Contactless acoustic manipulation of micro/nanoscale particles has attracted considerable attention owing to its near independence of the physical and chemical properties of the targets,making it universally applicabl...Contactless acoustic manipulation of micro/nanoscale particles has attracted considerable attention owing to its near independence of the physical and chemical properties of the targets,making it universally applicable to almost all biological systems.Thin-film bulk acoustic wave(BAW)resonators operating at gigahertz(GHz)frequencies have been demonstrated to generate localized high-speed microvortices through acoustic streaming effects.Benefitting from the strong drag forces of the high-speed vortices,BAW-enabled GHz acoustic streaming tweezers(AST)have been applied to the trapping and enrichment of particles ranging in size from micrometers to less than 100 nm.However,the behavior of particles in such 3D microvortex systems is still largely unknown.In this work,the particle behavior(trapping,enrichment,and separation)in GHz AST is studied by theoretical analyses,3D simulations,and microparticle tracking experiments.It is found that the particle motion in the vortices is determined mainly by the balance between the acoustic streaming drag force and the acoustic radiation force.This work can provide basic design principles for AST-based lab-on-a-chip systems for a variety of applications.展开更多
This study experimentally investigated two-phase acoustic streaming and droplet properties of aerosols, which were generated by a dental ultrasonic scaler. The velocity field of acoustic streaming was measured using p...This study experimentally investigated two-phase acoustic streaming and droplet properties of aerosols, which were generated by a dental ultrasonic scaler. The velocity field of acoustic streaming was measured using particle image velocimetry with the generated liquid droplets as tracers, and the shadowgraph technique was adopted to measure the droplet diameter. In the PIV measurement of the gas-liquid two-phase flow, the injection of oil smoke substantially suppressed the number of invalid vectors. The acoustic streaming of the ultrasonic scaler showed maximum velocity at a region away from the scaler tip, and the maximum velocity increased with an increase in the liquid flow rate. The droplets of the ultrasonic scaler were generated by capillary waves and had a diameter on the order of tens of micrometers. These droplets effectively enhanced the velocity of the acoustic streaming in the two-phase case compared to the single-phase case without the droplets.展开更多
The blood–brain barrier(BBB)is a structural and functional barrier necessary for brain homeostasis,and it plays an important role in the realization of neural function and in protecting the brain from damage by circu...The blood–brain barrier(BBB)is a structural and functional barrier necessary for brain homeostasis,and it plays an important role in the realization of neural function and in protecting the brain from damage by circulating toxins and pathogens.However,the extremely dense BBB also severely limits the transport of molecules across it,which is a great hindrance to the diagnosis and treatment of central nervous system(CNS)diseases.This paper reports a new method for controllable opening of the BBB,based on the gigahertz acoustic streaming(AS)generated by a bulk acoustic wave resonant device.By adjusting the input power and working distance of the device,AS with tunable flow rate can be generated to disrupt tight junction proteins(TJs)between endothelial cells.The results obtained with this method show that the gigahertz AS promotes the penetration of dextran molecules with different molecular weights across the BBB.This work provides a new platform for studying the mechanical regulation of BBB by fluid shear forces and a new method for improving the efficiency of drug delivery.展开更多
In recent decades,the importance of surface acoustic waves,as a biocompatible tool to integrate with microfluidics,has been proven in various medical and biological applications.The numerical modeling of acoustic stre...In recent decades,the importance of surface acoustic waves,as a biocompatible tool to integrate with microfluidics,has been proven in various medical and biological applications.The numerical modeling of acoustic streaming caused by surface acoustic waves in microchannels requires the effect of viscosity to be considered in the equations which complicates the solution.In this paper,it is shown that the major contribution of viscosity and the horizontal component of actuation is concentrated in a narrow region alongside the actuation boundary.Since the inviscid equations are considerably easier to solve,a division into the viscous and inviscid domains would alleviate the computational load significantly.The particles'traces calculated by this approximation are excellently alongside their counterparts from the completely viscous model.It is also shown that the optimum thickness for the viscous strip is about 9-fold the acoustic boundary layer thickness for various flow patterns and amplitudes of actuation.展开更多
