The Experts below are selected from a list of 23514 Experts worldwide ranked by ideXlab platform

Tony Jun Huang - One of the best experts on this subject based on the ideXlab platform.

  • three dimensional continuous particle focusing in a Microfluidic Channel via standing surface acoustic waves ssaw
    Lab on a Chip, 2011
    Co-Authors: Shahrzad Yazdi, Ikao Chiang, Kendra V Sharp, Xiaoyun Ding, Tony Jun Huang
    Abstract:

    Three-dimensional (3D) continuous microparticle focusing has been achieved in a single-layer polydimethylsiloxane (PDMS) Microfluidic Channel using a standing surface acoustic wave (SSAW). The SSAW was generated by the interference of two identical surface acoustic waves (SAWs) created by two parallel interdigital transducers (IDTs) on a piezoelectric substrate with a microChannel precisely bonded between them. To understand the working principle of the SSAW-based 3D focusing and investigate the position of the focal point, we computed longitudinal waves, generated by the SAWs and radiated into the fluid media from opposite sides of the microChannel, and the resultant pressure and velocity fields due to the interference and reflection of the longitudinal waves. Simulation results predict the existence of a focusing point which is in good agreement with our experimental observations. Compared with other 3D focusing techniques, this method is non-invasive, robust, energy-efficient, easy to implement, and applicable to nearly all types of microparticles.

  • continuous particle separation in a Microfluidic Channel via standing surface acoustic waves ssaw
    Lab on a Chip, 2009
    Co-Authors: Jinjie Shi, Hua Huang, Zak Stratton, Yiping Huang, Tony Jun Huang
    Abstract:

    This work introduces a method of continuous particle separation through standing surface acoustic wave (SSAW)-induced acoustophoresis in a Microfluidic Channel. Using this SSAW-based method, particles in a continous laminar flow can be separated based on their volume, density and compressibility. In this work, a mixture of particles of equal density but dissimilar volumes was injected into a microChannel through two side inlets, sandwiching a deonized water sheath flow injected through a central inlet. A one-dimensional SSAW generated by two parallel interdigital transducers (IDTs) was established across the Channel, with the Channel spanning a single SSAW pressure node located at the Channel center. Application of the SSAW induced larger axial acoustic forces on the particles of larger volume, repositioning them closer to the wave pressure node at the center of the Channel. Thus particles were laterally moved to different regions of the Channel cross-section based on particle volume. The particle separation method presented here is simple and versatile, capable of separating virtually all kinds of particles (regardless of charge/polarization or optical properties) with high separation efficiency and low power consumption.

Dae-gab Gweon - One of the best experts on this subject based on the ideXlab platform.

  • quantitative analysis of methyl parathion pesticides in a polydimethylsiloxane Microfluidic Channel using confocal surface enhanced raman spectroscopy
    Applied Spectroscopy, 2006
    Co-Authors: Gi Hun Seong, Jaebum Choo, Dae-gab Gweon
    Abstract:

    A fast and ultra-sensitive trace analysis of methyl parathion pesticides in a polydimethylsiloxane (PDMS) Microfluidic Channel was investigated using confocal surface-enhanced Raman spectroscopy (SERS). A three-dimensional PDMS-based passive micromixer was fabricated for this purpose. This PDMS micromixer showed a high mixing efficiency because a strong chaotic advection was developed by the simultaneous vertical and transverse dispersion of the confluent streams. The confocal SERS signal was measured after methyl parathion pesticides were effectively adsorbed onto silver nanoparticles while flowing along the upper and lower alligator-teeth-shaped PDMS Channel. A quantitative analysis of the methyl parathion pesticides was performed based on the measured peak height at 1246 cm−1. Our method has a detection limit of 0.1 ppm. This value satisfies the requirement recommended by the Collaborative International Pesticides Analytical Council (CIPAC) for the determination of methyl parathion in pesticide formulations. This study demonstrates the feasibility of using confocal SERS for the highly sensitive detection of methyl parathion pesticides in a PDMS Microfluidic Channel.

