Figure 1.

(a) Schematics of the working principle of IRIS showing the interference of light reflected from the reference plane (Si-SiO₂ interface) with that from the top surface. (b) Resulting shift in the wavelength dependent reflectance characteristics due to added biomass. A simple optical imaging system (c) using either continuously tunable or discrete wavelength sources can be used to determine the surface profile as shown in a typical IRIS image of protein spots (d) allowing for measuring molecular binding for thousands of spots.