Laser, Electric Fields Combined for Novel Lab-on-a-Chip Technology

New technologies that combine a laser with electric fields promise new lab-on-a-chip designs for manipulating bacteria, viruses and DNA in a range of potential applications.

A new method, dubbed “hybrid optoelectric manipulation in microfluidics,” is a potential tool for applications including medical diagnostics, testing food and water, crime scene forensics and pharmaceutical manufacturing. It could result in innovative analytical devices for lab-on-a-chip applications, said Steven T. Wereley, a Purdue University professor of mechanical engineering.

"This is a cutting-edge technology that has developed over the last decade from research at a handful of universities," said Aloke Kumar of Oak Ridge National Laboratory, formerly a colleague of Wereley’s at Purdue.

Kumar is the lead author of an article about the technology featured on the cover of the July 7 issue of Lab on a Chip magazine.

This graphic illustrates a new technology that combines a laser and electric fields to manipulate fluids and tiny particles such as bacteria, viruses and DNA for a range of potential applications from drug manufacturing to food safety. (Image: Stuart J. Williams, University of Louisville)

"A very important aspect is that we have achieved an integration of technologies that enables manipulation across a very wide length scale spectrum," he said. "This enables us to manipulate not only big-sized objects like droplets but also tiny DNA molecules inside droplets by using one combined technique. This can greatly enhance efficiency of lab-on-a-chip sensors."

The technologies are ready for some applications, including medical diagnostics and environmental samples, said Stuart J. Williams of the University of Louisville, another co-author and former colleague of Wereley’s at Purdue.

"There are two main thrusts in applications," Williams said. "The first is micro- and nanomanufacturing, and the second is lab-on-a-chip sensors. The latter has demonstrated biologically relevant applications in the past couple of years, and its expansion in this field is immediate and ongoing."

The technology works by first using a red laser to position a droplet on a specially fabricated platform. Next, a highly focused infrared laser is used to heat the droplets, and then electric fields cause the heated liquid to circulate in a "microfluidic vortex." This vortex is used to isolate specific types of particles in the circulating liquid, as with a microcentrifuge. Particle concentrations replicate the size, location and shape of the infrared laser pattern.

"This works very fast," Wereley said. "It takes less than a second for particles to respond and get pulled out of solution."

Systems using the hybrid optoelectric approach can be designed to precisely detect, manipulate and screen certain types of bacteria, including particular strains that render heavy metals less toxic. The researchers also are pursuing use of the technology for pharmaceutical manufacturing, and it may be used someday as a tool for nanomanufacturing, because it shows promise for the assembly of suspended colloids.

For more information, visit: www.purdue.edu