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You searched for +publisher:"University of Arkansas" +contributor:("Chao-Hung S. Tung"). Showing records 1 – 3 of 3 total matches.

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University of Arkansas

1. Sahore, Vishal. Microfluidics Guided by Redox-Magnetohydrodynamics (MHD) for Lab-on-a-Chip Applications.

Degree: PhD, 2013, University of Arkansas

Unique microfluidic control actuated by simply turning off and on microfabricated electrodes in a small-volume system was investigated for lab-on-a-chip applications. This was accomplished using a relatively new pumping technique of redox-magnetohydrodynamics (MHD), which as shown in this dissertation generated the important microfluidic features of flat flow profile and fluid circulation. MHD is driven by the body force, FB = j × B, which is the magnetic part of the Lorentz force equation, and its direction is given by the right hand rule. The ionic current density, j, was generated in an equimolar solution of potassium ferri/ferro cyanide by applying a constant current/potential across the gap between an anode-cathode pair of the electrodes. The magnetic field, B, was produced with an NdFeB permanent magnet beneath the chip. Two types of microelectrode geometries were used in this dissertation: microbands and concentric disks and rings. Horizontal flow profiles having uniform velocities (≤124.0 µm/s) at fixed heights across different gaps were sustained along a ~25.0 mm path using microband electrodes, in a small volume contained over an insulated silicon chip. Microfluidic rotational flow with velocity ≤ 14 µm/s was also achieved over an annular region between concentric disk (radius: 80 µm) and ring (inner radius: 800 µm) microelectrodes. In a different but related series of studies, natural convection generated by electrochemical processes was studied in a steady state microfluidic system, but without using redox-MHD convection. Natural convection was found to generate a maximum fluid velocity of < 10 µm/s radially across the gap between concentric disk-ring microelectrodes. A proof-of-concept magnetic microbead enzyme assay was also integrated with the redox-MHD flat flow profile generated by [Ru(NH3)6]3+/2+ in Tris buffer. Selective placement of the assay complex at different locations combined with the uniform transport of the electroactive species by-product generated a strong current signal at the locations that were on the same flow path as the detector. When the assay complex was placed at other locations that were on parallel flow paths the current signal at the detector was insignificant (20%), thus confirming the potential of redox-MHD microfluidics to perform multiple, parallel assay detections. Advisors/Committee Members: Ingrid Fritsch, Chao-Hung S. Tung, Christa Hestekin.

Subjects/Keywords: Pure sciences; applied sciences; Biosensing; Electrochemistry; Lab-on-a-chip; Microfabrication; Microfluidics; Redox-magnettohydrodynamics; Analytical Chemistry; Electrical and Electronics

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Sahore, V. (2013). Microfluidics Guided by Redox-Magnetohydrodynamics (MHD) for Lab-on-a-Chip Applications. (Doctoral Dissertation). University of Arkansas. Retrieved from https://scholarworks.uark.edu/etd/952

Chicago Manual of Style (16th Edition):

Sahore, Vishal. “Microfluidics Guided by Redox-Magnetohydrodynamics (MHD) for Lab-on-a-Chip Applications.” 2013. Doctoral Dissertation, University of Arkansas. Accessed July 15, 2019. https://scholarworks.uark.edu/etd/952.

MLA Handbook (7th Edition):

Sahore, Vishal. “Microfluidics Guided by Redox-Magnetohydrodynamics (MHD) for Lab-on-a-Chip Applications.” 2013. Web. 15 Jul 2019.

Vancouver:

Sahore V. Microfluidics Guided by Redox-Magnetohydrodynamics (MHD) for Lab-on-a-Chip Applications. [Internet] [Doctoral dissertation]. University of Arkansas; 2013. [cited 2019 Jul 15]. Available from: https://scholarworks.uark.edu/etd/952.

Council of Science Editors:

Sahore V. Microfluidics Guided by Redox-Magnetohydrodynamics (MHD) for Lab-on-a-Chip Applications. [Doctoral Dissertation]. University of Arkansas; 2013. Available from: https://scholarworks.uark.edu/etd/952


University of Arkansas

2. Yang, Teng. Cross-Linked PDMS Expansion Due to Submersion in Liquid and Supercritical CO2.

Degree: MSME, 2012, University of Arkansas

Characterization of micro/nano-copper particles impregnated Polydimethylsiloxane (PDMS) submersed in supercritical carbon dioxide (scCO2) was studied. The purpose of this investigation was to advance micro-corrosion sensor technology utilizing PDMS and micro-metal particle composite as the sensing element currently under-development. One of the key challenges encountered was the removal of the native oxides inherently existing on the metal particles. Numerous techniques were experimented with to counter this problem at the UA Engineered Micro/Nano Systems Laboratory (EMNSL), with swell-based protocols being identified as the most promising solution. In terms of compatibility to Micro-electro-mechanical Systems (MEMS) fabrication, CO2 is often used in the release of stiction for sensitive microstructures. The experimental method was classified as low temperature techniques (less than 100 degrees Celsius). Commonly, the composite exhibits expansion ratio from 2.5% to 20%, exhibiting more sensitivity to the percentage content of the metal particles, albeit below those reported in literature for pure cross-linked PDMS. The expansion time-constant is found to be on the order of 100 to 1000 seconds. Advisors/Committee Members: Po-Hao A. Huang, Douglas E. Spearot, Chao-Hung S. Tung.