The speed of the streaming flow in the liquid layer loaded on a thin plate, in which Lamb waves are propagating, was calculated. The results are good agreement with Moroney’s
Rotational manipulation of massive particles and biolo gical samples is essential for the development of miniaturized lab-on-a-chip platforms in the fields of chemical,medical,and biological applications.In this paper...Rotational manipulation of massive particles and biolo gical samples is essential for the development of miniaturized lab-on-a-chip platforms in the fields of chemical,medical,and biological applications.In this paper,a device concept of a two-dimensional acoustofluidic chamber actuated by multiple nonlinear vibration sources is proposed.The functional chamber enables the generation of acoustic streaming vortices for potential applications that include strong mixing of multiphase flows and rotational manipulation of micro-/nano-scale objects without any rotating component.Using numerical simulations,we find that diversified acoustofluidic fields can be generated in the chamber under various actuations,and massive polystyrene beads inside can experience different acoustophoretic motions under the combined effect of an acoustic radiation force and acoustic streaming.Moreover,we investigate and clarify the effects of structural design on modulation of the acoustofluidic fields in the chamber.We believe the presented study could not only provide a promising potential tool for rotational acoustofluidic manipulation,but could also bring this community some useful design insights into the achievement of desired acoustofluidic fields for assorted microfluidic applications.展开更多
Nano manipulation technology has great potential applications in the assembly,measurement and fabrication of nano materials,actuating and high-sensitivity sensing of biological samples,manufacture of nano sensors,deco...Nano manipulation technology has great potential applications in the assembly,measurement and fabrication of nano materials,actuating and high-sensitivity sensing of biological samples,manufacture of nano sensors,decontamination of air and water,etc. As an actuating technology which is far from being mature,the nano manipulation still faces lots of challenges in the device principles,design,scaling up,sample safety,etc.The ultrasonic nano manipulation, in which nanoscale objects are handled and actuated by controlled ultrasound,is an emerging technology to meet some of challenges in nano manipulations. The author's research team and other groups have proposed and realized a series of nano manipulation functions such as trapping,transfer, rotation and concentration since 2012, by controlled ultrasound. Compared with other nano manipulating techniques,the ultrasonic method has the merits such as very low temperature rise at the manipulation area,little selectivity to the material properties of manipulated samples,capability of being implemented on the substrates without MENS or NEMS structure,etc. This paper reviews the progresses in principles,functions,structures and characteristics of the ultrasonic devices for nano manipulations.展开更多
The standing-wave thermoacoustic engines(TAE)are applied in practice to convert thermal power into acoustic one to generate electricity or to drive cooling devices.Although there is a number of existing numerical rese...The standing-wave thermoacoustic engines(TAE)are applied in practice to convert thermal power into acoustic one to generate electricity or to drive cooling devices.Although there is a number of existing numerical researches that provides a design tool for predicting standing-wave TAE performances,few existing works that compare TAE driven by cryogenic liquids and waste heat,and optimize its performance by varying the stack plate spacing.This present work is primarily concerned with the numerical investigation of the performance of TAEs driven by cryogenic liquids and waste heat.For this,three-dimensional(3-D)standing-wave TAE models are developed.Mesh-and time-independence studies are conducted first.Model validations are then performed by comparing with the numerical results available in the literature.The validated model is then applied to simulate the standing-wave TAEs driven by the cryogenic liquids and the waste heat,as the temperature gradientΔT is varied.It is found that limit cycle oscillations in both systems are successfully generated and the oscillations amplitude is increased with increasedΔT.Nonlinearity is identified with acoustic streaming and the flow reversal occurring through the stack.Comparison studied are then conducted between the cryogenic liquid-driven TAE and that driven by waste heat in the presence of the same temperature gradientΔT.It is shown that the limit cycle frequency of the cryogenic liquid system is 4.72%smaller and