Micropumps Based on the Enhanced Electroosmotic Effect of Aluminum Oxide Membranes

Miao, Jianying; Xu, Zuli; Zhang, Xinyi; Wang, Naiyan; Yang, Zheng; Sheng, Ping

doi:10.1002/adma.200700767

Cited by 53 publications

(52 citation statements)

References 17 publications

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“…Traditionally, most EOPs have been constructed with beds of packed silica particles (Zeng et al 2001) or relatively rigid porous materials such as anodic aluminum oxide (Ai et al 2010;Miao et al 2007). Polymeric, porous membranes function well as this media in flexible low-voltage EOPs since they are relatively thin, mechanically flexible, and can be highly porous.…”

Section: Introductionmentioning

confidence: 99%

A large-area, all-plastic, flexible electroosmotic pump

Bengtsson

Robinson

2017

Microfluid Nanofluid

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A large-area, fabric-like pump would potentially have applications, for example, in controlling water transport through a garment, such as a rain jacket, regardless of the external temperature and humidity. This paper presents an all-plastic, flexible electroosmotic pump, constructed from commercially available materials: A polycarbonate membrane combined with the electrochemically active polymer poly(3,4-ethylenedioxythiophene) polystyrene sulfonate that actively transports water using an electric potential that can be supplied by a small battery. By using electrochemically active polymer electrodes instead of metal electrodes, the electrochemical reaction that drives flow avoids the oxygen and hydrogen gas production or pH changes associated with water electrolysis. We observe a water mass flux up to 23 mg min −1 per cm 2 polycarbonate membrane (porosity 10-15%), at an applied potential of 5 V, and a limiting operating pressure of 0.3 kPa V −1 , similar to previously reported membrane-based electroosmotic pumps.

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Section: Introductionmentioning

confidence: 99%

A large-area, all-plastic, flexible electroosmotic pump

Bengtsson

Robinson

2017

Microfluid Nanofluid

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“…However, piezoelectric units generally require operating voltages larger than 100 V (13,15). Alternatively, nonmechanical pumps with no moving parts generate a driving force using ions energized via electrohydrodynamic (16), electroosmotic (17), or electrochemical (18,19) effects. However, ion pumps are generally only applicable for low-conductivity liquids, produce relatively low flow rates, and need very high voltages (in the order of kilovolts) to operate (13).…”

mentioning

confidence: 99%

Liquid metal enabled pump

Tang¹,

Khoshmanesh²,

Sivan³

et al. 2014

Proc. Natl. Acad. Sci. U.S.A.

334

285

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Small-scale pumps will be the heartbeat of many future micro/ nanoscale platforms. However, the integration of small-scale pumps is presently hampered by limited flow rate with respect to the input power, and their rather complicated fabrication processes. These issues arise as many conventional pumping effects require intricate moving elements. Here, we demonstrate a system that we call the liquid metal enabled pump, for driving a range of liquids without mechanical moving parts, upon the application of modest electric field. This pump incorporates a droplet of liquid metal, which induces liquid flow at high flow rates, yet with exceptionally low power consumption by electrowetting/deelectrowetting at the metal surface. We present theory explaining this pumping mechanism and show that the operation is fundamentally different from other existing pumps. The presented liquid metal enabled pump is both efficient and simple, and thus has the potential to fundamentally advance the field of microfluidics.E ngines are systems that convert different kinds of energy into mechanical motion, which are used in various microscale systems, including laboratory-on-a-chip microreactors (1-3), microelectromechanical (MEMS) actuators (4), and microscale heat exchangers (5, 6), to name just a few. Some of the most important members of the engine family are liquid pumps. In the small-scale regime, such pumps can be mainly classified into mechanical and nonmechanical. For mechanical pumps, the driving force is generated by moving parts that are energized using piezoelectric (7), electrostatic (8), thermopneumatic (9), pneumatic (10), electromagnetic (11) effects, or deformation through electrowetting (12). Mechanical pumping systems have several drawbacks, which largely stem from the fact that moving parts cause energy loses due to heat generated by friction and their rather complicated fabrication processes (13,14). In addition, the existence of moving parts increases the potential for failure, which can become acute in complex systems and which could potentially include numerous pumps. Among the varieties of mechanical pumps, only piezoelectric units can produce high flow rates as large as 20,000 μL/min at relatively low input power (>50 mW) (13, 15). However, piezoelectric units generally require operating voltages larger than 100 V (13, 15). Alternatively, nonmechanical pumps with no moving parts generate a driving force using ions energized via electrohydrodynamic (16), electroosmotic (17), or electrochemical (18, 19) effects. However, ion pumps are generally only applicable for low-conductivity liquids, produce relatively low flow rates, and need very high voltages (in the order of kilovolts) to operate (13). Therefore, a pumping system with no moving parts, high flow rate, and low power consumption is ideal for many present-day and emerging applications in microfluidic systems. An ambitious vision is that such pumps can potentially be used for moving small objects on demand, assembling them to create new structures, or could ...

