Article
Chemistry, Physical
Saebom Lee, Jinkee Lee, Jesse T. Ault
Summary: Variable zeta potential plays an important role in diffusiophoresis and diffusioosmosis, and different surface models should be selected for accurate simulations.
COLLOIDS AND SURFACES A-PHYSICOCHEMICAL AND ENGINEERING ASPECTS
(2023)
Review
Biochemical Research Methods
Blanca H. Lapizco-Encinas
Summary: This review article discusses the evolution of insulator-based dielectrophoresis (iDEP) and insulator-based electrokinetic (iEK) systems, highlighting recent studies that suggest particle trapping in these systems is mainly due to a balance between electroosmotic and electrophoretic effects under DC and low-frequency AC potentials, rather than dielectrophoresis. The proposed renaming of the field from DC-iDEP to DC-iEK reflects the shift in understanding particle manipulation and separation mechanisms in these systems.
ANALYTICAL AND BIOANALYTICAL CHEMISTRY
(2022)
Article
Chemistry, Multidisciplinary
Xianglong Lyu, Jingyuan Chen, Jiayu Liu, Yixin Peng, Shifang Duan, Xing Ma, Wei Wang
Summary: Understanding and controlling the swimming direction of synthetic nano- and micromotors is of great importance. By studying the effects of platinum oxides on the movement of micromotors, a new method for controlling the swimming direction of these motors has been discovered.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2022)
Article
Chemistry, Multidisciplinary
Yun Huang, Jianhe Guo, Yufan Li, Huaizhi Li, Donglei Emma Fan
Summary: 2D materials like MoS2 show unique performance in the field of micro/nanomachines and robots, and when combined with TiO2 can enhance light absorption capability, potentially allowing for solar-powered water disinfection.
ADVANCED MATERIALS
(2022)
Article
Chemistry, Multidisciplinary
Yixin Peng, Pengzhao Xu, Shifang Duan, Jiayu Liu, Jeffrey Lawrence Moran, Wei Wang
Summary: This article proposes and experimentally confirms the rule that the speeds of self-diffusiophoretic colloidal motors scale inversely to their population density, while self-electrophoretic motors do not follow this rule. These rules are simple, powerful, and applicable to various colloidal motors.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2022)
Review
Biochemistry & Molecular Biology
Brian Gidudu, Evans M. N. Chirwa
Summary: Electrokinetic remediation is a promising technology for remediating polluted environments. It utilizes five fundamental processes - electrolysis, electroosmosis, electrophoresis, diffusion, and electromigration - to achieve decontamination. To ensure sustainability, effective processes with low environmental impact and cleaner alternative solutions need to be pursued.
Article
Nanoscience & Nanotechnology
Qing Liu, Shuaishuai Meng, Tingting Zheng, Yaming Liu, Xing Ma, Huanhuan Feng
Summary: Researchers have developed LM Janus micromotors using Gallium- and indium-based liquid metal to address the biotoxicity and biocompatibility issues in potential biomedical applications. They found that the choice of sputtering materials on the metallic surface affects the motors' performance, with self-electrophoresis resulting in faster movement than self-diffusiophoresis. The ability to switch driving mechanisms allows for adaptation to different biochemical application scenarios.
ACS APPLIED MATERIALS & INTERFACES
(2021)
Article
Materials Science, Multidisciplinary
Kang Xiong, Jinwei Lin, Qiang Chen, Tianyu Gao, Leilei Xu, Jianguo Guan
Summary: In this study, axis-asymmetric hollow bowl-shaped Janus micromotors are developed, which can perform unusual precession motion and significantly enhance liquid medium convection in a large area. By modulating the fuel concentration and depression degree, these micromotors achieve synchronistic self-rotation and translation, resulting in improved solute mixing and diffusion efficiencies compared to conventional Janus counterparts. This work demonstrates a novel motion mode, precession, of self-driven micro/nanomotors that greatly enhances micro-convection and rapid diffusion of liquid medium.
Review
Biophysics
Vahid Kordzadeh-Kermani, Masoud Madadelahi, Seyed Nezameddin Ashrafizadeh, Lawrence Kulinsky, Sergio O. Martinez-Chapa, Marc J. Madou
Summary: This review introduces the on-board power supply and electrokinetic applications of electrified-LOD (eLOD) devices. By utilizing electrokinetic phenomena, different microfluids can be propelled, separated, and manipulated. While extensive research exists on stationary platforms, the applications on rotating platforms are still underdeveloped.
BIOSENSORS & BIOELECTRONICS
(2022)
Article
Chemistry, Multidisciplinary
Chaofan Ma, Wei Xu, Wei Liu, Changhui Xu, Wei Si, Jingjie Sha
Summary: Inspired by nature, nanomotors have been developed that have great potential in microfluidics and biomedical applications. The rotary nanomotor, made up of carbon nanotubes (CNTs) and a circular single-stranded DNA (ssDNA), can be controlled by selectively manipulating ion transport through charged nanopores. The rotation of the nanomotor is driven by the electroosmotic flow (EOF) generated by the oppositely charged dual nanopores, resulting in promising opportunities for precise control of nanomotors.
