Schemes of measurement setups, instrumentation setups and sensor cross section. Homemade two filter read-out approach (a) for ratiometric measurements and pH-mini setup (b) for intensity based measurements. Plastic head sensor setup (c) for longtime measurements of multiple sensor spots, homemade flow-through cell (d) for all intensity based measurements and imaging setup (e) for chemical imaging. Schematic cross-section of the sensor foil (f). Sizes are not to scale.