Engineering Styrofoam Into ‘Biofoam’

Plastic food packaging is a major source of pollution, but finding sustainable alternatives has proved challenging. This research team thinks fungi might be the answer.

If you see what looks like a beaker full of tiramisu in the lab of engineering professor Radika Bhaskar, PhD, you probably shouldn’t eat it.

“I’ve been asking my students to clean out this beaker for months, but they just want to see what’s going to happen,” Dr. Bhaskar laughs.

Dr. Bhaskar is bringing her engineering expertise to the biology lab to see if mycelium — the root structure of mushrooms — can be used as a sustainable alternative to Styrofoam. But as any biologist can tell you, working with living material can lead to some unexpected results.

When the students in Dr. Bhaskar’s lab noticed one beaker of fungi growing in unexpectedly wild ways, rather than throwing it out, they asked to keep it and see what happened. Over the course of the summer, the fungi stratified into layers that almost resembled tiramisu, with a thick white slab of mycelium on the bottom and a cocoa powder-like layer of mushrooms dusting the top. But when it finally came time to clean up, the fungi definitely didn’t feel like tiramisu.

“I thought I could just pull it out of the beaker, but it was stuck,” says Manni Zhang, a senior studying mechanical engineering. As Zhang used a hard scraper to loosen the mycelium from the beaker, she found that it had formed a dense, particle board-like structure, so strong she needed a bandsaw to cut it.

“It was crazy,” says Zhang.

Even though the experiment was an accident, it showed exactly what mycelium was capable of: forming dense, strong mycelial networks called “biofoams” that could help replace plastic products like Styrofoam. In a collaborative project with urban agriculture company Think and Grow Farms, Dr. Bhaskar hopes to harness that power to reimagine food packaging.

A hand compresses hemp growth medium into molds using a heavy weight.
To produce the mycelium, hemp chip growth medium must be compressed into molds using a heavy weight.

Styrofoam has been a mainstay of food packaging since the mid-20th century. But like all plastics, it relies on fossil fuels, and it can take upwards of 500 years to decompose. With over 1,000 tons of Styrofoam buried in US landfills every day, many are calling for a more sustainable alternative.

“It’s going to be really important to limit the amount of plastic we’re using, so we need to develop a substitute that’s easy to make,” says Tanisha Rutledge, a fifth year dual-degree student studying physics and mechanical engineering.

Dr. Bhaskar’s research also doubles down on sustainability by using chopped hemp — which is discarded in large quantities as a byproduct of the CBD industry — as the material the mycelium grows on. With high levels of lignin and cellulose that give it a woodchip-like texture, the hemp provides a perfect base for mycelial networks to grow dense and strong.

Coaxing fungi to grow Styrofoam-like mycelium still isn’t easy, though. Most industrial fungi growers are interested in growing fruiting bodies — known commonly as mushrooms — whereas Dr. Bhaskar hopes to block their growth, focusing on mycelium instead. That requires precisely balancing factors like temperature, light, and humidity levels to keep the fruiting bodies from sprouting, as well as ensuring as little external contamination as possible.

Tanisha Rutledge and Radika Bhaskar working on mycelium packaging projects
Tanisha Rutledge and Radika Bhaskar prepare to incubate the next tray of mycelium-hemp bricks.

The students in Dr. Bhaskar’s lab play a big role in helping overcome those challenges. When the research team struggled to maintain consistent moisture levels with a humidifier that needed to be filled daily, students like Zhang and Rutledge helped build a makeshift humidifier modeled after a toilet tank that only needed to be filled weekly.

“It’s really fun to see how energized the students are,” says Dr. Bhaskar, who prioritizes building a diverse team of students to help her with the research. “They really all bring their own interests into it.”

As they perfect their growing techniques, Dr. Bhaskar and her students also run engineering tests in the Bruner materials characterization lab to evaluate the strength and durability of the mycelium. Using small squares and long bricks of the fungal material, they can carefully subject it to tests of compression and bending strength to see how it holds up — and if it can replace Styrofoam. For now, their results are still in progress.

Though the tiramisu brick of mycelium her students made didn’t end up being part of their ultimate project — it used a different growth material — Dr. Bhaskar fondly looks back on it as she muses on how she strikes a balance between the precision of engineering and the unpredictability of biology.

“It makes you think in different ways,” she says. “Scientific discoveries are spurred by working across disciplines, so I love bringing the study of the natural world into this space of engineering.”

(From left to right: Manni Zhang, Tanisha Rutledge, Radika Bhaskar, Benjamin Ellenbecker)
Dr. Bhaskar works with a team of undergraduate students to engineer a fungal styrofoam alternative. (From left to right: Manni Zhang, Tanisha Rutledge, Radika Bhaskar, Benjamin Ellenbecker)
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Science and Technology