  • quantitative analysis of methyl parathion pesticides in a polydimethylsiloxane Microfluidic Channel using confocal surface enhanced raman spectroscopy
    Applied Spectroscopy, 2006
    Co-Authors: Gi Hun Seong, Jaebum Choo, Dae-gab Gweon
    Abstract:

    A fast and ultra-sensitive trace analysis of methyl parathion pesticides in a polydimethylsiloxane (PDMS) Microfluidic Channel was investigated using confocal surface-enhanced Raman spectroscopy (SERS). A three-dimensional PDMS-based passive micromixer was fabricated for this purpose. This PDMS micromixer showed a high mixing efficiency because a strong chaotic advection was developed by the simultaneous vertical and transverse dispersion of the confluent streams. The confocal SERS signal was measured after methyl parathion pesticides were effectively adsorbed onto silver nanoparticles while flowing along the upper and lower alligator-teeth-shaped PDMS Channel. A quantitative analysis of the methyl parathion pesticides was performed based on the measured peak height at 1246 cm−1. Our method has a detection limit of 0.1 ppm. This value satisfies the requirement recommended by the Collaborative International Pesticides Analytical Council (CIPAC) for the determination of methyl parathion in pesticide formulations. This study demonstrates the feasibility of using confocal SERS for the highly sensitive detection of methyl parathion pesticides in a PDMS Microfluidic Channel.

  • Highly sensitive signal detection of duplex dye-labelled DNA oligonucleotides in a PDMS Microfluidic chip: confocal surface-enhanced Raman spectroscopic study.
    Lab on a chip, 2005
    Co-Authors: Taehan Park, J B Choo, Yang S Kim, Won Ho Ji, Sangyeop Lee, Gi Hun Seong, Seung Yong Hwang, Eun-kyu Lee, Dae-gab Gweon
    Abstract:

    Rapid and highly sensitive detection of duplex dye-labelled DNA sequences in a PDMS Microfluidic Channel was investigated using confocal surface enhanced Raman spectroscopy (SERS). This method does not need either an immobilization procedure or a PCR amplification procedure, which are essential for a DNA microarray chip. Furthermore, Raman peaks of each dye-labelled DNA can be easily resolved since they are much narrower than the corresponding broad fluorescence bands. To find the potential applicability of confocal SERS for sensitive bio-detection in a Microfluidic Channel, the mixture of two different dye-labelled (TAMRA and Cy3) sex determining Y genes, SRY and SPGY1, was adsorbed on silver colloids in the alligator teeth-shaped PDMS Microfluidic Channel and its SERS signals were measured under flowing conditions. Its major SERS peaks were observable down to the concentration of 10(-11) M. In the present study, we explore the feasibility of confocal SERS for the highly sensitive detection of duplex dye-labelled DNA oligonucleotides in a PDMS Microfluidic chip.

Sungjoon Lim - One of the best experts on this subject based on the ideXlab platform.

  • complementary split ring resonator loaded Microfluidic ethanol chemical sensor
    Sensors, 2016
    Co-Authors: Ahmed Salim, Sungjoon Lim
    Abstract:

    In this paper, a complementary split-ring resonator (CSRR)-loaded patch is proposed as a Microfluidic ethanol chemical sensor. The primary objective of this chemical sensor is to detect ethanol’s concentration. First, two tightly coupled concentric CSRRs loaded on a patch are realized on a Rogers RT/Duroid 5870 substrate, and then a Microfluidic Channel engraved on polydimethylsiloxane (PDMS) is integrated for ethanol chemical sensor applications. The resonant frequency of the structure before loading the Microfluidic Channel is 4.72 GHz. After loading the Microfluidic Channel, the 550 MHz shift in the resonant frequency is ascribed to the dielectric perturbation phenomenon when the ethanol concentration is varied from 0% to 100%. In order to assess the sensitivity range of our proposed sensor, various concentrations of ethanol are tested and analyzed. Our proposed sensor exhibits repeatability and successfully detects 10% ethanol as verified by the measurement set-up. It has created headway to a miniaturized, non-contact, low-cost, reliable, reusable, and easily fabricated design using extremely small liquid volumes.

  • stretchable complementary split ring resonator csrr based radio frequency rf sensor for strain direction and level detection
    Sensors, 2016
    Co-Authors: Seunghyun Eom, Sungjoon Lim
    Abstract:

    In this paper, we proposed a stretchable radio frequency (RF) sensor to detect strain direction and level. The stretchable sensor is composed of two complementary split ring resonators (CSRR) with Microfluidic Channels. In order to achieve stretchability, liquid metal (eutectic gallium-indium, EGaIn) and Ecoflex substrate are used. Microfluidic Channels are built by Ecoflex elastomer and Microfluidic Channel frames. A three-dimensional (3D) printer is used for fabrication of Microfluidic Channel frames. Two CSRR resonators are designed to resonate 2.03 GHz and 3.68 GHz. When the proposed sensor is stretched from 0 to 8 mm along the +x direction, the resonant frequency is shifted from 3.68 GHz to 3.13 GHz. When the proposed sensor is stretched from 0 to 8 mm along the -x direction, the resonant frequency is shifted from 2.03 GHz to 1.78 GHz. Therefore, we can detect stretched length and direction from independent variation of two resonant frequencies.

