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The SeaFETâ„¢ Ocean pH Sensor was developed by Dr. Kenneth Johnson of the Monterey Bay Aquarium Research Institute (MBARI) and Dr. Todd Martz of the Scripps Institution of Oceanography, University of California San Diego. Satlantic has collaborated with MBARI and Scripps to make the instrument commercially available to the research community.

The sensing element of the SeaFETâ„¢ is an ion sensitive field effect transistor (ISFET). This class of device has been used for pH sensing in industrial processes, food processing, clinical analysis and environmental monitoring. The advantages of the ISFET include robustness, stability and precision that make it suitable for ocean pH measurement at low pressure.

The SeaFETâ„¢ reports pH determined potentiometrically in two different ways. The ISFET potential is measured against a reference electrode bearing a liquid junction (internal reference) and against a solid state reference electrode without a liquid junction (external reference). This approach provides the user with the ability to quality assess instrument performance and ultimately achieve a greater understanding of the state of acid/base equilibria in seawater.