the critical temperatureΔT_(cri)=131 K is lower than that of the waste heat system(ΔT_(cri)=187 K).Furthermore,the acoustic power is increased by 31%and the energy conversion efficiency is found to increase by 0.42%.Finally,optimization studies on the stack plate spacing are conducted in TAE system driven by cryogenic liquids.It is found that the limit cycle oscillation frequency is increased with the decreased ratio between the stack plate spacing and the heat penetration depth.When the ratio is set to between 2 and 3,the overall performance of the cryogenic liquid-driven TAE has been greatly improved.In summary,the present model can be used as a design tool to evaluate standing-wave TAE performances with detailed thermodynamics and acoustics characteristics.The present findings provide useful guidance for the design and optimization of high-efficiency standing-wave TAE for recovering low-temperature fluids or heat sources.展开更多
We propose a novel on-chip 3D cell rotation method based on a vibration-induced flow.When circular vibration is applied to a microchip with micropillar patterns,a highly localized whirling flow is induced around the m...We propose a novel on-chip 3D cell rotation method based on a vibration-induced flow.When circular vibration is applied to a microchip with micropillar patterns,a highly localized whirling flow is induced around the micropillars.The direction and velocity of this flow can be controlled by changing the direction and amplitude of the applied vibration.Furthermore,this flow can be induced on an open chip structure.In this study,we adopted a microchip with three micropillars arranged in a triangular configuration and an xyz piezoelectric actuator to apply the circular vibration.At the centre of the micropillars,the interference of the vibration-induced flows originating from the individual micropillars induces rotational flow.Consequently,a biological cell placed at this centre rotates under the influence of the flow.Under three-plane circular vibrations in the xy,xz or yz plane,the cell can rotate in both the focal and vertical planes of the microscope.Applying this 3D cell rotation method,we measured the rotational speeds of mouse oocytes in the focal and vertical planes as 63.7±4.0°s^(−1) and 3.5±2.1°s^(−1),respectively.Furthermore,we demonstrated the transportation and rotation of the mouse oocytes and re-positioned their nuclei into a position observable by microscope.展开更多
The pulsed power ultrasonic-assisted gas metal arc welding(PU-GMAW)is a new development hybrid welding method.The influences of the pulsed power ultrasonic on the microstructure evolution of the welded joint of Al-Cu ...The pulsed power ultrasonic-assisted gas metal arc welding(PU-GMAW)is a new development hybrid welding method.The influences of the pulsed power ultrasonic on the microstructure evolution of the welded joint of Al-Cu alloy were investigated by using scanning electron microscopy,transmission electron microscope and electron back scattering diffraction.The results showed that the efficient heat input in the PU-GMAW was increased by above 100%compared with the traditional GMAW.The grain and eutectic of the PU-GMAW weld seam were refined compared with that of the GMAW.Cavitation and acoustic streaming induced the dendrite fragmentation(α-Al)and heterogeneous nucleation,which were the main reasons for the grain refinement.The microhardness of the PU-GMAW welded joint was improved compared with that of the GMAW owing to the change of the eutectic and grain.展开更多
基金The authors gratefully acknowledge financial support from the National Key R&D Program of China(2018YFE0118700)the Natural Science Foundation of China(NSFC No.62174119)+1 种基金Tianjin Applied Basic Research and Advanced Technology(17JCJQJC43600)the 111 Project(B07014).
文摘Contactless acoustic manipulation of micro/nanoscale particles has attracted considerable attention owing to its near independence of the physical and chemical properties of the targets,making it universally applicable to almost all biological systems.Thin-film bulk acoustic wave(BAW)resonators operating at gigahertz(GHz)frequencies have been demonstrated to generate localized high-speed microvortices through acoustic streaming effects.Benefitting from the strong drag forces of the high-speed vortices,BAW-enabled GHz acoustic streaming tweezers(AST)have been applied to the trapping and enrichment of particles ranging in size from micrometers to less than 100 nm.However,the behavior of particles in such 3D microvortex systems is still largely unknown.In this work,the particle behavior(trapping,enrichment,and separation)in GHz AST is studied by theoretical analyses,3D simulations,and microparticle tracking experiments.It is found that the particle motion in the vortices is determined mainly by the balance between the acoustic streaming drag force and the acoustic radiation force.This work can provide basic design principles for AST-based lab-on-a-chip systems for a variety of applications.
