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3D microfluidic chip targets water, food safety

Posted: 24 Jun 2013 ?? ?Print Version ?Bookmark and Share

Keywords:3D microfluidic chip? microfabrication? 3D-πDEP?

A team of researchers at Virginia Tech's Microelectromechanical Systems Laboratory (MEMS) Laboratory in the Bradley Department of Electrical and Computer Engineering has developed a microfabrication technique for making 3D microstructuresin polymers . According to them, the devices can be used in the analysis of cells that could prove useful in counterterrorism measures and in water and food safety concerns.

Microfluidics deals with the performance, control and treatment of fluids that are constrained in some fashion, explained Masoud Agah, associate professor of the Bradley Department of Electrical and Computer Engineering and of the Virginia TechCWake Forest School of Biomedical Engineering and Sciences. Together with Amy Pruden, professor of civil and environmental engineering at Virginia Tech, they received a National Science Foundation award of $353,091 to use the technology and develop new microchips named 3D-DEP standing for "three-dimensional, passivated-electrode, insulator-based dielectrophoresis" for pathogen detection.

The NSF grant will allow them to focus on the isolation of waterborne pathogens that represent one of the "grand challenges to human health, costing the lives of about 2.5 million people worldwide each year," Agah and Pruden noted.

According to the World Health Organisation, the isolation of pathogenic bacteria from the environment has not significantly changed since the 1960s, when methods for chemical treatment of samples to remove background organisms were first implemented.

In the past, Agah said, researchers have mainly used 2D microfluidic structures since this type of fabrication is more simplistic. With the 3D device developed by Agah and his collaborators, Yayha Hosseini and Phillip Zellner, both graduate students in the department, they are able to customise the shapes of the channels and cavities of the devices the fluids passed through.

The advantage of the fabrication process is that with a very economical technique it creates 3D varying channels and cavities in a microfluidic structure with rounded corners as well as many other customised shapes.

These shapes are important because they resemble the living conditions as they occur naturally and this allows the use of the 3D microfabrication technology beyond pathogen detection. As an example, in human blood vessels, cells interact with each other and their surrounding environment inside circular channels. They have varying diameters, along with multiple branching and joints.

"Only under this type of condition can one truly study the biology of cells within a system in vitro as if it is occurring in vivo, our new microfluidic fabrication technology can resemble more realistically the structures of a cell's true living conditions," Agah said. It is the introduction of the 3D that provides this distinctive environment.

To make their 3D structure, the Virginia Tech researchers used the material polydimethylsixolane, known for its elastic properties similar to rubber. This material is widely used because of its transparency, biocompatibility and low-cost.

"Our work establishes a reliable and robust, yet low-cost technique for the fabrication of versatile 3D structures in polydimethylsixolane," Agad said.

Microfluidic devices can be used to trap and sort living organisms such as bacteria, viruses and cells. With this 3D device that has a higher sensitivity and throughput than the 2D version, according to Agah, he is able to make their predictions of applications ranging from water and food safety to fighting biological and chemical terrorism and to healthcare by fishing for abnormal cells in body fluids.

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