Fabrication of microchip electrophoresis devices and effects of channel surface properties on separation efficiency

Kim, Minsu; Cho, Seung Il; Lee, Kook-Nyung; Kim, Yong-Kweon

doi:10.1016/j.snb.2004.12.069

Cited by 38 publications

(31 citation statements)

References 26 publications

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“…21,22 To make the three-layer microchip by thermal bonding, there are two aspects that should be taken into account. The bonding temperature should be lowered as much as possible to avoid fractures in the metal microelectrode.…”

Section: Two-step Bonding Processmentioning

confidence: 99%

A three-layer PMMA electrophoresis microchip with Pt microelectrodes insulated by a thin film for contactless conductivity detection

et al. 2011

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A three-layer poly (methyl methacrylate) (PMMA) electrophoresis microchip integrated with Pt microelectrodes for contactless conductivity detection is presented. A 50 mm-thick PMMA film is used as the insulating layer and placed between the channel plate (containing the microchannel) and the electrode plate (containing the microelectrode). The three-layer structure facilitates the achievement of a thin insulating layer, obviates the difficulty of integrating microelectrodes on a thin film, and does not compromise the integration of microchips. To overcome the thermal and chemical incompatibilities of polymers and photolithographic techniques, a modified lift-off process was developed to integrate Pt microelectrodes onto the PMMA substrate. A novel two-step bonding method was created to assemble the complete PMMA microchip. A low limit of detection of 1.25 mg ml À1 for Na + and high separation efficiency of 77 000 and 48 000 plates/m for Na + and K + were obtained when operating the detector at a low excitation frequency of 60 kHz.

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Section: Two-step Bonding Processmentioning

confidence: 99%

A three-layer PMMA electrophoresis microchip with Pt microelectrodes insulated by a thin film for contactless conductivity detection

et al. 2011

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“…For example, in a comparison of capillary electrophoresis chips made of single materials vs. bonded dissimilar materials, the singlematerial devices performed better. 36 In this article, we detail the advantages offered by glass and silicon and suggest a framework for selecting fabrication processes. We also describe key considerations for designing a glass and/or silicon process flow.…”

Section: The Remaining Advantages Of Silicon and Glassmentioning

confidence: 99%

A practical guide for the fabrication of microfluidic devices using glass and silicon

Iliescu¹,

Taylor²,

Avram³

et al. 2012

Biomicrofluidics

311

207

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This paper describes the main protocols that are used for fabricating microfluidic devices from glass and silicon. Methods for micropatterning glass and silicon are surveyed, and their limitations are discussed. Bonding methods that can be used for joining these materials are summarized and key process parameters are indicated. The paper also outlines techniques for forming electrical connections between microfluidic devices and external circuits. A framework is proposed for the synthesis of a complete glass/silicon device fabrication flow. I. WHY USE SILICON AND GLASS IN MICRO-AND NANO-FLUIDIC APPLICATIONS?Micro-and nano-fluidic technology continues to be embraced by biologists, 1-3 chemists, 4 and engineers throughout academia and industry. As its applications have expanded, there has been an explosion in the range of materials and processes used to fabricate these devices. The earliest microfluidic devices (e.g., gas 5 and liquid 6 chromatography devices) were made from silicon and glass and borrowed processes directly from semiconductor and microelectromechanical systems (MEMS) manufacturing. 7 Now, however, many researchers have moved away from silicon and glass, and instead use cast elastomers such as polydimethylsiloxane (PDMS)-which is ideal for swift prototyping-or thermoplastic polymers, which can be hot-embossed or injection-molded and are well suited to inexpensive manufacturing. Yet, there remain many applications where glass and silicon offer advantages over polymeric materials. In this paper, we highlight these advantages and offer a framework for selecting fabrication processes when using silicon and glass. A. The dominance of soft lithographyOver the last decade, PDMS has become virtually the default material for forming microfluidic devices, 8 because of the sheer ease with which it can be cast on to a micro-scale mould and then strongly bonded to glass. 9 The elastomeric nature of the material has been exploited to integrate fluidic valves and pumps on-chip and has simplified the production of multi-layer devices because the soft layers readily conform to each other. 10,11 Yet, the low stiffness (usually <1 MPa) of PDMS relative to amorphous thermoplastics, silicon, and glass has its own a) Authors to whom correspondence should be addressed. Electronic addresses: ciliescu@ibn.a-star.edu.sg and hkt@ntu.edu.sg. 6, 016505 (2012) drawbacks. High aspect-ratio channels are notoriously difficult to fabricate in PDMS because of their propensity to collapse. 12 Moreover, difficulties in automating the handling of such a soft material have hampered efforts to scale up PDMS device manufacturing. Meanwhile, PDMS's high oxygen and water permeabilities have proved both a blessing and a curse in different applications.The hydrophobic nature of PDMS can be an important consideration for some biological applications. In drug screening applications, for example, hydrophobic drugs as well as metabolites (urea or albumin) can be absorbed into the device's material due to hydrophobic--hydrophobic interaction...

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“…However, polymer capillaries could potentially be an attractive alternative to fused silica ones because of the inertness or different surface chemistry of their inner wall. But so far these materials have been rarely used in the production of CE microfluidic devices [14][15][16]. Over the last ten years only a few papers have been published on the employment of polyether ether ketone (PEEK) [17][18][19], PMMA [17,18], PTFE [20,21] and other organic polymer materials [22,23] as column material in CE.…”

Section: Introductionmentioning

confidence: 99%

CE separation of various analytes of biological origin using polyether ether ketone capillaries and contactless conductivity detection

2009

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The development of efficient and sensitive analytical methods for the separation, identification and quantification of complex biological samples is continuously a topic of high interest in biological science. In the present study, the possibility of using a polyether ether ketone (PEEK) capillary for the CE separation of peptides, proteins and other biological samples was examined. The performance of the tubing was compared with that of traditional silica capillaries. The CE analysis was performed using contactless conductivity detection (C(4)D), which eliminated any need for the detection window and was suitable for the detection of optically inactive compounds. In the PEEK capillary the cathodic EOF was low and of excellent stability even at extremes pH. In view of this fast biological anions were analyzed using an opposite end injection technique without compromising separation. A comparison of the performances of fused-silica and polymer capillaries during the separation of model sample mixtures demonstrated the efficiency and separation resolution of the latter to be higher and the reproducibility of the migration times and peak areas is better. Furthermore, PEEK capillaries allowed using simple experimental conditions without any complicated modification of the capillary surface or use of an intricate buffer composition. The PEEK capillaries are considered as an attractive alternative to the traditional fused-silica capillaries and may be used for the analysis of complex biological mixtures as well as for developing portable devices.

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Fabrication of microchip electrophoresis devices and effects of channel surface properties on separation efficiency

Cited by 38 publications

References 26 publications

A three-layer PMMA electrophoresis microchip with Pt microelectrodes insulated by a thin film for contactless conductivity detection

A three-layer PMMA electrophoresis microchip with Pt microelectrodes insulated by a thin film for contactless conductivity detection

A practical guide for the fabrication of microfluidic devices using glass and silicon

CE separation of various analytes of biological origin using polyether ether ketone capillaries and contactless conductivity detection

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