Simpson had bought a 3D printer for the lab in 2017. He hoped to use it to build custom parts that kept organisms alive inside of the NMR spectrometer for his research.
But the commercial resin he needed for high-quality light projection 3D printing (where light is used to form a solid) of those parts was expensive.
The dominant material for light projection printing is liquid plastic, which can cost upward of $500 a liter, according to Simpson.
Simpson closely analyzed the resin and spotted a connection. The molecules making up the commercial plastic resin were similar to fats found in ordinary cooking oil.
“The thought came to us. Could we use cooking oil and turn it into resin for 3D printing?” Simpson said.
Only one restaurant responded — McDonald’s
What came next was the hardest part of the two-year experiment for Simpson and his team of 10 students — getting a large sample batch of used cooking oil.
“We reached out to all of the fast-food restaurants around us. They all said no,” said Simpson.
Except for McDonald’s (MCD
In the summer of 2017, the students went to a McDonald’s location near the campus in Toronto, Ontario, that had agreed to give them 10 liters of waste oil.
Back in the lab, the oil was filtered to take out chunks of food particles.
The team successfully printed a high-quality butterfly with details as minute as 100 micrometers in size.
“We did analysis on the butterfly. It felt rubbery to touch, with a waxy surface that repelled water,” said Simpson. He described the butterfly as “structurally stable.” It didn’t break apart and held up at room temperature. “We thought you could possibly 3D print anything you like with the oil,” he said.
The experiment yielded a commercially viable resin that Simpson estimates could be sourced as cheaply as 30 cents a liter of waste oil.
Simpson was equally excited about another benefit of the butterfly the team had created.”The butterfly is essentially made from fat, which means it is biodegradable,” he said.
To test this, he buried a sample butterfly in soil and found that 20% of it disappeared in a two-week period.
“The concept of sustainability has been underplayed in 3D printing,” said Tim Greene, a research director for global research firm IDC who specializes in the 3D printing market. “The melted plastic currently being used as resin is not so great for the environment.”