Research & Innovation

If you have a clogged artery or a damaged joint, your body may be in need of some help to fix it. And if that help comes in the form of an artificial implant, wouldn’t it be ideal if the implant could simply break down over time and get safely absorbed by your body?

Such bioresorbable materials exist and are used, but making them for medical implants can be tricky and expensive. That’s why McAfee and colleagues at IT Sligo are seeking to make their manufacture more efficient.

Implants that don’t outstay their welcome

“Bioresorbable materials have been used for a whole host of different devices, such as stents, and they are increasing in popularity,” says McAfee, who is a lecturer in IT Sligo’s department of mechanical and electronic engineering. “Over time the material breaks down into carbon dioxide and water and lactic acid and we excrete it.”

Implanted materials can be used to deliver drugs in hard-to-reach places, such as inside arteries or in the eye, and they can also be used in bone-fixation screws, she explains.

“Bone needs loading to heal, so if you have metal in there it is taking the load and the bone doesn’t really regenerate with the same strength. But with resorbable implants the bone takes over the strain as the implant is resorbed. Also you don’t need more surgery to take out the implants afterwards.”

More efficient manufacturing

The downside of bioresorbable implants is their expense, notes McAfee, who is a researcher at the newCentre for Precision Engineering and Manufacturing at IT Sligo.

“These materials are very expensive to manufacture,” she says. “They are used for packaging, and in that application they are quite cheap, but to go into the body they need to be highly purified and that costs. They can also be difficult to process, too – to turn them into screws or fibres they are exposed to heat and pressure and they break down.”

McAfee is the co-ordinator and principal investigator on the EU-funded Bio-PolyTec project, which is figuring out how to keep a rein on those costs by monitoring quality during manufacture.

“We look at the degradation of the polymer and the dispersal of fillers,” she explains. “We are developing sensors that we can use during the manufacturing process to tell if degradation is occurring and also, if drugs or other bioactive particles are being added, we can see if they are being well dispersed. In the extrusion machine we shine a light source onto the melt and collect the light coming back – changes in light scattering can tell us about the structure of the material.”

The €1m project, which IT Sligo co-ordinates, kicked off last December and involves several partners, including Scaffdex, which makes resorbable ‘spacer’ devices to implant into joints in the hands and feet of people with arthritis – the device is gradually replaced by the patient’s own cells and tissues.

“They are soft discs of knitted fibre that go into the joint,” says McAfee. “They want to bring down the scrap rate of material so the implants can be produced more cost effectively, so we are working with them on that.”

The work should translate into other implants that use polymer-based materials, such as PLA, she notes.

“Different polymers or fillers might need some modification to the approach, but in this project we want to crack the physical hardware and analysis of the spectral data.”

Getting a kick out of research

McAfee liked physics and maths in school in her native Belcoo, Co Fermanagh, and she still gets a kick out of solving problems today.

“I love learning in research and trying to piece things together in your head, solving problems,” she says.

Her career saw her travel to England after A-levels, when she was awarded a scholarship with chemical company ICI. That whetted her appetite for engineering so she studied at Queen’s University Belfast(QUB), going on to do a PhD there in improving the efficiency of plastics processing.

When she got a lectureship position at QUB she was the second woman in her department. The other was Prof Eileen Harkin-Jones, whose success in academia McAfee found encouraging.

Engineering solutions to big issues

For the last five years, McAfee has been lecturing and researching at IT Sligo, and she encourages a wider view of engineering and the kinds of problems it can tackle.

“There are so many future challenges in the environment and transport and medicine, and personally I find it rewarding to be doing research to help make medical devices more available,” she says. “People think that engineering is heavy and dirty, but it is the exact opposite of that, it is trying to make our environment and our lives and health better.”