Publications by authors named "Cheng-Hsien Liu"

24 Publications

  • Page 1 of 1

Finger-powered agglutination lab chip with CMOS image sensing for rapid point-of-care diagnosis applications.

Lab Chip 2020 01 24;20(2):424-433. Epub 2019 Dec 24.

Department of Power Mechanical Engineering, National Tsing Hua University, Hsinchu City 30013, Taiwan, Republic of China.

Agglutination is an antigen-antibody reaction with visible expression of aggregation of the antigens and their corresponding antibodies. Applications extend to the identification of acute bacterial infection, hemagglutination, such as blood grouping, and diagnostic immunology. Our finger-powered agglutination lab chip with external CMOS image sensing was developed to support a platform for inexpensive, rapid point-of-care (POC) testing applications related to agglutination effects. In this paper, blood grouping (ABO and Rh grouping) was utilized to demonstrate the function of our finger-powered agglutination lab chip with CMOS image sensing. Blood antibodies were preloaded into the antibody reaction chamber in the lab chip. The blood sample was pushed through the antibody reaction chamber using finger-powered pressure actuation to initiate a hemagglutination reaction to identify the blood type at the on-chip detection area using our homemade CMOS image sensing mini-system. Finger-powered actuation without the need for external electrical pumping is excellent for low-cost POC applications, but the pumping liquid volume per finger push is hard to control. In our finger-powered agglutination lab chip with CMOS image sensing, we minimized the effects of different finger push depths and achieved robust performance for the test results with different push depths. The driving sample volume per finger push is about 0.79 mm. For different chips and different pushes, the driven sample volume per finger push was observed to vary in the range of 0.64 to 1.18 mm. The red blood cells were separated from the plasma on-chip after the whole blood sample was finger pumped and before the red blood cells reached the antibody chamber via an embedded plasma-separation membrane. Our homemade CMOS image mini-system robustly read and identified the agglutination results on our agglutination lab chip.
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http://dx.doi.org/10.1039/c9lc00961bDOI Listing
January 2020

Simultaneous detection of two growth factors from human single-embryo culture medium by a bead-based digital microfluidic chip.

Biosens Bioelectron 2020 Feb 9;150:111851. Epub 2019 Nov 9.

Department of Power Mechanical Engineering, National Tsing Hua University, Hsinchu, Taiwan.

The measurement of growth factors released in a culture medium is considered to be an attractive non-invasive approach, apart from the embryo morphology, to identify the condition of an embryo development after fertilization in vitro (IVF), but the available embryo culture medium in the current method is only a few microlitres. This small sample volume, also of small concentration, makes difficult the application of a conventional detection method, such as an enzyme-linked immunosorbent assay (ELISA). A reliable detection of the growth factor from each embryo culture medium of such a small concentration hence remains a challenge. Here for the first time we report the results of measurement of not just one, but two, growth factors, human IL-1β and human TNF-α, from an individual droplet of embryo culture medium with a bead-based digital microfluidic chip. The required sample volume for a single measurement is only 520 nL; the total duration of the on-chip process is less than 40 min. Using the culture media of human embryos with normal morphologic features, we found that the concentrations of TNF-α change little from day 3 to day 5-6, but the concentrations of IL-1β for some embryos might double from day 3 to day 5-6. For other embryos even with similar normal morphologic features, some growth factors, such as IL-1β, might exhibit different expressions during the culture period. Those growth factors could serve to distinguish the development conditions of each embryo, not merely from an observation of embryo morphology.
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http://dx.doi.org/10.1016/j.bios.2019.111851DOI Listing
February 2020

Cancer immunotherapy μ-environment LabChip: taking advantage of optoelectronic tweezers.

Lab Chip 2017 12;18(1):106-114

Department of Power Mechanical Engineering, National Tsing Hua University, Hsinchu City 30013, Taiwan, R.O.C.

