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Lapizco-Encinas BH. Nonlinear Electrokinetic Methods of Particles and Cells. ANNUAL REVIEW OF ANALYTICAL CHEMISTRY (PALO ALTO, CALIF.) 2024; 17:243-264. [PMID: 38360552 DOI: 10.1146/annurev-anchem-061622-040810] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/17/2024]
Abstract
Nonlinear electrokinetic phenomena offer label-free, portable, and robust approaches for particle and cell assessment, including selective enrichment, separation, sorting, and characterization. The field of electrokinetics has evolved substantially since the first separation reports by Arne Tiselius in the 1930s. The last century witnessed major advances in the understanding of the weak-field theory, which supported developments in the use of linear electrophoresis and its adoption as a routine analytical technique. More recently, an improved understanding of the strong-field theory enabled the development of nonlinear electrokinetic techniques such as electrorotation, dielectrophoresis, and nonlinear electrophoresis. This review discusses the operating principles and recent applications of these three nonlinear electrokinetic phenomena for the analysis and manipulation of particles and cells and provides an overview of some of the latest developments in the field of nonlinear electrokinetics.
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Affiliation(s)
- Blanca H Lapizco-Encinas
- Microscale Bioseparations Laboratory and Department of Biomedical Engineering, Rochester Institute of Technology, Rochester, New York, USA;
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Kordzadeh-Kermani V, Ashrafizadeh SN, Madadelahi M. Dielectrophoretic separation/classification/focusing of microparticles using electrified lab-on-a-disc platforms. Anal Chim Acta 2024; 1310:342719. [PMID: 38811136 DOI: 10.1016/j.aca.2024.342719] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2023] [Revised: 05/01/2024] [Accepted: 05/10/2024] [Indexed: 05/31/2024]
Abstract
BACKGROUND Separation, classification, and focusing of microparticles are essential issues in microfluidic devices that can be implemented in two categories: using labeling and label-free methods. Label-free methods differentiate microparticles based on their inherent properties, including size, density, shape, electrical conductivity/permittivity, and magnetic susceptibility. Dielectrophoresis is an advantageous label-free technique for this objective. Besides, centrifugal microfluidic devices exploit centrifugal forces to move liquid and particles. The simultaneous combination of dielectrophoretic and centrifugal forces exerted on microparticles still needs to be scrutinized more to predict their trajectories in such devices. RESULTS An integrated system utilizing two categories in microfluidics is proposed: dielectrophoretic manipulation of microparticles and centrifugal-driven microfluidics, followed by a numerical analysis. In this regard, we assumed a rectangular microchannel with internal unilateral planar electrodes equipped with three equal-sized outlets placed radially on a centrifugal platform where microparticles flow toward the disc's outer edge. The effect of different coordinate-based parameters, including radial and lateral distances (X and Y offsets)/tilting angles toward the radius direction (α), on the particles' movement was investigated. Additionally, the effect of operational parameters, including applied voltage, the microchannel width, the number of enabled electrodes, the diameter of particles, and the configuration of electrodes, were analyzed, and the distributions of particles toward the outlets were monitored. It was found that enhanced particle focusing becomes possible at lower rotation speeds and higher electric field values. Furthermore, the proposed centrifugal-DEP system's efficiency for classifying red blood cells/platelets and Live/Dead yeast cells systems was evaluated. SIGNIFICANCE Our integrated system is introduced as a novel method for focusing and classifying various microparticles with no need for sheath flows, having the ability to conduct particles at desired routes and focusing width. Furthermore, the system effectively separates various bioparticles and offers ease of operation and high-efficiency throughput over conventional dielectrophoretic devices.
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Affiliation(s)
- Vahid Kordzadeh-Kermani
- Research Lab for Advanced Separation Processes, Department of Chemical Engineering, Iran University of Science and Technology, Narmak, Tehran, 16846-13114, Iran
| | - Seyed Nezameddin Ashrafizadeh
- Research Lab for Advanced Separation Processes, Department of Chemical Engineering, Iran University of Science and Technology, Narmak, Tehran, 16846-13114, Iran.
| | - Masoud Madadelahi
- School of Engineering and Sciences, Tecnologico de Monterrey, Monterrey, 64849, NL, Mexico.
