Sweet science – how sugar could make 3D-printing better

​The type of sugar found in cough sweets could be the key to printing detailed structures that are currently impossible to produce with commercial 3D-printers.

Engineers at the University of Illinois built a 3D-printer that uses ribbons of hardened sugar alcohol isomalt, a water-soluble, biodegradable form of sugar. The substance sets almost instantly as it leaves the nozzle, allowing for ‘free form’ printing, and the creation of shapes that would not be possible using the layering technique of traditional additive manufacturing.

Sugar-printing has been explored in the past, but has faced problems with the sugar burning or crystallising, according to Matthew Gelber, the lead author of the research paper.

After finding a substance less prone to those problems, the team had to develop a machine that had the right mechanical details to print it properly – including temperature, pressure, nozzle diameter and speed.

“After the materials and the mechanics, the third component was computer science,” said Gelber. “You have a design of a thing you want to make; how do you tell the printer to make it? How do you figure out the sequence to print all these intersecting filaments so it doesn’t collapse?” 

The new device could have applications in biomedical engineering, cancer research and device manufacturing. “This is a great way to create shapes around which we can pattern soft materials or grow cells and tissue, then the scaffold dissolves away,” said Rohit Bhargava, a professor of bioengineering and director of the Cancer Center at the University of Illinois.

“For example, one possible application is to grow tissue or study tumours in the lab. Cell cultures are usually done on flat dishes. That gives us some characteristics of the cells, but it’s not a very dynamic way to look at how a system actually functions in the body. In the body, there are well-defined shapes, and shape and function are very closely related.”

Another advantage is the ability to make thin tubes with circular cross-sections, which is not currently possible with conventional 3D-printing. These could be used as scaffolds for tissue growth – the sugar would dissolve to leave tunnels that could be used like blood vessels.

“This printer is an example of engineering that has long-term implications for biological research,” said Bhargava. “This is fundamental engineering coming together with materials science and computer science to make a useful device for biomedical applications.”