Reliable Calibration-Free Long-Term Ion Monitoring

在化学系化学测量与成像（CMI）项目的资助下，明尼苏达大学双城分校的Philippe Buhlmann教授及其同事将寻求解决当前离子传感器的主要失效模式，即当暴露于重复机械应力时，离子载体掺杂的聚合物传感膜从底层平台衬底上分层。在大尺寸的设备中，可以通过螺旋盖和o型圈等机械手段避免分层，但在小型设备中则不可能。小型化的设备更适合在线监测，并且对于更广泛的影响应用来说更经济实惠。将带有化学键的离子载体掺杂的传感膜附着在传感器平台材料和将传感膜与底层电子导体分离的传感器层上，对于电分析传感器的开发至关重要，这些传感器(i)不会因膜分层而灾难性地失效，（ii）在长期的原位监测中表现出最小的信号漂移。传感膜的共价连接为具有长寿命的无需校准的传感器打开了一个场所，因为它们需要在环境，工业过程和健康监测中进行长期测量。在这个研究项目中，明尼苏达大学的Buhlmann团队的目标是实现离子载体掺杂聚合物传感膜与惰性塑料和导电碳材料的共价附着。这将通过使用耐化学、无增塑剂和生物相容性的聚合物膜材料、纳米多孔碳固体触点和氧化还原缓冲液来实现，这些缓冲液用于制造强大的电位固态传感器，用于无需校准的长期监测。在这个项目中使用的化学接枝和光或等离子体引发的原位聚合的传感膜的共价附着是一种非常普遍的方法，它没有硅基化学的缺点，硅基化学在过去已经用于这一目的。特别是，它适用于从聚酯、聚氨酯、聚烯烃到含氟聚合物的一系列基材。如果成功，这种方法将消除频繁重新校准电位离子传感器的需要，这需要不断提供校准溶液，需要复杂的流体处理系统或训练有素的人员。因此，该项目有可能在从学术界到工业界到政府实验室的广泛离子传感器应用中产生广泛的科学影响。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

With funding from the Chemical Measurement and Imaging (CMI) program in the Division of Chemistry, Professor Philippe Buhlmann and coworkers at the University of Minnesota-Twin Cities will seek to address a major failure mode of current ion sensors, which is the delamination of ionophore-doped polymeric sensing membranes from underlying platform substrates when exposed to repeated mechanical stress. In macro-sized devices, delamination can be avoided by mechanical means such as screw lids and O-rings, but that is not possible in miniaturized devices. Miniaturized devices are better suited for on-line monitoring and are more affordable for broader impact applications. The attachment of ionophore-doped sensing membranes with chemical bonds to the sensor platform material and the transducer layer that separates the sensing membranes from the underlying electron conductors is crucial to the development of electroanalytical sensors that (i) do not fail catastrophically by membrane delamination and (ii) exhibit minimal signal drift in long-term in-situ monitoring. Covalent attachment of the sensing membrane opens a venue to calibration-free sensors with long lifetimes, as they are needed for long-term measurements in the environment, in industrial processes, and for health monitoring.In this research project, the Buhlmann team at the University of Minnesota aims to achieve the covalent attachment of ionophore-doped polymeric sensing membranes to inert plastics and conductive carbon materials. This will be achieved using chemically resistant, plasticizer-free and biocompatible polymeric membrane materials, nanoporous carbon solid contacts, and redox buffers for the fabrication of robust potentiometric solid-state sensors for calibration-free long-term monitoring. The covalent attachment of the sensing membrane using chemical grafting and photo- or plasma-initiated in-situ polymerization as used in this project is a very general approach that does not suffer from the disadvantages of silyl chemistry, which has been used for this purpose in the past. In particular, it is suitable for a range of substrates from polyesters, polyurethanes, and polyolefins to fluoropolymers. If successful, this approach will eliminate the need for frequent recalibration of potentiometric ion sensors, which requires a constant supply of calibration solutions and either complex fluid handling systems or trained personnel. Thus, the project has the potential for broad scientific impact across a wide range of ion sensor applications from academia, to industry to government laboratories.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.