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Microdroplet-Based Universal Logic Gates By Electrorheological Fluid, Mengying Zhang, Limu Wang, Xiang Wang, Jinbo Wu, Jiaxing Li, Xiuqing Gong, Jianhua Qin, Weihua Li, Weijia Wen
Microdroplet-Based Universal Logic Gates By Electrorheological Fluid, Mengying Zhang, Limu Wang, Xiang Wang, Jinbo Wu, Jiaxing Li, Xiuqing Gong, Jianhua Qin, Weihua Li, Weijia Wen
Professor Weihua Li
We demonstrate a uniquely designed microfluid logic gate with universal functionality, which is capable of conducting all 16 logic operations in one chip, with different input voltage combinations. A kind of smart colloid, giant electrorheological (GER) fluid, functions as the translation media among fluidic, electronic and mechanic information, providing us with the capability of performing large integrations either on-chip or off-chip, while the on-chip hybrid circuit is formed by the interconnection of the electric components and fluidic channels, where the individual microdroplets travelling in a channel represents a bit. The universal logic gate reveals the possibilities of achieving a large-scale …
The Effect Of Friction On Magnetorheological Fluids, W H. Li, X Z. Zhang
The Effect Of Friction On Magnetorheological Fluids, W H. Li, X Z. Zhang
Professor Weihua Li
This paper presents an experimental approach to study the effect of friction on magnerorheological (MR) fluids. Both steady and dynamic modes were employed to investigate MR fluid behaviors. The experimental results indicate that the total MR effects are dominated by two factors: magnetic force and friction force. Conventionally, the magnetic force contribution to MR effect has been intensively studied while the friction force effect has attracted less attention. This study provides a method to quantitatively predict the friction contribution to the total MR effect. It may be used to effectively analyze enhanced MR effects reported by other groups. Also, it …
Mre Properties Under Shear And Squeeze Modes And Applications, Kristin Popp, Matthias Kroger, Weihua Li, Xianzhou Zhang, Prabuono B. Kosasih
Mre Properties Under Shear And Squeeze Modes And Applications, Kristin Popp, Matthias Kroger, Weihua Li, Xianzhou Zhang, Prabuono B. Kosasih
Professor Weihua Li
Magnetorheological elastomers (MREs) are smart materials whose mechanical properties, like their modulus and elasticity, can be controlled by an external magnetic field. This feature has resulted in a number of novel applications, such as adaptive tuned dynamic vibration absorbers for suppressing unwanted vibrations over a wide frequency range. MRE-based devices operate in different modes, such as shear mode and squeeze mode; however, the study of mechanical performances of MREs under squeeze mode is very rare. This article aims to investigate MRE performances under both shear and squeeze modes. Experimental studies and simulations were conducted to analyze the MR effect in …
Design And Analysis Of General And Travelling Dielectrophoresis, T. Kinkeldei, W.H Li
Design And Analysis Of General And Travelling Dielectrophoresis, T. Kinkeldei, W.H Li
Professor Weihua Li
This paper presents the simulation of general and travelling dielectrophoretic forces, as well as the movement of the particles in a sandwich structure micro-device. The electrode geometry of the micro device used for simulation is an interdigitated bar electrode. The simulation method used to solve the equations is based on the least square finite difference method (LSFD). The simulation first calculates all forces acting at any place in the chamber, with these forces the trajectory of a particle can now be proposed. All of the particles parameters like radius, voltage, initial height, etc can easily be changed and the simulation …
Mr Damper In Reducing Pounding Effect Of Base-Isolated Rc Highway Bridge, M Neaz Sheikh, Jingya Xiong, Weihua Li
Mr Damper In Reducing Pounding Effect Of Base-Isolated Rc Highway Bridge, M Neaz Sheikh, Jingya Xiong, Weihua Li
Professor Weihua Li
