What are the acceptable slope limits for an ISFET electrode?

Document ID

Document ID TE2767

Published Date

Published Date 27/05/2017
Question
What are the acceptable slope limits for an ISFET electrode?
Summary
Slope limits with ISFET.
Answer
Unlike the limits for a glass electrode, the limits in the software for the system are 67% to 110% for the ISFET slope.  Any slope value obtained after calibration that is within this range is considered acceptable.  The ISFET probes are a solid state device and work on slightly different electrochemical principles from the traditional glass electrodes.  The actual algorithm is proprietary, but it is designed to approximate glass electrodes.  If, the slope value is outside the 67%-110% criteria curing calibration, an E06 is triggered.