Electrowetting in Carbon Nanotubes

Chen, J. Y.; Kutana, Alex; Collier, C. Patrick; Giapis, Konstantinos P.

doi:10.1126/science.1120385

Cited by 127 publications

(98 citation statements)

References 23 publications

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“…[22][23][24] This is an important characteristic that potentially allows electrocapillary manipulation and construction of highperformance imbibition systems.A CNT sponge is a macroscopic assembly of nanotubes with high porosity, electrical conductivity, and mechanical fl exibility. [ 25 ] Here, we show that these CNT sponges could serve as an electrocapillary imbiber to achieve effi cient water imbibition under low voltages and on-off switchability.…”

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confidence: 99%

A Switchable and Compressible Carbon Nanotube Sponge Electrocapillary Imbiber

et al. 2015

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Carbon nanotube sponges are lightweight, conductive, highly porous, and flexible. An integration of these properties is suitable for constructing high-performance electrocapillary imbibers. Water imbibition into the sponges can be initiated at low potentials with tunable uptake rates and switched on and off reversibly. These controllable nanoporous imbibers have potential applications in a wide range of flexible micro- and nanofluidic systems.

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confidence: 99%

A Switchable and Compressible Carbon Nanotube Sponge Electrocapillary Imbiber

et al. 2015

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“…Complications in our system would be resulted from tube end effects, 19 structural perfectness, and chirality of CNTs, and possible electrowetting effect. 20,21 Because of the compensation between different factors and their minor effects on this experiment, 19À21 it is believed not to change the order of magnitude for the obtained results. Hence the obtained enhancement and slip length values should reflect the intrinsic nanofluidics of water in CNTs.…”

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Measurement of the Rate of Water Translocation through Carbon Nanotubes

Qin

Yuan²,

Zhao³

et al. 2011

Nano Lett.

304

320

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E nhanced water flow through atomic smooth and hydrophobic carbon nanotubes (CNTs) have been demonstrated by both theoretical calculations and experiments. 1À5 There is, however, a great controversy between theory and experiments and even between experiments. The very limited experiments using CNTs membrane demonstrated enormous water flow velocity up to 5 orders of magnitude faster than predicted from conventional fluid-flow theory with three orders of deviation from different sources.1,2 In contrast, molecular dynamics (MD) calculation only gives a rate enhancement of 47À6500 for CNTs with diameters of 4.99À0.81 nm.3,5 One more general debate is whether there exists a clear transition from continuum to subcontinuum transport as the tube diameter shrinks to subnanometer regime. 5 The bottleneck for experimental attempts arises from fabrication of CNTs membrane with well-defined structures and the rational estimation of the available flow area.1 Here we show a single-tube level approach for elucidating such fundamental nanofluidic issues. The unique field effect transistors (FETs) array-based experimental design enables a direct measurement of water flow velocity inside individual CNTs. Our work demonstrates a rate enhancement of 51 to 882 for CNTs with diameters of 1.59 to 0.81 nm, which supports the MD calculation.3,5 Additionally, we achieved the first experimental evidence for the transition from continuum to subcontinuum flow by varying the diameters of CNTs.The key of our approach is to trace the water flow "front" inside an individual millimeter long CNT electrically with a configuration of three FETs in series (Figure 1a,b). The FET1 is used to "in-situ" open the tube end under water droplet by electrical breakdown, 6,7 and the synchronous FET2 and FET3 to detect the water front flowing in based on its influence on the current flow (Figure 2). 8,9 It should be emphasized that opening the tube end under water is a determinant factor for the success of this experimental design. A bias voltage of 0.01 V was applied on FET2 and FET3 (no gate voltage) all the time to detect current change. Simply by measuring the time delay of current signal jumps between FET2 and FET3 with a given interspacing, we can then estimate the average water flow velocity inside the nanotube. The CNT-FETs structure was constructed through directly growing ultralong CNT on SiO 2 /Si substrate with predesigned Pt-pattern (Figure 1b,c). Carbon nanotubes were synthesized by gas flow-directed chemical vapor deposition (CVD) method. 10À12 The catalysts pattern was made on growth substrate using PDMS stamp from the ethanol solution of 0.01 mol/L FeCl 3 . The typical growth conditions are 930À950°C, 3 sccm CH 4 and 5 sccm H 2 . Pt was sputtered and patterned as electrodes on SiO 2 /Si substrate by standard technique of photolithography and magnetron sputtering. The as-grown CNTs were characterized by scanning electron microscopy (SEM) followed by gold-wire wedge bonding, water filling and velocity measurement. A drop of pure water (18.2MΩ ...

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“…Nanofluidic experiments were performed on stand-alone nanotubes grown with an encapsulated fluid, on nanotubes vertically grown on a substrate, on nanotubes mounted at the end of the tip of an AFM, and on nanotubes inserted across a polymer film. [44][45][46][47][48] However, a planar integration would be more convenient. Karnik et al from Berkeley deposited and patterned a silicon dioxide layer on nanotubes dispersed on a glass substrate.…”

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confidence: 99%