Question: how do these chemical switches work

Thomas Farrugia answered on 25 Jun 2015:

Hey hassanali – had answered this in the chat today, but in general the idea is that you can think of chemical reactions as being “on” or “off” if they require the presence of another chemical to make them work.

In my case the enzymes in the films are used to cause a reaction to happen – without them the chemical reaction can’t happen, so if they’re not in solution the reaction is “off”, but can be switched “on” if the film is placed inside. You could also turn it on by adding the enzyme directly into the solution, but hten it’d be very hard to remove – you’d need some form of separation technique.

With a material that is made mostly of protein you could easily stop the reaction by just removing the film, especially if it is stuck onto something.