A cancer immunotherapy μ-environment LabChip, equipped with titanium oxide phthalocyanine (TiOPc)-based optoelectronic tweezers (OET) to achieve direct cell-cell contact, can be used to study the interaction between immune cells and other cells for real-time analysis of NK cells' behavior. In microfluidic devices, it is difficult to solve dead zone problems and observe dynamic cell-cell interactions. We have created a stable and static culture μ-environment which can enhance NK cell activities. In addition, OET is used to solve dead zone problems by manipulating a single cell into four-leaf-clover-shaped (FLCS) microwells made of poly(ethylene glycol) diacrylate (PEG-DA) through optofluidic maskless lithography, causing direct cell-cell contact. Our design reconstructed an in vitro human immune system for the study of dynamic immunological response. When the NK cells came into contact with the target cells in the μ-environment LabChip, we observed that the target cells showed apoptotic characteristics (i.e. cell shrinkage and blebbing within 2 h and then die within 3 h). In addition, our μ-environment LabChip demonstrated higher NK cell activity compared with conventional analysis. We have created an innovative cancer immunotherapy μ-environment LabChip to provide a stable and static μ-environment for cell-cell interaction study. Furthermore, our μ-environment LabChip showed the potential to enhance NK cell activity and to study immunological interactions between immune cells and cancer cells dynamically.
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http://dx.doi.org/10.1039/c7lc00963aDOI Listing
December 2017

A highly efficient bead extraction technique with low bead number for digital microfluidic immunoassay.

Biomicrofluidics 2016 Jan 12;10(1):011901. Epub 2016 Jan 12.

Department of Mechanical Engineering, National Chiao Tung University , Hsinchu, Taiwan.

Here, we describe a technique to manipulate a low number of beads to achieve high washing efficiency with zero bead loss in the washing process of a digital microfluidic (DMF) immunoassay. Previously, two magnetic bead extraction methods were reported in the DMF platform: (1) single-side electrowetting method and (2) double-side electrowetting method. The first approach could provide high washing efficiency, but it required a large number of beads. The second approach could reduce the required number of beads, but it was inefficient where multiple washes were required. More importantly, bead loss during the washing process was unavoidable in both methods. Here, an improved double-side electrowetting method is proposed for bead extraction by utilizing a series of unequal electrodes. It is shown that, with proper electrode size ratio, only one wash step is required to achieve 98% washing rate without any bead loss at bead number less than 100 in a droplet. It allows using only about 25 magnetic beads in DMF immunoassay to increase the number of captured analytes on each bead effectively. In our human soluble tumor necrosis factor receptor I (sTNF-RI) model immunoassay, the experimental results show that, comparing to our previous results without using the proposed bead extraction technique, the immunoassay with low bead number significantly enhances the fluorescence signal to provide a better limit of detection (3.14 pg/ml) with smaller reagent volumes (200 nl) and shorter analysis time (<1 h). This improved bead extraction technique not only can be used in the DMF immunoassay but also has great potential to be used in any other bead-based DMF systems for different applications.
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http://dx.doi.org/10.1063/1.4939942DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4714987PMC
January 2016

A microfluidic approach towards hybridoma generation for cancer immunotherapy.

Oncotarget 2015 Nov;6(36):38764-76

Department of Power Mechanical Engineering, National Tsing Hua University, Hsinchu, Taiwan, R.O.C.

Dendritic cells/tumor fusions have shown to elicit anti-cancer immunity in different cancer types. However, the application of these vaccines for human cancer immunotherapy are limited by the instable quality and insufficient quanity of fusion cells. We present a cell electrofusion chip fabricated using soft lithography technique, which combines the rapid and precise cell pairing microstructures and the high yield electrofusion micro-electrodes to improve the cell fusion. The design uses hydrodynamic trapping in combination with positive dielectrophoretic force (pDEP) to achieve cell fusion. The chip consists of total 960 pairs of trapping channels, which are capable of pairing and fusing both homogeneous and heterogeneous types of cells. The fused cells can be easily taken out of the chip that makes this device a distinguishable from other designs. We observe pairing efficiency of 68% with fusion efficiency of 64%.
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http://dx.doi.org/10.18632/oncotarget.5550DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4770735PMC
November 2015

Digital Microfluidic Dynamic Culture of Mammalian Embryos on an Electrowetting on Dielectric (EWOD) Chip.

PLoS One 2015 1;10(5):e0124196. Epub 2015 May 1.

Institute of Nanoengineering and Microsystem, National Tsing Hua University, Hsinchu, Taiwan; Department of Power Mechanical Engineering, National Tsing Hua University, Hsinchu, Taiwan.