Significant structural damage due to pounding between adjacent superstructures of multispan reinforced concrete (RC) highway bridges has been observed in past earthquakes. Different methods have been proposed in the literature to mitigate the adverse pounding effect. This paper presents an analytical investigation on the use of magnetorheological (MR) dampers in reducing the pounding effect of base-isolated multi-span RC highway bridges. It has been observed that MR damper can effectively reduce adverse pounding effect. Three control strategies (passive off, passive on, and bang bang control) of MR damper have been investigated. Although all the control strategies are found to be effective, …
The Effects Of Oil Concentration And Droplet Diameter In Oil-In-Water Emulsion On Strip Rolling, Prabuono B. Kosasih, A. K. Tieu, Weihua Li, Cheng Lu
The Effects Of Oil Concentration And Droplet Diameter In Oil-In-Water Emulsion On Strip Rolling, Prabuono B. Kosasih, A. K. Tieu, Weihua Li, Cheng Lu
Professor Weihua Li
A numerical scheme, which allows tracking of the concentration process within both the inlet and wok zones, has been developed. The scheme allowed us to calculate the rolling pressure and friction associated with the process for different emulsion’s oil concentrations, and oil droplets diameter, ds. Hence the intertwined effect of A,ds, ds and rolling speed on strip rolling parameters could be analyzed. The result shows that rapid concentration, which occurs in the inlet zone, increases the emulsion’s oil concentration sharply. This process effectively transforms the oil into the continuous phase of the emulsion. The analysis of the results also suggests …
Magnetorheological Properties Of Aqueous Ferrofluids, Yongbo Yang, Lin Li, Guang Chen, Weihua Li
Magnetorheological Properties Of Aqueous Ferrofluids, Yongbo Yang, Lin Li, Guang Chen, Weihua Li
Professor Weihua Li
The nanosized magnetite particles were synthesized by means of a coprecipitation method and used to prepare the aqueous ferrofluids with various volume fractions. The magnetorheological properties of the aqueous ferrofluids have been investigated as a function of magnetic field. Under steady-state shear, the apparent viscosity for all of the ferrofluids exhibited a shear thinning behavior. But the Bingham model was invalid since the ferrofluids did not show a yield stress before they began to flow. However, the shear stress increased linearly with shear rate after a critical shear rate, showing a Bingham-like behavior. A Bingham-like yield stress, which was obtained …
Simulation Of Travelling Wave Dielectrophoresis Using A Meshless Method, Dafeng Chen, Hejun Du, Weihua Li, Chang Shu
Simulation Of Travelling Wave Dielectrophoresis Using A Meshless Method, Dafeng Chen, Hejun Du, Weihua Li, Chang Shu
Professor Weihua Li
Manipulation and separation of micron-sized particles, particularly biological particles, using the dielectrophoretic effect is an emerging application in BioMEMS technology. This paper presents a numerical simulation for the four-phase traveling dielectrophoresis (DEP) using a novel meshless method - weighted least square finite difference (LSFD) scheme. The exact boundary condition and nonuniform point distribution were used in the calculation. Numerical results including the electrical potential, electrical field, traveling wave DEP forces and particle behavior are presented. Although the LSFD scheme was originally proposed in solving incompressible viscous flow, it is further demonstrated in this paper that the method is also well …
Variable Stiffness And Damping Mr Isolator, Xianzhou Zhang, Weihua Li, Xingyu Wang, Kosta Kostidis
Variable Stiffness And Damping Mr Isolator, Xianzhou Zhang, Weihua Li, Xingyu Wang, Kosta Kostidis
Professor Weihua Li
This paper presents the development of a magnetorheological (MR) fluid-based variable stiffness and damping isolator for vibration suppressions. The MR fluid isolator used a sole MR control unit to achieve the variable stiffness and damping in stepless and relative large scope. A mathematical model of the isolator was derived, and a prototype of the MR fluid isolator was fabricated and its dynamic behavior was measured in vibration under various applied magnetic fields. The parameters of the model under various magnetic fields were identified and the dynamic performances of isolator were evaluated.
