Conference Paper

Micromachined porous polymer for bubble free electro-osmotic pump

Dept. of Electr. Eng. & Comput. Sci., Michigan Univ., Ann Arbor, MI
DOI: 10.1109/MEMSYS.2002.984050 Conference: Micro Electro Mechanical Systems, 2002. The Fifteenth IEEE International Conference on
Source: IEEE Xplore


A novel porous polymer was microfabricated to serve as a porous
plug for a new device, the porous plug electro-osmotic pump (pp-EOP).
The plug eliminates any back pressure effects while enhances
electro-osmotic flow in a channel. The pp-EOP was batch fabricated by
surface micromachining on top of a silicon wafer. The pp-EOP device is
driven by a periodic, zero-average injected current signal at low
frequencies producing bubble-free electro-osmotic flow with reversible
net movement. Testing of the device produced an average water-air
interface velocity of 1.8 μm/s at 0.8 Hz. The velocity was increased
to 4.8 and to 13.9 μm/s by necking the channel size

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Available from: Senol Mutlu, May 09, 2014
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    • "In-situ photopolymerization techniques can fabricate various microstructures in microfluidic channels by photopatterning of liquid-phase photocurable polymer materials [1] [2] [3] [4]. Examples include the fabrication of 'anchored' [1] [2] [3] and 'unanchored' [4] polymeric structures, such as valves [1], plugs [2], electrodes [3], and two-phase microparticles [4]. Especially, continuous-flow lithography techniques [4] can continuously generate various types of free-floating microstructures by selectively polymerizing photopolymer solutions flowing in the microfluidic channels. "
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    ABSTRACT: We propose and demonstrate an optofluidic maskless lithography technique to fabricate various polymer microparticles and microwires in microfluidic channels. Combining maskless lithography and microfluidic systems, we demonstrate temporal and spatial control of polymeric micro structure generation in microfluidic channels.
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    • "However, the hydraulic resistance increases 10,000 times, effectively blocking pressure driven flow. Devices were fabricated with a four-mask surface micromachining process described in [3]. The polymer used was the product of polymerization of a mixture of ethylene dimethacrylate, butyl methacrylate and propenasulfonic acid in the presence of a porogenic solvents consisting of propanol, butanediol and water. "
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    ABSTRACT: We have previously demonstrated that polymer plugs with sub-micron pores can suppress unwanted pressure-driven flow and enhance electro-osmotic flow in a microchannel. This paper presents two separate concepts related to electrode placement and biasing strategy that further abate generation of bubbles in the main flow. In the first concept the drive signal is applied to a main EOF porous plug through high flow resistance porous bridges present outside the main flow. In the second approach, metal electrodes are located within the main channel across a series of dielectrically isolated narrow channels. Bubble generation is suppressed with a high-frequency square wave drive, and net unidirectional flow is achieved by modulation of the zeta potential on the narrow channel surfaces. Flow velocities of 10-66 μm/sec in 20-μm high channels have been achieved by these two methods.
    Micro Electro Mechanical Systems, 2004. 17th IEEE International Conference on. (MEMS); 02/2004

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