Current human fertilization in vitro (IVF) bypasses the female oviduct and manually inseminates, fertilizes and cultivates embryos in a static microdrop containing appropriate chemical compounds. A microfluidic microchannel system for IVF is considered to provide an improved in-vivo-mimicking environment to enhance the development in a culture system for an embryo before implantation. We demonstrate a novel digitalized microfluidic device powered with electrowetting on a dielectric (EWOD) to culture an embryo in vitro in a single droplet in a microfluidic environment to mimic the environment in vivo for development of the embryo and to culture the embryos with good development and live births. Our results show that the dynamic culture powered with EWOD can manipulate a single droplet containing one mouse embryo and culture to the blastocyst stage. The rate of embryo cleavage to a hatching blastocyst with a dynamic culture is significantly greater than that with a traditional static culture (p<0.05). The EWOD chip enhances the culture of mouse embryos in a dynamic environment. To test the reproductive outcome of the embryos collected from an EWOD chip as a culture system, we transferred embryos to pseudo-pregnant female mice and produced live births. These results demonstrate that an EWOD-based microfluidic device is capable of culturing mammalian embryos in a microfluidic biological manner, presaging future clinical application.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0124196PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4416819PMC
January 2016

Controlled release of growth factors for regenerative medicine.

Curr Pharm Des 2015 ;21(12):1627-32

Center of Organ Manufacturing, Department of Mechanical Engineering, Tsinghua University, Beijing 100084, P.R. China.

How to release growth factors (GFs) scientifically to promote stem cell proliferation and differentiation is one of the most significant research focuses in the field of regenerative medicine. In a controlled release system, growth factors, extracellular matrices or biomaterial carriers, and sometimes stem cells together form a geometric entirety. Biomaterial carriers provide GFs with a support structure to be adhered, immobilized, encapsulated or/and protected. As a unity, the release rate and rhythm of GFs on cells are normally very delicate and precise. Up to now, the best strategy for clinical applications is the combination systems that encapsulate GFs in microspheres, particularly the nano- or micro-encapsulation techniques integrated GFs with biomaterial carriers. In this mini review, we summarize the current progress in GF delivery systems for regenerative medicine and provide an outlook on two main aspects: one is the classes of stem cells and GFs that have been used frequently in regenerative medicine, including their respective application conditions and functions; the other is the controlled GF release systems, in which various GFs are released orderly and continuously without diffusing simply and rapidly, including their respective opportunities and challenges.
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http://dx.doi.org/10.2174/1381612821666150115154602DOI Listing
December 2015

A biologically inspired lung-on-a-chip device for the study of protein-induced lung inflammation.

Integr Biol (Camb) 2015 Feb;7(2):162-9

Institute of NanoEngineering and MicroSystems, National Tsing Hua University, Hsinchu, Taiwan, Republic of China.

This study reports a biomimetic microsystem that reconstitutes the lung microenvironment for monitoring the role of eosinophil cationic protein (ECP) in lung inflammation. ECP induces the airway epithelial cell expression of CXCL-12, which in turn stimulates the migration of fibrocytes towards the epithelium. This two-layered microfluidic system provides a feasible platform for perfusion culture, and was used in this study to reveal that the CXCL12-CXCR4 axis mediates ECP induced fibrocyte extravasation in lung inflammation. This 'lung-on-a-chip' microdevice serves as a dynamic transwell system by introducing a flow that can reconstitute the blood vessel-tissue interface for in vitro assays, enhancing pre-clinical studies. We made an attempt to develop a new microfluidic model which could not only simulate the transwell for studying cell migration, but could also study the migration in the presence of a flow mimicking the physiological conditions in the body. As blood vessels are the integral part of our body, this model gives an opportunity to study more realistic in vitro models of organs where the blood vessel i.e. flow based migration is involved.
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http://dx.doi.org/10.1039/c4ib00239cDOI Listing
February 2015

Fibrocyte trafficking in patients with chronic obstructive asthma and during an acute asthma exacerbation.

J Allergy Clin Immunol 2015 May 24;135(5):1154-62.e1-5. Epub 2014 Oct 24.

Department of Thoracic Medicine, Chang Gung Memorial Hospital, Taipei, Taiwan; Department of Medicine, Chang Gung University, Taoyuan, Taiwan. Electronic address:

Background: Fibrocytes express several chemokine receptors (CCR7 and CXCR4) that regulate their recruitment and trafficking into tissue-damage sites in response to specific chemokine gradients (CCL19 and CXCL12).

Objective: We investigated whether these chemoattractants and S100A9, through the receptor for advanced glycation end-products (RAGE; ie, its receptor), are involved in fibrocyte trafficking in patients with chronic obstructive asthma (COA) and during an acute exacerbation (AE) in patients without airflow obstruction (Asthma AE group).

Methods: We collected peripheral blood from 14 asthmatic patients with normal pulmonary function, 14 patients with COA, 11 patients in the Asthma AE group, and 14 healthy subjects. Isolated circulating fibrocytes were used for migration assay. Expression of CCR7, CXCR4, S100A9, and RAGE in fibrocytes was measured by using flow cytometry. CCL19 and CXCL12 expression in bronchial tissues was determined by using immunohistochemistry and RT-PCR.

