Okay so what is the nitty gritty science that is happening to let us detect these microscopic things that can make us so sick? It is really easy to say in one sentence:

This method is based on an antibody-antigen immunoassay using fluorescent labeled antibodies.

Below each of those bits are broken down:

1. Antibody-Antigen

Antibodies and antigen behave a lot like those lock-and-key examples you may have heard about. The antigen in this case is the virus. If you have norovirus, that means you have norovirus antigens floating around in you making you sick. The antibody is what your body creates to fight off the antigen. It does this by creating an antibody that is unique for norovirus antigens, so it will float around until it finds a norovirus antigen, and hten it will bind to it. By binding to the antigen this takes it off the market for injuring you.

2. Antibody-Antigen Immunoassay

In this device we are recreating what naturally happens in your body to detect and fight off viruses, also referred to as an immune response. Immunoassay means that we are testing (assaying) the immune response between antibodies and antigens. In your body that means that you are fighting off the virus. In our device we purchase norovirus antibodies, and then we mix them with a water sample. If the water sample is clean, nothing will happen, the norovirus antibodies wont have anything to bind with. BUT if the water sample has norovirus, then the norovirus antibodies will explore the entire water sample and bind to any norovirus antigen they come across. We measure the level of binding that occurs as an indicator of how much norovirus antigen was present in the sample.

3. Antibody-Antigen Immunoassay using Fluorescent labeled antibodies

Unfortunately, norovirus is extremely small. A typical norovirus antigen is less than 10nm in diameter. That is 100 times smaller than the width of your hair. Even if you had a water sample with crazy high amount of antibody-antigen binding ocurring, it would be impossible to actually see anything happening. Not only is it impossible to see with your eyes, but it is so small it is even hard to see with many microscopes. This is why we label our antibodies with fluorescent particles. A fluorescent particle is a type of nanoparticle. Imagine a beach ball that glows when you shine it with light. Now imagine a beach ball that is 1um wide (10 times smaller than your hair). We label all of our norovirus antibodies with a micro-glowing-beach ball. Everything is still really small, but now when antibodies bind to antigens, they have the added size contribution of the fluorescent particle so we can see it with our smartphone microscope. And thats it! Although there is lots of amazing science going on behind the scenes, all we see is tiny pinpricks of bright light that correlate to clumps of these fluorescent antibodies binding to the norovirus antigen. The bigger the clumps of light = the higher the concentration of antigen.