Advanced Top-Down Fabrication for a Fused Silica Nanofluidic Device

Morikawa, Kyojiro; Kazoe, Yutaka; Takagi, Yoshiteru; Tsuyama, Yoshiyuki; Pihosh, Yuriy; Tsukahara, Takehiko; Kitamori, Takehiko

doi:10.3390/mi11110995

Cited by 37 publications

(31 citation statements)

References 56 publications

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“…Microchip 1 having a microchannel (depth, 30 ± 1.5 m; width, 1000 ± 50 m; outer circumference, 2060 ± 70 m; cross-sectional area, 3.0 ± 0.2 × 10 4 m 2 ) was fabricated via photolithography and dry etching, as described in previous studies. 21,22 A quartz glass substrate (size, 30 × 70 mm; thickness, 0.7 mm; VIOSIL-SX, Shin-Etsu Quartz Co., Ltd., Tokyo, Japan) was used. The glass substrate was sputtered with Cr to a thickness of 50 µm.…”

Section: Microchip Fabricationmentioning

confidence: 99%

Design of Microchannel Suitable for Packing with Anion Exchange Resins: Uranium Separation from Seawater Containing a Large Amount of Cesium

et al. 2021

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We present a resin-packed microchannel that can reduce the radiation exposure risk and secondary radioactive wastes during uranium (U) separation by downscaling the separation using a microchip. Two types of microchips were designed to densely pack the microchannels with resins. The microchannels had almost the same cross-sectional area but different outer circumferences. A satisfactory separation performance could be obtained by arranging more than ca. 10 resins along the depth and width of the microchannels. The resin-packed microchannel is an effective separation technique for determining U concentration via inductively coupled plasma mass spectrometry owing to its ability to avoid the contamination of the equipment by cesium and reduce the matrix effect. The size of the separation site was scaled down to <1/5000 compared to commonly used counterparts. The radiation exposure risk and secondary radioactive wastes can be reduced by 10-and 800-fold, respectively, using the resin-packed microchannel.

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Section: Microchip Fabricationmentioning

confidence: 99%

Design of Microchannel Suitable for Packing with Anion Exchange Resins: Uranium Separation from Seawater Containing a Large Amount of Cesium

et al. 2021

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“…Microchannels and nanochannels were fabricated on glass substrates (VIO-SILSX, Shin-Etsu Quartz Co., Ltd., Tokyo, Japan) by photolithography and electron beam lithography followed by reactive ion etching. 28 After modifying all the nanochannels with hydrophobic molecules (octadecyltrimethoxysilane, ODS), the modification on one half of the side of the nanochannel was removed by irradiating with a FIB (Fig. 1).…”

Section: Fabrication Processmentioning

confidence: 99%

“…[22][23][24][25][26][27] Our group has been exploiting this field utilizing 10-1000 nm sized nanochannels on a glass substrate. 28 Based on the high surface area effect in such a small volume, novel unit operations at the molecular level such as single-molecule ELISA (enzyme-linked immunosorbent assay), 29 single DNA molecule sorting, 30 nano-chromatography using the channel as a separation column, 31 and picoliter enzyme reactors 32 have been performed. These operations are called nano unit operations (NUOs) and in order to interconnect NUOs and realize integrated nanofluidic analytical systems, formation of parallel multiphase flows in nanochannels is required.…”

Section: Introductionmentioning

confidence: 99%

Stable Formation of Aqueous/Organic Parallel Two-phase Flow in Nanochannels with Partial Surface Modification

2021

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In microfluidics, various chemical processes can be integrated utilizing parallel multiphase flows. Our group has extended this research to nanofluidics and recently performed extraction of lipids using parallel two-phase flow in nanochannels. Although this was achieved in surface-modified nanochannels, a stable condition of parallel twophase flow remains unknown due to difficulties in device fabrication, for a suitable method of bonding surface-modified substrates is lacking. Therefore, research on parallel two-phase flow in nanochannels has been limited. Herein, a new bonding method which improves the wash process for the substrates and increases the bonding rate to ~100% is described. The conditions to achieve parallel organic/aqueous two-phase flow were then studied. It was revealed that in nanochannels, higher capillary numbers for the organic phase flow were required compared to that in microchannels. The newly developed fabrication process and flow regimes will contribute to realize integrated nanofluidic devices capable of analyzing single molecules/cells.

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“…Contamination during nanochannel fabrication processes is no exception. Electron beam (EB) lithography, photolithography, and dry etching are the main processes we employ for the fabrication of fused silica nanochannels/microchannels [ 33 ]. In these processes, different etching masks are used based on the target channel dimensions.…”

Section: Introductionmentioning

confidence: 99%

Metal-Free Fabrication of Fused Silica Extended Nanofluidic Channel to Remove Artifacts in Chemical Analysis

et al. 2021

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In microfluidics, especially in nanofluidics, nanochannels with functionalized surfaces have recently attracted attention for use as a new tool for the investigation of chemical reaction fields. Molecules handled in the reaction field can reach the single–molecule level due to the small size of the nanochannel. In such surroundings, contamination of the channel surface should be removed at the single–molecule level. In this study, it was assumed that metal materials could contaminate the nanochannels during the fabrication processes; therefore, we aimed to develop metal-free fabrication processes. Fused silica channels 1000 nm-deep were conventionally fabricated using a chromium mask. Instead of chromium, electron beam resists more than 1000 nm thick were used and the lithography conditions were optimized. From the results of optimization, channels with 1000 nm scale width and depth were fabricated on fused silica substrates without the use of a chromium mask. In nanofluidic experiments, an oxidation reaction was observed in a device fabricated by conventional fabrication processes using a chromium mask. It was found that Cr6+ remained on the channel surfaces and reacted with chemicals in the liquid phase in the extended nanochannels; this effect occurred at least to the micromolar level. In contrast, the device fabricated with metal-free processes was free of artifacts induced by the presence of chromium. The developed fabrication processes and results of this study will be a significant contribution to the fundamental technologies employed in the fields of microfluidics and nanofluidics.

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Advanced Top-Down Fabrication for a Fused Silica Nanofluidic Device

Cited by 37 publications

References 56 publications

Design of Microchannel Suitable for Packing with Anion Exchange Resins: Uranium Separation from Seawater Containing a Large Amount of Cesium

Design of Microchannel Suitable for Packing with Anion Exchange Resins: Uranium Separation from Seawater Containing a Large Amount of Cesium

Stable Formation of Aqueous/Organic Parallel Two-phase Flow in Nanochannels with Partial Surface Modification

Metal-Free Fabrication of Fused Silica Extended Nanofluidic Channel to Remove Artifacts in Chemical Analysis

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