Results: There were higher numbers of circulating fibrocytes in patients in the Asthma AE group and patients with COA. The expression of CXCL12 in bronchial tissues and CXCR4 in circulating fibrocytes was higher in the Asthma AE group and, to a lesser extent, in patients with COA. The expression of CCL19 in bronchial tissues and CCR7 in fibrocytes was higher in patients with COA. CXCL12/CXCR4 and CCL19/CCR7 enhanced fibrocyte transmigration in the Asthma AE group and in patients with COA, respectively. The upregulated expression of S100A9 and RAGE in fibrocytes of patients in the Asthma AE group and those with COA contributes to the enhanced basal migratory motility of fibrocytes.

Conclusion: The CXCR4/CXCL12 axis contributes to chemotaxis of fibrocytes in patients in the Asthma AE group, whereas the CCR7/CCL19 axis plays an important role in patients with COA. S100A9 enhances the basal migratory motility of fibrocytes from patients in the Asthma AE group and patients with COA.
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http://dx.doi.org/10.1016/j.jaci.2014.09.011DOI Listing
May 2015

A microfluidic chip with a U-shaped microstructure array for multicellular spheroid formation, culturing and analysis.

Biofabrication 2014 Mar 4;6(1):015009. Epub 2014 Mar 4.

Institute of Molecular Medicine, Department of Life Science, National Tsing Hua University, No. 101, Section 2, Kuang-Fu Road, Hsin Chu, Taiwan 30013, Republic of China.

Multicellular spheroids (MCS), formed by self-assembly of single cells, are commonly used as a three-dimensional cell culture model to bridge the gap between in vitro monolayer culture and in vivo tissues. However, current methods for MCS generation and analysis still suffer drawbacks such as being labor-intensive and of poor controllability, and are not suitable for high-throughput applications. This study demonstrates a novel microfluidic chip to facilitate MCS formation, culturing and analysis. The chip contains an array of U-shaped microstructures fabricated by photopolymerizing the poly(ethylene glycol) diacrylate hydrogel through defining the ultraviolet light exposure pattern with a photomask. The geometry of the U-shaped microstructures allowed trapping cells into the pocket through the actions of fluid flow and the force of gravity. The hydrogel is non-adherent for cells, promoting the formation of MCS. Its permselective property also facilitates exchange of nutrients and waste for MCS, while providing protection of MCS from shearing stress during the medium perfusion. Heterotypic MCS can be formed easily by manipulating the cell trapping steps. Subsequent drug susceptibility analysis and long-term culture could also be achieved within the same chip. This MCS formation and culture platform can be used as a micro-scale bioreactor and applied in many cell biology and drug testing studies.
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http://dx.doi.org/10.1088/1758-5082/6/1/015009DOI Listing
March 2014

Cell patterning via diffraction-induced optoelectronic dielectrophoresis force on an organic photoconductive chip.

Lab Chip 2013 Oct;13(19):3893-902

Department of Mechanical and Automation Engineering, Chinese University of Hong Kong, Hong Kong.

A laser diffraction-induced dielectrophoresis (DEP) phenomenon for the patterning and manipulation of individual HepG2 cells and polystyrene beads via positive/negative DEP forces is reported in this paper. The optoelectronic substrate was fabricated using an organic photoconductive material, TiOPc, via a spin-coating process on an indium tin oxide glass surface. A piece of square aperture array grid grating was utilized to transform the collimating He-Ne laser beam into the multi-spot diffraction pattern which forms the virtual electrodes as the TiOPc-coating surface was illuminated by the multi-spot diffraction light pattern. HepG2 cells were trapped at the spot centers and polystyrene beads were trapped within the dim region of the illuminated image. The simulation results of light-induced electric field and a Fresnel diffraction image illustrated the distribution of trapped microparticles. The HepG2 morphology change, adhesion, and growth during a 5-day culture period demonstrated the cell viability through our manipulation. The power density inducing DEP phenomena, the characteristics of the thin TiOPc coating layer, the operating ac voltage/frequency, the sandwiched medium, the temperature rise due to the ac electric fields and the illuminating patterns are discussed in this paper. This concept of utilizing laser diffraction images to generate virtual electrodes on our TiOPc-based optoelectronic DEP chip extends the applications of optoelectronic dielectrophoretic manipulation.
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http://dx.doi.org/10.1039/c3lc50351hDOI Listing
October 2013

Liver-cell patterning lab chip: mimicking the morphology of liver lobule tissue.

