Sea Technology

FEB 2017

The industry's recognized authority for design, engineering and application of equipment and services in the global ocean community

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18 st / February 2017 providing the ship time to collect the validation data pre- sented in this article. References For a list of references, contact Charles W. Branham at ST The Deep SeaFET has been used in field validation on floats during the development process. It was also evaluat- ed during the Wendy Schmidt Ocean Health XPRIZE com- petition in a field trial off the coast of Hawaii in May 2015. In the surface ocean and across the thermocline, the Deep SeaFET performed extremely well, to within ±0.005 pH units of the validation measurements. In the deep ocean, however, the sensor was less accurate, measuring pH to ±0.02 of the validation measurements. Overall, the Deep SeaFET performed extremely well in comparison to other technologies tested and was awarded second prize for accuracy by the XPRIZE award committee in 2015. Ef- forts to improve the modeling of the pressure response of the sensor in the deep ocean have continued, with updated designs and additional field testing by scientists at both Sea- Bird Scientific and MBARI. Conclusion Laboratory and field tests of the Deep SeaFET have demonstrated the stability and accuracy of ISFET technol- ogy necessary for incorporation of pH sensors into routine ocean monitoring on autonomous vehicles. Further work by Sea-Bird Scientific engineers and sci- entists will be directed toward improving the calibration methodology, mechanical robustness and manufacturabil- ity. In the coming year, the improved Deep SeaFET proto- types will be evaluated and validated in the field. Acknowledgments We thank the Wendy Schmidt Ocean Health XPRIZE for Charles W. Branham is the senior chemist at Sea-Bird Scientific with responsibilities including oceano- graphic sensor design focusing on the characteriza- tion, optimization, calibration and validation of the pH sensor line. He received his Ph.D. in process analytical chemistry from the University of Washing- ton. His research interests are focused on developing stable, robust, precise and fast-responding sensors for the analysis of complex systems. David J. Murphy is the director of science for Sea- Bird Scientific with specific responsibilities in oceanographic sensor design, characterization and calibration. In his 25 years with Sea-Bird, Murphy's responsibilities include providing science input for product development, SBE's metrology work, over- sight of SBE's calibration facilities, consultation with Sea-Bird's key customers, presentations at scientific conferences, and customer training. Ian D. Walsh is the science director and senior ocean- ographer at Sea-Bird Scientific with responsibilities over the biogeochemical and optical instrument lines. Walsh oversees Sea-Bird Scientific's training classes and over-the-Web training. Walsh has a Ph.D. from Texas A&M University and an extensive background as a seagoing oceanographer. JW Fishers Mfg. Inc. 1953 County Street, East Taunton MA 02718 USA (800)822-4744 or (508)822-7330 / Email: / www.jwfish Get a clear view of the bottom with a JW Fishers Side Scan Sonar! - Low cost - 500' depth capability - Single or dual frequency - Up to 2,000' (600m) range - Display on laptop or tablet - Simple to operate - "Turn key" system - Store files (XTF format) - Commercial construction Tires and debris on the ocean floor

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