  • Microfluidic eighth mode substrate integrated waveguide antenna for compact ethanol chemical sensor application
    IEEE Transactions on Antennas and Propagation, 2016
    Co-Authors: Yunsik Seo, Muhammad Usman Memon, Sungjoon Lim
    Abstract:

    In this communication, a Microfluidic antenna is proposed for chemical sensor applications. An eighth-mode substrate-integrated-waveguide (EMSIW) antenna with a Microfluidic Channel is introduced in order to devise a compact and nondestructive chemical sensor. The frequency response of the proposed antenna is controlled by changing the nanoliter liquid in the Microfluidic Channel, which further results in a change in the effective dielectric constant. First, the EMSIW antenna is designed, and then the Microfluidic Channel is designed for nondestructive chemical sensor applications. The S-parameters of the proposed Microfluidic EMSIW antenna are simulated and measured. The resonant frequency is successfully switched from 4.2 to 4.6 GHz when the concentration of ethanol is changed from 0% to 100%. The possibility of the proposed antenna to be used as an ethanol chemical sensor is demonstrated from the relationship between the resonant frequency and the concentration of ethanol.

Kazuhiko Ishihara - One of the best experts on this subject based on the ideXlab platform.

  • Label-Free Separation of Induced Pluripotent Stem Cells with Anti-SSEA-1 Antibody Immobilized Microfluidic Channel
    Langmuir, 2017
    Co-Authors: Akihisa Otaka, Kazuhiko Ishihara, Kazuki Kitagawa, Takahiko Nakaoki, Mitsuhi Hirata, Kyoko Fukazawa, Atsushi Mahara, Tetsuji Yamaoka
    Abstract:

    When induced pluripotent stem cells (iPSCs) are routinely cultured, the obtained cells are a heterogeneous mixture, including feeder cells and partially differentiated cells. Therefore, a purification process is required to use them in a clinical stage. We described a label-free separation of iPSCs using a Microfluidic Channel. Antibodies against stage-specific embryonic antigen 1 (SSEA-1) was covalently immobilized on the Channel coated with a phospholipid polymer. After injection of the heterogeneous cell suspension containing iPSCs, the velocity of cell movement under a liquid flow condition was measured. The mean velocity of the cell movement was 2.1 mm/sec in the unmodified Channel, while that in the Channel with the immobilized-antibody was 0.4 mm/sec. The eluted cells were fractionated by eluting time. As a result, the SSEA-1 positive iPSCs were mainly contained in later fractions, and the proportion of iPSCs was increased from 43% to 82% as a comparison with the initial cell suspension. These resu...

  • Label-Free Separation of Induced Pluripotent Stem Cells with Anti-SSEA‑1 Antibody Immobilized Microfluidic Channel
    2017
    Co-Authors: Akihisa Otaka, Kazuhiko Ishihara, Kazuki Kitagawa, Takahiko Nakaoki, Mitsuhi Hirata, Kyoko Fukazawa, Atsushi Mahara, Tetsuji Yamaoka
    Abstract:

    When induced pluripotent stem cells (iPSCs) are routinely cultured, the obtained cells are a heterogeneous mixture, including feeder cells and partially differentiated cells. Therefore, a purification process is required to use them in a clinical stage. We described a label-free separation of iPSCs using a Microfluidic Channel. Antibodies against stage-specific embryonic antigen 1 (SSEA-1) was covalently immobilized on the Channel coated with a phospholipid polymer. After injection of the heterogeneous cell suspension containing iPSCs, the velocity of cell movement under a liquid flow condition was measured. The mean velocity of the cell movement was 2.1 mm/sec in the unmodified Channel, while that in the Channel with the immobilized-antibody was 0.4 mm/sec. The eluted cells were fractionated by eluting time. As a result, the SSEA-1 positive iPSCs were mainly contained in later fractions, and the proportion of iPSCs was increased from 43% to 82% as a comparison with the initial cell suspension. These results indicated that iPSCs were selectively separated by the Microfluidic Channel. This Channel is a promising device for label-free separation of iPSCs based on their pluripotent state

