Nov 05, 2017

Researchers at the University of Wisconsin-Milwaukee will be presenting a graphene-based sensing platform for real-time, low-cost detection of various water contaminants at the AVS's 64th International Symposium & Exhibition, being held Oct. 29-Nov. 3, 2017, in Tampa, Florida. The new sensor detects heavy metals, bacteria, nitrates and phosphates.

The sensor works by placing graphene-based nanosheets that are semiconducting between an electrode gap. The electrical conductivity of the graphene material changes with the binding of substances, called analytes, to its surface and their chemical constituents are identified and measured. "The magnitude of the conductivity change can be correlated to the concentration of analyte, and the technology also involves the functionalization of the graphene material surface with specific probes that can target a specific analyte," said the researchers.

The sensor is based on a field-effect transistor (FET) device with reduced graphene oxide (rGO) as its sensing channel. "The working principle of the sensor is that the rGO conductivity (usually measured in resistance) changes with the binding of chemicals such as heavy metals to probes anchored on the rGO surface," the team said. "So the presence of the chemicals can be determined by measuring the sensor resistance change."

The idea of this technology is that by deploying these real-time sensors to monitor water contaminants in water distribution systems, it would be possible to provide early warning of chemical and biological contamination in water, improving water safety and public health benefits. "The platform technology can also be further engineered to detect various analytes for food and beverages, as well as for biomedical applications," said the researchers.

unhong Chen, distinguished professor of mechanical engineering, materials science and engineering at the University of Wisconsin-Milwaukee and leader of this project, has launched a startup, NanoAffix Science, to commercialize this water-quality sensing technology. With funding from the National Science Foundation and in partnership with several water companies, they've already developed a prototype of a hand-held device for rapid, low-cost detection of lead ions in drinking water. "We're now refining the prototype to make it a commercial product in the near future," said Chen.

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