Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:


A medical micropump

Device should aid development of 'laboratory-on-a-chip'
Using material similar to bathtub caulk, University of Utah engineers invented a tiny, inexpensive "micropump" that could be used to move chemicals, blood or other samples through a card-sized medical laboratory known as a lab-on-a-chip.

"The purpose of this micropump is to make it easier for people to receive the results of medical tests when they are in the doctor's office rather than waiting a couple of days or weeks," says bioengineering graduate student Mark Eddings. "It also might deliver pain medication or other drugs through a device attached to the skin."

Bruce Gale, an assistant professor of mechanical engineering at the University of Utah, says an inexpensive, portable and easy-to-manufacture pump should aid development of a lab-on-a-chip, in which "we take all the components that would fill a room in a medical lab and put them all down on a chip the size of a credit card."

Eddings and Gale outlined development of the new micropump in the November 2006 issue of the Journal of Micromechanics and Microengineering, published Monday, Nov. 13.

Gale says labs-on-a-chip are not yet available commercially, although some are getting close. Eddings says possible uses include detection of biowarfare agents, monitoring drug levels in patients, detecting gene mutations, monitoring insulin levels in people with diabetes and many diagnostic tests.

Because liquid can flow slowly through the tiny pump, it also could be used in a drug-delivery device, such as a skin patch with tiny needles, Eddings says.

Gale expects it will take three or four years before the new micropump shows up on commercial lab-on-a-chip devices and in drug-delivery devices.

Building Tiny Pumps with Silicone Resembling Bathroom Caulk

While a lab-on-a-chip would have hundreds to thousands of micropumps – sets of tiny fluid and air channels and larger chambers in which samples were tested – Eddings and Gale demonstrated their invention by building an array of 10 of the tiny pumps.

They molded tube-like "microchannels" – each the width of a human hair – into the top and bottom layers of a three-layered piece of silicone polymer material about the size of a deck of playing cards. The polymer is named polydimethylsiloxane, or PDMS.

"It's made out of bathroom caulk," Gale quips. "It is very similar to the clear silicones you'd use to seal your bathtub."

The card deck-sized array has three layers of rubbery PDMS:

  • A top fluid channel layer, with wells into which blood or other samples are placed, and microchannels through which they can flow toward small chambers.
  • A crucial middle layer, a thin, permeable membrane of PDMS. Gas can pass through the caulk-like PDMS, while liquid cannot.
  • A bottom control channel layer, with inlets and tiny channels through which air pressure or a vacuum is applied.

The air pressure or vacuum, respectively, push or pull air through channels in the bottom layer, transmitting pressure or suction through the middle-layer membrane to push or draw fluids through channels in the upper layer.

While an outside air pump or vacuum is needed to run the device, Gale says the membrane is, in effect, the pump because a pump creates a pressure difference, which is what the membrane does to move fluids.

Because gas, not fluid, flows through the middle layer, liquid in the upper-layer microchannels can flow into and fill dead-end channels or chambers without trapping air. That allows the pump to carry samples like blood or fluids with protein or DNA through the microchannels to dead-end chambers that contain chemicals needed for a test.

The outside device to run the lab-on-a-chip – including air pressure or a vacuum to run the micropumps – "would be as big your wallet, and the chip would be like a credit card that goes in your wallet," Gale says.

Each micropump can produce a flow of up to 200 nanoliters of fluid per minute. A nanoliter is one-billionth of a liter, and a liter is less than 1.1 quarts.

"If you had a drop on the end of a pin, that would be five times as much fluid as this pump would move in a minute," Gale says. "In some respects, we are bragging that's a large flow" for such a tiny pump. Yet the flow could be slowed considerably if the pump was used to deliver drugs, he adds.

Of Micropumps and Miniature Laboratories

The idea of a lab-on-a-chip is to reduce the price and time for lab tests and to conduct them where patients are treated. On such a chip, micropumps replace the large equipment normally used to move blood and other samples through a laboratory test.

The first micropumps were developed 20 years ago, and some are used commercially now, particularly for various sensor devices and for cooling computer chips, Gale says. "But almost all the micropumps you find in the last 15 or 20 years are complicated, multilayered devices not conducive to inexpensive manufacturing, and you can't put a whole bunch of them on a chip," he adds.

Gale says there are at least 20 categories of micropumps, including ones that move fluids using piston-like devices, magnets, pressure from silicone membranes and electrical charges.

"Compared with our pump, existing micropumps are difficult to make and more expensive," Gale says. "They are bulky, and it is difficult to integrate thousands of them simultaneously into a lab-on-a-chip."

Another advantage of the new micropump is that the mechanical air pressure device or vacuum that powers the pump never contacts blood or other medical samples.

"Most of these biological fluids are very sensitive," Gale says. "If you have a medical sample, you don't want to contaminate it. We've removed the complexity of the pump from the microdevice to an external location."