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Adelantado C, Lapizco-Encinas BH, Jordens J, Voorspoels S, Velimirovic M, Tirez K. Capillary Electrophoresis as a Complementary Analytical Tool for the Separation and Detection of Nanoplastic Particles. Anal Chem 2024; 96:7706-7713. [PMID: 38688471 PMCID: PMC11099890 DOI: 10.1021/acs.analchem.4c00822] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2024] [Revised: 04/15/2024] [Accepted: 04/16/2024] [Indexed: 05/02/2024]
Abstract
Capillary electrophoresis (CE) is presented as a technique for the separation of polystyrene nanoparticles (NPs, particle diameters ranging from 30 to 300 nm) through a bare fused silica capillary and ultraviolet detection. The proposed strategy was also assessed for other types of nanoplastics, finding that stronger alkaline conditions, with an ammonium hydroxide buffer (7.5%, pH = 11.9), enabled the separation of poly(methyl methacrylate), polypropylene, and polyethylene NP for the first time by means of CE for particle diameters below 200 nm. Particle behavior has been investigated in terms of its effective electrophoretic mobility, showing an increasing absolute value of effective electrophoretic mobility from the smaller to the larger sizes. On the other hand, the absolute value of surface charge density decreased with increasing size of NPs. It was demonstrated and quantified that the separation mechanism was a combination of linear and nonlinear electrophoretic effects. This work is the first report on the quantification of nonlinear electrophoretic effects on nanoplastic particles in a CE system.
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Affiliation(s)
- Carlos Adelantado
- Flemish
Institute for Technological Research (VITO), Boeretang 200, 2400 Mol, Belgium
| | - Blanca H. Lapizco-Encinas
- Microscale
Bioseparations Laboratory and Biomedical Engineering Department, Rochester Institute of Technology, 160 Lomb Memorial Drive, Rochester, New York 14623, United States
| | - Jan Jordens
- Flemish
Institute for Technological Research (VITO), Boeretang 200, 2400 Mol, Belgium
| | - Stefan Voorspoels
- Flemish
Institute for Technological Research (VITO), Boeretang 200, 2400 Mol, Belgium
| | - Milica Velimirovic
- Flemish
Institute for Technological Research (VITO), Boeretang 200, 2400 Mol, Belgium
| | - Kristof Tirez
- Flemish
Institute for Technological Research (VITO), Boeretang 200, 2400 Mol, Belgium
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Nasir Ahamed NN, Mendiola-Escobedo CA, Perez-Gonzalez VH, Lapizco-Encinas BH. Manipulating the insulating post arrangement in DC-biased AC-iEK devices to improve microparticle separations. Analyst 2024; 149:2469-2479. [PMID: 38516870 DOI: 10.1039/d3an02160b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/23/2024]
Abstract
There is a growing interest in the advancement of microscale electrokinetic (EK) systems for biomedical and clinical applications, as these systems offer attractive characteristics such as portability, robustness, low sample requirements and short response time. The present work is focused on manipulating the characteristics of the insulating post arrangement in insulator-based EK (iEK) systems for separating a binary mixture of spherical microparticles with same diameter (5.1 μm), same shape, made from the same substrate material and only differing in their zeta potential by ∼14 mV. This study presents a combination of mathematical modeling and experimental separations performed by applying a low-frequency alternating current (AC) voltage in iEK systems with 12 distinct post arrangements. These iEK devices were used to systematically study the effect of three spatial characteristics of the insulating post array on particle separations: the horizontal separation and the vertical separation between posts, and introducing an offset to the posts arrangement. Through normalization of the spatial separation between the insulating posts with respect to particle diameter, guidelines to improve separation resolution for different particle mixtures possessing similar characteristics were successfully identified. The results indicated that by carefully designing the spatial arrangement of the post array, separation resolution values in the range of 1.4-2.8 can be obtained, illustrating the importance and effect of the arrangement of insulating posts on improving particle separations. This study demonstrates that iEK devices, with effectively designed spatial arrangement of the insulating post arrays, have the capabilities to perform discriminatory separations of microparticles of similar characteristics.
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Affiliation(s)
- Nuzhet Nihaar Nasir Ahamed
- Microscale Bioseparations Laboratory and Biomedical Engineering Department, Rochester Institute of Technology, 160 Lomb Memorial Drive, Rochester, New York, 14623, USA.
| | | | - Victor H Perez-Gonzalez
- School of Engineering and Sciences, Tecnologico de Monterrey, Monterrey, Nuevo Leon 64849, Mexico.
| | - Blanca H Lapizco-Encinas
- Microscale Bioseparations Laboratory and Biomedical Engineering Department, Rochester Institute of Technology, 160 Lomb Memorial Drive, Rochester, New York, 14623, USA.
