Auburn researchers turning plant waste into water quality detection devices
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Inside every plant and tree nature has hidden amazing fibrous building blocks called cellulose nanocrystals, and a team of Auburn researchers is turning them into microelectromechanical system (MEMS) sensors to help ensure that Alabamians have safe water.
The Alabama Department of Economic and Community Affairs (ADECA) has awarded a grant to support this research aimed at producing MEMS sensors that can be used in detection devices to ensure the safety of water resources such as lakes and individual wells. Specifically, the research targets developing MEMS sensors to detect the presence of antibiotics and pesticides in Alabama water sources.
MEMS manufacturing to date has required large, multi-million-dollar production facilities — that is until the Auburn team recently proved these micro miracles can be fabricated using readily available waste materials from the forest and agriculture industries. Moreover, they can be produced significantly more economically and in a more environmentally friendly way than is possible using current large-scale manufacturing processes.
This “Cellulose MEMS” biosensor development program is conducted by Dr. Virginia Davis, Alumni Professor, and Dr. Robert Ashurst, the Uthlaut Family Associate Professor from the Department of Chemical Engineering in the Samuel Ginn College of Engineering, and Dr. Soledad Peresin, assistant professor of forest biomaterials in the School of Forestry and Wildlife Sciences.
There are two major types of sensors the team believes can be improved using the cellulose nanocrystals. First, that cellulose nanocrystals can be used to improve the sensitivity of a technique called ELISA — one of the most common sensing methods used by doctors and environmental researchers.
In previous work, Peresin and her colleague, Assistant Professor Dr. Sarah Zohdy, showed that cellulose materials can enhance the sensitivity of ELISA for detecting malaria biomarkers. However, since ELISA requires expensive equipment and sending samples to a lab, the team is also looking at a second area: MEMS which promise faster and more portable sensing.
MEMS devices have not been that widely used in sensors because of the associated manufacturing complexities, according to Davis. However, the team has proven that these cellulose nanocrystals can be used to economically produce MEMS, thus making MEMS more readily available and practical for sensor applications.
MEMS production technology, or microfabrication, uses the same technology to produce integrated circuits from silicon, Davis explains.“This technology revolutionized circuit miniaturization, allowing powerful computers to shrink from the size of a room half a century ago, to the smart phones that we carry in our pockets today,” Davis said. “But silicon MEMS fabrication processes are expensive, energy intensive — reaching temperatures of approximately 1000º C, and utilize hazardous chemicals — such as hydrofluoric acid.
“One of the really awesome things about using the nanocrystals for sensors is that they can simply be painted onto a surface and then fabricated into devices using a relatively easy process,” Davis said. “lt does not have to be done in a large-scale, major manufacturing environment like is needed for silicon. We have proven that our devices can be made very quickly and in a very small lab setting. This makes it an excellent opportunity for small business to become a player in the growing MEMS manufacturing industry.”
Davis and her research collaborators are rising to meet the challenge of developing better sensor technologies — ones that are more affordable, more energy efficient and more environmentally friendly and — more tailored to meet specific detection needs. Their work has progressed through numerous stages of proof and development and has prior funding to explore a variety of potential applications, including cancer detection.
Their initial funding from the National Science Foundation resulted in two patents which are available for licensing through the university’s Office of Innovation Advancement and Commercialization (IAC). The IAC assisted in pursuing the ADECA funding to study water sensors as well as Auburn LAUNCH Research and Innovation funding to progress the MEMS technology. The team has also received funding from Auburn’s intramural grants program and Auburn University Research Initiative in Cancer.
Although their work in the cancer detection arena continues, the team’s newest research is focused on the MEMS biosensors.
“We are really excited to receive this new funding from the state so we can use resources that are abundant in Alabama to develop better devices for the detection of antibiotics and pesticides in water,” Davis said. “These are two significant concerns in the state of Alabama. These potential contaminants in water sources are simply a result of our modern life. A reliable, rapid, easy-to-use and economical detection system is a real need that we are excited to try to meet.”
