Fig. 2

24-h measurement profile of the contact lens sensor in the water bath without external electromagnetic interference to assess signal drift and noise. The profile is flat, the fluctuations between the measurements are between the minimum of 18.8 mV eq at 10:00 o’clock and the maximum of 27.0 mV eq at 02:05 on the next day (8.2 mV eq difference, noise). In the first two hours, an “adaptation” took place, in which the curve increases for an unknown cause. X-axis time, Y-axis from − 15 to 30 mV eq.