Lab Chip 2013 Sep;13(18):3578-87

Department of Power Mechanical Engineering, National Tsing Hua University, Hsinchu, Taiwan 300, ROC.

A lobule-mimetic cell-patterning technique for on-chip reconstruction of centimetre-scale liver tissue of heterogeneous hepatic and endothelial cells via an enhanced field-induced dielectrophoresis (DEP) trap is demonstrated and reported. By mimicking the basic morphology of liver tissue, the classic hepatic lobule, the lobule-mimetic-stellate-electrodes array was designed for cell patterning. Through DEP manipulation, well-defined and enhanced spatial electric field gradients were created for in-parallel manipulation of massive individual cells. With this liver-cell patterning labchip design, the original randomly distributed hepatic and endothelial cells inside the microfluidic chamber can be manipulated separately and aligned into the desired pattern that mimicks the morphology of liver lobule tissue. Experimental results showed that both hepatic and endothelial cells were orderly guided, snared, and aligned along the field-induced orientation to form the lobule-mimetic pattern. About 95% cell viability of hepatic and endothelial cells was also observed after cell-patterning demonstration via a fluorescent assay technique. The liver function of CYP450-1A1 enzyme activity showed an 80% enhancement for our engineered liver tissue (HepG2+HUVECs) compared to the non-patterned pure HepG2 for two-day culturing.
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http://dx.doi.org/10.1039/c3lc50402fDOI Listing
September 2013

A microfluidic device mimicking acinar concentration gradients across the liver acinus.

Biomed Microdevices 2013 Oct;15(5):767-80

Institute of NanoEngineering and MicroSystem, National Tsing Hua University, No. 101, Section 2, Kuang-Fu Road, Hsinchu, 30013, Taiwan, Republic of China.

The acinus-mimicking microfluidic chip, which simulates the in vivo condition of the liver, was developed and reported in this paper. The gradient microenvironment of the liver acinus is replicated within this proposed microfluidic chip. The advantage of this acinus-mimicking chip is capable of adjusting the concentration gradient in a relatively short period of time at around 10 s. At the same instance the non-linear concentration gradient can be presented in the various zones within this microfluidic chip. The other advantage of this proposed design is in the convenience of allowing the direct injection of the cells into the chip. The environment within the chip is multi-welled and gel-free with high cell density. The multi-row pillar microstructure located at the entrance of the top and bottom flow channels is designed to be able to balance the pressure of the perfusion medium. Through this mechanism the shear stress experienced by the cultured cells can be minimized to reduce the potential damage flow from the perfusion process. The fluorescence staining and the observations of the cell morphology verify the life and death of the cells. The shear stress experienced by the cells in the various zones within the chip can be effectively mapped. The serum glutamic oxaloacetic transaminase (SGOT) collected from the supernatants was used to determine the effects of the degassing process and the shear stress of the medium flow on the cultured cells.
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http://dx.doi.org/10.1007/s10544-013-9762-zDOI Listing
October 2013

Identification of protein domains on major pilin MrkA that affects the mechanical properties of Klebsiella pneumoniae type 3 fimbriae.

Langmuir 2012 May 1;28(19):7428-35. Epub 2012 May 1.

Institute and Department of Electrophysics, National Chiao Tung University, 1001 University Road, Hsinchu 300, Taiwan, Republic of China.

The Klebsiella pneumoniae type 3 fimbriae are mainly composed of MrkA pilins that assemble into a helixlike filament. This study determined the biomechanical properties of the fimbriae and analyzed 11 site-directed MrkA mutants to identify domains that are critical for the properties. Escherichia coli strains expressing type 3 fimbriae with an Ala substitution at either F34, V45, C87, G189, T196, or Y197 resulted in a significant reduction in biofilm formation. The E. coli strain expressing MrkAG189A remained capable of producing a normal number of fimbriae. Although F34A, V45A, T196A, and Y197A substitutions expressed on E. coli strains produced sparse quantities of fimbriae, no fimbriae were observed on the cells expressing MrkAC87A. Further investigations of the mechanical properties of the MrkAG189A fimbriae with optical tweezers revealed that, unlike the wild-type fimbriae, the uncoiling force for MrkAG189A fimbriae was not constant. The MrkAG189A fimbriae also exhibited a lower enthalpy in the differential scanning calorimetry analysis. Together, these findings indicate that the mutant fimbriae are less stable than the wild-type. This study has demonstrated that the C-terminal β strands of MrkA are required for the assembly and structural stability of fimbriae.
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http://dx.doi.org/10.1021/la300224wDOI Listing
May 2012

Structural and mechanical properties of Klebsiella pneumoniae type 3 Fimbriae.