文摘This study experimentally investigated two-phase acoustic streaming and droplet properties of aerosols, which were generated by a dental ultrasonic scaler. The velocity field of acoustic streaming was measured using particle image velocimetry with the generated liquid droplets as tracers, and the shadowgraph technique was adopted to measure the droplet diameter. In the PIV measurement of the gas-liquid two-phase flow, the injection of oil smoke substantially suppressed the number of invalid vectors. The acoustic streaming of the ultrasonic scaler showed maximum velocity at a region away from the scaler tip, and the maximum velocity increased with an increase in the liquid flow rate. The droplets of the ultrasonic scaler were generated by capillary waves and had a diameter on the order of tens of micrometers. These droplets effectively enhanced the velocity of the acoustic streaming in the two-phase case compared to the single-phase case without the droplets.
基金financial support from the National Natural Science Foundation of China(Grant No.61971302)。
文摘The blood–brain barrier(BBB)is a structural and functional barrier necessary for brain homeostasis,and it plays an important role in the realization of neural function and in protecting the brain from damage by circulating toxins and pathogens.However,the extremely dense BBB also severely limits the transport of molecules across it,which is a great hindrance to the diagnosis and treatment of central nervous system(CNS)diseases.This paper reports a new method for controllable opening of the BBB,based on the gigahertz acoustic streaming(AS)generated by a bulk acoustic wave resonant device.By adjusting the input power and working distance of the device,AS with tunable flow rate can be generated to disrupt tight junction proteins(TJs)between endothelial cells.The results obtained with this method show that the gigahertz AS promotes the penetration of dextran molecules with different molecular weights across the BBB.This work provides a new platform for studying the mechanical regulation of BBB by fluid shear forces and a new method for improving the efficiency of drug delivery.
文摘In recent decades,the importance of surface acoustic waves,as a biocompatible tool to integrate with microfluidics,has been proven in various medical and biological applications.The numerical modeling of acoustic streaming caused by surface acoustic waves in microchannels requires the effect of viscosity to be considered in the equations which complicates the solution.In this paper,it is shown that the major contribution of viscosity and the horizontal component of actuation is concentrated in a narrow region alongside the actuation boundary.Since the inviscid equations are considerably easier to solve,a division into the viscous and inviscid domains would alleviate the computational load significantly.The particles'traces calculated by this approximation are excellently alongside their counterparts from the completely viscous model.It is also shown that the optimum thickness for the viscous strip is about 9-fold the acoustic boundary layer thickness for various flow patterns and amplitudes of actuation.
文摘The speed of the streaming flow in the liquid layer loaded on a thin plate, in which Lamb waves are propagating, was calculated. The results are good agreement with Moroney’s
基金Project supported by the National Natural Science Foundation of China(Grant No.11904117)the IndustryUniversity-Research Collaboration Project of Jiangsu Province,China(Grant No.BY2019058)+1 种基金the Scientific Research Foundation of Huaiyin Institute of Technology(Grant No.Z301B19529)the Training Foundation of Postgraduate Supervisor(Grant No.Z206E20555)。
文摘Rotational manipulation of massive particles and biolo gical samples is essential for the development of miniaturized lab-on-a-chip platforms in the fields of chemical,medical,and biological applications.In this paper,a device concept of a two-dimensional acoustofluidic chamber actuated by multiple nonlinear vibration sources is proposed.The functional chamber enables the generation of acoustic streaming vortices for potential applications that include strong mixing of multiphase flows and rotational manipulation of micro-/nano-scale objects without any rotating component.Using numerical simulations,we find that diversified acoustofluidic fields can be generated in the chamber under various actuations,and massive polystyrene beads inside can experience different acoustophoretic motions under the combined effect of an acoustic radiation force and acoustic streaming.Moreover,we investigate and clarify the effects of structural design on modulation of the acoustofluidic fields in the chamber.We believe the presented study could not only provide a promising potential tool for rotational acoustofluidic manipulation,but could also bring this community some useful design insights into the achievement of desired acoustofluidic fields for assorted microfluidic applications.
