Multifunctional microfluidic papers and ionic liquids as basis for selective and sensitive electrochemical sensors

项目扩展的目标是实现一种新的纸夹层结构作为多功能元件（微流控、乳剂分离、相变材料局部温度可控、电化学）的平台。该平台将利用最少量离子液体的有效利用来提高电化学重金属传感器的选择性和灵敏度。为了有效地从水溶液中提取重金属离子，必须使用临界溶液温度介于室温和水沸腾温度之间的液体/水混合物。在临界温度以上，IL在均相溶液中迅速混合。低于临界温度后，形成一种乳剂，其中重金属富集在IL相中。这两相的缓慢沉降特性应通过纸微流体技术加以改善。乳化液通过与纸表面接触而破碎，然后选择性地将IL相进一步输送到电化学分析所需要的地方。此外，应该通过提高温度和最小化电极之间的距离来增强IL低电导率的负面影响。特别是对于最后一点，定制纸是理想的，因为它们同时作为µm范围内的间隔器和IL的流体通道。为了在纸夹层结构中实现足够的局部可变温度控制，相变材料夹层元件与石墨纸加热器的组合正在研究中。从长远来看，我们的目标是利用这种新型的纸夹层结构为纸基和电化学应用建立一个新的平台。

Objective of the project extension is to realize a new paper sandwich structure as a platform for a multifunctional element (microfluidic, emulsion-separating, locally temperature-controllable with phase change materials, electrochemical). This platform will leverage the efficient use of minimal amounts of ILs (ionic liquids) to enhance the selectivity and sensitivity of electrochemical heavy metal sensors. For an efficient extraction of heavy metal ions from aqueous solutions, ILs/water mixtures with a critical solution temperature between room temperature and water boiling temperature are to be used. Above the critical temperature, the IL mixes rapidly in the homogeneous solution. After falling beneath the critical temperature, an emulsion is formed in which the heavy metals are enriched in the IL phase. The slow settling behavior of the two phases should be improved by paper microfluidics. The emulsion is broken by contact with paper surface and then the IL phase is to be selectively transported further, where it is required for the electrochemical analysis. Furthermore, the negative influence of the low conductivity of the IL should be enhanced by increasing the temperature and minimizing the distance between the electrodes. Especially for the last point, tailor made papers are ideal, as they act simultaneously as spacer in the µm range and as fluid channel for the IL. In order to achieve sufficient locally variable temperature control in the paper sandwich structure, phase change material sandwich elements in combination with graphite paper heaters are being investigated. In the longer term, the objective is to establish a new platform for paper-based and electrochemical applications using the novel paper-sandwich structures.