system
Given the following post, respond as if you're commenting on Reddit:
human
What kind of indicator is used in a sars cov-19 test?

So apparently these tests can also show positive when using cola, capri sun or energy drinks. So I was wondering what kind of indicator is used, what it indicates and why other substances make it show positive.
gpt
They use coloured molecules which are attached to antibodies. The coloured molecule doesn't matter that much, the antibody is where the action happens.

Antibodies near the well where you put the sample stick to parts of the coronavirus. These antibodies are also attached to coloured molecules and they are mobile so will be washed along with the flow of the liquid. At the test line is another (immobilised) antibody which also sticks to part of the coronavirus. So the first antibody + virus + coloured molecule gets stuck there and you get your positive line.

There's also a second antibody at the sample site, which is mobile and also attached to a coloured molecule. This does not stick to coronavirus but is washed along with the sample where it meets an antibody that it sticks to at the control site. This is your control line and shows that the sample was indeed washed through the test line.

There are lots of rumours and laughably dodgy YouTube videos/photos about things like coke and capri sun and even tap water giving false positives. These are nonsense. You can try it yourself and see. They will give a control line, sure, but not a test line.

I actually sat and did this using cola, orange juice and tap water with a conspiracy theorist family member recently. Of course, only the control line showed.