Issue 3, 2007
Innovation at Macquarie
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| Working together: Chiropractor Dr Ray Hayek, Masters student Samar Hamid, Dr Russell Connally and Alf Sfrise with a prototype coil (far right) and the successful design (middle). |
Regenerating damaged spinal nerves
Staff from Physics, Chiropractic and Macquarie Engineering & Technical Services have joined forces to work on a project aimed at regenerating damaged spinal nerves, Dr Russell Connally brings us the story.
This project started as a pain in the neck. Like most kids, my son loves to ride on his dad's shoulders and after a weekend of pony riding, my neck was killing me. Over the next week the strain got worse and I was advised to seek the help of Dr Ray Hayek, an academic and chiropractor at Macquarie University. As Ray corrected the problem with my neck, we discussed his project aimed at regenerating damaged spinal nerves through gentle in-situ electrical stimulation. The project, which began as part of postgraduate student Samar Hamid's Masters research, interested me and I suggested I might be able to help with the electronics.
Our ambitious project required the electronics to be powered and controlled via an external magnetic field. A test animal (rat) would undergo treatment within a cylindrical induction coil similar to MRI chambers used for human subjects. We needed to make the electronics small to minimize both the surgery and likelihood of post-operative irritation. Efficiently powering the electronics proved to be a tougher task than originally envisaged and a number of coil designs were tried and discarded.
Professional toolmaker Alf Sfirse from Macquarie Engineering and Technical Services (METS) took on the task of winding our induction coils, all seven of them. Looking back, the first coil was the most difficult and worst design we could have envisaged. We used about two kilometres of wire and the assembly weighed about 20 kg, but the coil was roomy enough for a rat and his extended family over a generation or two! The difficulty we faced was matching the magnetic characteristics of the very large drive coil with the very small coil implanted within the animal. By a gradual process, we arrived at a successful design and are currently working on encapsulating the implantable electronics in a biocompatible polymer to protect both the circuit and surrounding tissues. Once complete we will move to testing the device in an animal model.