Energy harvesting breakthrough

Energy harvesting breakthrough

Ubito, a member of the Fraba family of technology companies and new product idea startup, has announced a breakthrough in the use of Wiegand technology as a power source for smart sensors. After just over two years of work at Fraba's R&D center in Aachen, Germany, a research team presented a prototype wireless sensor powered by Wiegand technology that could be easily integrated into an IoT network during a lab demonstration.

The project involved the development of a new powerful 'Wiegand Harvester' capable of harvesting enough energy to power the complete sensor electronics, including a highly efficient ultra-wideband/UWB radio transmitter. This laboratory breakthrough, a world first, opens up entirely new opportunities and will help embed Wiegand systems (which harvest energy from the movements of an external magnetic field) alongside established energy harvesting techniques such as solar, piezoelectric or thermoelectric as a reliable source of power for autonomous sensor nodes in booming IoT networks.

"Wiegand sensors, which are trimmed for low power output and have been manufactured by us in huge quantities as SMD-mountable components since 2014, have been a core component of our Posital encoder division for more than 15 years," says Tobias Best, who coordinates the global Ubito initiative to develop new Wiegand applications from Singapore, Fraba's headquarters in Asia. "While Wiegand systems offer a very reliable battery-free, energy-autonomous way to detect and record revolutions in multiturn encoders and flow meters, we've long had our sights set on a much higher output in energy harvesting coupled to completely new applications." With this goal in mind, an ambitious R&D project was launched in early 2020 aimed at significantly improving the energy performance of Wiegand devices and demonstrating their practical use in operating energy-autonomous IoT sensor node. 

In the R&D project, which was funded by the German Federal Ministry of Education and Research, the Fraba team worked closely with Aachen University of Applied Sciences. Once again, all of Wiegand's previous know-how was put to the test, with central parameters being readjusted in detail in extensive magnetic field simulations. The latest low-power advances in microcontrollers, innovative wireless protocols such as UWB and clever energy management solutions were incorporated into the planning.

The main requirement was to keep the size of the new power sensor, with the basic components Wiegand wire and coil, as compact as possible. After a good two years of intensive work, the project team was able to announce the breakthrough.  With the new 'Wiegand Harvester', a prototype was presented that generates 50 times more energy than the conventional Wiegand sensor. "With this level of performance, we were finally able to tackle Wiegand-based IoT sensor nodes whose data can be transmitted wirelessly over a greater distance to a remote communication gateway," Best said.

When designing the demo project in the laboratory, the decision was made in Aachen to use an IoT node in combination with a window sensor, which as a complete system is powered entirely by the energy provided by the 'Wiegand Harvester'. Two 'Wiegand Harvesters' and the associated electronics were mounted on the window, while bar magnets were attached to the frame. The compact harvesters consist of a 21 mm long, elaborately conditioned Wiegand wire surrounded by a copper coil. They are the size of an AAA battery (d=7.5 mm).

Each time the window is opened or closed, the harvesters slide past the magnets, triggering abrupt magnetic polarity changes in the highly sensitive Wiegand wires. The amount of energy generated via these pulses is independent of how fast or slow the window is moved - a key USP of Wiegand technology. The current pulses triggered by the pole reversal generate 10 μJ of energy per harvester. This amount of energy was sufficient to activate the microcontroller and read out the temperature sensor integrated in the system.

The team added a UWB transmitter module that allowed the 134-byte data packet to be easily radioed to a receiving station 60 meters away. This lab demonstration, which represents a milestone on the road to self-sufficient Wiegand-based IoT sensor nodes, was presented during the year at various trade conventions such as 'EnerHarv 2022' in the US, which focus on the latest trends in energy harvesting.

"We are still dealing with initial prototypes and a lab demonstrator, not a finished product," Best summarizes. "At least we have shown the potential of Wiegand technology and what can already be done by combining our energy harvesters with commercially available electronic components." A look at serious forecasts shows what market opportunities there will be in the future for commercial sensor systems based on Wiegand. For example, the Industrial Internet of Things (IIoT) is expected to grow threefold in the next ten years. "Exciting times," says Ubito man Best. "For us - and for Wiegand!"