Chun-Ping Jen

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$Research paper thumbnail of Effects of hydrodynamic chromatography on colloid-facilitated migration of radionuclides in the fractured rock$

Effects of hydrodynamic chromatography on colloid-facilitated migration of radionuclides in the fractured rock

Waste Management, 2001

The performance assessment of high level radioactive waste disposal has emphasized the role of co... more The performance assessment of high level radioactive waste disposal has emphasized the role of colloids in the migration of radionuclides in the geosphere. Previous literature [Nagasaki S, Tanaka S, Suzuki A. Fast transport of colloidal particles through quartz-packed columns. J. Nucl. Sci. Technol. 1975;30(11):1136] indicates that owing to hydrodynamic chromatography the colloid velocity may not be equal to that of groundwater. Using hydrodynamic chromatography, this work investigates the effects of the size of colloidal particles on the radionuclide migration facilitated by colloids in a single fractured porous rock. Also, a methodology is proposed to develop a predictive model to assess transport within the fracture rock as well as various other phenomenological coefficients, particularly the size of colloidal particles. In addition, a fully developed concentration profile for non-reactive colloids in the fracture is developed to elucidate hydrodynamic chromatography of colloids in geological media. The external forces acting on colloidal particles hypothesized in the model proposed herein include inertial force, van der Waals attractive force, double layer force as well as gravitational force. The dispersion coefficient of colloids and the distribution coefficient for radionuclides with colloids are also considered as they pertain to the size of the colloid. In addition, the size distributions of colloids are utilized to investigate the effects of polydispersed colloids.

Investigation of Thermal Analysis on the Process of Laser-Assisted Nanoimprinting Lithography

Numerical Heat Transfer Part A-applications, Dec 20, 2007

ABSTRACT

Migration of radionuclides in porous rock in the presence of colloids: effects of kinetic interactions

Waste Management, 2001

This work investigates the colloid-facilitated migration of radionuclides with radioactive decay ... more This work investigates the colloid-facilitated migration of radionuclides with radioactive decay in porous media. The sorption processes for radionuclides with both the solid matrix and colloids are treated as equilibrium or nonequilibrium. An analytical solution is obtained from a simplified linear equilibrium interaction mechanism. In addition, the adsorption processes for radionuclides with colloids and porous rock can be assumed as nonequilibrium and modeled by the linear kinetic adsorption. The numerical method is employed to solve the coupled colloid and radionuclide transport equations under nonequilibrium sorption assumption. Moreover, the reaction rates of the adsorption processes for radionuclides with the solid matrix and colloids affect the transport characteristics of radionuclides. The fast reaction rate of radionuclides with colloids causes a higher concentration of radionuclides adsorbed on colloids in a dispersed phase and enlarges acceleration caused by colloids. However, the fast reaction rate for radionuclides with solid matrix increases the retardation effect caused by the solid matrix. This work developed a predictive model for the transport of colloid-facilitated radionuclides in porous medium and to assess the importance of various phenomenological coefficients, particularly parameters for the adsorption interactions.

Modeling of Colloid Transport Mechanisms Facilitating Migration of Radionuclides in Fractured Media

Nuclear Technology, Dec 1, 2004

Abstract Performance assessments of high-level radioactive waste disposal have emphasized the rol... more Abstract Performance assessments of high-level radioactive waste disposal have emphasized the role of colloids in the migration of radionuclides in the geosphere. The transport of colloids often brings them in contact with fracture surfaces or porous rock matrix. Colloids that attach to these surfaces are treated as being immobile and are called filtered colloids. The filtered colloids could be released into the fracture again; that is, the attachment of colloids may be reversible. Also, the colloids in the fracture could diffuse into the porous matrix rock. A methodology is proposed to evaluate a predictive model to assess transport within the fractured rock as well as various phenomenological coefficients employed in the different mechanisms, such as filtration, remobilization, and matrix diffusion of colloids. The governing equations of colloids considering mechanisms of the colloidal transport in the fractured media, including filtration, remobilization, and matrix diffusion, have been modeled and solved analytically in previous studies. In the present study, transport equations of colloids and radionuclides that consider the combination of the aforementioned transport mechanisms have also been solved numerically and investigated. The total concentration of mobile radionuclides in the fracture becomes lower because the concentration of mobile colloids in the fracture decreases when the filtration coefficient for colloids increases. Additionally, the concentration of mobile radionuclides was increased at any given time step due to the higher sorption partition coefficient of radionuclides associated with colloids. The results also show that the concentration of radionuclides in the fracture zone decreases when the remobilization coefficient of colloids or the percentages of the matrix diffusion flux of colloids increase.

