Department of Mechanical & Aerospace Engineering, University of Texas at Arlington, USA.
Department of Mechanical & Aerospace Engineering, University of Texas at Arlington, USA.
Biosens Bioelectron. 2018 May 30;106:37-42. doi: 10.1016/j.bios.2018.01.048.
This paper presents the demonstration of on-chip fabrication of a potassium-selective sensor array enabled by electrowetting on dielectric digital microfluidics for the first time. This demonstration proves the concept that electrochemical sensors can be seamlessly integrated with sample preparation units in a digital microfluidic platform. More significantly, the successful on-chip fabrication of a sensor array indicates that sensors become reconfigurable and have longer lifetime in a digital microfluidic platform. The on-chip fabrication of ion-selective electrodes includes electroplating Ag followed by forming AgCl layer by chemical oxidation and depositing a thin layer of desired polymer-based ion selective membrane on one of the sensor electrodes. In this study, potassium ionophores work as potassium ion channels and make the membrane selective to potassium ions. This selectiveness results in the voltage difference across the membrane layer, which is correlated with potassium ion concentration. The calibration curve of the fabricated potassium-selective electrode demonstrates the slope of 58 mV/dec for potassium concentration in KCl sample solutions and shows good agreement with the ideal Nernstian response. The proposed sensor platform is an outstanding candidate for a portable home-use for continuous monitoring of ions thanks to its advantages such as easy automation of sample preparation and detection processes, elongated sensor lifetime, minimal membrane and sample consumption, and user-definable/reconfigurable sensor array.
本文首次展示了基于介电上电润湿的芯片上钾选择性传感器阵列的制造，用于数字微流控。该演示证明了电化学传感器可以与数字微流控平台中的样品制备单元无缝集成的概念。更重要的是，传感器在数字微流控平台上的成功芯片制造表明传感器变得可重构且具有更长的寿命。离子选择性电极的芯片制造包括电镀 Ag，然后通过化学氧化形成 AgCl 层，并在传感器电极之一上沉积一层所需的聚合物基离子选择性膜。在这项研究中，钾离子载体作为钾离子通道工作，使膜对钾离子具有选择性。这种选择性导致膜层之间的电压差，该电压差与钾离子浓度相关。制造的钾选择性电极的校准曲线表明，在 KCl 样品溶液中钾浓度的斜率为 58 mV/dec，与理想的 Nernstian 响应吻合良好。由于其易于自动化的样品制备和检测过程、延长的传感器寿命、最小的膜和样品消耗以及用户定义/可重构传感器阵列等优点，该传感器平台是用于连续监测离子的便携式家用的优秀候选者。
