Lab-on-a-chip technology gets a flexible upgrade

Jul 12, 2013
Credit: 2013 Elsevier

Microfluidic devices move liquids through tiny, hair-sized pathways carved into glass slides and have distinct advantages over traditional laboratories when it comes to medical diagnostics. At these reduced scales, fluid transport is enhanced by factors such as diffusion and high surface-to-volume ratios, making testing procedures much faster. By constructing parallel arrays of microfluidic pathways, researchers are working to produce 'lab-on-a-chip' technologies that allow multiple biological tests to be performed using just a drop of blood or urine. In a development that promises to make lab-on-a-chip devices more portable and economic to construct, Yo Tanaka from the RIKEN Quantitative Biology Center and colleagues have now produced a new type of microfluidic control valve that takes up significantly less space on a microchip than existing approaches.

In the majority of today's , silicone pneumatic valves are used to manipulate liquid samples. Pneumatic valves, however, require noisy compressors and complicated air channel systems, which are often too bulky for practical lab-on-a-chip applications. Piezoelectric actuators—inorganic crystals that change shape when electrically stimulated—are feasible alternatives, but while are less obtrusive than pressurized air technology, they are excessively large when compared to the size of the microchip itself.

Tanaka and his colleagues instead investigated the remarkable properties of electroactive polymers. These materials are rubber-like that expand and contract when exposed to an electric current. As electroactive polymers can exhibit large force at small scales, the team deduced that creating membranes incorporating these materials could be a promising way to miniaturize microfluidic control valves.

After experimenting with many valve shapes, the researchers settled on a micrometer-sized, dome-shaped polymer diaphragm sandwiched between soft electrode sheets (Fig. 1). They tested its ability to stop flow by fabricating it on top of a small hole drilled into a microfluidic channel. By monitoring fluorescent polystyrene tracking beads using high-speed video cameras, the team saw that stimulating the electroactive polymer caused the diaphragm to expand and close off the microchannel at sub-second speeds, nearly identical to the response time of piezoelectric actuators but with an order-of-magnitude smaller form factor. Furthermore, the polymer structure strongly resisted leaks because of its resilient structure.

The researchers note that the improved size-scaling of their valve system should prove more efficient for the sorting of biological cells than current fluorescent technology. Other—more mobile—applications also may be on the horizon. "Many portable devices for personal diagnosis, environmental analysis, or fuel cells could benefit from these miniaturized valves," says Tanaka.

Explore further: Devices designed to identify pathogens in food

More information: Tanaka, Y., Fujikawa, T., Kazoe, Y. & Kitamori, T. An active valve incorporated into a microchip using a high strain electroactive polymer. Sensors and Actuators B: Chemical 184, 163–169 (2013). dx.doi.org/10.1016/j.snb.2013.04.025

Related Stories

An all-glass lab-on-a-chip

Jul 04, 2013

Lab-on-a-chip devices are microfluidic cells that incorporate pipes, reaction vessels, valves and a host of other implements typically found in laboratories. These components are typically carved into a flat ...

Recommended for you

Devices designed to identify pathogens in food

15 hours ago

Researchers at the National Polytechnic Institute (IPN) in Mexico have developed a technology capable of identifying pathogens in food and beverages. This technique could work in the restaurant industry as ...

Biosensor may improve clinical diagnosis of influenza A

16 hours ago

Sensors based on special sound waves known as surface acoustic waves (SAWs) are capable of detecting tiny amounts of antigens of Influenza A viruses. Developed by A*STAR researchers, the biosensors have the ...

New chip makes testing for antibiotic-resistant bacteria faster, easier

May 26, 2015

We live in fear of 'superbugs': infectious bacteria that don't respond to treatment by antibiotics, and can turn a routine hospital stay into a nightmare. A 2015 Health Canada report estimates that superbugs have already cost Canadians $1 billion, and are a "serious and growing issue." Each year two million people in the U.S. contract antibiotic-re ...

Use your smartphone for biosensing

May 26, 2015

An Australian research team has shown that smartphones can be reconfigured as cost-effective, portable bioanalytical devices, with details reported in the latest edition of the Open Access Journal 'Sensors'.

Faster, portable microbial analysis in the field

May 25, 2015

Until recently, it took hours – sometimes days – to analyze biological samples after they were frozen in the field and brought back to the laboratory. But now there is a faster, cheaper and smaller way ...

User comments : 1

Adjust slider to filter visible comments by rank

Display comments: newest first

arq
not rated yet Jul 13, 2013
Lab on a chip...one of my favorite subjects....

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.