This project outlines a research plan for the development of a sensor to measure supersaturation activity in solution. The sensor consists of a tube chamber which is immersed in the solution and which is filled with a buffer solution containing a probe molecule pyranine. One side of the chamber consists of a ion exchange membrane which allows for the selective transport of protons from the exterior solution into the chamber, but does not allow the transport of the probe molecule out into the solution. The proton concentration determines the equilibrium between the protonated and unprotonated forms of pyranine. The chamber is irradiated by UV light through a fiber optic inserted into the chamber. The radiation excites both protonated and unprotonated forms of the molecule, causing emission of the protonated form at 440 nm and of the unprotonated form at 511 nm. The ration of the intensities at these two wavelengths is a function of the ratio of the ratio of the two molecular forms, and this in turn characterizes the proton concentration in the chamber (and presumably in the solution). The intensities are measured using a second fiber optic immersed in the chamber and connected to a photodiode detector. This sensor will be used to measure supersaturation. Recent evidence for source indicates that the concentration level affects the proton availability. In particular, previous research reviewed in the proposal demonstrates that the emission intensities of the protonated form of the molecular increases with sucrose concentration, while that of the unprotonated form decreases with increasing sucrose concentration.