A Simple And Cost-Effective Method For Fabrication Of Integrated Electronic-Microfluidic Devices Using A Laser-Patterned Pdms Layer, Ming Li, Shunbo Li, Jinbo Wu, Weijia Wen, Weihua Li, Gursel Alici
A Simple And Cost-Effective Method For Fabrication Of Integrated Electronic-Microfluidic Devices Using A Laser-Patterned Pdms Layer, Ming Li, Shunbo Li, Jinbo Wu, Weijia Wen, Weihua Li, Gursel Alici
Professor Weihua Li
We report a simple and cost-effective method for fabricating integrated electronic-microfluidic devices with multilayer configurations. A CO2 laser plotter was employed to directly write patterns on a transferred polydimethylsiloxane (PDMS) layer, which served as both a bonding and a working layer. The integration of electronics in microfluidic devices was achieved by an alignment bonding of top and bottom electrode-patterned substrates fabricated with conventional lithography, sputtering and lift-off techniques. Processes of the developed fabrication method were illustrated. Major issues associated with this method as PDMS surface treatment and characterization, thickness-control of the transferred PDMS layer, and laser parameters optimization were discussed, …
A 3-D Microelectrode System For Dielectrophoretic Manipulation Of Microparticles, Dafeng Chen, Hejun Du, Haiqing Gong, Weihua Li
A 3-D Microelectrode System For Dielectrophoretic Manipulation Of Microparticles, Dafeng Chen, Hejun Du, Haiqing Gong, Weihua Li
Professor Weihua Li
This paper presents a microfluidic system for manipulation and separation of micron-sized particles based on the combined use of negative dielectrophoresis (DEP) and hydrodynamic forces. A 3-D microelectrode structure (so called paired electrode array) are constructed face to face on the top and bottom sides of the microchannel and driven with highfrequency AC voltage to generate dielectrophoretic gates. Depending on the relative strengths of the two forces, particles such as polystyrene beads or cells carrying by a laminar flow can either penetrate the gate or settle there. This gives rise to certain applications including selectively concentrating particles from the flow, …
Microdroplet-Based Universal Logic Gates By Electrorheological Fluid, Mengying Zhang, Limu Wang, Xiang Wang, Jinbo Wu, Jiaxing Li, Xiuqing Gong, Jianhua Qin, Weihua Li, Weijia Wen
Microdroplet-Based Universal Logic Gates By Electrorheological Fluid, Mengying Zhang, Limu Wang, Xiang Wang, Jinbo Wu, Jiaxing Li, Xiuqing Gong, Jianhua Qin, Weihua Li, Weijia Wen
Professor Weihua Li
We demonstrate a uniquely designed microfluid logic gate with universal functionality, which is capable of conducting all 16 logic operations in one chip, with different input voltage combinations. A kind of smart colloid, giant electrorheological (GER) fluid, functions as the translation media among fluidic, electronic and mechanic information, providing us with the capability of performing large integrations either on-chip or off-chip, while the on-chip hybrid circuit is formed by the interconnection of the electric components and fluidic channels, where the individual microdroplets travelling in a channel represents a bit. The universal logic gate reveals the possibilities of achieving a large-scale …
Mre Properties Under Shear And Squeeze Modes And Applications, Kristin Popp, Matthias Kroger, Weihua Li, Xianzhou Zhang, Prabuono B. Kosasih
Mre Properties Under Shear And Squeeze Modes And Applications, Kristin Popp, Matthias Kroger, Weihua Li, Xianzhou Zhang, Prabuono B. Kosasih
Professor Weihua Li
Magnetorheological elastomers (MREs) are smart materials whose mechanical properties, like their modulus and elasticity, can be controlled by an external magnetic field. This feature has resulted in a number of novel applications, such as adaptive tuned dynamic vibration absorbers for suppressing unwanted vibrations over a wide frequency range. MRE-based devices operate in different modes, such as shear mode and squeeze mode; however, the study of mechanical performances of MREs under squeeze mode is very rare. This article aims to investigate MRE performances under both shear and squeeze modes. Experimental studies and simulations were conducted to analyze the MR effect in …
