A sterile, biocompatible sensor spot for detection of dissolved oxygen or pH in the physiological range is immobilised at the bottom of a flask or well. The sample diffuses into the sensor and changes the fluorescence of the incorporated dye depending on its pH value and oxygen content, respectively. The sensor signal is read out from the bottom via fluorescence lifetime detection with the reader and transformed to the pH or oxygen values automatically by the software. Measuring points are taken at user-defined intervals. Due to the non-invasive, optical method, no sampling or staining has to be performed.