Article
Biochemical Research Methods
Jugal Saharia, Y. M. Nuwan D. Y. Bandara, Min Jun Kim
Summary: Electrolyte chemistry plays a crucial role in the transport properties of analytes through nanopores. In this study, the translocation properties of human serum transferrin (hSTf) protein were investigated under different salt concentrations with positive or negative chemical gradients. The experiments showed that translocations occurred in all configurations under positive gradient conditions, while no translocations were observed under negative gradient conditions.
Article
Chemistry, Multidisciplinary
Viet Sang Doan, SungGyu Chun, Jie Feng, Sangwoo Shin
Summary: The research on nanoparticle transport in collagen hydrogels revealed a nonmonotonic behavior where maximum diffusiophoretic mobility is observed at intermediate confinement, contrary to common expectations. This behavior is attributed to the interplay between multiple size-dependent effects, highlighting the potential for enhanced nanoparticle transport in physiologically relevant conditions under tight confinement, particularly for drug delivery in compressed tissues.
Article
Biochemical Research Methods
Fabio Henrique Barros Barbosa, Reverson Fernandes Quero, Kionnys Novaes Rocha, Samuel Carvalho Costa, Dosil Pereira de Jesus
Summary: Electroosmotic flow (EOF) was measured in tridimensional (3D)-printed microchannels, and it was found that the material used for fabrication affects the EOF mobility. Addition of a cationic surfactant caused a reversal in the EOF direction.
Article
Nanoscience & Nanotechnology
Dongwoo Seo, Dongjun Kim, Sangjin Seo, Jungyul Park, Taesung Kim
Summary: We report a nanopore-integrated microfluidic platform to characterize ion transport in the presence of electrolyte and temperature gradients. Various nanopores with different pore sizes were produced using our previous self-assembled particle membrane (SAPM)-integrated microfluidic platform. Pore-size-dependent ionic transport was quantified by measuring the short circuit current (SCC) and open circuit voltage (OCV) across different nanopores by manipulating the electrolyte and temperature gradients. Three simple theoretical models heavily depending on pore size, electrolyte concentration, and temperature were established and validated with experimental results. The results of this study would help clarify ion transport phenomena at low-temperature conditions and enable practical applications of cryo-anesthesia in the near future.
ACS APPLIED MATERIALS & INTERFACES
(2023)
Review
Chemistry, Physical
Tatiana Nizkaya, Evgeny S. Asmolov, Olga Vinogradova
Summary: Self-propelling particles or microswimmers, as ideal model objects for experimental studies and applications, have attracted significant attention. This article summarizes recent advances in the theoretical description of the self-propulsion of catalytic microswimmers that non-uniformly release ions, focusing on nonlinear effects and geometric tuning.
CURRENT OPINION IN COLLOID & INTERFACE SCIENCE
(2022)
Article
Biochemical Research Methods
Ren H. Luo, Huan J. Keh
Article
Chemistry, Physical
Meng X. Li, Huan J. Keh
JOURNAL OF PHYSICAL CHEMISTRY B
(2020)
Article
Biochemical Research Methods
Yi C. Lai, Huan J. Keh
Summary: This study examines the startup of electrophoretic motion in a suspension of spherical colloidal particles with constant zeta potential or surface charge density. Explicit formulas for the transient electrophoretic velocity of the particles are obtained, showing that the transient electrophoretic mobility is influenced by various parameters such as particle density ratio, volume fraction, and the ratio of particle radius to Debye length.
Article
Mechanics
Chin Y. Chou, Huan J. Keh
Summary: This study presents a semi-analytical investigation of the steady flow around a rotating spherical particle in an incompressible Newtonian fluid inside an eccentric spherical cavity with slip surfaces at low Reynolds numbers. Accurate results of the torque exerted by the fluid on the particle are obtained based on various dimensionless parameters. The boundary effect of the cavity with a slip wall on the rotation of the slip particle is substantial and intriguing, showing different trends based on the values of the parameters involved.
EUROPEAN JOURNAL OF MECHANICS B-FLUIDS
(2021)
Article
Mechanics
Ming C. Lee, Huan J. Keh
Summary: The analytical study focuses on the steady rotational motion of a spherical particle with a slip surface in a quiescent unbounded fluid. It reveals that the hydrodynamic torque is influenced by the Reynolds number and slip coefficient, while the inertial effect on the hydrodynamic torque varies significantly at different Reynolds numbers.