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Bentor J, Xuan X. Nonlinear electrophoresis of nonspherical particles in a rectangular microchannel. Electrophoresis 2024; 45:712-719. [PMID: 37880863 DOI: 10.1002/elps.202300188] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2023] [Revised: 10/04/2023] [Accepted: 10/13/2023] [Indexed: 10/27/2023]
Abstract
Nonlinear electrophoresis offers advantageous prospects in microfluidic manipulation of particles over linear electrophoresis. Existing theories established for this phenomenon are entirely based on spherical particle models, some of which have been experimentally verified. However, there is no knowledge on if and how the particle shape may affect the nonlinear electrophoretic behavior. This work presents an experimental study of the nonlinear electrophoretic velocities of rigid peanut- and pear-shaped particles in a rectangular microchannel, which are compared with rigid spherical particles of similar diameter and surface charge in terms of the particle slenderness. We observe a decrease in the nonlinear electrophoretic mobility, whereas an increase in the nonlinear index of electric field when the particle slenderness increases from the peanut- to pear-shaped and spherical particles. The values of the nonlinear index for the nonspherical particles are, however, still within the theoretically predicted range for spherical particles. We also observe an enhanced nonlinear electrophoretic behavior in a lower concentration buffer solution regardless of the particle shape.
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Affiliation(s)
- Joseph Bentor
- Department of Mechanical Engineering, Clemson University, Clemson, South Carolina, USA
| | - Xiangchun Xuan
- Department of Mechanical Engineering, Clemson University, Clemson, South Carolina, USA
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Vaghef-Koodehi A, Cyr P, Lapizco-Encinas BH. Improving device design in insulator-based electrokinetic tertiary separations. J Chromatogr A 2024; 1722:464853. [PMID: 38579611 DOI: 10.1016/j.chroma.2024.464853] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2024] [Revised: 03/20/2024] [Accepted: 03/26/2024] [Indexed: 04/07/2024]
Abstract
This study presents a methodology for designing effective insulator-based electrokinetic (iEK) systems for separating tertiary microparticle samples, which can be extended to more complex samples. First, 144 distinct iEK microchannel designs were built considering different shapes and arrangements of the insulating posts. Second, a mathematical model was developed with COMSOL software to predict the retention time of each particle type in the microchannel, this allowed identifying the best channel designs for two distinct types of separations: charge-based and sized-based. Third, the experimental charge-based and size-based separations of the tertiary microparticle mixtures were performed employing the improved designs identified with COMSOL modeling. The experimental results demonstrated successful separation in terms of separation resolution and good agreement with COMSOL predictions. The findings from this study show that the proposed method for device design, which combines mathematical modeling with varying post shape and post arrangement is an effective approach for identifying iEK systems capable of separating complex microparticle samples.
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Affiliation(s)
- Alaleh Vaghef-Koodehi
- Microscale Bioseparations Laboratory and Biomedical Engineering Department, Rochester Institute of Technology, 160 Lomb Memorial Drive, Rochester, NY 14623, United States
| | - Patricia Cyr
- Department of Industrial and Systems Engineering, Rochester Institute of Technology, 160 Lomb Memorial Drive, Rochester, NY 14623, United States
| | - Blanca H Lapizco-Encinas
- Microscale Bioseparations Laboratory and Biomedical Engineering Department, Rochester Institute of Technology, 160 Lomb Memorial Drive, Rochester, NY 14623, United States.
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Bentor J, Xuan X. Particle Size-Dependent Electrophoresis in Polymer Solutions. Anal Chem 2024. [PMID: 38321932 DOI: 10.1021/acs.analchem.3c05655] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2024]
Abstract
It has long been known that the electrophoretic velocity of a charged particle is independent of its size under the thin-Debye-layer limit. This so-called Smoluchowski velocity is, however, valid only for Newtonian fluids. A couple of recent theoretical studies predict the rheology-induced particle size dependence of electrophoresis in non-Newtonian fluids. This work presents the first experimental demonstration of such dependence in viscoelastic poly(ethylene oxide) (PEO) solutions. Three different-sized particles are observed to travel at the same electrophoretic velocity in a Newtonian buffer through a rectangular microchannel. In contrast, their measured electrophoretic velocities in the PEO solution exhibit an increasing trend for larger particles, which is consistent with theoretical prediction. This particle size dependence is found to grow with an increasing concentration or length of the PEO polymer. Both trends are attributed to enhanced fluid elasticity, as characterized by the increasing elasticity number.
