Immobilization of ionic liquids on microfluidic paper as a basis for electrochemical sensors

该项目的目标是开发基于离子液体（IL）和微流控纸基板的功能器件，为电化学传感器的应用提供一个新的平台。这种装置可以显示出巨大的潜力，以克服现有的使用水性电解质的纸质系统的主要缺点（例如，低电化学电位窗口，不良的蒸发效应和由此产生的测量不准确性）。此外，IL的溶剂性质可以在装置内用于选择性溶解不同的分析物。该项目将侧重于开发一种传感器设备，用于重金属离子的定性和定量检测。由于重金属是不可生物降解的，这种材料造成的环境污染是一个关键问题，特别是在发展中国家。目前，检测和分析这种环境污染的标准程序需要复杂的分析过程，以及实验技能。因此，简单的分析方法，可以进行低仪器的努力，如纸基电化学传感器，如果成功开发，提供了巨大的潜力。纸本征（例如孔隙度、纤维类型或预处理）以及纤维表面功能化，在最近的过去已经被用于定制纸基设备内水相的微流体流动。然而，为了有针对性地利用离子液体作为流动相，有关IL与纸质基质(i)、电催化剂（ii）和分析物（iii）相互作用的几个基本科学问题仍然具有挑战性：哪些纸的内在和外在参数会影响IL在纸质基质多孔基质中的流体动力学？-通过合理设计微流控平台，能否控制本文中IL的毛细管流动？- IL的哪些促进/限制/中毒特性会影响电化学检测？-溶液或扩散行为是否可用于选择性萃取和增加多组分分析的选择性？通过一系列关于IL与纸底物的相互作用、电催化和分析物的作用的实验，将探索基本机制，这将作为回答上述主要科学问题的基础。就后者而言，Etzold教授和Biesalski教授的专业知识将微流控纸的生成和研究经验与IL在多孔介质中的行为和电催化活性材料的专业知识相结合，完美地互补。

The Goal of the project is the development of functional devices based on ionic liquids (IL) and microfluidic paper substrates to provide a novel platform for electrochemical sensor applications. Such devices can exhibit a large potential to overcome major drawbacks of existing paper-based systems using aqueous electrolytes (e.g. low electrochemical potential windows, undesirable evaporation effects and measurement inaccuracies derived thereof). Furthermore, the solvent properties of IL can be utilized within the device for selective dissolution of different analytes. The project will focus on the development of a sensor device for qualitative as well as quantitative detection of heavy metal ions. Since heavy metals are non-biodegradable, environment pollution by such materials is a critical issue, in particular in developing countries. Currently, the standard procedures for detection and analysis of this environmental pollution require complex analytical processes, as well as experimental skills. Consequently, simple methods for analysis which can be carried out with low instrumental effort, such as paper-based electrochemical sensors, if successfully developed, offer great potential. Paper-intrinsic (e.g. porosity, fiber-type or pre-treatment), as well as fiber surface functionalization, have been used in the recent past to tailor the microfluidic flow of aqueous phases inside paper-based devices. For targeted utilization of ionic liquids as the mobile phase, however, several fundamental scientific questions concerning the interaction of the IL with the paper substrate (i), the electrocatalyst (ii) and the analyte (iii), are still challenging:- Which paper-intrinsic and -extrinsic parameters do have an influence on fluid dynamics of IL in the porous matrix of paper substrates?- Can the capillary flow of IL in the paper be controlled by rational design of the microfluidic platform?- Which promoting/limiting/poisoning properties of IL affect the electrochemical detection?- Can the solution or diffusion behavior be utilized for selective extraction and for increase of selectivity in multicomponent analysis?Through a distinct set of generic experiments on the interaction of IL with the paper substrate, the electrocatalysis and the role of the analyte, fundamental mechanisms will be explored, which serves as base to answer the above outlined major scientific questions. With respect to the latter, the expertise of Prof. Etzold and Prof. Biesalski perfectly complement each other by combining experience in generation and investigation of microfluidic paper with expertise on the behavior of IL in porous media and expertise on electrocatalytically active materials.