Microfluidic Lab on a Chip

New to me.  

ACM NEWS

Bring the Laboratory With You

By R. Colin Johnson

For decades, laboratory procedures have been a popular target for automation; sequencing the human genome, for instance, would not have been feasible without it. Now the scale of automation is being reduced to individual laboratories on a chip by virtue of micron-level manipulation of fluid droplets (microfluidics)—not for complete genome sequencing (yet), but for the myriad of simpler medical procedures today performed by human technicians in full-sized laboratories worldwide.

The main contribution of the lab on a chip, so far, has been the development of medical point-of-care devices that can diagnose specific maladies in minutes, rather than requiring the capture of a blood (or other bodily fluid) sample and its transportation to a lab for analysis.

"Point-of-care diagnostic devices have proved incredibly useful in the last 20 years, in particular delivering much-needed rapid HIV and tuberculosis diagnosis to the developing world [where traditional labs are often not available]," said Maïwenn Kersaudy-Kerh, a professor in Heriot-Watt University's School of Engineering and Physical Sciences and in Scotland's Institute of Biological Chemistry, Biophysics, and Bioengineering, as well as an Honorary Lecturer in the Deanery of Biomedical Sciences of Scotland's University of Edinburgh.

A microfluidic lab on a chip consists of pipe-like micron-sized channels and reservoirs to hold droplet samples—usually blood or other body fluids—to be processed by mixing them with reagents and other chemicals needed to identify a malady. Such a lab on a chip also requires closely integraed electronics to control the processing steps.

A subset of micro-electromechanical systems (MEMS), these microfluidic implementations perform precisely the same steps as in a conventional lab, but using individual droplets of samples instead of test tubes. As a result, they use less reagents and less energy, cost less, and are faster in execution than traditional lab procedures, providing in-house results in minutes, rather than overnight (at best).

Just last month, hepatitis-C diagnoses were added to the list of applications provided by labs on chips. It was demonstrated with a working lab-on-a-chip prototype developed at Florida Atlantic University's (FAU) College of Engineering and Computer Science. According to FAU associate professor Waseem Asghar, about 80% of the 354 million people infected with Hepatitis-C worldwide will develop cancer, cirrhosis, or complete liver failure if not treated. Unfortunately, only about 20% have been identified in developed countries, and only 1% in developing countries.

Asghar said the new "disposable microfluidic lab-on-a-chip device is fully automated and offers reliable diagnoses—by changing a dye color from orange to green—in about 45 minutes and costs only about $2."

Many more medical diagnostic labs on a chip are under development. Many of those are destined not only for point-of-care and in-the-field usage, but for over-the-counter pharmacy shelves as well. This burgeoning development effort has attracted green-minded researchers to analyze the environmental impact of these one-use devices. In hospitals and clinics, for instance, the risk of infection from the body fluids inside require the devices to be incinerated after use. Since many use polymers and other fossil-derived materials, their incineration means a larger carbon footprint for the medical institutions (as burning them releases CO2). If even they are used in the home, the devices will end up in landfills, where cyanide and other toxic chemicals they contain will be released into the environment, according to Kersaudy-Kerh

"The medical waste issue is problematic, with the production of massive amount of plastics, as well as toxic chemical by-products. Now is the time to develop sustainable solutions. Researchers, manufacturers, and practitioners need to come together to design novel solutions using safer, less-polluting, and more easily degradable materials, form-factor reduction and recycling solutions," said Kersaudy-Kerh. "In our lab, we are reviewing existing and possible solutions to make diagnostic development more sustainable, in the hope to inspire and empower researchers to find alternative solutions, as well as reviewing their current practices."

One viable solution is to replace the polymers used in labs on chips with paper-based devices. Off-the-shelf pregnancy tests, for instance, already use paper-based innards within a plastic shell ... '