To understand what's described in this article, it helps to start by understanding how a lateral flow test works: [0]. Basically, the active ingredient in a lateral flow test consists of two components chemically bonded together: a colored material and a chemical that bonds to the thing we're testing for, called the "conjugate".<p>If the desired material is present in the flowing liquid, the conjugate bonds to the test material, and the entire particle is carried along in the flow of liquid. Then, we look for the presence of the colored material downstream. If the color shows up, the test is positive, if not the test is negative.<p>The problem that this paper is trying to solve is that previously used colored materials (e.g. tiny particles of gold) can't be detected in very small amounts because the color blends in with the background noise, if there's only a very small amount of it.<p>These new particles consist of a tiny diamond with a carefully designed irregularity in the crystal structure, where a carbon atom in the diamond is replaced by a nitrogen atom. These diamonds don't just emit a single color of light. Instead, they can emit different colors of light if you shine the right type/amount of microwaves on the diamonds.<p>As a result, these diamonds don't blend in with the background noise, even at very small amounts, because the background doesn't change color as you shine different microwaves on it.<p>They were able to detect a concentration of these diamond particles 100,000 times less strong than the prior gold particles. As a result, a test made with these particles can return a positive test result with much smaller amounts of the material being detected in the initial sample.<p>As an example, the researchers were able to make a test that could detect the presence or absence of single HIV RNA molecule. This test combined a 10 minute chemical treatment step (amplification), followed by a lateral flow test based on these diamond particles and a (previously known) conjugate for the HIV RNA molecule.<p>[0]: <a href="https://en.wikipedia.org/wiki/Lateral_flow_test" rel="nofollow">https://en.wikipedia.org/wiki/Lateral_flow_test</a>