Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

A medical micropump

14.11.2006
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:
http://www.utah.edu
http://www.unews.utah.edu

More articles from Medical Engineering:

nachricht 'Neuron-reading' nanowires could accelerate development of drugs for neurological diseases
12.04.2017 | University of California - San Diego

nachricht PET radiotracer design for monitoring targeted immunotherapy
10.04.2017 | Society of Nuclear Medicine

All articles from Medical Engineering >>>

The most recent press releases about innovation >>>

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

Im Focus: Making lightweight construction suitable for series production

More and more automobile companies are focusing on body parts made of carbon fiber reinforced plastics (CFRP). However, manufacturing and repair costs must be further reduced in order to make CFRP more economical in use. Together with the Volkswagen AG and five other partners in the project HolQueSt 3D, the Laser Zentrum Hannover e.V. (LZH) has developed laser processes for the automatic trimming, drilling and repair of three-dimensional components.

Automated manufacturing processes are the basis for ultimately establishing the series production of CFRP components. In the project HolQueSt 3D, the LZH has...

Im Focus: Wonder material? Novel nanotube structure strengthens thin films for flexible electronics

Reflecting the structure of composites found in nature and the ancient world, researchers at the University of Illinois at Urbana-Champaign have synthesized thin carbon nanotube (CNT) textiles that exhibit both high electrical conductivity and a level of toughness that is about fifty times higher than copper films, currently used in electronics.

"The structural robustness of thin metal films has significant importance for the reliable operation of smart skin and flexible electronics including...

Im Focus: Deep inside Galaxy M87

The nearby, giant radio galaxy M87 hosts a supermassive black hole (BH) and is well-known for its bright jet dominating the spectrum over ten orders of magnitude in frequency. Due to its proximity, jet prominence, and the large black hole mass, M87 is the best laboratory for investigating the formation, acceleration, and collimation of relativistic jets. A research team led by Silke Britzen from the Max Planck Institute for Radio Astronomy in Bonn, Germany, has found strong indication for turbulent processes connecting the accretion disk and the jet of that galaxy providing insights into the longstanding problem of the origin of astrophysical jets.

Supermassive black holes form some of the most enigmatic phenomena in astrophysics. Their enormous energy output is supposed to be generated by the...

Im Focus: A Quantum Low Pass for Photons

Physicists in Garching observe novel quantum effect that limits the number of emitted photons.

The probability to find a certain number of photons inside a laser pulse usually corresponds to a classical distribution of independent events, the so-called...

Im Focus: Microprocessors based on a layer of just three atoms

Microprocessors based on atomically thin materials hold the promise of the evolution of traditional processors as well as new applications in the field of flexible electronics. Now, a TU Wien research team led by Thomas Müller has made a breakthrough in this field as part of an ongoing research project.

Two-dimensional materials, or 2D materials for short, are extremely versatile, although – or often more precisely because – they are made up of just one or a...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Expert meeting “Health Business Connect” will connect international medical technology companies

20.04.2017 | Event News

Wenn der Computer das Gehirn austrickst

18.04.2017 | Event News

7th International Conference on Crystalline Silicon Photovoltaics in Freiburg on April 3-5, 2017

03.04.2017 | Event News

 
Latest News

DGIST develops 20 times faster biosensor

24.04.2017 | Physics and Astronomy

Nanoimprinted hyperlens array: Paving the way for practical super-resolution imaging

24.04.2017 | Materials Sciences

Atomic-level motion may drive bacteria's ability to evade immune system defenses

24.04.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>