Modeling of Hydrodynamic Chromatography for Colloid Migration in Fractured Rock

Nuclear Technology, Feb 1, 2001

ABSTRACT

Numerical investigation of laser-assisted nanoimprinting on a copper substrate from a perspective of heat transfer analysis

The technique of laser-assisted nanoimprinting lithography (LAN) has been proposed to utilize an ... more The technique of laser-assisted nanoimprinting lithography (LAN) has been proposed to utilize an excimer laser to irradiate through a quartz mold and melts a thin polymer film on the substrate for micro-to nano-scaled fabrications. In the present study, the novel concept of that copper was adopted as the substrate instead of silicon, which is conventionally used, was proposed. The micro/nano structures on the copper substrate could be fabricated by chemical/electrochemical etching or electroforming; following by the patterns have been transferred onto the substrate using LAN process. Alternatives of the substrate materials could lead versatile applications in micro/nano-fabrication. To demonstrate the feasibility of this concept numerically, this study introduced optical multiple reflection theory to perform both analytical and numerical modeling during the process and to predict the thermal response theoretically.

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A Serpentine Microchannel with Added Cavities Platform for Magnetic Separation of Lung Adenocarcinoma Cells Utilizing Aptamer-Conjugated Magnetic Bead Approach

This study presents an efficient isolation of human lung carcinoma cell line (A549) platform by u... more This study presents an efficient isolation of human lung carcinoma cell line (A549) platform by utilizing the proposal a serpentine microchannel with added cavities (SMAC) platform. The magnetic micro-bead isolation performance in proposed serpentine channel was simulated using COMSOL Multiphysics. The experimental procedures of aptamer molecular conjugation on magnetic microbeads affined to A549 cell line were also reported. The experimental results indicated that at the flow rate of 5 µL/s, the capture rate of human lung carcinoma cell reached above 70% in less than 15 min, whereas non-target cell capture rate was around 1.5%. The proposed platform shows its potential of high selectivity, portable, and simple-to-operate, which are suitable considerations for developing point-of-care applications in various biological and clinical purposes.

Numerical Investigation of Phase-Change Heat Transfer for Laser-Assisted Direct Nano Imprint Processing

The melting duration and molten depth are key information for Laser-Assisted Direct Imprinting, w... more The melting duration and molten depth are key information for Laser-Assisted Direct Imprinting, which raises the issue of the melting & solidification induced by excimer-pulse-laser shining through unilaterally transparent binary materials. Based on the matured laser-annealing analysis, the thermal-contact resistance is taken into account to simulate and predict the melting behavior for this process. The result in this study indicates the laser-annealing case as well as the perfect-contact case provide the upper-bound and the lower-bound values for the physical quantities involved in this process even without the detail information of the changing of thermal-contact resistance during process.

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The experimental studies of bio-particle trapping using electrodeless dielectrophoresis

The ability to manipulate particles, especially living cells, is fundamental needed to many biolo... more The ability to manipulate particles, especially living cells, is fundamental needed to many biological and medical applications, including isolation and detection of sparse cancer cells, concentration of cells from dilute suspensions, separation of cells according to specific properties, and trapping and positioning of individual cells for characterization. The electrodeless dielectrophoretic (EDEP) trapping is composed of conductless tetragon structures in micro-chip. We have improved the design of EDEP geometries, correlated particle acted by DEP effects with electrical-field distributions determined through insulating microstructures produce non-uniform electric fields to drive particles in microsystems. This study is attempt to research on microfluidic trapping by using DEP force and to investigate the relation on important parameters of microchip device for our design to comprehend the factors containing the spacing between two structures, the applied voltage and flow velocity.

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Fabrication and Simulation of Nanostructures on Silicon by Laser Assisted Direct Imprint Technique

