From wooden computer chips to tree-based touchscreens, digital tech is taking an unexpected turn to bio.
Wood 2.0
Mui Labs’ wooden digital interface marks a radical departure from the metallic veneer of conventional smart devices. At a single tap, this simple wooden block lights up into an interactive screen. Compatible with Alexa, it is primed for the smart home devices market.
A raft of ‘augmented wood’ start-ups like Mui are toppling the assumption that digital tech must be made from oil-based plastic and metals. By altering wood’s molecular structure, they are obtaining materials that match conventional hardware on performance and surpass them on sustainability. Companies and researchers have already made significant advances in wood-based materials for LED screens, touchscreens, and wearables.
The biomaterial possibilities of wood lie within the natural polymers that make up its cell walls. These natural polymers are cellulose (nature’s most abundant polymer), hemicellulose, and lignin. By experimenting with these components, manufacturers can draw out wood’s hidden and unlikely properties. For example, ordinary wood is limited in its applications because it swells and shrinks depending on temperature and moisture. This can be mitigated by changing the structure and content of its cells.
Woodoo is one company using biochemistry to create tech-ready wood substitutes for glass and plastic. It was founded by Timothée Boitouzet in 2017 after studying architecture in Japan and material sciences at Harvard and MIT. So far, Woodoo has raised $5.2 million across 4 funding rounds with around $2.3 million of this from the EU.
Upcoming products are Jaspr, a translucent wood-based LED display screen, and Switchr, a touchscreen technology made from sheets of wood. Lightr is a wall lighting solution featuring flat mirrored panels made from Woodoo’s patented translucent wood. “The new materials feature unprecedented mechanical strength, durability, fire resistance and optical properties,” explains Boitouzet.
Woodoo’s creations are made by extracting air and lignin from the cells of wood, then filling the empty pores with bio-based polymers. Their feedstock is comprised of low-grade wood species such as beech, birch, pine, and aspen from sustainably managed forests within 300 km of the manufacturing plant. Woodoo claims that their biomaterials are 17 times less energy-intensive than glass, 130 times less than steel and 475 times less than aluminium. Another sustainability advantage of wood-based material is its comparative lightness. Wood-based digital components in smart cars can potentially make vehicle emissions savings.
Green electronics
Woodoo and Mui track an emerging interest in ‘green electronics’, also known as ‘organic electronics’. This cutting-edge sub-field aims to tackle toxic e-waste pollution with biodegradable electronic devices made from living materials. In 2106, disposed electronics totalled around 44.7 million metric tons globally, with an average contribution of 6.1 kg per person. Once in the environment, this waste releases toxic compounds including mercury, lead, cadmium, flame retardants, barium, and lithium.
Researchers have shown that cellulose, found in the non-starchy and fibrous parts of trees, is a prime candidate for building sustainable devices. Already, laboratory researchers have developed cellulose materials ideal for illuminated, interactive screens. Cellulose nanofibrils, highly ordered bundles of cellulose molecules, can be used to make organic versions of thin-film transistors, an essential component of interactive displays on tablets, smart phones, computers, and wearable devices. In 2017, a paper in the journal Applied Material Interfaces demonstrated a clear and transparent film from cellulose nanofibrils with high touch location accuracy and optical properties. It even proved more durable than commercial touchscreens.
Digital hardware isn’t all rigid surfaces, however. In flexible electronics, circuit boards are mounted on stretchable pieces of material. This is widely used in keyboards and cell phones and in small industrial or medical devices where space is at a premium. An emerging application for this is in wearable technology, a segment where wood is poised to become an important biomaterial. The sustainability of wearable devices will come under greater scrutiny as they gain in popularity.
Finding wood-based material that can support circuitry while offering flexible comfort is a hot topic in the green electronics space. Currently, wearables are made from non-biodegradable polymers but in 2021, University of Missouri researchers created a paper-based wearable material that is breathable, flexible, disposable, and repels liquids. Paper is made of nano-scale cellulose fibres whose physical properties are eminently customisable. Even ordinary commercial paper can be treated chemically to improve mechanical strength. Compared to polymers, they are easily degraded by soil fungi, bacteria, and yeasts in soil.
Just this year, South China University of Technology researchers hit on another wood-based innovation by developing a low-cost composite electronics substrate. Substrates are any structural components that support the electric components in devices. This new wood-based substrate, which offers ‘plastic-like performance and paper-like degradability’, is made from lignin and nanocellulose, both abundant in trees. Wood can also be used to manufacture the base of computer chips as demonstrated in 2015 by University of Wisconsin researchers. They claim their material holds the same performance as a silicon chip base.
However, the active components on this wooden chip are still composed of gallium arsenide, a toxic material that typifies the hazardous substances in our electronic systems. Researchers are still working out how to make wood-based materials conductive so that they can replace metals in our digital circuits. Creating conductive biomaterials presents the biggest challenge for researchers in green electronics but it doesn’t appear insurmountable. In 2021, scientists at Nanking University made a transparent, flexible material by removing lignin from the wood cell and filling the empty spaces with a polymerising biodegradable solvent. The wood-based material displayed good electrical conductivity and temperature sensing properties.
In New Zealand, too, researchers have created a flexible electronic circuit that is wood-based right down to its conductive wiring. The circuit substrate was made by removing lignin and hemicellulose from organic matter. The wiring is made from a bio-based ink that uses lignin-derived carbon nanofibres. Best of all, this circuit is recyclable as it is easily dissolved in water. Lead researcher Qiliang Fu stated that “Transparent, flexible wood film could replace petroleum-based plastics and reduce our reliance on non-degradable polymers in our daily life.”
Sourcing and circularity
Although the timber industry is often maligned for its environmental credentials, the sector could receive an unexpected boost from wood-based bio-chemical firms. By supplying augmented wood companies with the means to replace polymers and metals in our gadgets, timber could become fully integrated into a future high-tech green bioeconomy.
Green electronics must draw on a green supply chain. Obtaining biomass feedstock only from accredited forest management schemes would be one way to ensure that green electronics do not come at the cost of carbon-sequestering ecosystems. This is the route being taken by Woodoo. However, systematically felling trees is not the only way to procure wood. ‘Forest operation residues’, the wood waste generated when non-commercial trees are maintained or have been destroyed in natural events, are another viable source of feedstock.
The biggest disadvantage of forest operation residues from a commercial perspective are the costs required to collect and transport leftover wood from potentially distant locations. However, the company Chrysalix Technologies is showing that there is room for circularity within green electronics. This wood chemical company is already using waste wood and agricultural byproducts such as sawdust to manufacture cellulose and lignin-based materials. In 2019, European Innovation Council‘s Accelerator programme awarded the company with a €2.3m grant to scale their operations.
Green electronics must also pay attention to just how biodegradable next-gen wood really is. In 2021, US researchers raised concerns that altered cellulose may not have the biodegradability performance of untreated organic matter. They urged that there is a strong need to study the environmental persistence of new bio-based materials to make good the green claims that surround augmented wood.
Companies like Woodoo are the earliest commercial pioneers in green electronics but we could be seeing plenty more follow suit. The last five years have seen a flurry of scientific innovations around wood-based tech that will likely lead to more commercial spin-offs, particularly as wearable devices gain ground. The biggest breakthrough would be for manufacturers to produce flexible and conductive wood-based circuitry materials at scale. With wood biomaterials that display the versatility of metal, a green digital device could finally become a possibility.
Thanks to digital tech’s turn to wood, it could only be a matter of time before this most traditional of materials hits augmented reality hardware. With Woodoo’s translucent wood now on the market, we could well see bio-based eyewear mediating our encounters with virtual reality.