Eddings says only three or four steps are required to make the new micropump, compared with many steps for existing models.

The new micropump – known technically as a "PDMS-based gas permeation pump" – was developed for about $20,000 at the university's Center for Biomedical Fluidics, part of Utah's Centers of Excellence program, Gale says. The National Science Foundation also helped fund the research.

"This pump would not ever be sold as an independent system," Gale says. "It would be integrated directly into the device you are making."

Gale says he is working to develop a lab-on-a-chip that would test the blood of multiple sclerosis patients to determine if they are developing resistance to a new MS drug.

He also is developing a lab-on-a-chip blood test that would detect genes that affect how quickly various patients break down blood-thinning drugs used to treat heart disease. The test would be used by doctors to decide the right dose for each individual patient, something done now by trial and error, he says.

Lee Siegel | EurekAlert!
Further information:

More articles from Medical Engineering:

nachricht Münster researchers make a fly’s heartbeat visible / Software automatically recognizes pulse
12.03.2018 | Westfälische Wilhelms-Universität Münster

nachricht 3-D-written model to provide better understanding of cancer spread
05.03.2018 | Purdue University

All articles from Medical Engineering >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Space observation with radar to secure Germany's space infrastructure

Satellites in near-Earth orbit are at risk due to the steady increase in space debris. But their mission in the areas of telecommunications, navigation or weather forecasts is essential for society. Fraunhofer FHR therefore develops radar-based systems which allow the detection, tracking and cataloging of even the smallest particles of debris. Satellite operators who have access to our data are in a better position to plan evasive maneuvers and prevent destructive collisions. From April, 25-29 2018, Fraunhofer FHR and its partners will exhibit the complementary radar systems TIRA and GESTRA as well as the latest radar techniques for space observation across three stands at the ILA Berlin.

The "traffic situation" in space is very tense: the Earth is currently being orbited not only by countless satellites but also by a large volume of space...

Im Focus: Researchers Discover New Anti-Cancer Protein

An international team of researchers has discovered a new anti-cancer protein. The protein, called LHPP, prevents the uncontrolled proliferation of cancer cells in the liver. The researchers led by Prof. Michael N. Hall from the Biozentrum, University of Basel, report in “Nature” that LHPP can also serve as a biomarker for the diagnosis and prognosis of liver cancer.

The incidence of liver cancer, also known as hepatocellular carcinoma, is steadily increasing. In the last twenty years, the number of cases has almost doubled...

Im Focus: Researchers at Fraunhofer monitor re-entry of Chinese space station Tiangong-1

In just a few weeks from now, the Chinese space station Tiangong-1 will re-enter the Earth's atmosphere where it will to a large extent burn up. It is possible that some debris will reach the Earth's surface. Tiangong-1 is orbiting the Earth uncontrolled at a speed of approx. 29,000 km/h.Currently the prognosis relating to the time of impact currently lies within a window of several days. The scientists at Fraunhofer FHR have already been monitoring Tiangong-1 for a number of weeks with their TIRA system, one of the most powerful space observation radars in the world, with a view to supporting the German Space Situational Awareness Center and the ESA with their re-entry forecasts.

Following the loss of radio contact with Tiangong-1 in 2016 and due to the low orbital height, it is now inevitable that the Chinese space station will...

Im Focus: Alliance „OLED Licht Forum“ – Key partner for OLED lighting solutions

Fraunhofer Institute for Organic Electronics, Electron Beam and Plasma Technology FEP, provider of research and development services for OLED lighting solutions, announces the founding of the “OLED Licht Forum” and presents latest OLED design and lighting solutions during light+building, from March 18th – 23rd, 2018 in Frankfurt a.M./Germany, at booth no. F91 in Hall 4.0.

They are united in their passion for OLED (organic light emitting diodes) lighting with all of its unique facets and application possibilities. Thus experts in...

Im Focus: Mars' oceans formed early, possibly aided by massive volcanic eruptions

Oceans formed before Tharsis and evolved together, shaping climate history of Mars

A new scenario seeking to explain how Mars' putative oceans came and went over the last 4 billion years implies that the oceans formed several hundred million...

All Focus news of the innovation-report >>>



Industry & Economy
Event News

New solar solutions for sustainable buildings and cities

23.03.2018 | Event News

Virtual reality conference comes to Reutlingen

19.03.2018 | Event News

Ultrafast Wireless and Chip Design at the DATE Conference in Dresden

16.03.2018 | Event News

Latest News

For graphite pellets, just add elbow grease

23.03.2018 | Materials Sciences

Unique communication strategy discovered in stem cell pathway controlling plant growth

23.03.2018 | Agricultural and Forestry Science

Sharpening the X-ray view of the nanocosm

23.03.2018 | Physics and Astronomy

Science & Research
Overview of more VideoLinks >>>