In the days when I was an active experimental scientist, one of my areas of interest was in how things stick together – living cells, mineral particles, oil drops, etc. Another of my interests was distance running. Not that I was much good at it, but I did keep on trying, until eventually I tore a cartilage in my knee during a half-marathon.

There came a time when I had to make a decision as to whether to keep doing real science, or focus on making science accessible to others through writing and broadcasting. I chose the latter, but if I had chosen the former I would have spent my next decade working on self-repairing glues – both in biology, where nature is well ahead of us, and in engineering, where we still have a lot to learn.

Sometimes I rather wish that I had kept at it, because my knee is now at the stage where the ends of the bones are rubbing together, and my doctor is making ominous noises about replacing it with an artificial one. The problem with artificial knees, though, is that sooner or later the glue holding the metal to the bone starts to fail and the joint gets wobbly.

It would be great to have a glue, or a material, that self-repairs. Scientists at NASA and the University of Michigan have now developed such a material for use in spacecraft ( It consists of two layers of polymer with a liquid trapped in between. The trick is that the liquid solidifies when it comes into contact with air, as might happen if a micrometeorite punctures the shell of a spacecraft.

Clever, eh? But cleverer still would be to develop a similar material (maybe with multiple layers) where the liquid solidifies on contact with bone or bodily fluids. Then, perhaps, we could have artificial joints that don’t work loose over time.

I’d be all for that. All it needs is lateral thinking to overcome lateral movement.

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