Development Of A Force Sensor Working With Mr Elastomers, Weihua Li, Kosta Kostidis, Xianzhou Zhang, Yang Zhou
Development Of A Force Sensor Working With Mr Elastomers, Weihua Li, Kosta Kostidis, Xianzhou Zhang, Yang Zhou
Professor Weihua Li
This paper presents the development of a new force sensor with MR elastomer as a sensing element. One key element in this study was to find a suitable material with high sensing capabilities which can be used for developing a sensor. Thus different MR elastomers, with ingredients of carbonyl iron particle, graphite, silicone oil and silicone rubber, were manufactured and measured with a modified rheometer. The effects of additives on the sensing capabilities were systematically investigated and an optimal MR elastomer sample was selected for design and manufacturing of a force sensor prototype. The development sensor prototype consists of three …
Design And Analysis Of General And Travelling Dielectrophoresis, T. Kinkeldei, W.H Li
Design And Analysis Of General And Travelling Dielectrophoresis, T. Kinkeldei, W.H Li
Professor Weihua Li
This paper presents the simulation of general and travelling dielectrophoretic forces, as well as the movement of the particles in a sandwich structure micro-device. The electrode geometry of the micro device used for simulation is an interdigitated bar electrode. The simulation method used to solve the equations is based on the least square finite difference method (LSFD). The simulation first calculates all forces acting at any place in the chamber, with these forces the trajectory of a particle can now be proposed. All of the particles parameters like radius, voltage, initial height, etc can easily be changed and the simulation …
Analysis Of Jet Characteristics And Structural Optimization Of A Liquamatic Fire Water Monitor With Self-Swinging Mechanism, Guoliang Hu, Ming Long, Juxing Liang, Weihua Li
Analysis Of Jet Characteristics And Structural Optimization Of A Liquamatic Fire Water Monitor With Self-Swinging Mechanism, Guoliang Hu, Ming Long, Juxing Liang, Weihua Li
Professor Weihua Li
This paper presents analysis and optimization of a liquamatic fire water monitor with a novel self-swinging mechanism. The design of the self-swinging mechanism has adopted a four-bar linkage driven by an impeller. The Fluent software was used to simulate the internal flow performance of the fire water monitor. In particular, the effects of the cross-sectional shape, diameters of the monitor body, inlet water pressure, and drive set of the self-swinging mechanism on the jet characteristics were analyzed. These analyses have led to optimal structural parameters of the flow channel. A prototype of the fire ware monitor was manufactured, and the …
Characterization Of Conducting-Polymer-Based Bimorph Vibration Sensors, Weihua Li, Geoffrey M. Spinks, Lianbin Zhao, Yanzhe Wu, Dezhi Zhou, G G. Wallace
Characterization Of Conducting-Polymer-Based Bimorph Vibration Sensors, Weihua Li, Geoffrey M. Spinks, Lianbin Zhao, Yanzhe Wu, Dezhi Zhou, G G. Wallace
Professor Weihua Li
This paper presents theoretical and experimental investigation of mechanical-electrical properties of conducting polymers based bimorph sensors. A material parameter, hCP , is proposed to represent linear relationship between induction charge and the applied external deformation. Based on this assumption, a constitutive equation for bimorph sensors under steady-state external loadings are constructed and then solved. Mechanical-electrical properties of bimorph sensors are experimentally studied using both vibration-amplitude sweep mode and frequency sweep mode. The material parameter hCP , is identified by comparing theoretical analysis and experimental results. The applications of conducting polymers based bimorph sensors in smart structures are also discussed.
A Variable Stiffness Mr Damper For Vibration Suppression, Xianzhou Zhang, Weihua Li, Yang Zhou
A Variable Stiffness Mr Damper For Vibration Suppression, Xianzhou Zhang, Weihua Li, Yang Zhou
Professor Weihua Li
