Can you imagine a smartphone with a wooden touchscreen? Or a house with wooden windows? Probably not — unless you’ve heard of transparent wood. Made by modifying wood’s natural structure, this material has been proposed as a sturdy, eco-friendly plastic alternative.
However, wood’s biodegradability is often sacrificed in the process.
Now, researchers hope to change that by creating transparent woods from almost entirely natural materials and making them electrically conductive. Last week, they presented the findings as part of the American Chemical Society (ACS) Spring 2025, which ran from March 23-27 in San Diego.
This slice of semi-transparent wood is made with natural materials and could be used in applications from wearable sensors to energy-efficient windows: “In the modern day, plastic is everywhere, including our devices that we carry around. And it’s a problem when we reach the end of that device’s life. It’s not biodegradable,” explains Bharat Baruah, a professor of chemistry at Kennesaw State University and the presenter of this research. “So, I asked, what if we could create something natural and biodegradable instead?”
Baruah became interested in transparent woods thanks to his outside-of-work pursuits — his woodworking hobby. However, he realised that the transparent woods reported by other scientists used materials such as epoxies, a form of plastic, for strength. To find natural materials that would keep wood sturdy and stable over time, he again turned to his personal experiences.
Growing up in Assam in northeastern India, Baruah encountered buildings that had stood for centuries, long before the modern-day cement version was invented. Instead, ancient masons created cement by mixing sand with sticky rice and egg whites. This led Baruah to hypothesise that those same materials might be perfect for incorporating strength and stability into his transparent woods.
According to Baruah, wood has three components: namely cellulose, hemicellulose and lignin. And to make it transparent, the lignin and hemicellulose are removed, leaving behind a porous, paper-like cellulose network. Then, a colourless material fills those pores, restoring some rigidity.
Joined by Ridham Raval, an undergraduate student at the university, Baruah transformed pieces of balsa wood into natural, semi-transparent woods by pulling out the lignin and hemicellulose using a vacuum chamber and chemicals, including sodium sulphite (a lignin-dissolving agent), sodium hydroxide (a version of lye) and diluted bleach.
Then, the pores were refilled with an egg white and rice extract mixture and a curing agent called diethylenetriamine to keep the material see-through. The researchers say that these reagents, when used in small amounts, such as in this experiment, pose little threat to the environment.
In the end, the team was left with semi-transparent slices of wood that were durable and flexible. The team next investigated some potential applications for their engineered woods, including replacing glass windows. Again, Baruah tapped into his woodworker skills and renovated a birdhouse into a tiny, one-windowed, insulated home.
He put the birdhouse under a heat lamp and placed a temperature gauge inside to test the modernised abode’s energy efficiency. The temperature inside the house was between 9 and 11 degrees Fahrenheit (5 and 6 degrees Celsius) cooler when transparent wood was used than when glass was, suggesting that this new material could be an energy-efficient alternative to glass in windows.
To expand the potential applications of transparent wood, the team also incorporated silver nanowires into certain samples. This addition allowed the wood to conduct electricity, which could be useful for wearable sensors or solar cell coatings. Silver nanowires aren’t biodegradable, but the team hopes to conduct further experiments using other conductive materials like graphene to maintain their fully natural transparent woods.
Though additional research is needed to boost the woods’ transparency, Baruah is happy that this initial step used natural and inexpensive materials. “I want to send a message to my undergraduate students that you can do interesting research without spending thousands of dollars.”
Please Note: This article was republished under a 4.0 Creative Commons License from the American Chemical Society (ACS).