Springer eBooks, Jul 10, 2006

In this paper a newly proposed nano-patterning technology, namely laser assisted direct imprintin... more In this paper a newly proposed nano-patterning technology, namely laser assisted direct imprinting (LADI), is adopted with fabrication and numerical simulation for nano-scaled structures. We focused on the target material as silicon and utilized a single KrF excimer laser pulse (248nm wavelength and 30ns pulse duration) as heating source. We also demonstrated the fabrication of a positive quartz mold within micro-level and nano-level trenches by combination of conventional photolithography and novel focused ion beam (FIB) system. The influence of laser fluence and imprinting pressure on resulting nanostructure is evaluated by varying the laser fluence (0.6~1.2 J/cm 2 ) and imprint pressure (370~1120 MPa). The results show that the magnitude of imprinting pressure and the laser characteristics can affect the thickness of the melted layer on the substrate surface and the morphology of the resulting nanostructures. In the other aspect, an analytical modeling of laser induced melting and solidification during LADI process was also established for the comparison between experimental results and numerical simulation. The transient temperature profiles inside the substrate, melt depth and melting duration after the irradiation of a laser pulse were evaluated by various fabrication parameters; such as materials of the substrate (silicon and copper were investigated) and the characteristics of the laser pulse (including wavelength, fluence and pulsed duration). Generally speaking, the nanostructures fabricated by LADI are quite consistent with the results of numerical simulation.

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A dielectrophoretic preconcentrator with circular microelectrodes for biological cells in stepping electric fields

Symposium on Design, Test, Integration and Packaging of MEMS/MOEMS, May 11, 2011

ABSTRACT

Development of an Impedance Spectroscopy Measurement Circuit Board for Protein Detection

This study reports the results on the development of an electrical impedance-based protein detect... more This study reports the results on the development of an electrical impedance-based protein detection circuit board for the protein detection biochip. A digital quadrature phase shift module, which can generate two sine waves with 90-degree difference in phase in a large frequency range is employed for lock-in amplifier block for impedance profiling. A microcontroller is used for frequency selection and data acquisition. The measurement module is connected with a computer to display the impedance profile. The implemented board were applied to protein detection biochip to detect the presence of the protein of interest in an essay sample. Experiment is performed for 10 μM Bovine serum albumin (BSA) labeled with fluorescein isothiocyanate (FITC-BSA) protein sample in 10 mM PBS medium solution with the frequency range from 10 kHz to 200 kHz. The measured results reveal a clear impedance change between before and after trapping protein on the microelectrodes of the biochip. The developed electrical impedance spectroscopy board enables rapid and effective protein detection at low concentration.

Experimental Verification of A Bi-Directional Driving System for Microfluids

A bi-directional microfluidic driving system was developed experimentally in this work. The bi-di... more A bi-directional microfluidic driving system was developed experimentally in this work. The bi-directional driving module combines two individual components for suction and exclusion. The individual components can be combined using a T-shape connection as well as in parallel. Modular devices with a parallel connection, presented herein, can provide flexible, predictable and linear control of bi-directional microfluid pumping. This work demonstrated the driving system and investigated the influences of the characteristics of the working liquids. The driving force, both suction and exclusion, for the liquid with the lower viscosity is stronger than those with the higher viscosity. Furthermore, the required flow rate at the suction component is quite large due to the strong surface tension of water.

Development of a Passive Capacitively Coupled Contactless Conductivity Detection (PC4D) Sensor System for Fluidic Channel Analysis Toward Point-of-Care Applications

IEEE Sensors Journal, Aug 1, 2019

A sensor system based on a modified capacitively coupled contactless conductivity detection senso... more A sensor system based on a modified capacitively coupled contactless conductivity detection sensor is proposed and developed. The proposed system provides a passive and wireless readout technique, through which the conductivity of fluidic flow can be analyzed and foreign objects occurring in the fluidic flow can be detected. The proposed sensor system takes advantage of the series resonance principle and detects shifts in the resonance frequency and reflection coefficient to estimate the conductivity of the fluidic flow. In this study, the working principle of the device is proposed and analyzed using a multiphysics simulation, and its performance is validated experimentally. The sensing performance is confirmed by measuring the conductivity of the fluidic media and the detection of foreign objects, such as air bubbles or water droplets, occurring in the flow. The influence of the distance between the inductors on the resonance frequency for different solution conductivities is also investigated and reported. The proposed sensor system shows its potential for use in various applications in biomedicine and chemistry, particularly in point-of-care applications, where the sensing chip can be easily set up for measurement and disposed of after use.

