Dylan Sun/Staff Photographer

Materials engineering professor Trevor Harding owns more than 200 species of cacti.

Sophia Levin
Special to Mustang News

Cal Poly material engineering students are working on a prickly problem: formulating cactus-inspired material that could be the future of food packaging and biomedical devices.

Led by materials engineering professor Trevor Harding, the project’s current focus is replicating cactus spine composites.

“Instead of using petroleum-based plastics for food packaging as we currently do, we could use materials that derive from completely natural ingredients,” Harding said. “So that when you throw the packaging away, it would completely biodegrade and disappear without doing any harm to the environment.”

Instead of taking many years to decompose like products used now, this cactus material could decompose in just one year.

 I kind of got the idea that, well, if this guy could do this work, I could do it too, and maybe better.

Professor Trevor Harding

Another possible application of the material is in biomedical devices, where it would dissolve in the human body once it is no longer needed. Harding’s personal research largely focuses on materials for biomedical application, specifically studying how things degrade in the human body.

Surprisingly, the inspiration behind the project was an accident. Harding is very interested in cacti and owns more than 200 species. While looking through cactus books online, he discovered something unique.

“I came across a Ph.D. dissertation about replicating cactus spine structures for use in biomedical applications,” he said. “So I decided I was going to buy this dissertation. It cost about $100. It was terribly written, but when I read it, I kind of got the idea that, well, if this guy could do this work, I could do it too, and maybe better.”

And that is exactly what he did. Gathering a team composed of chemistry professor Hasan Palandoken, mechanical engineering professor Thomas Mackin and a group of six undergraduate students — who Harding is quick to admit are responsible for the bulk of the hard work — the project came to life.

The use of cactus spines might seem arbitrary, but Harding explained how unique the spines really are.

“They are a nature-made composite that is as stiff as fiberglass, but without any of the hazardous chemicals that we have when we make fiberglass,” Harding said.

The project is focused on trying to replicate cactus spines in the form of flat sheets, which can be done by extracting ingredients from the cactus itself or buying the ingredients, then mixing them to replicate the material. Either way, the project has proven to be extremely time-consuming. It takes approximately two days to make just one sample, and they need a large quantity of samples for the project to move forward. Students working on the project spend approximately 20 to 30 hours per week on it.

One of these students is materials engineering senior Ross Johnson, who said his work on the project is challenging, but rewarding.

Besides the project’s large focus on chemistry, the most challenging aspect of the project, Johnson said, “is learning how to organize a team of people, and how to work together to make sure that everyone is having an equal share.”

The project is currently funded by internal Cal Poly grants as well as Harding’s discretionary funds. The project’s next step will become clearer later this month, when Harding hears back from the National Science Foundation about a $250,000 grant. Receiving the grant will enable the team to do more research, develop the material more fully, produce more samples and collect more data.

If the team is able to make a material that can withstand a large series of tests, the next step will be talking to venture capitalists about marketing the material to vendors, though Harding admits that step is a long way away.

What Harding is most excited about, he said, “is the research side of it. If we can make a material that looks really good and somebody picks that up and runs with it, that’s fine.”

So far, more than 15 students have been involved in the project. By working on the project, students like Johnson have considered whether they would like to pursue further research. Harding hopes it will help to improve Cal Poly’s overall research reputation.

But beyond its impact at Cal Poly, Harding’s research has the potential to make a difference in food packaging and biomedical devices across the country.

Of all the possibilities for this project, Johnson said “the idea that these (cactus-inspired packagings) are readily biodegradable” is the most intriguing.

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