The analysis of dissolved inorganic carbon in liquid using a microfluidic conductivity sensor with membrane separation of CO2.
The analysis of dissolved inorganic carbon in liquid using a microfluidic conductivity sensor with membrane separation of CO2.
复制标题
使用具有 CO2 膜分离功能的微流体电导率传感器分析液体中溶解的无机碳。
DOI：
10.1007/s10404-020-02339-1
复制
发表时间：
2020
影响因子：
2.8
通讯作者：
Tweedie M
中科院分区：
文献类型：
--
作者：
Tweedie M
海洋溶解无机碳(DIC)浓度随深度的自主连续分析对于研究海洋酸化和气候变化具有重要意义。然而，传统光学仪器的尺寸、成本和功率要求阻碍了原位分析系统的小型化。在这里，我们报告了一种基于二氧化碳分离和电导测量的低成本微流控替代方案，该方案可能导致集成的芯片上实验室系统，用于海洋浮标部署，或用于系泊或自主水面车辆应用。使用微流控薄膜电极电导池和膜基气体交换池，实现了海水浓度在1000-3000umol.kg−1范围内的电导测定。样品酸化通过膜释放二氧化碳，在氢氧化钠载体中反应，随后通过亚微米L电导池提取，用于阻抗随时间的测量。峰高测量的精密度(相对标准偏差)为 ~ 0.2%，在−1为2000时。用C4D电泳头获得了类似测量体积的 ~ 0.25%的精确值。小体积平板膜气体交换池所需的总样品和试剂体积为 ~ 500ug L。相比之下，以前的基于电导的DIC分析系统需要5000到10,000微升的总体积，通过在气体交换单元中加入平面膜(PDMS)，并通过将钛/金电极直接溅射到热塑性塑料(PMMA)歧管上，避免了长膜管和宏观金属丝电极。未来的性能改进将解决膜的化学和机械稳定性、进一步缩小体积以及将组件集成到单一歧管中。
Autonomous continuous analysis of oceanic dissolved inorganic carbon (DIC) concentration with depth is of great significance with regard to ocean acidification and climate change. However, miniaturisation of in situ analysis systems is hampered by the size, cost and power requirements of traditional optical instrumentation. Here, we report a low-cost microfluidic alternative based on CO2separation and conductance measurements that could lead to integrated lab-on-chip systems for ocean float deployment, or for moored or autonomous surface vehicle applications. Conductimetric determination of concentration, in the seawater range of 1000–3000 µmol kg−1, has been achieved using a microfluidic thin-film electrode conductivity cell and a membrane-based gas exchange cell. Sample acidification released CO2through the membrane, reacting in a NaOH carrier, later drawn through a sub-µL conductivity cell, for impedance versus time measurements. Precision values (relative standard deviations) were ~ 0.2% for peak height measurements at 2000 µmol kg−1. Comparable precision values of ~ 0.25% were obtained using a C4D electrophoresis headstage with similar measurement volume. The required total sample and reagent volumes were ~ 500 µL for the low volume planar membrane gas exchange cell. In contrast, previous conductivity-based DIC analysis systems required total volumes between 5000 and 10,000 µL. Long membrane tubes and macroscopic wire electrodes were avoided by incorporating a planar membrane (PDMS) in the gas exchange cell, and by sputter deposition of Ti/Au electrodes directly onto a thermoplastic (PMMA) manifold. Future performance improvements will address membrane chemical and mechanical stability, further volume reduction, and component integration into a single manifold.