesting techniques that can be integrated into textiles for kinetic, solar and wireless power transfer – for example, developing fabric with inbuilt photovoltaic properties rather than using traditional solar cells.

When it comes to powering wearable IoT, another challenge is power storage. Conventional batteries are too rigid to incorporate into textile-based devices, so work is underway on new flexible batteries and supercapacitors that can be integrated into fabric.

Innovation in this area is opening the door to a range of new technologies – activity sensors to help monitor the wellbeing of older people and wearable pollution sensors to provide data for smart city systems are just two applications being investigated by our researchers.

Another example of system-level design is a project undertaken with a local ferry company, during which our researchers developed and deployed condition monitoring sensors powered by the vibration of the engine. This resulted in the first real-world demonstration of a tunable energy harvesting sensor system that could adapt to different speeds rather than working at a fixed frequency.

Energy-driven and intermittent computing

Researchers are undertaking leading investigation in the field of energy-driven design, which looks at the energy resources and

The ambient energy sources used to power IoT devices, such as light or motion, tend to be dynamic and therefore don’t provide a constant energy supply. Our researchers are investigating ways to solve some of the problems this poses, particularly when the device size and cost has been minimised by removing batteries or other forms of energy storage. For example, a device may be in the middle of processing some data when its power cuts out. How can its position be saved so that it can continue where it left off when the power returns? And what’s the best way to manage communication between intermittently powered devices, where the receiving device might not be powered at the time data is transmitted?

Innovations in electromagnetic energy harvesting include the development of a novel airflow energy harvester, which generates power from the oscillation created by moving air. The idea is that airflow-powered sensor systems can be placed in air conditioning, ventilation or heating vents, using power generated from the airflow in the vents to sense and transmit data about temperature, humidity and the presence of gas, and thereby contributing to safer and more efficient buildings management.

Thermoelectric energy harvesting projects have included putting sensors on radiators for smart home energy management, in aircraft engines for condition monitoring and in agricultural sensors, and our researchers are continuing to develop and optimise thermoelectric materials and devices. Harvesting thermoelectric energy becomes more challenging where heat differentials are small – for example, in wearable devices the difference between body temperature and the ambient temperature – and this is another area under exploration.