J Bacteriol 2011 Apr 14;193(7):1718-25. Epub 2011 Jan 14.

Institute and Department of Electrophysics, National Chiao Tung University, 1001 University Road, Hsinchu 300, Taiwan, Republic of China.

This study investigated the structural and mechanical properties of Klebsiella pneumoniae type 3 fimbriae, which constitute a known virulence factor for the bacterium. Transmission electron microscopy and optical tweezers were used to understand the ability of the bacterium to survive flushes. An individual K. pneumoniae type 3 fimbria exhibited a helix-like structure with a pitch of 4.1 nm and a three-phase force-extension curve. The fimbria was first nonlinearly stretched with increasing force. Then, it started to uncoil and extended several micrometers at a fixed force of 66 ± 4 pN (n = 22). Finally, the extension of the fimbria shifted to the third phase, with a characteristic force of 102 ± 9 pN (n = 14) at the inflection point. Compared with the P fimbriae and type 1 fimbriae of uropathogenic Escherichia coli, K. pneumoniae type 3 fimbriae have a larger pitch in the helix-like structure and stronger uncoiling and characteristic forces.
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http://dx.doi.org/10.1128/JB.01395-10DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3067671PMC
April 2011

Enhanced cell viability and cell adhesion using low conductivity medium for negative dielectrophoretic cell patterning.

Biotechnol J 2010 Oct;5(10):1005-15

Department of Power Mechanical Engineering, National Tsing Hua University, Hsin Chu, Taiwan.

Negative dielectrophoretic (n-DEP) cell manipulation is an efficient way to pattern human liver cells on micro-electrode arrays. Maintaining cell viability is an important objective for this approach. This study investigates the effect of low conductivity medium and the optimally designed microchip on cell viability and cell adhesion. To explore the influence of conductivity on cell viability and cell adhesion, we have used earlier reported dielectrophoresis (DEP) buffer with a conductivity of 10.2 mS/m and three formulated media with conductivity of 9.02 (M1), 8.14 (M2), 9.55 (M3) mS/m. The earlier reported isotonic sucrose/dextrose buffer (DEP buffer) used for DEP manipulation has the drawback of poor cell adhesion and cell viability. A microchip prototype with well-defined positioning of titanium electrode arrays was designed and fabricated on a glass substrate. The gap between the radial electrodes was accurately determined to achieve good cell patterning performance. Parameters such as dimension of positioning electrode, amplitude, and frequency of voltage signal were investigated to optimize the performance of the microchip.
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http://dx.doi.org/10.1002/biot.201000194DOI Listing
October 2010

Dynamic manipulation and patterning of microparticles and cells by using TiOPc-based optoelectronic dielectrophoresis.

Opt Lett 2010 Jun;35(12):1959-61

Department of Electrophysics, National Chiao Tung University, Taiwan, China.

We develop light-driven optoelectronic tweezers based on the organic photoconductive material titanium oxide phthalocyanine. These tweezers function based on negative dielectrophoresis (nDEP). The dynamic manipulation of a single microparticle and cell patterning are demonstrated by using this light-driven optoelectronic DEP chip. The adaptive light patterns that drive the optoelectronic DEP onchip are designed by using Flash software to approach appropriate dynamic manipulation. This is also the first reported demonstration, to the best of our knowledge, for successfully patterning such delicate cells from human hepatocellular liver carcinoma cell line HepG2 by using any optoelectronic tweezers.
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http://dx.doi.org/10.1364/OL.35.001959DOI Listing
June 2010

Effects of garlic oil on the migration of neutrophil-like cell studied by using a chemotactic gradient Labchip.

J Biomed Biotechnol 2010 3;2010:319059. Epub 2010 May 3.

Department of Electrophysics, National Chiao Tung University, Hsinchu 300, Taiwan.

We have designed and fabricated a novel chemotactic gradient Labchip for studying cell migration quantitatively. Owing to the great potential of garlic and its preparations in developing antiinflammatory drugs, the aim of the present study is to investigate the effect of garlic oil on the locomotion of a neutrophil-like cell by measuring the dynamic features of cell migration including migration direction, average migration speed, chemotactic index (CI), and motility index (MI) with the newly designed Labchip. We found that garlic oil treatment lowered the values of CI and MI and reduced the average speed of cell migration from 13 to 8 microm/min. The results indicate that garlic oil is a potential inhibitor for neutrophil-like cell migration and chemotactic responsiveness. By comparing with the effects of nocodazole and cytochalasin B, we also suggest that the antiinflammatory activity exhibited by garlic oil was mainly through inhibiting the assembly-disassembly processes of the cytoskeleton.
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http://dx.doi.org/10.1155/2010/319059DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2862952PMC
September 2010

An air-bubble-actuated micropump for on-chip blood transportation.

