“…19 The experimentally recorded response times are also faster than for optodes based on plasticized PVC as a substrate, which require up to minutes to establish an equilibrium. [20][21][22] On the other hand, optodes using a hydrogel matrix as the substrate show response times that are below 30 s; however, indicator leaching is clearly observed under continuous flow operation. 23 Finally, the present response times are shorter than in the case of our previously presented sensors 15,24 using porous silica glass (thickness: 1 mm) as the substrate, which required 5 min or longer until equilibrium.…”