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Affiliation(s)
- Joseph Bentor
- Department of Mechanical Engineering, Clemson University, Clemson, South Carolina 29634-0921, United States
| | - Xiangchun Xuan
- Department of Mechanical Engineering, Clemson University, Clemson, South Carolina 29634-0921, United States
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Krebs F, Zagst H, Stein M, Ratih R, Minkner R, Olabi M, Hartung S, Scheller C, Lapizco-Encinas BH, Sänger-van de Griend C, García CD, Wätzig H. Strategies for capillary electrophoresis: Method development and validation for pharmaceutical and biological applications-Updated and completely revised edition. Electrophoresis 2023; 44:1279-1341. [PMID: 37537327 DOI: 10.1002/elps.202300158] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2023] [Accepted: 07/19/2023] [Indexed: 08/05/2023]
Abstract
This review is in support of the development of selective, precise, fast, and validated capillary electrophoresis (CE) methods. It follows up a similar article from 1998, Wätzig H, Degenhardt M, Kunkel A. "Strategies for capillary electrophoresis: method development and validation for pharmaceutical and biological applications," pointing out which fundamentals are still valid and at the same time showing the enormous achievements in the last 25 years. The structures of both reviews are widely similar, in order to facilitate their simultaneous use. Focusing on pharmaceutical and biological applications, the successful use of CE is now demonstrated by more than 600 carefully selected references. Many of those are recent reviews; therefore, a significant overview about the field is provided. There are extra sections about sample pretreatment related to CE and microchip CE, and a completely revised section about method development for protein analytes and biomolecules in general. The general strategies for method development are summed up with regard to selectivity, efficiency, precision, analysis time, limit of detection, sample pretreatment requirements, and validation.
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Affiliation(s)
- Finja Krebs
- Institute, of Medicinal and Pharmaceutical Chemistry, Technische Universität Braunschweig, Braunschweig, Lower Saxony, Germany
| | - Holger Zagst
- Institute, of Medicinal and Pharmaceutical Chemistry, Technische Universität Braunschweig, Braunschweig, Lower Saxony, Germany
| | - Matthias Stein
- Institute, of Medicinal and Pharmaceutical Chemistry, Technische Universität Braunschweig, Braunschweig, Lower Saxony, Germany
| | - Ratih Ratih
- Department of Pharmaceutical Chemistry, Faculty of Pharmacy, University of Surabaya, Surabaya, East Java, Indonesia
| | - Robert Minkner
- Institute, of Medicinal and Pharmaceutical Chemistry, Technische Universität Braunschweig, Braunschweig, Lower Saxony, Germany
| | - Mais Olabi
- Institute, of Medicinal and Pharmaceutical Chemistry, Technische Universität Braunschweig, Braunschweig, Lower Saxony, Germany
| | - Sophie Hartung
- Institute, of Medicinal and Pharmaceutical Chemistry, Technische Universität Braunschweig, Braunschweig, Lower Saxony, Germany
| | - Christin Scheller
- Institute, of Medicinal and Pharmaceutical Chemistry, Technische Universität Braunschweig, Braunschweig, Lower Saxony, Germany
| | - Blanca H Lapizco-Encinas
- Department of Biomedical Engineering, Kate Gleason College of Engineering, Rochester Institute of Technology, Rochester, New York, USA
| | - Cari Sänger-van de Griend
- Kantisto BV, Baarn, The Netherlands
- Department of Medicinal Chemistry, Faculty of Pharmacy, Uppsala Universitet, Uppsala, Sweden
| | - Carlos D García
- Department of Chemistry, Clemson University, Clemson, South Carolina, USA
| | - Hermann Wätzig
- Institute, of Medicinal and Pharmaceutical Chemistry, Technische Universität Braunschweig, Braunschweig, Lower Saxony, Germany
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Vaghef-Koodehi A, Ernst OD, Lapizco-Encinas BH. Separation of Cells and Microparticles in Insulator-Based Electrokinetic Systems. Anal Chem 2023; 95:1409-1418. [PMID: 36599093 DOI: 10.1021/acs.analchem.2c04366] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Presented here is the first continuous separation of microparticles and cells of similar characteristics employing linear and nonlinear electrokinetic phenomena in an insulator-based electrokinetic (iEK) system. By utilizing devices with insulating features, which distort the electric field distribution, it is possible to combine linear and nonlinear EK phenomena, resulting in highly effective separation schemes that leverage the