We wanted to create a detector, thus we could have designed it like following:
Where X is the molecule to detect, and Z the fluorescent signal. However, with this design, the communication between the bacteria (quorum sensing) wouldn’t have worked really well, we would have needed an important quantity of X at the initial time to be able to obtain an important diffusion that we could actually see. Indeed, the evolution of X would have been like following:
Thus, the next idea was to amplify X:
Like this, as soon as it would be detected, by a bacterium, the bacterium would re-create some X, and the quorum sensing would work, as we would have this evolution of X: