Buried centimeter-long micro- and nanochannel arrays in porous silicon and glass

Azimi, Sara; Dang, Zhiya; Zhang, Ce; Song, Jianjian; Breese, M.B.H.; Sow, Chorng Haur; Kan, J.A. van; Maarel, Johan R. C. van der

doi:10.1039/c4lc00062e

Cited by 14 publications

(15 citation statements)

References 61 publications

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“…It would also be worthwhile to consider other ways that the channel shape can affect the hydrodynamic interactions, either using circular channels to eliminate the corner flows or using triangular channels [123,124] to enhance the importance of these flows. Such simulations for circular confinement are driven more by curiosity, since fabrication of transparent circular nanochannels suitable for fluorescence microscopy is challenging but possible [125]. In contrast, triangular channels are easily fabricated [123,124] and provide a stronger extension than a square channel for a given cross-sectional area [126,127].…”

Section: Discussionmentioning

confidence: 99%

Hydrodynamics of DNA confined in nanoslits and nanochannels

Dorfman

Gupta

Jain

et al. 2014

Eur. Phys. J. Spec. Top.

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Modeling the dynamics of a confined, semi exible polymer is a challenging problem, owing to the complicated interplay between the configurations of the chain, which are strongly affected by the length scale for the confinement relative to the persistence length of the chain, and the polymer-wall hydrodynamic interactions. At the same time, understanding these dynamics are crucial to the advancement of emerging genomic technologies that use confinement to stretch out DNA and “read” a genomic signature. In this mini-review, we begin by considering what is known experimentally and theoretically about the friction of a wormlike chain such as DNA confined in a slit or a channel. We then discuss how to estimate the friction coefficient of such a chain, either with dynamic simulations or via Monte Carlo sampling and the Kirk-wood pre-averaging approximation. We then review our recent work on computing the diffusivity of DNA in nanoslits and nanochannels, and conclude with some promising avenues for future work and caveats about our approach.

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Section: Discussionmentioning

confidence: 99%

Hydrodynamics of DNA confined in nanoslits and nanochannels

Dorfman

Gupta

Jain

et al. 2014

Eur. Phys. J. Spec. Top.

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“…Applications in optoelectronics, [ 1,2 ] photonics, [ 3 ] microthermal systems, [ 4 ] lab on a chip, [ 5 ] biodegradable materials, [ 6,7 ] in vivo bioimagining, and properties of the substrate. Applications in optoelectronics, [ 1,2 ] photonics, [ 3 ] microthermal systems, [ 4 ] lab on a chip, [ 5 ] biodegradable materials, [ 6,7 ] in vivo bioimagining, and properties of the substrate.…”