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“…The term "maximum product of flow rate and pressure" implies that the product can vary, depending on the flow rate variation as a function of the pressure difference. In this paper, the efficiency χ is defined as (Q P ) max /I V , in agreement with the usual definition for the EOP [1][2][3][4][5]9].…”

Section: Introductionmentioning

confidence: 75%

“…The separation between the electrodes placed on the both sides of the sample is ∼300 μm. The silica coating layer on the wall of the microchannels can be visualized via electron microscope images [9]. The silica coating layer provides the necessary ζ potential for the EK effect in the AAO membranes, which would otherwise exhibit small or no EK activity.…”

Section: Anodic Aluminum Oxide Coated With Silicamentioning

confidence: 99%

“…The pH value of the silica sol-gel was kept at <5. The AAO film was immersed in the silica sol-gel at room temperature for more than 30 h in order to induce the silica sol-gel into the microchannels (nanochannels) [9]. The silica-coated AAO membranes were initially dried at 60 • C and then annealed at 600 • C in air for 6 h. Subsequently, the AAO membranes were washed with hot deionized (DI) water (>80 • C).…”

Section: Anodic Aluminum Oxide Coated With Silicamentioning

confidence: 99%

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Maximum efficiency of the electro-osmotic pump

Miao

Wang

et al. 2011

Phys. Rev. E

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Electro-osmotic effect in a porous medium arises from the electrically charged double layer at the fluid-solid interface, whereby an externally applied electric field can give rise to fluid flow. The electro-osmotic pump (EOP) is potentially useful for a variety of engineering and biorelated applications, but its generally low efficiency is a negative factor in this regard. A study to determine the optimal efficiency of the EOP and the condition(s) under which it can be realized is therefore of scientific interest and practical importance. We present the results of a theoretical and experimental study on the maximum efficiency optimization of the electrokinetic effect in artificially fabricated porous media with controlled pore diameters. It is shown that whereas the EOP efficiency increases with decreasing channel diameter, from 4.5 to 2.5 μm for samples fabricated on oxidized silicon wafers as expected for the interfacial nature of the electro-osmotic effect, the opposite trend was observed for samples with much smaller channel diameters fabricated on anodized aluminum oxide films, with the pore surface coated with silica. These results are in agreement with the theoretical prediction, based on the competition between interfacial area and the no-slip flow boundary condition, that an optimal efficiency of ∼1% is attained at a microchannel diameter that is five times the Debye length, with a zeta potential of ∼100 mV.

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Micropumps Based on the Enhanced Electroosmotic Effect of Aluminum Oxide Membranes

Cited by 53 publications

References 17 publications

A large-area, all-plastic, flexible electroosmotic pump

A large-area, all-plastic, flexible electroosmotic pump

Liquid metal enabled pump

Maximum efficiency of the electro-osmotic pump

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