A quarterly research and development magazine.Winter 2006/2007
Volume 8, No. 4
The microvalves include a multiport selector valve that has been continuously improved over the last two years and is now frequently and reliably employed in microflow and nanoflow systems.
Sandia researchers have improved upon using this well-known force phenomenon (termed dielectrophoresis) by placing insulating obstacles within microchannels, and the associated electrodes outside in reservoirs. The insulating posts, arrayed in the middle of the microchannel, constrict the electric field and create an electrical field gradient that gives rise to the particle separation. This approach is much easier to fabricate (using injection-molded polymers) than the previous glass-based approach. Some believe this technology, known as iDEP (for insulator-based dielectrophoresis), could revolutionize biological sample preparation. iDEP technology is currently the focus of a cooperative research and development agreement with Lockheed Martin Corp.
In New Mexico, these tools are enabling a discovery platform for mechanical testing, optical interrogation, electronic manipulation, and measurement at the Center for Integrated Nanotechnologies. Researchers envision applications in medical, defense, and similar fields.
One medical diagnostic application is a small portable device that within minutes could screen saliva for markers of periodontal disease and blood samples for early indicators of heart disease. Funded by the National Institutes of Health, this effort includes collaborators at the University of Michigan’s schools of dentistry and engineering, as well as the Cornell University’s applied and engineering physics program.
“The initial investment blossomed into a real success story, and a fundamental strong element of that was the engineering,” Renzi says. “It’s gone a long way. ... We have great science here, and we also have great engineering to enable the science.” More than 20 second-generation MicroChemLab boxes relying on these technologies are currently used in Sandia programs. The components are modular and employ a common breadboard and control architecture.
“Researchers can grab the components, draw a flow schematic, integrate and assemble the parts in hours instead of days, weeks, or months,” Renzi says. “We want to take the chemist away from the problem and not be doing wet chemistry out in the field.”
Renzi is also lead engineer on a team incorporating the fittings and other enabling technologies into the BioBriefcase project, an environmental monitoring collaboration with Lawrence Livermore National Laboratory. The Department of Homeland Security-sponsored project calls for a compact broad-spectrum bioagent detector that autonomously collects, prepares, and analyzes samples using three techniques in a portable unit complete with a system to archive samples for further analysis.
Another DHS-funded project using this suite of microfluidic tools is the Enhanced Bioaerosol Detection project. Besides Sandia, it includes Lawrence Livermore, Oak Ridge, Pacific Northwest, and Los Alamos national laboratories, as well as Yale University and the Army Research Laboratory. The prototype is a selective aerosol collector and fluorescence spectrometer under investigation for potential use as a low-false-alarm-rate early warning sensor.
“The technologies have propagated through different programs,” Renzi says, “not all of which they were invented for.” This is likely to continue as the field of microfluidics and its applications evolves.
Media contact: Mike Janes (925) 294-2447, mejanes@sandia.gov
Technical contact: Ron Renzi (925) 294-3606, rfrenzi@sandia.gov