Section: Introductionmentioning

confidence: 99%

Direct Imprinting of Porous Silicon via Metal‐Assisted Chemical Etching

Azeredo

Lin

Avagyan

et al. 2016

Adv Funct Materials

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2929wileyonlinelibrary.com drug delivery, [ 8,9 ] and biosensing [ 10,11 ] are derived from such integration. However, micro-and nanopatterning of PS has remained a challenge due to the inability of standard microfabrication processes (e.g., photolithography, wet and dry etching) to effectively pattern PS. [ 12 ] In this paper, we demonstrate a low-cost, low-stress, ambient and high-throughput chemical nanoimprint approach to patterning smooth 3D curvilinear PS surfaces in a single imprinting operation. As a demonstration of this process, sinusoidal and parabolic surfaces with potential uses as diffraction gratings and concentrators are fabricated to demonstrate potential onchip micro-optical components.Traditional approaches to patterning Si do not extend to PS because of the permeability and reactivity of the latter. During photolithography and micromachining, photoresist, developers, and etchants infi ltrate the pores, leading to contamination of the substrate, poor sidewall control and over-etching and, in general, poor fi delity of pattern transfer. [ 12,13 ] A simple route to bypass these issues is to perform lithography prior to anodization. The patterned photoresist fi lm is used as a mask during the anodization step leading to 2D embedded PS patterns with micron-scale resolution. [ 14 ] Cost-effective wet-etching processes such as KOH cannot selectively etch PS since multi ple crystal facets are exposed. Recipes for dry etching methods must be specifi cally tailored to a particular pore morphology of the PS being etched and high-aspect ratio features are seldom reported. [ 12 ] To circumvent these issues, micro-contact printing (MP), [ 15 ] dry-removal soft-lithography (DWSL), [ 16 ] and direct imprinting of PS (DIPS) [ 17,18 ] methods have been developed to pattern PS. The MP method uses a stamp that blocks diffusion of reactants during anodization of the silicon surface. As a result, it offers few degrees of freedom for 3D patterning and, thus, is limited to fabricating shallow corrugated patterns. The latter two patterning methods exploit the controlled fracturing or collapsing of the brittle porous material to selectively strip or compress PS. While DWSL is restricted to 2D patterning with microscale resolution, DIPS can generate 3D features with sub-100 nm resolution. DIPS relies on the compaction of PS leading to permanent deformation of the substrate and, thus, modifying spatially the porous morphology and the optical Conventional lithographical techniques used for bulk semiconductors produce dramatically poor results when used for micro and mesoporous materials such as porous silicon (PS). In this work, for the fi rst time, a high-throughput, single-step, direct imprinting process for PS not involving plastic deformation or high-temperature processing is reported. Based on the underlying mechanism of metal-assisted chemical etching (MACE), this process uses a pre-patterned polymer stamp coated with a noble metal catalyst to etch PS immersed in an HF-oxidizer mixture. The process not only overcome...

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“…1. 1 The range of j we consider in this paper is from 30 to 300 mA cm À2 , indicated by the double headed arrow. 2a shows the porosity of different resistivity p-type silicon aer anodization, data taken from ref.…”

Section: Characterization Of Unirradiated Wafersmentioning

confidence: 99%

“…This process is based on focused, high energy ion irradiation in a nuclear microprobe 2 of low resistivity, 0.02 U cm, p-type silicon, where the defect generation rate peaks close to the ion end-of-range depth, see Fig. [3][4][5] For low uence ion irradiation these end-of-range regions are only partially depleted of charge carriers and during subsequent electrochemical anodization in hydrouoric acid (HF) solution (24% HF, from a 1 : 1 solution of HF (48%)-ethanol), they become much more porous than the surrounding unirradiated porous silicon (PS) by a process of increased current ow and increased resistivity, 1,6,7 Fig. Focused ion beam irradiation, typically with protons or helium ions, results in a small volume at the end-of-range depth being highly damaged, while the portion closer to the surface is damaged to a lesser extent.…”

Section: Introductionmentioning

confidence: 99%

A study of buried channel formation in oxidized porous silicon

et al. 2014

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We have studied the formation of buried, hollow channels in oxidized porous silicon produced by a process based on focused high-energy ion irradiation of low resistivity, p-type silicon. This is followed by electrochemical anodization and various oxidation stages, all of which may influence the channel size, shape and roughness. We have identified several mechanisms by which the irradiation fluence can alter the channel size and shape, and studied the dependence on anodization current density and oxidation temperature. A low anodization current density combined with high temperature oxidation results in hollow channels in oxidized porous silicon being shrunk to dimensions of about 50 nm. Highly smooth, symmetric channels are produced using viscous flow of the oxidized porous silicon during high temperature oxidation.

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Buried centimeter-long micro- and nanochannel arrays in porous silicon and glass

Cited by 14 publications

References 61 publications

Hydrodynamics of DNA confined in nanoslits and nanochannels

Hydrodynamics of DNA confined in nanoslits and nanochannels

Direct Imprinting of Porous Silicon via Metal‐Assisted Chemical Etching

A study of buried channel formation in oxidized porous silicon

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