Insulin pumps improve the lives of many of the 415 million people with diabetes around the world
by monitoring blood sugar, delivering insulin, and preventing the need for constant finger-pricking and blood testing.
These small machines include a pump and a needle, which can sense glucose levels, feed back to the pump,
and then calculate how much insulin to deliver through the needle. But they have a catch: they’re temporary.
Within a few days, glucose sensors have to be moved and replaced. And it’s not just glucose monitors and insulin pumps that have this problem,
but all bodily implants, at different time scales. Plastic prosthetic knees have to be replaced after about 20 years.
Other implants, such as those used for cosmetic reasons, can meet the same fate in about 10.
That isn’t just a nuisance: it can be expensive and risky. This inconvenience happens because of our bodies’ immune systems.
Honed by several hundred million years of evolution, these defensive fronts
have become exceptionally good at identifying foreign objects. Our immune systems boast
