From wooden computer chips to tree-like touch screens, digital technology is taking an unexpected turn towards organic.
Mui Labs’ wooden digital interface marks a radical departure from the metal plating of conventional smart devices. With just one click, this simple block of wood turns into an interactive screen. Compatible with Alexa, it is designed for the smart home device market.
A series of “augmented wood” start-ups like Mui are overturning the assumption that digital technology must be made from petroleum-based plastics and metals. By modifying the molecular structure of wood, they obtain materials that match conventional hardware in terms of performance and surpass them in terms of durability. Companies and researchers have already made significant progress in wood-based materials for LED displays, touchscreens and wearable devices.
The biomaterial possibilities of wood lie in the natural polymers that make up its cell walls. These natural polymers are cellulose (the most abundant polymer in nature), hemicellulose and lignin. By experimenting with these components, manufacturers can bring out the hidden and unlikely properties of wood. For example, ordinary wood is limited in its applications because it swells and shrinks with temperature and humidity. This can be mitigated by altering the structure and content of its cells.
Woodoo is a company that uses biochemistry to create ready-to-use wood substitutes for glass and plastic. It was founded by Timothée Boitouzet in 2017 after studying architecture in Japan and materials science at Harvard and MIT. So far, Woodoo has raised $5.2m across 4 funding rounds, including approximately $2.3m from the EU.
Upcoming products are Jaspr, a wood-based translucent LED display screen, and Switchr, a touchscreen technology made from wood sheets. Lightr is a wall lighting solution comprised of flat mirrored panels made from Woodoo’s patented translucent wood. “The new materials exhibit unprecedented mechanical strength, durability, fire resistance and optical properties,” explains Boitouzet.
Woodoo’s creations are made by extracting air and lignin from wood cells, then filling the empty pores with bio-based polymers. Their raw material is made up of lower quality 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 aluminum. Another durability benefit of the wood-based material is its relative lightness. Wood-based digital components of smart cars have the potential to reduce vehicle emissions.
Woodoo and Mui follow an emerging interest in “green electronics”, also known as “organic electronics”. This cutting-edge subfield aims to combat toxic electronic waste pollution with biodegradable electronic devices made from living materials. In 2106, electronics disposed totaled approximately 44.7 million metric tons worldwide, 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, fibrous parts of trees, is a prime candidate for building durable devices. Already, lab researchers have developed cellulosic materials ideal for illuminated interactive displays. 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, an article in the journal Applied hardware interfaces demonstrated a clear and transparent film from cellulose nanofibrils with tactile localization accuracy and high optical properties. It even proved to be more durable than commercial touch screens.
However, digital material is not only composed of rigid surfaces. In flexible electronics, printed 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 limited. An emerging application for this is in wearable technology, a segment where wood is poised to become an important biomaterial. The durability of portable devices will come under greater scrutiny as they grow in popularity.
Finding a wood-based material that can support circuitry while providing flexible comfort is a hot topic in green electronics. Currently, clothing is made from non-biodegradable polymers, but in 2021 researchers at the University of Missouri created a wearable, paper-based material that is breathable, flexible, disposable, and repels liquids. Paper is made of nanoscale cellulose fibers whose physical properties are highly customizable. Even ordinary commercial paper can be chemically treated to improve its mechanical strength. Compared to polymers, they are easily degraded by soil fungi, bacteria and soil yeasts.
Again this year, researchers at the South China University of Technology pioneered another wood-based innovation by developing a low-cost composite electronic substrate. Substrates are all the structural components that support the electrical components of devices. This new wood-based substrate, which offers “plastic-like performance and paper-like degradability”, is made from lignin and nanocellulose, both of which are abundant in trees. Wood can also be used to make the base of computer chips as demonstrated in 2015 by researchers at the University of Wisconsin. They claim that their material has the same performance as a silicon chip base.
However, the active components of this woodchip are still composed of gallium arsenide, a toxic material that characterizes hazardous substances in our electronic systems. Researchers are still working on how to make wood-based materials conductive so they can replace metals in our digital circuits. Creating conductive biomaterials is the biggest challenge for green electronics researchers, but it doesn’t seem insurmountable. In 2021, scientists at Nanjing University made a transparent, flexible material by removing lignin from the wood cell and filling the empty spaces with a polymerizing biodegradable solvent. The wood-based material exhibited good electrical conductivity and temperature sensing properties.
Also in New Zealand, researchers have created a flexible electronic circuit based on wood 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 nanofibers. Even better, this circuit is recyclable because it dissolves easily in water. Lead researcher Qiliang Fu said “transparent and flexible wood film could replace petroleum-based plastics and reduce our reliance on non-degradable polymers in our daily lives.”
Sourcing and circularity
Although the wood industry is often maligned for its environmental credentials, the sector could get an unexpected boost from wood-based biochemical companies. By providing augmented wood companies with the means to replace polymers and metals in our gadgets, wood could become fully integrated into a future high-tech green bioeconomy.
Green electronics must rely on a green supply chain. Obtaining biomass feedstock only from accredited forest management systems would be one way to ensure that green electronics does not come at the expense of carbon-sequestering ecosystems. This is the route taken by Woodoo. However, the systematic felling of trees is not the only way to obtain wood. “Logging residues,” wood waste generated when non-commercial trees are tended or have been destroyed by natural events, is another viable source of raw material.
The biggest disadvantage of logging residues from a commercial perspective are the costs required to collect and transport the wood scraps from potentially remote locations. Yet Chrysalix Technologies is showing that there is room for circularity in green electronics. This wood chemical company already uses wood waste and agricultural by-products such as sawdust to make cellulose and lignin-based materials. In 2019, the European Innovation Council’s Accelerator program awarded the company a €2.3 million grant to scale its operations.
Green electronics should also pay attention to the biodegradability of next-generation wood. In 2021, US researchers raised concerns that weathered cellulose might not have the biodegradability performance of untreated organic matter. They insisted that there is a strong need to study the environmental persistence of new bio-based materials to assert the green claims that surround augmented wood.
Companies like Woodoo are early commercial pioneers of green electronics, but we could see many more following suit. The last five years have seen a flurry of scientific innovation around wood-based technology that will likely lead to more commercial spillovers, especially as portable devices gain traction. The biggest breakthrough would be for manufacturers to mass-produce wood-based flexible and conductive circuit materials. With wood biomaterials displaying the versatility of metal, a green digital device could finally become a possibility.
Thanks to the transition from digital technology to wood, it could only be a matter of time before this most traditional material reaches augmented reality material. With Woodoo’s translucent wood now on the market, we may well see bio-based eyewear mediating our encounters with virtual reality.