Lab Chip 2009 Jun 6;9(11):1524-33. Epub 2009 Apr 6.

Institute of Nanoengineering and Microsystems, National Tsing Hua University, Hsinchu, Taiwan 300, ROC.

A novel electrolysis-based micropump using air bubbles to achieve indirect actuation is proposed and demonstrated. Compared with other electrochemical micropumps, our micropump can drive microfluids without inducing the pH value variation in the main channel and the choking/sticking phenomena of electrolytic bubbles. It is promising for biomedical applications, especially for blood transportation. Our proposed on-chip electrolysis-bubble actuator with the features of room temperature operation, low driving voltage, low power consumption and large actuation force not only can minimize the possibility of cell-damage but also may enable portable and implantable lab-on-a-chip microsystems. Utilizing our proposed hydrophobic trapeziform pattern located at the junction of the T-shaped microchannel, the micropump makes the pumped fluid in the main channel be isolated from the electrolytic bubbles. It can be used for a variety of applications without the constraints on the pumped liquid. Experimental results show that the liquid displacement and the pumping rate could be easily and accurately controlled via the signal of a two-phase peristaltic sequence and the periodic generation of electrolytic bubbles. With an applied voltage of 2.5 V, the maximum pumping rate for DI water and whole blood were 121 nl min(-1) and 88 nl min(-1), respectively, with a channel cross section of 100 x 50 microm. Maximum back-pressure of 16 kPa and 11 kPa for DI water and whole blood, respectively, were achieved in our present prototype chips.
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http://dx.doi.org/10.1039/b900139eDOI Listing
June 2009

A novel microfluidic driver via AC electrokinetics.

Lab Chip 2008 May 18;8(5):725-33. Epub 2008 Mar 18.

Department of Power Mechanical Engineering, National Tsing-Hua University, Hsinchu, Taiwan 30043, Republic of China.

A novel ac electrokinetic microfluidic driver based on alternating current electro-osmosis flow induced by asymmetrically capacitance/chemistry-modulated microelectrode arrays has been successfully developed and demonstrated. Asymmetric capacitance modulation (ACM) is made of comb electrode arrays and parts of individual electrode surfaces are modulated/deposited with a SiO(2) dielectric layer. This proposed design can be utilized to shift the optimal operation frequency of maximum velocity to a higher frequency to minimize electrolytic bubble generation and enhance micropumping performance. The pumping velocity, described in this paper, is measured via the tracing of microbeads and is a function of applied potential, signal frequency, buffer concentration, and dielectric layer thickness. A maximum pumping velocity up to 290 microm s(-1) in 5 mM buffer solution with the applied potential of 10 Vpp is observed in our prototype device, and the estimated maximum flow rate is up to 26.1 microl h(-1). This is the first successful demonstration regarding bubble-free ac electrokinetic micropumping via such asymmetrically capacitance-modulated electrode arrays. Design, simulation, microfabrication, experimental result, and theoretical model are described in this paper to characterize and exhibit the performance of the proposed novel bubble-free ac electrokinetic microfluidic driver.
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http://dx.doi.org/10.1039/b719968fDOI Listing
May 2008

Measurement of the adhesive force between a single Klebsiella pneumoniae type 3 fimbria and collagen IV using optical tweezers.

Biochem Biophys Res Commun 2006 Nov 12;350(1):33-8. Epub 2006 Sep 12.

Department of Photonics and Institute of Electro-Optical Engineering, National Chiao Tung University, Hsinchu City 300, Taiwan.

Type 3 fimbriae are important adhesive filaments that assist Klebsiella pneumoniae to establish an infection. Different MrkD adhesin variants on the fimbriae are known to display distinct adherence capability for the bacteria to bind extracellular matrix proteins, although the difference has not been determined physically. For this reason, the adhesive force between type 3 fimbriae and collagen IV were measured using optical tweezers. The measured force data displayed a periodic histogram thus Fourier analysis was applied to group it to extract the adhesive force of a single molecular pair. Specifically, we showed that grouping should begin with an offset at the first half of the period. Finally, we first present the adhesive force between each mrkD(V2)-, mrkD(V3)-, and mrkD(V4)-expressed fimbriae and collagen IV is 2.03, 3.79, and 2.87 pN, respectively. This result can be referred to further research on mrkD allelic effect on bacteria infection.
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http://dx.doi.org/10.1016/j.bbrc.2006.08.190DOI Listing
November 2006

Dielectrophoresis based-cell patterning for tissue engineering.

