Nano-pump Research Project Could Eventually Help Save Lives
With an eyedropper, Diefeng Gu places a tiny droplet of de-ionized water on the flat, black disk, which consists of a nanoporous alumina membrane, meaning it has only tiny openings for material to pass through.
Next, the Old Dominion University postdoctoral researcher hooks up what look like tiny booster cables to the metal strips that protrude from each side of the disk. The wires run to a power supply box.
Gu then turns on the power supply and applies a few volts of electricity. Slowly the droplet of water is moved through the nanoporous membrane and reappears at the backside.
"Watch what happens now," Gu says. He reverses the current, and in an instant, the water reappears, seemingly defying gravity.
What he's demonstrating is just about the smallest electroosmotic (EO) pump ever seen. Using groundbreaking Atomic Layer Deposition (ALD) technology, Old Dominion University researchers have created a novel device that will transport fluid through an otherwise impenetrable membrane, at the precise rate desired, using only a few volts, which will allow the EO pump to be operated by batteries in a handheld portable device.
The work is being done at the Applied Research Center (ARC) in Newport News, a consortium of four local universities, including ODU, whose collaborative goal is to be a leader in applied research.
The process Gu works with is known as electroosmosis, and it can be achieved up to four times more efficiently using the ARC's technology. The potential uses for this valveless "pump" with no moving mechanical parts cross the spectrum - from medicine, to desalination, to energy generation.
Project leader Helmut Baumgart, professor and Virginia Microelectronics Consortium Chair with ODU's Frank Batten College of Engineering and Technology, uses the example of the handheld device diabetics use to take blood sugar readings.
This miniature EO pump is envisioned to be an integral part of future lab-on-a-chip (LOC) devices, which are capable of providing medical information that previously was available only through time-consuming lab tests. If blood or saliva can be moved through the device, a whole host of tests could be done, right in the palm of one's hand.
Further, the mechanism can be modified to selectively analyze liquid being moved through the membrane. Possible applications for the technology include using the pumps to detect problematic molecules in fluids, such as testing water for harmful bacteria.
"It could save people's lives. When integrated into a portable lab-on-a-chip device, such a system can be utilized at any remote location or accident scene far from any hospital, and soldiers could use it on the battlefield," Baumgart said. "There are currently two patents pending out of this lab on this technology."
Furthermore, this miniature EO pump can find applications in direct drug delivery in conjunction with a programmable microchip.
No micropumps developed to date in any laboratory meet the diverse requirements of LOC technology - namely that they can run on low voltage, are relatively insensitive to pH, work with a wide range of drugs and chemical agents, and are constructed simply, with no moving parts.
Building a miniature EO pump with those requirements is the motivation behind the work at ARC.
Among the keys to the process are the nano-sized pores that the lab has created in the alumina membrane and the research using ALD technology to allow the inner pore walls to control the EO flow, both actively and passively.
Nanotechnology "runs the gamut," Baumgart said, noting that it involves any scientific work being done with materials at dimensions as small as 10 to the negative ninth power of a meter. Baumgart's team at ARC specializes in ALD technology, which allows these nano-sized pores to be evenly coated with selected films which, when combined with an electric field, offer superior control of the flow of liquids through the EO pump membrane.
ARC is proposing a comprehensive and interdisciplinary research program to design, fabricate and describe the potential of electroosmotic pumps using thin membranes with nano-sized pores. Baumgart said the plan is to experiment with three electric terminals, so the direction of water flow can be controlled without reversing the electric current.
For this research, the team has applied for a three-year, $300,000 grant from the National Science Foundation. In the meantime, the interdisciplinary research project is being funded by a six-month seed grant from ODU's Office of Research, with Shizhi Qian, ODU assistant professor of aerospace engineering, as the principal investigator.
Baumgart, who envisions the ARC becoming a leader in the field, says that interdisciplinary collaboration is one of the best things about this research project.
The other principal team members involved in the project are Ali Beskok, professor and Batten Endowed Chair in the aerospace engineering department at ODU; Tarek Abdel-Fattah, associate professor of biology, chemistry and environmental science at Christopher Newport University; and several graduate students from the two schools' engineering departments.