Patent ID: 7615140
Filing Date: 2009-11-10
Classification: G01N

Abstract:
1. A potentiometric sensor for measuring a potentiometric variable of a medium, comprising: a ISFET whose gate region has an ion-sensitive surface which can be exposed to the medium and which outputs an output signal which depends on the concentration of the ions at the ion-sensitive surface of the gate region; an evaluation circuit with a measuring input to which the output signal of said ISFET is applied, wherein said evaluation circuit is designed to output a measured value for the potentiometric variable depending on the output signal; a measuring resistor that is arranged between the output of said ISFET and the input of said evaluation circuit; a monitoring circuit to determine the voltage drop over said measuring resistor; and a bridge section running parallel to said measuring resistor to bridge said measuring resistor wherein said bridge section exhibits a switch with which said bridge section can be opened and closed.