Special-shaped microscale structures have shed light on new possibilities in key fields of chemistry,medicine,and energy.Asymmetrical microrobots with sensitive magnetic responses can be useful tools in controlled che...Special-shaped microscale structures have shed light on new possibilities in key fields of chemistry,medicine,and energy.Asymmetrical microrobots with sensitive magnetic responses can be useful tools in controlled chemical reactions,drug delivery,and functional material synthesis.Microfluidic-based emulsion generation technology is adopted as a powerful platform for the fabrication of steerable microrobots with refined control.Specifically,Janus droplets are generated in microfluidic chips featuring a flow-focusing configuration.Asymmetrical morphologies of the Janus droplets are achieved by balancing the interfacial tensions,where the portion containing magnetic nanoparticles is solidified through the UV-initiated polymerization process right after the formation while the Janus structure is left intact.We succeed in controlling the morphology of the Janus droplet along with the moon-shaped robots hydrodynamically and applying them in flow control at the microscale under external magnetic fields,which are characterized and quantified by three-dimensional profile measurement and high-speed microparticle velocimetry measurement.Our proposed on-chip fabrication method using a microfluidic platform not only provides a method for fabricating magnetic robots but also enables tuning the complex morphologies and functionalities at the microscale,which could shed light on new possibilities in key fields of controlled chemistry reaction,medicine synthesis,and energy generation.展开更多
Numerical simulation of stratified flow of two fluids between two infinite parallel plates using the Moving Particle Semi-implicit(MPS)method is presented.The developing process from entrance to fully development flow...Numerical simulation of stratified flow of two fluids between two infinite parallel plates using the Moving Particle Semi-implicit(MPS)method is presented.The developing process from entrance to fully development flow is captured.In the simulation,the computational domain is represented by various types of particles.Governing equations are described based on particles and their interactions.Grids are not necessary in any calculation steps of the simulation.The particle number density is implicitly required to be constant to satisfy incompressibility.The weight function is used to describe the interaction between different particles.The particle is considered to constitute the free interface if the particle number density is below a set point.Results for various combinations of density,viscosity,mass flow rates,and distance between the two parallel plates are presented.The proposed procedure is validated using the derived exact solution and the earlier numerical results from the Level-Set method.Furthermore,the evolution of the interface in the developing region is captured and compares well with the derived exact solutions in the developed region.展开更多
基金National Natural Science Foundation of China,Grant/Award Number:52006005Academic Research Fund of Ministry of Education Singapore,Grant/Award Number:Projects MOE Tier 1,RG 98/18。
文摘Special-shaped microscale structures have shed light on new possibilities in key fields of chemistry,medicine,and energy.Asymmetrical microrobots with sensitive magnetic responses can be useful tools in controlled chemical reactions,drug delivery,and functional material synthesis.Microfluidic-based emulsion generation technology is adopted as a powerful platform for the fabrication of steerable microrobots with refined control.Specifically,Janus droplets are generated in microfluidic chips featuring a flow-focusing configuration.Asymmetrical morphologies of the Janus droplets are achieved by balancing the interfacial tensions,where the portion containing magnetic nanoparticles is solidified through the UV-initiated polymerization process right after the formation while the Janus structure is left intact.We succeed in controlling the morphology of the Janus droplet along with the moon-shaped robots hydrodynamically and applying them in flow control at the microscale under external magnetic fields,which are characterized and quantified by three-dimensional profile measurement and high-speed microparticle velocimetry measurement.Our proposed on-chip fabrication method using a microfluidic platform not only provides a method for fabricating magnetic robots but also enables tuning the complex morphologies and functionalities at the microscale,which could shed light on new possibilities in key fields of controlled chemistry reaction,medicine synthesis,and energy generation.
文摘Numerical simulation of stratified flow of two fluids between two infinite parallel plates using the Moving Particle Semi-implicit(MPS)method is presented.The developing process from entrance to fully development flow is captured.In the simulation,the computational domain is represented by various types of particles.Governing equations are described based on particles and their interactions.Grids are not necessary in any calculation steps of the simulation.The particle number density is implicitly required to be constant to satisfy incompressibility.The weight function is used to describe the interaction between different particles.The particle is considered to constitute the free interface if the particle number density is below a set point.Results for various combinations of density,viscosity,mass flow rates,and distance between the two parallel plates are presented.The proposed procedure is validated using the derived exact solution and the earlier numerical results from the Level-Set method.Furthermore,the evolution of the interface in the developing region is captured and compares well with the derived exact solutions in the developed region.
