Nanoengineering cyborgs

What’s he building in there?

the Fulcrum
Published: Mar 14

The problem

CYBORGS AREN’T SCIENCE fiction. All around us people with pacemakers, insulin pumps, and prosthetic implants continue to live normal lives because of mechanical and electronic parts within their bodies. It’s not sci-fi; it’s mundane.
But that doesn’t mean combining human bodies with technology is scientifically simple. Even relatively straightforward implants need to be biocompatible or human tissues won’t accept them. Implants also need to be reliable.
We may take it for granted, but our bodies are amazingly robust. When we sustain injuries, we heal—but implants don’t. Hip replacements are some of the most successful prosthetics, but even they have a 20 per cent failure rate after 20 years.

The researcher

Amirhossein Ketabchi came to Canada to do his undergraduate degree in engineering at the University of Ottawa. Here he found a tight-knit community of students and decided to stay in Ottawa to continue graduate studies. Ketabchi is now a master’s student in the Surface Nanoengineering Laboratory with an interest in medicine and bio-materials.

The project

Titanium is one of the best bio-materials for implants. It’s light, strong, non-toxic, resistant to corrosion, and isn’t bad at osseointegration—the merging of bone and non-bone into a single object. Not all metals are good at this, but titanium isn’t bad. Ketabchi thinks he can engineer it to be better.

The key

In order to engineer better biocompatibility, Ketabchi modifies the surface of the titanium. Because your body’s cells are in contact with implants, modifications must change nanoscopic details. Ketabchi does this nanoengineering by dipping titanium into an acid mixtures. The acid causes an oxide layer of open nanotubes to form on the surface of the titanium, which human bone can then grow into. Nanoengineering the surface of titanium like this improves its biocompatibility.
But soaking metal in strong acid for hours and hours weakens it, and the last thing you want is a titanium pin in an implant snapping. So Ketabchi knows there has to be a tradeoff between biocompatiblity and preserving strength to withstand years of fatigue. He tests the endurance limit of pin after pin, looking for the perfect compromise between biocompatibility and strength.

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