9. The Science Behind pH Monitoring
The TrakStation technology is based on the principle that fluorescent dyes emit characteristic wavelength spectra at different pH levels.
The sv2 sensor is a modified optical cuvette that creates a liquid well in which the pH of a media sample can be tracked. The sensor fits into a fiber optic fixture and includes a special membrane located at the bottom of the liquid well. The membrane is impregnated with a fluorescent dye that emits characteristic wavelength spectra at different pH levels. Periodically, the instrument measures the pH of the sensor. (You can choose the timing of this measurement to be at one or thirty-minute intervals.)
During measurement, the fiber optic delivers flashes of green light from a monochromatic light source to the sensor. The light excites the dye in the membrane and induces fluorescent light emission at two wavelengths. At 600 nm, the intensity of light emission varies with the pH of the media. At the second, reference wavelength, 568 nm, the emission does not depend on the pH.
The intensities of emissions at these two wavelengths are collected by photo-detectors in the TrakPod. The instrument calculates the ratio of the two wavelengths and converts it to the pH. Using a ratio of emission intensities allows determining the pH independently of any varying characteristics of the particular instrument used. The instrument also uses the reading frequency and the duration of the test to make small automatic corrections to the pH signal.