Development of a quantitative optical biochip based on a double integrating sphere system that determines absolute photon number in bioluminescent solution: application to quantum yield scale realization.

We report a new design of an optical biochip based on a double integrating sphere system to quantify the absolute number of the emitted photons or the total photon flux by a whole cell bioluminescent biosensor, for water toxicity detection, based on genetically engineered Escherichia coli bacteria carrying a recA::luxCDABE promoter-reporter fusion. The new design of the double integrating sphere system does not require any external standard light source for calibration of the tested bioluminescent solution and allows a direct determination of the total photon flux of the bioluminescent solution. In our design, we required that the two spheres are symmetric (have the same radius and reflectance) with a surface area larger than the cut cap area between the spheres.