A 7 μW Offset- and Temperature-Compensated pH-to-Digital Converter

Figure 7

Measured digital output of the sensor, as expressed in (2), for buffer solutions of different pH levels (a), pH-sensor output drift and noise at pH7 (b), and sensor nonlinearity versus pH of buffer solution (c). (Note that for every pH step, the data of 10 minutes of cleaning and refilling the plastic cubic container have been removed.)

(a)

(b)

(c)