Researchers at the National Institute of Standards and Technology (NIST) have added yet another innovation—miniature valves—to their ever-growing collection of inexpensive, easy-to-manufacture and highly efficient microfluidic devices made from plastic films and double-sided tape.
Traditionally, microfluidic devices—tiny gadgets with fluid-carrying channels used in medical diagnostics, DNA forensics and "lab-on-a-chip" chemical analyzers—have been fabricated like microchips using photolithography.
Double-sided tape is cut with channels and ports that will align when folded (A). The polymer membrane that supplies the valve function for the microfluidic device is sandwiched between (B). The completed apparatus (C) has ports for fluid flow into and out of the device, as well as a valve inlet for air. Air pressure pushes the membrane into the flow channel, blocking fluid movement.
Credit: Gregory A. Cooksey/National Institute of Standards and Technology
A desired pattern of micrometer-sized channels and ports is created on top of a silicon substrate, which can then be replicated many times by techniques such as molding or embossing. However, the process requires specialized cleanroom equipment and can take several days to complete.
If valves are needed in the system, they traditionally have been made from silicones. Unfortunately, silicones are not the best materials to use with particular laboratory assays or for manufacturing lab-on-a-chip structures.
NIST researchers have spent the past few years developing and refining a method for making microfluidic devices using plastic films and double-sided tape that produces a functional apparatus in hours rather than days and requires only simple tools to create channels and ports.
The NIST designs allow for folding the films to make multilayer or three-dimensional structures, can be used to make devices with multiple functions, and cost a fraction of traditional fabrication techniques.
But until now, there has not been a practical way to incorporate valves for dynamic control of fluid flow in these devices. In a new paper in the journal Lab on a Chip,* NIST bioengineer Gregory Cooksey and research engineer Javier Atencia describe the first-ever technique for building pneumatic microvalves into 2-D and 3-D microfluidic devices made with plastic films and tape.
Like previous NIST systems,** the new valved microfluidic device is built in layers. Narrow slits and holes are cut into pieces of double-sided tape that become tiny channels and ports when the tape is folded on itself.
The microvalve is made by sandwiching a flexible membrane between two channels that intersect, one on top of the other. Applying air pressure to the top channel pushes the membrane down like a diaphragm valve, closing the lower channel.
Cooksey and Atencia have demonstrated that their novel microvalve also can work with more complex configurations of the NIST microfluidic system. These include devices with different designs for performing different tasks simultaneously, multiple layers with different flow rates, and single units with multiple "microfluidic walls" that can fold together to form a 3-D shape.
In one trial with a cubed-shaped device, the researchers filled it with agar and grew nematodes (Caenorhabditis elegans) inside. Using the microchannels, ports and valves built into the cube's walls, they injected chemicals at controlled concentrations that either attracted or repelled the worms. This showed that the cube was a unique setup for studying a living organism's response to chemical stimuli within a closed environment.
*G.A. Cooksey and J. Atencia. Pneumatic valves in folded 2-D and 3-D fluidic devices made from plastic films and tapes. Lab on a Chip (March 2014). DOI:10.1039/C4LC00173G
**See NIST Tech Beat issue of Feb. 7, 2012, "New NIST 'Cell Assay on a Chip': Solid Results from Simple Means" at http://www.nist.gov/mml/bbd/fluidics-020712.cfm.
Michael E. Newman | EurekAlert!
An evolutionary heads-up – The brain size advantage
22.05.2015 | Veterinärmedizinische Universität Wien
Endocrine disrupting chemicals in baby teethers
21.05.2015 | Goethe-Universität Frankfurt am Main
Physicists have developed an innovative method that could enable the efficient use of nanocomponents in electronic circuits. To achieve this, they have developed a layout in which a nanocomponent is connected to two electrical conductors, which uncouple the electrical signal in a highly efficient manner. The scientists at the Department of Physics and the Swiss Nanoscience Institute at the University of Basel have published their results in the scientific journal “Nature Communications” together with their colleagues from ETH Zurich.
Electronic components are becoming smaller and smaller. Components measuring just a few nanometers – the size of around ten atoms – are already being produced...
Development and implementation of an advanced automobile parking navigation platform for parking services
To fulfill the requirements of the industry, PolyU researchers developed the Advanced Automobile Parking Navigation Platform, which includes smart devices,...
The world's first electrical car and passenger ferry powered by batteries has entered service in Norway. The ferry only uses 150 kWh per route, which...
On Tuesday, 19 May 2015 the research icebreaker Polarstern will leave its home port in Bremerhaven, setting a course for the Arctic. Led by Dr Ilka Peeken from the Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research (AWI) a team of 53 researchers from 11 countries will investigate the effects of climate change in the Arctic, from the surface ice floes down to the seafloor.
RV Polarstern will enter the sea-ice zone north of Spitsbergen. Covering two shallow regions on their way to deeper waters, the scientists on board will focus...
Nanoengineers at the University of California, San Diego developed a gel filled with toxin-absorbing nanosponges that could lead to an effective treatment for skin and wound infections caused by MRSA (methicillin-resistant Staphylococcus aureus), an antibiotic-resistant bacteria. This "nanosponge-hydrogel" minimized the growth of skin lesions on mice infected with MRSA - without the use of antibiotics. The researchers recently published their findings online in Advanced Materials.
To make the nanosponge-hydrogel, the team mixed nanosponges, which are nanoparticles that absorb dangerous toxins produced by MRSA, E. coli and other...
20.05.2015 | Event News
18.05.2015 | Event News
12.05.2015 | Event News
22.05.2015 | Materials Sciences
22.05.2015 | Information Technology
22.05.2015 | Materials Sciences