Figure: A Nafion tube is sitting upright in a glass chamber and is held in place with a wire bent 90 degrees into the plane of the video. A microsphere suspension is then deposited into the chamber. Within seconds a black clear band (void of microspheres and matching the original black background) forms around the Nafion tube. This is the exclusion zone.
Figure: The same setup, except that instead of a microsphere suspension, pH-sensitive dye is pipetted into the chamber. Immediately, the dye is excluded from the interfacial water layers adjacent to the Nafion tube (visualized by the clear yellow-white ring around the Nafion tube). A pH color calibration is given at the top and middle of the video, and demonstrates that as the exclusion zone forms, the outer bulk water is filled with protons (denoted by the red color).