Subjects/Keywords: Applied sciences; Pure sciences; Composite; Pdms; Supercritical CO2; Polymer and Organic Materials; Polymer Chemistry

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Yang, T. (2012). Cross-Linked PDMS Expansion Due to Submersion in Liquid and Supercritical CO2. (Masters Thesis). University of Arkansas. Retrieved from https://scholarworks.uark.edu/etd/407

Chicago Manual of Style (16th Edition):

Yang, Teng. “Cross-Linked PDMS Expansion Due to Submersion in Liquid and Supercritical CO2.” 2012. Masters Thesis, University of Arkansas. Accessed July 15, 2019. https://scholarworks.uark.edu/etd/407.

MLA Handbook (7th Edition):

Yang, Teng. “Cross-Linked PDMS Expansion Due to Submersion in Liquid and Supercritical CO2.” 2012. Web. 15 Jul 2019.

Vancouver:

Yang T. Cross-Linked PDMS Expansion Due to Submersion in Liquid and Supercritical CO2. [Internet] [Masters thesis]. University of Arkansas; 2012. [cited 2019 Jul 15]. Available from: https://scholarworks.uark.edu/etd/407.

Council of Science Editors:

Yang T. Cross-Linked PDMS Expansion Due to Submersion in Liquid and Supercritical CO2. [Masters Thesis]. University of Arkansas; 2012. Available from: https://scholarworks.uark.edu/etd/407


University of Arkansas

3. Dong, Zhuxin. Design, Fabrication, Testing of CNT Based ISFET and Characterization of Nano/Bio Materials Using AFM.

Degree: PhD, 2012, University of Arkansas

A combination of Carbon Nanotubes (CNTs) and Ion Selective Field Effect Transistor (ISFET) is designed and experimentally verified in order to develop the next generation ion concentration sensing system. Micro Electro-Mechanical System (MEMS) fabrication techniques, such as photolithography, diffusion, evaporation, lift-off, packaging, etc., are required in the fabrication of the CNT-ISFET structure on p-type silicon wafers. In addition, Atomic Force Microscopy (AFM) based surface nanomachining is investigated and used for creating nanochannels on silicon surfaces. Since AFM based nanomanipulation and nanomachining is highly controllable, nanochannels are precisely scratched in the area between the source and drain of the FET where the inversion layer is after the ISFET is activated. Thus, a bundle of CNTs are able to be aligned inside a single nanochannel by Dielectrophoresis (DEP) and the drain current is improved greatly due to CNTs` remarkable and unique electrical properties, for example, high current carrying capacity. ISFET structures with or without CNTs are fabricated and tested with different pH solutions. Besides the CNT-ISFET pH sensing system, this dissertation also presents novel AFM-based nanotechnology for learning the properties of chemical or biomedical samples in micro or nano level. Dimensional and mechanical property behaviors of Vertically Aligned Carbon Nanofibers (VACNFs) are studied after temperature and humidity treatment using AFM. Furthermore, mechanical property testing of biomedical samples, such as microbubbles and engineered soft tissues, using AFM based nanoindentation is introduced, and the methodology is of great directional value in the area. Advisors/Committee Members: Uchechukwu C. Wejinya, Chao-Hung S. Tung, Po-Hao A. Huang.

Subjects/Keywords: Applied sciences; Afm; Cnt; Isfet; Mems; Nanoindentation; Nanoscratching; Electro-Mechanical Systems; Nanoscience and Nanotechnology; Polymer and Organic Materials

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Dong, Z. (2012). Design, Fabrication, Testing of CNT Based ISFET and Characterization of Nano/Bio Materials Using AFM. (Doctoral Dissertation). University of Arkansas. Retrieved from https://scholarworks.uark.edu/etd/612

Chicago Manual of Style (16th Edition):

Dong, Zhuxin. “Design, Fabrication, Testing of CNT Based ISFET and Characterization of Nano/Bio Materials Using AFM.” 2012. Doctoral Dissertation, University of Arkansas. Accessed July 15, 2019. https://scholarworks.uark.edu/etd/612.

MLA Handbook (7th Edition):

Dong, Zhuxin. “Design, Fabrication, Testing of CNT Based ISFET and Characterization of Nano/Bio Materials Using AFM.” 2012. Web. 15 Jul 2019.

Vancouver:

Dong Z. Design, Fabrication, Testing of CNT Based ISFET and Characterization of Nano/Bio Materials Using AFM. [Internet] [Doctoral dissertation]. University of Arkansas; 2012. [cited 2019 Jul 15]. Available from: https://scholarworks.uark.edu/etd/612.

Council of Science Editors:

Dong Z. Design, Fabrication, Testing of CNT Based ISFET and Characterization of Nano/Bio Materials Using AFM. [Doctoral Dissertation]. University of Arkansas; 2012. Available from: https://scholarworks.uark.edu/etd/612

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