We’ve already seen the idea of harnessing the power of human motion to generate electricity used in many fields, including footwear, roads, and, just this week, an implantable stimulator device for treating injured tendons,media reported. One of these possibilities is a floor that can power electronic devices, and scientists at ETH Zurich have now developed an efficient form of this technology that is powerful enough to power LED light bulbs and small electronic devices.
Over the years, scientists have investigated a number of innovative flooring solutions capable of generating electricity from human movement, including ceramic tiles for indoor and outdoor use, and spongy wood that relies on the piezoelectric effect to generate voltage under mechanical pressure. This new example shares some similarities with another we saw in 2016, in which scientists embedded cellulose nanofibers into wooden floors, creating an electrical charge when vibrated through the so-called triboelectric effect.
The triboelectric effect also forms the basis for the new smart wood floor, which consists of two treated wood veneers with electrodes layered underneath. But to get the performance to the desired level, some tinkering is required to address the limited power generation capacity of wood. "Wood is basically neutral," said Guido Panzarasa, senior author of the study. "This means that wood has no real tendency to gain or lose electrons. So the challenge is to make wood able to attract and lose electrons."
The team's solution involved coating one piece of wood with a silicone that readily gains electrons on contact, and embedding metal ions and organic molecules on another piece of wood, giving it a higher propensity to lose electrons. This treatment was tested on different species of wood cut in different directions, and the team then found the most efficient option, radially cut spruce.
According to the scientists, this treatment makes their wood 80 times more efficient at generating electricity than natural wood, and provides a stable output under constant stress for up to 1,500 cycles. Shaped into a floor about the size of A4 paper, the material can generate enough electricity to power household LED lights, calculators and other small electronics.
Panzarasa said: "Our focus was to demonstrate the possibility of modifying wood with a relatively environmentally friendly procedure to have a triboelectric effect. Spruce is cheap, available, and has good mechanical properties. This method of functionalization is quite Simple and scalable on an industrial level. It's just an engineering problem."
Scientists are now working to improve their handling of wood to make it more eco-friendly and easier to apply as they work towards commercial application. To their advantage, the "dynamo" maintains the natural look and durability of wood floors, which could make it an attractive option for style-conscious designers in future smart buildings.
"The ultimate goal is to understand the potential of wood, beyond those already known, and to give wood new properties for future sustainable smart buildings," said Panzarasa. The research was published in the journal Matter.