EUROPEAN JOURNAL OF MECHANICS B-FLUIDS
(2021)
Article
Biochemical Research Methods
Ren H. Luo, Huan J. Keh
Summary: This study analyzes the electrophoresis and electric conduction of charged spherical particles in a salt-free solution using a unit cell model. The research provides explicit analytical formulas for the electrophoretic mobility of particles and effective electric conductivity of the suspension, showing significant and interesting effects of particle interaction on these transport properties. The findings show that the zeta potential, electrophoretic mobility, and effective electric conductivity increase with the surface charge density of the particles and generally decrease with the particle volume fraction, remaining consistent under certain parameters.
Article
Mechanics
Meng X. Li, Huan J. Keh
Summary: The study focuses on the start-up of slow rotation of a spherical particle in a concentric spherical cavity with slip surfaces in a viscous fluid due to the sudden application of a constant torque. An analytical formula for the dimensionless transient angular velocity of the particle is obtained, showing that the confining slip cavity has a significant impact on the starting rotation of the slip sphere.
FLUID DYNAMICS RESEARCH
(2021)
Article
Mechanics
Chin Y. Chou, Huan J. Keh
Summary: The study investigated the rotation of a spherical soft particle in a viscous fluid within a nonconcentric spherical cavity, finding that the effect of the cavity on the torque of the rotating soft particle is weaker compared to a hard particle. The normalized torque of a soft sphere generally increases with the particle-to-cavity radius ratio, but may exhibit a weak minimum under certain conditions.
EUROPEAN JOURNAL OF MECHANICS B-FLUIDS
(2022)
Article
Mechanics
Ming C. Lee, Huan J. Keh
Summary: The study analyzes the steady rotation of a slip spherical particle in a slip circular tube filled with an incompressible Newtonian fluid at low Reynolds numbers. By solving the Stokes equations, results of the resisting torque acting on the particle are obtained, with a focus on the effect of tube wall stickiness on the particle rotation.
FLUID DYNAMICS RESEARCH
(2021)
Article
Mechanics
Jun Q. Liao, Huan J. Keh
Summary: This study analyzes the flow of an incompressible Newtonian fluid around a rotating spherical particle in the presence of slip plane walls. The torque exerted on the particle is found to increase when the walls have higher stickiness, and this torque is influenced by the stickiness of the particle surface and the ratio of particle radius to distance from the walls.
FLUID DYNAMICS RESEARCH
(2022)
Article
Mechanics
Liang J. Jhuang, Huan J. Keh
Summary: A semi-analytical study is conducted on the movement of a soft spherical particle, with a hard core covered by a permeable porous layer, in an incompressible Newtonian fluid rotating around a long circular cylinder. The study provides accurate results of the hydrodynamic torque on the particle and reveals the significant boundary effect of the cylinder on the rotation of the soft particle.
EUROPEAN JOURNAL OF MECHANICS B-FLUIDS
(2022)
Article
Chemistry, Physical
Chia L. Chang, Huan J. Keh
Summary: In this study, the creeping flow of a viscous fluid around a rotating soft colloidal sphere between two planar walls is investigated. The fluid velocity outside the particle is described by the general solutions of the Stokes equation in cylindrical and spherical coordinates, while the fluid velocity inside the porous surface layer of the particle is expressed by the general solution of the Brinkman equation in spherical coordinates. The torque exerted on the particle by the fluid is calculated, taking into account various parameters such as the core-to-particle radii ratio, particle radius to flow penetration length ratio, and relative particle-to-wall spacings.
COLLOIDS AND INTERFACES
(2023)
Article
Mechanics
Jai Prakash, Huan J. Keh
Summary: This article discusses the steady translational motion of a slightly deformed spherical fluid drop suspended in an immiscible viscous fluid. The flow fields in both the interior and exterior of the drop are studied using the method of perturbed expansions under suitable boundary conditions. The effect of the deformation parameter on the hydrodynamic drag force exerted on the drop is observed, and explicit expressions for specific cases are obtained.
Article
Chemistry, Physical
Wei C. Lin, Huan J. Keh
Summary: In this study, a unit cell model was used to analyze electrophoresis and electric conduction in a concentrated suspension of charged soft particles in a salt-free medium. The results show that an increase in fixed charge density leads to higher electrophoretic mobility and effective electric conductivity, while an increase in core-to-particle radius ratio and particle volume fraction results in decreased electrophoretic mobility.
COLLOIDS AND INTERFACES
(2021)
Article
Chemistry, Physical
Wei Lun Chen, Huan Jang Keh
Summary: This paper presents an analytical study of electroosmosis and electric conduction in electrolyte solutions within a fibrous medium composed of parallel charge-regulating cylinders with arbitrary electric double layer thickness. A linearized charge regulation model and unit cell model were used to analyze the interactions among the cylinders, with explicit formulas obtained for the electroosmotic mobility and effective electric conductivity in the fiber matrix. The results show that the equilibrium constants of reactions at cylinder surfaces and bulk concentration of charge-determining ions significantly influence surface charge density, potential, electroosmotic mobility, and effective electric conductivity.
COLLOIDS AND INTERFACES
(2021)
