2D-Confined Nanochannels Fabricated by Conventional Micromachining

Tas, Niels Roelof; Lammerink, Theodorus S.J.; Mela, P.; Jansen, Henricus V.; Elwenspoek, M.; Berg, Albert van den

doi:10.1021/nl025693r

Cited by 87 publications

(88 citation statements)

References 15 publications

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“…Long nanochannels on a silicon substrate have been realized by the fabrication of metal nanowires covered with a silicon nitride capping layer and subsequent metal line etching. Tas et al ͑2002͒ used the fabrication of nanowires on the sidewall of a submicrometer step ͑Fig. 31͒, whereas Peng et al ͑2003͒ applied electronbeam lithography to control the nanoscale dimension of the wires.…”

Section: B Sacrificial Layer Methodsmentioning

confidence: 99%

Transport phenomena in nanofluidics

2008

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The transport of fluid in and around nanometer-sized objects with at least one characteristic dimension below 100 nm enables the occurrence of phenomena that are impossible at bigger length scales. This research field was only recently termed nanofluidics, but it has deep roots in science and technology. Nanofluidics has experienced considerable growth in recent years, as is confirmed by significant scientific and practical achievements. This review focuses on the physical properties and operational mechanisms of the most common structures, such as nanometer-sized openings and nanowires in solution on a chip. Since the surface-to-volume ratio increases with miniaturization, this ratio is high in nanochannels, resulting in surface-charge-governed transport, which allows ion separation and is described by a comprehensive electrokinetic theory. The charge selectivity is most pronounced if the Debye screening length is comparable to the smallest dimension of the nanochannel cross section, leading to a predominantly counterion containing nanometer-sized aperture. These unique properties contribute to the charge-based partitioning of biomolecules at the microchannel-nanochannel interface. Additionally, at this free-energy barrier, size-based partitioning can be achieved when biomolecules and nanoconstrictions have similar dimensions. Furthermore, nanopores and nanowires are rooted in interesting physical concepts, and since these structures demonstrate sensitive, label-free, and real-time electrical detection of biomolecules, the technologies hold great promise for the life sciences. The purpose of this review is to describe physical mechanisms on the nanometer scale where new phenomena occur, in order to exploit these unique properties and realize integrated sample preparation and analysis systems.

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Section: B Sacrificial Layer Methodsmentioning

confidence: 99%

Transport phenomena in nanofluidics

2008

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“…This was only possible because of the recent advances in the innovative development of cost-effective fabrication methods of nanochannels [15,25,[34][35][36]. The filling rate decreased with diminishing channel depth (Fig.…”

Section: Washburn Kinetics In Channels With Different Depthmentioning

confidence: 99%

Filling kinetics of liquids in nanochannels as narrow as 27 nm by capillary force

Han

Mondin

Hegelbach

et al. 2006

Journal of Colloid and Interface Science

107

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We report the filling kinetics of different liquids in nanofabricated capillaries with rectangular cross-section by capillary force. Three sets of channels with different geometry were employed for the experiments. The smallest dimension of the channel cross-section was respectively 27, 50, and 73 nm. Ethanol, isopropanol, water and binary mixtures of ethanol and water spontaneously filled nanochannels with inner walls exposing silanol groups. For all the liquids the position of the moving liquid meniscus was observed to be proportional to the square root of time, which is in accordance with the classical Washburn kinetics. The velocity of the meniscus decreased both with the dimension of the channel and the ratio between the surface tension and the viscosity. In the case of water, air-bubbles were spontaneously trapped as channels were filled. For a binary mixture of 40% ethanol and water, no trapping of air was observed anymore. The filling rate was higher than expected, which also corresponds to the dynamic contact angle for the mixture being lower than that of pure ethanol. Nanochannels and porous materials share many physicochemical properties, e.g., the comparable pores size and extremely high surface to volume ratio. These similarities suggest that our nanochannels could be used as an idealized model to study mass transport mechanisms in systems where surface phenomena dominate.

