This proposal seeks funding for the Center for Center for Water Equipment and Policy (WEP) located at THE University of Wisconsin-Milwaukee. Funding Requests for Fundamental Research are authorized by an NSF approved solicitation, NSF 10-601. The solicitation invites I/UCRCs to submit proposals for support of industry-defined fundamental research.
This project aims to explore a novel, generic, and low-cost, and reliable grapheme based sensing platform to detect various chemicals (e.g., nitrate, lead) and microorganisms (e.g., E. coli) in water. The platform is based on hybrid structures of thermally-reduced graphene oxide (TRGO) decorated with probe-functionalized gold nanoparticles (Au NPs). The electrical detection of target agents that bind to probes is accomplished by measuring changes in electrical characteristics of the device. The proposed project will be carried out through close collaboration between UWM and WEP members (Badger Meter, A. O. Smith, and Pentair). The UWM team will be responsible for laboratory development and understanding of the novel graphene-based water sensing platform.
Project results will lead to inexpensive, ultrasensitive, rapid, and specific sensors for detecting aqueous chemicals and microorganisms and provide additional technological benefits to WEP members. The new water sensor will enable water quality monitoring not only at the water distribution center but also along water distribution lines and at the point of use. The proposed research will be extensively integrated into educational goals to promote interdisciplinary engineering education to attract more underrepresented students and to broadly disseminate findings. Special efforts to inspire underrepresented pre-college students include taking nanosensor technology into high school classrooms through collaboration with Lakeview Technology Academy, offering "Science Saturdays on Water Sensing Technology", and mentoring students on science projects. Additional outreach through posting the course module on a high-impact, NSF-sponsored National Center for Learning and Teaching Web site, a nanosensor technology exhibit in conjunction with the Milwaukee discovery World Museum, and regional science fairs, will effectively disseminate nanosensor technology to a wide range of audiences.
Water is essential for life and plays an important role in the economic world, as it is a key element of food and energy production as a solvent for a wide variety of chemical substances, and facilitates industrial cooling, transportation, and effluent discharge and re-use. Only 3% of available water is potable. Heavy metal ions, e.g., lead, mercury, and arsenic, are widely present in water systems. These heavy metal ions are poisonous and may lead to serious damage to organs, tissues and bones, and nervous systems of humans. The need for safe drinking water is rising: the National Academy of Engineering has identified "Providing access to clean water" as one of the top 10 grand challenges for engineering in the 21st century. Existing water quality monitoring mostly occurs at the water supply intake or water treatment plant, instead of along water distribution lines and at the point of use, which is considered inadequate given potential changes in water quality and associated risks within water distribution systems. Therefore, continuous water quality monitoring for various contaminants such as toxic heavy metal ions in water distribution and treatment systems is a core requirement for managing such a key natural resource. This requires accurate and accessible detection technologies to ensure continuous water quality control and early warning capabilities to avoid public safety catastrophes, like the very recent chemical spill disaster leading to water contamination impacting over 300,000 residents in West Virginia. This project aims to explore a novel, generic, low-cost, and reliable graphene-based sensing platform to detect various chemicals and microorganisms in water. Through this project we have demonstrated several sensing platforms that can detect heavy metal ions and bacteria in water in a real-time fashion. For example, a field-effect transistor (FET) device-based sensor is developed to specifically detect Pb2+ ions in water. Compared with conventional detection technologies, this sensor enabled real-time detection with a response time of 1-2 seconds. A lower detection limit for Pb2+ ions as low as 10 nM was achieved, which is much lower than the maximum contaminant level (MCL) for Pb2+ ions in drinking water recommended by the World Health Organization (WHO). Another example is a highly sensitive and selective FET sensor for detection of Escherichia coli (E. coli) bacteria. The sensor was able to detect E. coli bacteria cells with a concentration as low as 10 colony-forming units (cfu)/mL. These water sensing platforms are promising for large-scale, sensitive, selective, low-cost, and real-time detection of water contaminants. The close interplay between experiments and theoretical analysis provided a deeper physical understanding of these novel water sensing platforms, thereby offering tremendous opportunities for scientists to explore the forefront of nanotechnology. Broader impacts of the project are far-reaching as project results have led to inexpensive, ultrasensitive, rapid, and specific sensors for detecting aqueous chemicals and microorganisms and provide tremendous technological benefits to various water industries. The new water sensor will enable water quality monitoring not only at the water distribution center but also along water distribution lines and at the point of use. By deploying real-time sensors to monitor water contaminants in these water distribution systems, we could provide early warning of chemical and biological contamination in water and thus improve water safety and public health benefits. Project results were effectively disseminated through journal publications, invited talks at various universities and technical conferences. The project also trained one postdoc and three graduate students at the University of Wisconsin-Milwaukee in the areas of nanomaterials, nanodevices, and sensors.