Biotechnol J 2006 Sep;1(9):949-57

Institute of Molecular Medicine, National Tsing Hua University, Hsin Chu, Taiwan, ROC.

Engineering functional tissues and organs in vitro is considered integral to regenerative medicine. Many recent cell patterning technique developments position cells at a pre-designated pattern to improve tissue engineering efficiency and quality and to facilitate 3-D cell-cell interaction exploration. Among these techniques, dielectrophoresis (DEP)-based cell patterning advantageously offers speed, ease of operation, low degree of cell damage, and precision. This article reviews recent advances in DEP-based patterning techniques, including electrode design, suitable buffer and hydrogel, effects of the electric current to cells, combination potential with other techniques, as well as efforts to generate 3-D tissues.
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http://dx.doi.org/10.1002/biot.200600112DOI Listing
September 2006

Rapid heterogeneous liver-cell on-chip patterning via the enhanced field-induced dielectrophoresis trap.

Lab Chip 2006 Jun 3;6(6):724-34. Epub 2006 May 3.

Department of Power Mechanical Engineering, National Tsing Hua University, Hsinchu, Taiwan 300, ROC.

Biomimetic heterogeneous patterning of hepatic and endothelial cells, which start from randomly distributed cells inside the microfluidic chamber, via the chip design of enhanced field-induced dielectrophoresis (DEP) trap is demonstrated and reported in this paper. The concentric-stellate-tip electrode array design in this chip generates radial-pattern electric fields for the DEP manipulation of the live liver cells. By constructing the geometric shape and the distribution of stellate tips, the DEP electrodes enhance the desired spatial electric-field gradients to guide and snare individual cells to form the desired biomimetic pattern. With this proposed microfluidic chip design, the original randomly distributed hepatocytes inside the microfluidic chamber can be manipulated in parallel and align into the desired pearl-chain array pattern. This radial pattern mimics the lobular morphology of real liver tissue. The endothelial cells, then, are snared into the additional pearl-chain array and settle at the space in-between the previous hepatic pearl-chain array. By this cell-lab chip, we demonstrate the in vitro reconstruction of the heterogeneous lobule-mimetic radial pattern with good cell viability after cell patterning. This work reports the rapid in-parallel patterning of the dual types of live liver cells via the enhanced DEP trap inside the microfluidic chip.
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http://dx.doi.org/10.1039/b602036dDOI Listing
June 2006

Micromachined electrochemical T-switches for cell sorting applications.

Lab Chip 2005 Nov 21;5(11):1248-58. Epub 2005 Sep 21.

Department of Power Mechanical Engineering, National Tsing Hua University, Hsinchu, Taiwan 300, R.O.C.

MEMS micro-T-switches actuated via electrochemical bubbles for cell sorting applications in a monolithic chip level are proposed and successfully demonstrated. The electrolysis-bubble actuator, which has the features of low operation temperature and high surface-tension force, is developed to actuate the micro-T-switch sorting structure in our device. The double T-structure design, the T-shape microchannel with the movable micro-T-switch structure located at the junction of the T-shape microchannel, with the electrolysis-bubble actuator makes an active-binary switch function available for cell sorting applications. The room temperature operation and the low voltage required for electrolysis actuation minimize the possibility of cell-damage that happens in the conventional high electric separation instruments, such as flow cytometry. The function of our micro-T-switch chip with a low required actuation voltage of 3.0 approximately 3.5 V is demonstrated by using human hepatoma cells in this paper. The pH-value measurements characterize the pH-value variation and distribution in the actuating chambers and the mainstream microchannels to trace the possible liver-cell injury due to the pH-value variation during electrolysis-actuation operation. The 84.1% cell viability in the sorted human hepatoma cells through our micro-T-switch sorter is observed via the fluorescence assay technique. Furthermore, 70.2% of total injected cells recover in culture after sorting and grow into colonies after micro-T-switch sorting operation. In this paper, we describe the design, microfabrication, and characterization of our micro-T-switch cell-sorting chip. We also report the cell-sorting demonstration and the cell viability results for the mammalian liver cells through our micro-T-switch cell-sorting chip.
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http://dx.doi.org/10.1039/b507575kDOI Listing
November 2005