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“…DOI: 10.1103/PhysRevLett.93.035901 PACS numbers: 66.10.-x, 82.65.+r Nanoscale fluidic channels represent a new regime in the study of ion transport. Recent advances in the fabrication of ultraconfined fluidic systems such as nanoscale ''lab-on-a-chip'' type devices [1][2][3] and synthetic nanopores [4 -6] raise fundamental questions about the influence of surfaces on ion transport. In particular, surface charges induce electrostatic ion (Debye) screening and electrokinetic effects such as electro-osmosis, streaming potentials, and streaming currents [7][8][9] that may have large effects on conductance in nanochannels, as suggested by studies of colloidal suspensions [10] and biological protein channels [11].…”

mentioning

confidence: 99%

Surface-Charge-Governed Ion Transport in Nanofluidic Channels

2004

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A study of ion transport in aqueous-filled silica channels as thin as 70 nm reveals a remarkable degree of conduction at low salt concentrations that departs strongly from bulk behavior: In the dilute limit, the electrical conductances of channels saturate at a value that is independent of both the salt concentration and the channel height. Our data are well described by an electrokinetic model parametrized only by the surface-charge density. Using chemical surface modifications, we further demonstrate that at low salt concentrations, ion transport in nanochannels is governed by the surface charge. DOI: 10.1103/PhysRevLett.93.035901 PACS numbers: 66.10.-x, 82.65.+r Nanoscale fluidic channels represent a new regime in the study of ion transport. Recent advances in the fabrication of ultraconfined fluidic systems such as nanoscale ''lab-on-a-chip'' type devices [1][2][3] and synthetic nanopores [4 -6] raise fundamental questions about the influence of surfaces on ion transport. In particular, surface charges induce electrostatic ion (Debye) screening and electrokinetic effects such as electro-osmosis, streaming potentials, and streaming currents [7][8][9] that may have large effects on conductance in nanochannels, as suggested by studies of colloidal suspensions [10] and biological protein channels [11]. Here we present experiments that directly probe ion transport in the nanoscale regime, and reveal the role of surface charge in governing conductance at low salt concentrations.Nanofluidic channels [ Fig. 1(a)] were fabricated following a silicate bonding procedure similar to that of Wang et al. [12]. Briefly, channels 50 m wide and 4:5 mm long were patterned between 1:5 mm 1:5 mm reservoirs using electron beam lithography on fused silica substrate. A reactive CHF 3 =O 2 plasma then etched into the fused silica at a rate of 30 nm=min, and was timed to stop when the desired submicron channel depth was attained. The depth of the resulting channel, h, was measured using an -stepper profilometer. The channels were sealed by first spinning a 20 nm layer of sodium silicate from 2% solution onto a flat fused silica chip, then pressing the silicate-coated surface to the patterned channel surface, and finally curing the device at 90 o C for 2 h. The channels were filled by introducing distilled, deionized (18 M cm) water into the large fluidic reservoirs, from which point capillary forces were sufficient to draw the water across the channels. The electrical voltage source and IV converter were connected to the fluidic channel with negligible resistive loss via silver wires inserted into the reservoirs [ Fig. 1(b)]. The channels were cleaned of ionic contaminants using electrophoretic pumping: The ionic current was observed to decay while 10 V were applied across the channels to drive out ionic impurities. The reservoirs were periodically flushed with fresh solution until the current equilibrated to a minimum, which typically took 20 min. This procedure was also followed to replace different dilutions of 1 M potassium ...

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2D-Confined Nanochannels Fabricated by Conventional Micromachining

Cited by 87 publications

References 15 publications

Transport phenomena in nanofluidics

Transport phenomena in nanofluidics

Filling kinetics of liquids in nanochannels as narrow as 27 nm by capillary force

Surface-Charge-Governed Ion Transport in Nanofluidic Channels

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