  • Spherical phospholipid polymer hydrogels for cell encapsulation prepared with a flow-focusing Microfluidic Channel device.
    Langmuir, 2011
    Co-Authors: Tatsuo Aikawa, Madoka Takai, Tomohiro Konno, Kazuhiko Ishihara
    Abstract:

    : To prepare spherical polymer hydrogels, we used a flow-focusing Microfluidic Channel device for mixing aqueous solutions of two water-soluble polymers. Continuous encapsulation of cells in the hydrogels was also examined. The polymers were bioinspired 2-methacryloyloxyethyl phosphorylcholine polymer bearing phenyl boronic acid groups (PMBV) and poly(vinyl alcohol) (PVA), which spontaneously form a hydrogel in aqueous medium via specific molecular complexation upon mixing, even when they were in cell culture medium. The Microfluidic device was prepared with polydimethylsiloxan, and the surface of the Channel was treated with fluoroalkyl compound to prevent sticking of the polymers on the surface. The Microfluidic Channel process could control the diameter of the spherical hydrogels in the range of 30-90 μm and generated highly monodispersed diameter spherical hydrogels. We found that the polymer distribution in the hydrogel was influenced by the PVA concentration and that the hydrogel could be dissociated by the addition of d-sorbitol to the suspension. The single cells could be encapsulated and remain viable in the hydrogels. The localized distribution of polymers in the hydrogel may provide an environment for modulating cell function. It is concluded that the spontaneous hydrogel formation between PMBV and PVA in the flow-focusing Microfluidic Channel device is applicable for continuous preparation of a spherical hydrogel-encapsulating living cell.

Tetsuji Yamaoka - One of the best experts on this subject based on the ideXlab platform.

  • Label-Free Separation of Induced Pluripotent Stem Cells with Anti-SSEA-1 Antibody Immobilized Microfluidic Channel
    Langmuir, 2017
    Co-Authors: Akihisa Otaka, Kazuhiko Ishihara, Kazuki Kitagawa, Takahiko Nakaoki, Mitsuhi Hirata, Kyoko Fukazawa, Atsushi Mahara, Tetsuji Yamaoka
    Abstract:

    When induced pluripotent stem cells (iPSCs) are routinely cultured, the obtained cells are a heterogeneous mixture, including feeder cells and partially differentiated cells. Therefore, a purification process is required to use them in a clinical stage. We described a label-free separation of iPSCs using a Microfluidic Channel. Antibodies against stage-specific embryonic antigen 1 (SSEA-1) was covalently immobilized on the Channel coated with a phospholipid polymer. After injection of the heterogeneous cell suspension containing iPSCs, the velocity of cell movement under a liquid flow condition was measured. The mean velocity of the cell movement was 2.1 mm/sec in the unmodified Channel, while that in the Channel with the immobilized-antibody was 0.4 mm/sec. The eluted cells were fractionated by eluting time. As a result, the SSEA-1 positive iPSCs were mainly contained in later fractions, and the proportion of iPSCs was increased from 43% to 82% as a comparison with the initial cell suspension. These resu...

  • Label-Free Separation of Induced Pluripotent Stem Cells with Anti-SSEA‑1 Antibody Immobilized Microfluidic Channel
    2017
    Co-Authors: Akihisa Otaka, Kazuhiko Ishihara, Kazuki Kitagawa, Takahiko Nakaoki, Mitsuhi Hirata, Kyoko Fukazawa, Atsushi Mahara, Tetsuji Yamaoka
    Abstract:

    When induced pluripotent stem cells (iPSCs) are routinely cultured, the obtained cells are a heterogeneous mixture, including feeder cells and partially differentiated cells. Therefore, a purification process is required to use them in a clinical stage. We described a label-free separation of iPSCs using a Microfluidic Channel. Antibodies against stage-specific embryonic antigen 1 (SSEA-1) was covalently immobilized on the Channel coated with a phospholipid polymer. After injection of the heterogeneous cell suspension containing iPSCs, the velocity of cell movement under a liquid flow condition was measured. The mean velocity of the cell movement was 2.1 mm/sec in the unmodified Channel, while that in the Channel with the immobilized-antibody was 0.4 mm/sec. The eluted cells were fractionated by eluting time. As a result, the SSEA-1 positive iPSCs were mainly contained in later fractions, and the proportion of iPSCs was increased from 43% to 82% as a comparison with the initial cell suspension. These results indicated that iPSCs were selectively separated by the Microfluidic Channel. This Channel is a promising device for label-free separation of iPSCs based on their pluripotent state