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A cellular preconcentrator utilizing dielectrophoresis generated by curvy electrodes in stepping electric fields

Microelectronic Engineering, Aug 1, 2011

ABSTRACT

Design and Simulation of a Microfluidic Blood-Plasma Separation Chip Using Microchannel Structures

Separation Science and Technology, Dec 31, 2009

Current clinical methods for the separation of whole blood into blood cells and cell-free plasma ... more Current clinical methods for the separation of whole blood into blood cells and cell-free plasma are currently based on large facility equipment, such as centrifuges. The disadvantage of this process is that the patients must have assays performed at the hospital or laboratory where the separation facility is located. The present study presents a design for microfluidic chips with different microchannel structures, which utilizes backward facing step geometry and centrifugal force to extract the cell-free plasma from whole blood samples at the branch of the microchannel for further assay, avoiding the influence of blood cells. Numerical simulation was performed on a personal computer to analyze the effects of inlet velocity and the structures of the microchannel on the flow field and back-flow in the microchannel, as well as the efficiency of separation and the volumetric fraction of the flowrate of plasma extraction. The minimum radius of particles (R) that can be excluded from the side channel, and fraction of the volumetric flowrate were obtained to evaluate the efficiency of plasma extraction. Based on the numerical simulations, the design with both converging and bending channels was the best design among the four layouts proposed. In this design, the value of R could be set to less than the critical value (set as 1 mm because of the radius of platelets), and the volumetric fraction of the extraction flowrate was approximately 8.4% when Re was about 20. The preliminary experiments indicated the fluorescent particles with 2.5 mm in radius were successfully excluded from side (plasma outlet) channel of the microfluidic chip with converging a inlet channel and the bent microchannel, when the Reynolds number of the inlet flowrate equals 50.

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Nano-structure ZnO/Cu_2O photoelectrochemical and self-powered biosensor for esophageal cancer cell detection

Optics Express, Mar 24, 2017

The p-n heterojunction photoelectrochemical biosensor, which comprises a p-type Cu 2 O film forme... more The p-n heterojunction photoelectrochemical biosensor, which comprises a p-type Cu 2 O film formed by electrochemical deposition and n-type ZnO nanorods formed by the hydrothermal method, is prone to photoelectrochemical reactions and self-powered. Four types of human esophageal cancer cells (ECCs) were detected by this biosensor without requiring an extra bias voltage. The measured photocurrent values of high invasion capacity cancer cells was consistently 2 times higher than those measured by a slight invasion capacity cancer cells. The response time, which was about 0.5 s, allowed repeated measurement.

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Protein preconcentration using nanofissures generated by nanoparticle-facilitaed electric breakdown at the junction gaps

Symposium on Design, Test, Integration and Packaging of MEMS/MOEMS, Apr 16, 2013

ABSTRACT

U-shaped fiber optics fabricated with a femtosecond laser and integrated into a localized plasmon resonance biosensor

Symposium on Design, Test, Integration and Packaging of MEMS/MOEMS, Apr 1, 2009

A novel fiber-optic localized plasma resonance (FO-LPR) biosensor composed of a U-shaped optical ... more A novel fiber-optic localized plasma resonance (FO-LPR) biosensor composed of a U-shaped optical fiber was proposed and demonstrated in the present study. The U-shaped optical fiber was fabricated by a femtosecond laser micromachining system. It was 105 mum in depth measured from the surface of the polymer jacket layer and 80 mum in width in the jacket layer. After treatment of annealing, the mean roughness of the surface was 342.24 nm as determined by AFM. The exposed surface of the U-shaped fiber was modified with self-assembled gold colloids to produce the FO-LPR sensor. Preliminary results show that the colloidal Au-modified U-shaped fiber by transmission power interrogation has a sensitivity of 1.768times10-3 RIU.

Application of simulation on the design of phase-change optical recording disks

IEEE Transactions on Magnetics, Mar 1, 1998

Optical absorption and thermal conduction a r e the two key factors affecting temperature distrib... more Optical absorption and thermal conduction a r e the two key factors affecting temperature distribution and, recent worl<s [ 3 ] , [4] consid optical recording disk. Therefore, by using carefully measured film physical properties of each layer, this w o r k simulates a transient temperature profile while simultaneously considering optical absorption and thermal conduction. Through the simulated transient temperature profile, cooling-rate and reflectivity, dependence of phase-changed spot size on the laser power and laser pulse duration was observed. The proper combination of the disk structure and the associated write, erase as well as each layer's fihn density, were used for conditions are obtained as well. A disk structure can simulation. Consid subsequently be designed on the basis of this information. In addition, a novel dielectric layer, i.e. hydrogenated amorphous carbon (a-C:H), is simulated and compared with the disk applying conventionally used ZnS-SiOz dielectric layers. The disk structures used herein a r e PC/ZnS-SiO,/GeSbTe/ZnS-SiOz/AI and PCla-C:H/GeSbTe/a-C:H/Al. According to those results, a-C:H film is highly promising as a dielectric layer of the phase change optical recording disk for both wavelengths of 780 and 660 nm.

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