3D Printing in the Lab: University of Helsinki Researchers Create Polypropylene Microreactor

When it comes to creative uses of 3D printing, we usually think of art right away – but artists aren’t the only ones capable of thinking creatively and translating that creativity with their 3D printers. Scientists have been known to put 3D printers to ingenious use to improve or even create new lab equipment, and researchers on the Faculty of Pharmacy at the University of Helsinki recently built an entirely new 3D printed device to speed mass spectrometry analysis.

Typically, microchips used for mass spectrometry analysis at the university are prepared in large batches in the cleanroom, and researchers often get stuck waiting for the full batch to be ready before they can proceed with their work. Dr. Gianmario Scotti and Markus Haapala had a better idea, though – what if they could skip the cleanroom phase altogether by fabricating a small, disposable container that could be connected to a mass spectrometer for chemical reaction analysis?

(L to R) Nilsson, Scotti and Haapala


“I had been working with the 3D printing of stainless steel, so 3D printing was an obvious choice for the fabrication method,” said Dr. Scotti. “But 3D printing of steel is not very economical, so we decided to stay with plastics.”

Finding a plastic material that wouldn’t be damaged by the solvents used in chemical reaction tests was a bit difficult, however. The researchers decided that polypropylene would be perfect, thanks to its high chemical resistance, but although it’s one of the most commonly used plastics in the world, it’s difficult to 3D print and thus tough to find as a 3D printing material. Dr. Scotti finally found a supplier in Germany, however, and they began prototyping until they had a 3D printed microreactor.

A microreactor, for those not familiar with chemistry, is a small container with a stir bar for mixing chemical samples and a thin needle for spraying and ionizing the sample for analysis with a mass spectrometer. It sounds as though it should have been a multi-piece print job, but the researchers were able to 3D print it all in one piece by pausing the print job, inserting the stir bar and ionization tip, and then resuming. 3D printing each microreactor took about an hour. They also used a print platform made from polypropylene, as the material does not adhere well to other types of substrates.

Then it was time to test the microreactor with an actual mass spectrometer, which is fellow researcher Sofia Nilsson’s area of expertise.

“By hooking up a microreactor to a mass spectrometer, reactions can be followed in real time with high sensitivity and selectivity,” said Nilsson. “Thanks to this, it’s possible to detect intermediates and even transition states of reactions, making the stipulation of a reaction mechanism possible, which is what my research is focused on.”

[Photo: Elina Raukko]

The 3D printed microreactor worked just as well with the mass spectrometer as a standard microchip would, if not better – and there’s now no need to wait for a full batch of microchips to be prepared.

The research team documented their work in a paper entitled “A miniaturised 3D printed polypropylene reactor for online reaction analysis by mass spectrometry,” which you can access here. The paper’s authors include Gianmario Scotti, Sofia M.E. Nilsson, Markus Haapala, Päivi Pöhö,  Gustav Boije af Gennäs, Jari Yli-Kauhaluoma and Tapio Kotiaho.

[Source: University of Helsinki]

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