Aqueous chloramine sensors based on molecules acting as switchable dopant sites on graphene-like carbon films

水对我们生存的大多数方面都至关重要。饮用水水质最重要的监测参数之一是消毒剂的含量。如果它们的含量太低，微生物就会在水中生长，这对我们的健康有害。如果消毒剂的含量过高，消毒剂本身可能是有害的，或者至少对人类来说是不愉快的。在水处理厂完成一次消毒后，整个配水系统必须保持消毒剂水平（二次消毒）。氯胺化越来越多地用于这一目的，而不是氯化。虽然它的持久性在分销过程中是一个好处，但在消费者端更难检测（它是无味的）和去除（它是稳定的）。然而，在医疗保健、水产养殖、游泳池以及食品和饮料行业的应用中，通过过滤完全去除氯胺是必要的。过滤器的寿命很难仅仅通过年龄或水量来判断，因为它更直接地是过滤器容量和污染物负荷的函数。理想情况下，过滤器后的传感器可以立即警告由于缺陷或耗尽容量而导致的破坏。在这里，我们专注于氯胺传感器的开发点使用水过滤器。这项工作将建立在一种新型传感器设计的基础上，我们的研究团队最近证明了这种传感器可以有效地检测饮用水中的游离氯。该设计基于我们的发现，苯胺低聚物能够被水中的游离氯氧化，从而开启它们作为碳纳米管薄膜p掺杂剂的能力。一个简单的化学电阻器配置可以定量地检测由于掺杂切换而导致的纳米碳膜电导率的显著变化，从而在整个相关范围内作为定量氧化还原传感器。初步数据表明，这些传感器也可用于检测和区分各种氧化还原活性物质。通过使用不同的选择性可切换掺杂分子，同样的传感原理可以应用于pH或其他分析物。因此，我们建议为我们的工业合作伙伴3M加拿大公司开发一种能够在相关应用中定量检测氯胺的传感阵列。

Water is fundamentally important to most aspects of our existence. One of the most important monitoring parameters of drinking water quality is the level of disinfectants. If their levels are too low, microorganisms can grow in the water, which are harmful to our health. If the disinfectant levels are too high, the disinfectants themselves may be harmful, or at least unpleasant to humans. After primary disinfection at the water treatment plant is complete, disinfectant levels have to be maintained throughout the water distribution system (secondary disinfection). Chloramination is increasingly used for this purpose instead of chlorination. While its persistence is a benefit during distribution, monochloramine is harder to detect (it is odorless) and remove (it is stable) at the consumer end. For applications in health care, aqua culture, swimming pools, and in the food and beverage industry, however, complete removal of chloramines by filtration is imperative. Filter lifetime is difficult to judge just by age or water volume since it is more directly a function of filter capacity and contaminant load. Ideally, a sensor immediately after the filter could warn of breaches due to defects or exhausted capacity. Here we focus on the development of a chloramine sensor for point-of-use water filters. This work will build on a novel sensor design that our research team has recently demonstrated as effective for detecting free chlorine in drinking water. The design is based on our finding that aniline oligomers are capable of being oxidized by the free chlorine in water, thus switching on their ability to act as p-dopants for carbon nanotube films. A simple chemiresistor configuration can quantitatively detect the significant conductivity change of the nanocarbon film due to the dopant switching, and hence serve as a quantitative redox sensor across the entire relevant range. Preliminary data indicates that these sensors can also be used to detect and distinguish a variety of redox-active species. The same sensing principle can be applied to pH or other analytes by using different selectively switchable dopant molecules. Hence, we propose to develop a sensing array capable of quantitatively detecting chloramines in relevant applications for our industrial partner, 3M Canada.