Question: What kind of chemicals do you use to create a tissue expander?

Jess Smith answered on 11 Mar 2014:

This is a really good question!

We use special types of polymer. Polymers are molecules that are made of long chains of connected atoms, and they have really interesting properties. Plastics are made up of polymers, and they can be designed to be hard or soft, stretchy or rigid, and have different interactions with solvents (like water).

Our polymer is a hydrogel. Imagine a big 3d net of polymer chains. The individual chains are ‘cross-linked’ (this means that there are extra bonds tying different polymer chains together). When the polymer is dry this net is all squashed up and the chains are crumpled together. When we get the polymer wet, the water comes in to the net and pushes the chains apart. Now all of the long chains are stretched out straight, and the volume of the whole device has increased.

In the body we put a device in dry, and it absorbs water from inside of the person. This makes it grow, which stretches the skin. When skin is stretched, the cells multiply making new skin. When the operation needs to happen, they take out the tissue expander, and pull the newly made skin across. This is helpful in operations where you need to remove some skin (because of damage or disease).

When the polymer is dry it is hard and like glass. When it is wet it is still solid, but it is also squishy- a bit like a hard jelly!

I hope this helps