Reliable Calibration-Free Long-Term Ion Monitoring

在化学系化学测量和成像（CMI）计划的资助下，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故障模式，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与底层平台基板分层。在宏观尺寸的设备中，可以通过机械手段（例如螺旋盖和O形环）来避免分层，但这在小型化设备中是不可能的。小型化装置更适合在线监测，对于更广泛的影响应用来说，价格也更便宜。离子载体掺杂的传感膜与传感器平台材料和将传感膜与下面的电子导体分离的转换器层的化学键的附接对于电分析传感器的开发是至关重要的，所述电分析传感器（i）不会由于膜分层而灾难性地失效，并且（ii）在长期原位监测中表现出最小的信号漂移。传感膜的共价连接为长寿命的免校准传感器开辟了一条道路，因为它们需要在环境中进行长期测量，在工业过程中，以及用于健康监测。在这个研究项目中，明尼苏达大学的Buhlmann团队旨在实现离子载体掺杂的聚合物传感膜与惰性塑料和导电碳材料的共价连接。这将通过使用耐化学腐蚀、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，用于制造用于免校准长期监测的强大的电位固态传感器。如在该项目中所使用的，使用化学接枝和光或等离子体引发的原位聚合的感测膜的共价附着是一种非常通用的方法，其不受甲硅烷基化学的缺点的影响，甲硅烷基化学在过去已用于该目的。特别是，它适用于从聚酯、聚氨酯和聚烯烃到含氟聚合物的各种基材。如果成功，这种方法将消除对电位离子传感器的频繁重新校准的需要，这需要不断供应校准溶液和复杂的流体处理系统或训练有素的人员。 因此，该项目具有广泛的科学影响的潜力，在广泛的离子传感器的应用，从学术界，工业界到政府实验室。这个奖项反映了NSF的法定使命，并已被认为是值得的支持，通过评估使用基金会的知识价值和更广泛的影响审查标准。

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.