This paper presents the development of a magnetorheological (MR) fluid-based variable stiffness damper and analysis its applications in vibration suppression. The MR fluid isolator used a MR valve control unit and bladders to achieve the variable stiffness and damping in stepless and relative large scope. A mathematical model of the isolator was derived, a prototype of the MR fluid isolator was fabricated and its dynamic behavior was measured in vibration under various applied magnetic fields. The effective stiffness and damping coefficients of the isolator under various magnetic fields were identified and the dynamic performances of isolator were evaluated with simulation. …
Mr Damper In Reducing Pounding Effect Of Base-Isolated Rc Highway Bridge, M Neaz Sheikh, Jingya Xiong, Weihua Li
Mr Damper In Reducing Pounding Effect Of Base-Isolated Rc Highway Bridge, M Neaz Sheikh, Jingya Xiong, Weihua Li
Professor Weihua Li
Significant structural damage due to pounding between adjacent superstructures of multispan reinforced concrete (RC) highway bridges has been observed in past earthquakes. Different methods have been proposed in the literature to mitigate the adverse pounding effect. This paper presents an analytical investigation on the use of magnetorheological (MR) dampers in reducing the pounding effect of base-isolated multi-span RC highway bridges. It has been observed that MR damper can effectively reduce adverse pounding effect. Three control strategies (passive off, passive on, and bang bang control) of MR damper have been investigated. Although all the control strategies are found to be effective, …
The Effects Of Oil Concentration And Droplet Diameter In Oil-In-Water Emulsion On Strip Rolling, Prabuono B. Kosasih, A. K. Tieu, Weihua Li, Cheng Lu
The Effects Of Oil Concentration And Droplet Diameter In Oil-In-Water Emulsion On Strip Rolling, Prabuono B. Kosasih, A. K. Tieu, Weihua Li, Cheng Lu
Professor Weihua Li
A numerical scheme, which allows tracking of the concentration process within both the inlet and wok zones, has been developed. The scheme allowed us to calculate the rolling pressure and friction associated with the process for different emulsion’s oil concentrations, and oil droplets diameter, ds. Hence the intertwined effect of A,ds, ds and rolling speed on strip rolling parameters could be analyzed. The result shows that rapid concentration, which occurs in the inlet zone, increases the emulsion’s oil concentration sharply. This process effectively transforms the oil into the continuous phase of the emulsion. The analysis of the results also suggests …
Reduction Of Seismic Pounding Effects Of Base-Isolated Rc Highway Bridges Using Mr Damper, M N. Sheikh, J Xiong, W H. Li
Reduction Of Seismic Pounding Effects Of Base-Isolated Rc Highway Bridges Using Mr Damper, M N. Sheikh, J Xiong, W H. Li
Professor Weihua Li
Significant structural damages due to pounding between adjacent superstructures of multispan reinforced concrete (RC) highway bridges have been observed in past eanhquakes. Different methods have been proposed in the literature to mitigate the adverse seismic pounding effects. This paper presents an analytical investigation on the use of magnetorheological (MR) dampers in reducing seismic pounding elIects of base-isolated multi-span RC highway bridges. It has been observed that MR damper can elIectively reduce tbe seismic pounding elIect. Three control strategies (passive off, passive on, and bang bang control) of MR damper have been investigated. Although all the conlrol strategies are found to …
Damping Of Magnetorheological Elastomers, Lin Chen, Xinglong Gong, Weihua Li
Damping Of Magnetorheological Elastomers, Lin Chen, Xinglong Gong, Weihua Li
Professor Weihua Li
The damping property of magnetorheological (MR) elastomers is characterized by a modi¯ed dynamic mechanical-magnetic coupled analyzer. The in°uences of the external magnetic °ux density, damping of the matrix, content of iron particles, dynamic strain, and driving frequency on the damping properties of MR elastomers were investigated experimentally. The experimental results indicate that the damping properties of MR elastomers greatly depend on the interfacial slipping between the inner particles and the matrix. Di®erent from general composite materials, the interfacial slipping in MR elastomers is a®ected by the external applied magnetic field.
