A novel design is demonstrated for a solid state, reagent-less sensor capable of rapid and simultaneous measurement of pH and Total Alkalinity (A_T) using ion sensitive field effect transistor (ISFET) technology to provide a simplified means of characterization of the aqueous carbon dioxide system through measurement of two “master variables”: pH and A_T. ISFET-based pH sensors that achieve 0.001 precision are widely used in various oceanographic applications. A modified ISFET is demonstrated to perform a nanoliter-scale acid–base titration of A_T in under 40 s. This method of measuring A_T, a Coulometric Diffusion Titration, involves electrolytic generation of titrant, H⁺, through the electrolysis of water on the surface of the chip via a microfabricated electrode eliminating the requirement of external reagents. Characterization has been performed in seawater as well as titrating individual components (i.e., OH^–, HCO₃^–, CO₃^2–, B(OH)₄^–, PO₄^3–) of seawater A_T. The seawater measurements are consistent with the design in reaching the benchmark goal of 0.5% precision in A_T over the range of seawater A_T of ∼2200–2500 μmol kg^–1 which demonstrates great potential for autonomous sensing.

中文翻译：

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同时测量海水总碱度和pH值的固态传感器

演示了一种新颖的固态无试剂传感器设计，该传感器能够使用离子敏感场效应晶体管（ISFET）技术快速且同时测量pH和总碱度（A _T），以提供表征碳水的简化方法通过测量两个“主变量”：pH和A _T来生成二氧化硫系统。达到0.001精度的基于ISFET的pH传感器被广泛用于各种海洋应用中。改进的ISFET被证明可以在40 s内完成纳升规模的酸碱滴定A _T。库仑扩散滴定法A _T的这种测量方法涉及滴定剂H ^+的电解生成通过微制造电极在芯片表面上电解水，从而消除了对外部试剂的需求。在海水中进行了表征，还滴定了海水A _T的各个成分（即OH ^–，HCO ₃ ^–，CO ₃ ^2–，B（OH）₄ ^–，PO ₄ ^3–）。海水测量与设计相一致，达到了在海水A _T约为2200–2500μmolkg ^–1的范围内A _T精度达到0.5％的基准目标，这表明了自动感应的巨大潜力。