new advancements in nonlinear electrophoresis. This work combines mathematical modeling and experimentation to separate four distinct binary mixtures of particles and cells. A computational model with COMSOL Multiphysics was used to predict the retention times (tR,p) of the particles and cells in iEK devices. Then, the experimental separations were carried out using the conditions identified with the model, where the experimental retention time (tR,e) of the particles and cells was measured. A total of four distinct separations of binary mixtures were performed by increasing the level of difficulty. For the first separation, two types of polystyrene microparticles, selected to mimic Escherichia coli and Saccharomyces cerevisiae cells, were separated. By leveraging the knowledge gathered from the first separation, a mixture of cells of distinct domains and significant size differences, E. coli and S. cerevisiae, was successfully separated. The third separation also featured cells of different domains but closer in size: Bacillus cereus versus S. cerevisiae. The last separation included cells in the same domain and genus, B. cereus versus Bacillus subtilis. Separation results were evaluated in terms of number of plates (N) and separation resolution (Rs), where Rs values for all separations were above 1.5, illustrating complete separations. Experimental results were in agreement with modeling results in terms of retention times, with deviations in the 6-27% range, while the variation between repetitions was between 2 and 18%, demonstrating good reproducibility. This report is the first prediction of the retention time of cells in iEK systems.
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Affiliation(s)
- Alaleh Vaghef-Koodehi
- Microscale Bioseparations Laboratory and Biomedical Engineering Department, Rochester Institute of Technology, 160 Lomb Memorial Drive, Rochester, New York14623, United States
| | - Olivia D Ernst
- Microscale Bioseparations Laboratory and Biomedical Engineering Department, Rochester Institute of Technology, 160 Lomb Memorial Drive, Rochester, New York14623, United States
| | - Blanca H Lapizco-Encinas
- Microscale Bioseparations Laboratory and Biomedical Engineering Department, Rochester Institute of Technology, 160 Lomb Memorial Drive, Rochester, New York14623, United States
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Bentor J, Dort H, Chitrao RA, Zhang Y, Xuan X. Nonlinear electrophoresis of dielectric particles in Newtonian fluids. Electrophoresis 2022. [PMID: 36495043 DOI: 10.1002/elps.202200213] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2022] [Revised: 11/25/2022] [Accepted: 12/06/2022] [Indexed: 12/14/2022]
Abstract
In classical electrokinetics, the electrophoretic velocity of a dielectric particle is a linear function of the applied electric field. Theoretical studies have predicted the onset of nonlinear electrophoresis at high electric fields because of the nonuniform surface conduction over the curved particle. However, experimental studies have been left behind and are insufficient for a fundamental understanding of the parametric effects on nonlinear electrophoresis. We present in this work a systematic experimental study of the effects of buffer concentration, particle size, and particle zeta potential on the electrophoretic velocity of polystyrene particles in a straight rectangular microchannel for electric fields of up to 3 kV/cm. The measured nonlinear electrophoretic particle velocity is found to exhibit a 2(±0.5)-order dependence on the applied electric field, which appears to be within the theoretically predicted 3- and 3/2-order dependences for low and high electric fields, respectively. Moreover, the obtained nonlinear electrophoretic particle mobility increases with decreasing buffer concentration (for the same particle) and particle size (for particles with similar zeta potentials) or increasing particle zeta potential (for particles with similar sizes). These observations are all consistent with the theoretical predictions for high electric fields.
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Affiliation(s)
- Joseph Bentor
- Department of Mechanical Engineering, Clemson University, Clemson, South Carolina, USA
| | - Heston Dort
- Department of Mechanical Engineering, Clemson University, Clemson, South Carolina, USA
| | | | - Youwei Zhang
- Shanghai Diecheng Photoelectronics Technology Co., Ltd, Shanghai, P. R. China
| | - Xiangchun Xuan
- Department of Mechanical Engineering, Clemson University, Clemson, South Carolina, USA
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