Magnetorheological Properties Of Aqueous Ferrofluids, Yongbo Yang, Lin Li, Guang Chen, Weihua Li
Magnetorheological Properties Of Aqueous Ferrofluids, Yongbo Yang, Lin Li, Guang Chen, Weihua Li
Professor Weihua Li
The nanosized magnetite particles were synthesized by means of a coprecipitation method and used to prepare the aqueous ferrofluids with various volume fractions. The magnetorheological properties of the aqueous ferrofluids have been investigated as a function of magnetic field. Under steady-state shear, the apparent viscosity for all of the ferrofluids exhibited a shear thinning behavior. But the Bingham model was invalid since the ferrofluids did not show a yield stress before they began to flow. However, the shear stress increased linearly with shear rate after a critical shear rate, showing a Bingham-like behavior. A Bingham-like yield stress, which was obtained …
Simulation Of Travelling Wave Dielectrophoresis Using A Meshless Method, Dafeng Chen, Hejun Du, Weihua Li, Chang Shu
Simulation Of Travelling Wave Dielectrophoresis Using A Meshless Method, Dafeng Chen, Hejun Du, Weihua Li, Chang Shu
Professor Weihua Li
Manipulation and separation of micron-sized particles, particularly biological particles, using the dielectrophoretic effect is an emerging application in BioMEMS technology. This paper presents a numerical simulation for the four-phase traveling dielectrophoresis (DEP) using a novel meshless method - weighted least square finite difference (LSFD) scheme. The exact boundary condition and nonuniform point distribution were used in the calculation. Numerical results including the electrical potential, electrical field, traveling wave DEP forces and particle behavior are presented. Although the LSFD scheme was originally proposed in solving incompressible viscous flow, it is further demonstrated in this paper that the method is also well …
Variable Stiffness And Damping Mr Isolator, Xianzhou Zhang, Weihua Li, Xingyu Wang, Kosta Kostidis
Variable Stiffness And Damping Mr Isolator, Xianzhou Zhang, Weihua Li, Xingyu Wang, Kosta Kostidis
Professor Weihua Li
This paper presents the development of a magnetorheological (MR) fluid-based variable stiffness and damping isolator for vibration suppressions. The MR fluid isolator used a sole MR control unit to achieve the variable stiffness and damping in stepless and relative large scope. A mathematical model of the isolator was derived, and a prototype of the MR fluid isolator was fabricated and its dynamic behavior was measured in vibration under various applied magnetic fields. The parameters of the model under various magnetic fields were identified and the dynamic performances of isolator were evaluated.
A Simple And Cost-Effective Method For Fabrication Of Integrated Electronic-Microfluidic Devices Using A Laser-Patterned Pdms Layer, Ming Li, Shunbo Li, Jinbo Wu, Weijia Wen, Weihua Li, Gursel Alici
A Simple And Cost-Effective Method For Fabrication Of Integrated Electronic-Microfluidic Devices Using A Laser-Patterned Pdms Layer, Ming Li, Shunbo Li, Jinbo Wu, Weijia Wen, Weihua Li, Gursel Alici
Professor Weihua Li
We report a simple and cost-effective method for fabricating integrated electronic-microfluidic devices with multilayer configurations. A CO2 laser plotter was employed to directly write patterns on a transferred polydimethylsiloxane (PDMS) layer, which served as both a bonding and a working layer. The integration of electronics in microfluidic devices was achieved by an alignment bonding of top and bottom electrode-patterned substrates fabricated with conventional lithography, sputtering and lift-off techniques. Processes of the developed fabrication method were illustrated. Major issues associated with this method as PDMS surface treatment and characterization, thickness-control of the transferred PDMS layer, and laser parameters optimization were discussed, …
Performance Comparison Between An Mrf Damper And An Mre Isolator Incorporated With A Building Structure, Yang Zhou, Weihua Li, Muhammad N. S Hadi
Performance Comparison Between An Mrf Damper And An Mre Isolator Incorporated With A Building Structure, Yang Zhou, Weihua Li, Muhammad N. S Hadi
Professor Weihua Li
As an important member of smart materials, magnetorheological elastomers (MREs) exhibit characteristics that their modulus can be controlled by an external magnetic field. Based on these experimental results, a viscoelastic solid model with four parameters was proposed to predict the performance of MRE. A building model, three stories high, was constructed using MATLAB SIMULINK to evaluate the performance of an MRE device in structural control. In addition, the performance of an MRF damper and an MRE device in structural control, where the resultant peak force was selected as a criterion in the evaluation process, was compared and discussed. Two controllers, …
A 3-D Microelectrode System For Dielectrophoretic Manipulation Of Microparticles, Dafeng Chen, Hejun Du, Haiqing Gong, Weihua Li
A 3-D Microelectrode System For Dielectrophoretic Manipulation Of Microparticles, Dafeng Chen, Hejun Du, Haiqing Gong, Weihua Li
Professor Weihua Li
This paper presents a microfluidic system for manipulation and separation of micron-sized particles based on the combined use of negative dielectrophoresis (DEP) and hydrodynamic forces. A 3-D microelectrode structure (so called paired electrode array) are constructed face to face on the top and bottom sides of the microchannel and driven with highfrequency AC voltage to generate dielectrophoretic gates. Depending on the relative strengths of the two forces, particles such as polystyrene beads or cells carrying by a laminar flow can either penetrate the gate or settle there. This gives rise to certain applications including selectively concentrating particles from the flow, …