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Medical applications expand limits of 3D printing
from AMT OCT/NOV 2021
by AMTIL
Medical applications extend the limits of 3D printing
It’s a safe bet that as time passes, the number of things you can additively manufacture and the ways in which you can do so will keep growing. One increasingly promising area is in the field of biofabrication.
After graduating as a materials engineer in the early 2000s and spending a decade working with newer production technologies such as 3D printing in the manufacturing industry, David Forrestal sought a career change and headed back to university for a PhD in tissue engineering. He graduated with a doctorate in 2019, developing new systems and methods for seeding living cells in 3D-printed bioresorbable polymer scaffolds – culturing cells and keeping them alive so a patient’s body can use them to restore tissue. Nowadays, Forrestal is an Advanced Biomedical Engineer at Herston Biofabrication Institute, a multidisciplinary institute at Royal Brisbane and Women’s Hospital (RBWH) which officially opened in February. It focuses on 3D scanning, 3D modelling and 3D printing of medical devices, bone, cartilage and human tissue. It has programs based around orthopaedics; burns, skin & wounds; vascular & endovascular surgery; urology; cancer care; craniofacial; and anaesthesia & intensive care. “We’re an institute, but we’re directly in the health system, with Queensland Health,” explains Forrestal, who says the work is about clinical impact rather than blue sky scientific projects. “We have an affiliation with the University of Queensland, but are focused on bringing new developments in biofabrication to benefit patients directly.” Among its facilities, Herston has a tissue culture lab, mechanical workshop, scanning and visualisation equipment, and a bank of various kinds of 3D printers. Current projects range from “lowrisk, ready-to-go now work”, such as anatomic models for surgical preparation on complicated fractures, to “more futuristic regenerative medicine techniques” involving organoids (lab-grown tissue grown from stem cells that is able to perform some of the functions of a full organ, which is therefore interesting for drug development and testing.) “From 3D printed surgical models to custom surgical guides to place drill-holes,” adds Forrestal. “And custom 3D-printed devices to change the shape of a radiation beam to dose a tumour more effectively, in a more focussed way, with fewer side effects. A workflow is currently set up for that.” As with most facilities with a collection of printers, each of Herston’s machines plays a different role. While not appropriate for biocompatible devices, their continuous fibre composite printer, for example, has great potential with external devices, such as splints and prosthetics, where a patient’s body has to be held in a certain way to help restore mechanical function. “The reason it’s so good is you’ve got other techniques, but none of them really match up to the stiffness and strength you get with the Markforged, especially when you’ve got the reinforcing fibre,” Forrestal explains. “It can bridge a gap between making a much more complex, assembled device with lots of metal reinforcement or even having to go and CNC something. That’s really the niche I see for that within our organisation.” The ‘horses for courses’ nature of 3D printing –an umbrella term for an array of technology families that are each themselves quite broad – can get missed by non-users. Throughout his work, Forrestal has used 3D printing for everything from tissue regeneration research to prototyping as a product design engineer at a major plumbing company. In a quirk of his academic career, his most-cited paper is on melt extrusion 3D printing with chocolate, based on a group project for a science expo. He and a student designed a heated jacket that could accommodate large-diameter syringes, with opensource slicing software, control software and an XYZ stage.
David Forrestal, Advanced Biomedical Engineer at Herston Biofabrication Institute.
“It was just a controlled way of pushing material out of a syringe in a robotically controlled pattern and then keeping it at the right temperature,” he recalls. “You could actually use that same printer as a bioprinter. You can mix in a hydrogel with live cells and you could do your bioprinting.” Since its beginnings in the 1980s, 3D printing has burgeoned, and both the number of solutions it offers and its overall market size have expanded handsomely. Even during 2020, the global industry grew 7.5% to be worth US$12.8bn. Average growth for the decade has been 27.4% annually. As for emerging additive manufacturing technologies, Forrestal says he sees great promise for volumetric 3D printing to impact his work as a bioengineer. Volumetric methods use a rotating vat of photopolymer resin, cured at many different angles by a light source. The engineering challenges are multi-faceted – including in chemistry, software and mechatronics – but the potential for highspeed jobs is vast. “That’s a really exciting development in bioprinting, because it means you can print these structures with living cells in them, and you don’t have a problem where you’re printing a whole day, while you’ve got to keep all the cells viable and fed with nutrients,” says Forrestal. “I think you’ll be seeing that 3D printing method in all sorts of different areas over the next 10 years or so.”
