ISFET pH electrodes: Are they used in Senova Systems’ pH Sensor?

We have received some questions lately about whether Senova Systems is releasing a calibration-free pH scanner that uses an ISFET electrode. This is definitely not part of our technology platform, and I’m here to explain why.

An ISFET is an ion-sensitive field-effect transistor used for measuring ion concentrations in solution. An ISFET electrode sensitive to H+ concentration can be used in place of a conventional glass electrode to measure the pH of a solution. However, it also requires a reference electrode to operate. If the reference electrode is of the AgCl or HgCl2 classical type, it will suffer the same limitations as conventional glass pH electrodes (junction potential, KCl leak, and glycerol leak in case of gel electrode)1.

How the pHit sensor works

The Senova Systems pHit sensor utilizes a carbon surface containing proprietary analyte sensing molecules (ASMs). When subjected to a voltage scan, these ASMs reversibly bind protons (hydronium ions); the voltage at which this reaction occurs is dependent upon the concentration of hydrogen ions in the sample. The pHit sensor contains a novel solid state reference which renders the sensor completely wet-dry reversible so it can be kept dry between uses. This feature not only reduces drift, but eliminates the expenses associated with wet storage and multiple calibration buffers, time consuming maintenance, and an often contaminated workplace.

Do you have any questions you want answered or myths you want clarified? Send us an email to and we’d be happy to address your questions or concerns.


1 – Wikipedia contributors. “ISFET.” Wikipedia, The Free Encyclopedia. Wikipedia, The Free Encyclopedia, 3 Jul. 2012. Web. 11 Sep. 2012.

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