基金Sponsored by the State Key Lab of Mechanics and Control of Mechanical Structures(Grant No.MCMS-0314G01)and PAPD
文摘Nano manipulation technology has great potential applications in the assembly,measurement and fabrication of nano materials,actuating and high-sensitivity sensing of biological samples,manufacture of nano sensors,decontamination of air and water,etc. As an actuating technology which is far from being mature,the nano manipulation still faces lots of challenges in the device principles,design,scaling up,sample safety,etc.The ultrasonic nano manipulation, in which nanoscale objects are handled and actuated by controlled ultrasound,is an emerging technology to meet some of challenges in nano manipulations. The author's research team and other groups have proposed and realized a series of nano manipulation functions such as trapping,transfer, rotation and concentration since 2012, by controlled ultrasound. Compared with other nano manipulating techniques,the ultrasonic method has the merits such as very low temperature rise at the manipulation area,little selectivity to the material properties of manipulated samples,capability of being implemented on the substrates without MENS or NEMS structure,etc. This paper reviews the progresses in principles,functions,structures and characteristics of the ultrasonic devices for nano manipulations.
基金the financial support (452DISDZ) from University of Canterbury, New ZealandUniversity of Canterbury for providing PhD scholarship。
文摘The standing-wave thermoacoustic engines(TAE)are applied in practice to convert thermal power into acoustic one to generate electricity or to drive cooling devices.Although there is a number of existing numerical researches that provides a design tool for predicting standing-wave TAE performances,few existing works that compare TAE driven by cryogenic liquids and waste heat,and optimize its performance by varying the stack plate spacing.This present work is primarily concerned with the numerical investigation of the performance of TAEs driven by cryogenic liquids and waste heat.For this,three-dimensional(3-D)standing-wave TAE models are developed.Mesh-and time-independence studies are conducted first.Model validations are then performed by comparing with the numerical results available in the literature.The validated model is then applied to simulate the standing-wave TAEs driven by the cryogenic liquids and the waste heat,as the temperature gradientΔT is varied.It is found that limit cycle oscillations in both systems are successfully generated and the oscillations amplitude is increased with increasedΔT.Nonlinearity is identified with acoustic streaming and the flow reversal occurring through the stack.Comparison studied are then conducted between the cryogenic liquid-driven TAE and that driven by waste heat in the presence of the same temperature gradientΔT.It is shown that the limit cycle frequency of the cryogenic liquid system is 4.72%smaller and the critical temperatureΔT_(cri)=131 K is lower than that of the waste heat system(ΔT_(cri)=187 K).Furthermore,the acoustic power is increased by 31%and the energy conversion efficiency is found to increase by 0.42%.Finally,optimization studies on the stack plate spacing are conducted in TAE system driven by cryogenic liquids.It is found that the limit cycle oscillation frequency is increased with the decreased ratio between the stack plate spacing and the heat penetration depth.When the ratio is set to between 2 and 3,the overall performance of the cryogenic liquid-driven TAE has been greatly improved.In summary,the present model can be used as a design tool to evaluate standing-wave TAE performances with detailed thermodynamics and acoustics characteristics.The present findings provide useful guidance for the design and optimization of high-efficiency standing-wave TAE for recovering low-temperature fluids or heat sources.
基金This study was financially supported by Grant-in-Aid for JSPS Fellows Number 13J03580Grant-in-Aid for Scientific Research on Innovative Areas(No.23106002)(No.26630094).
文摘We propose a novel on-chip 3D cell rotation method based on a vibration-induced flow.When circular vibration is applied to a microchip with micropillar patterns,a highly localized whirling flow is induced around the micropillars.The direction and velocity of this flow can be controlled by changing the direction and amplitude of the applied vibration.Furthermore,this flow can be induced on an open chip structure.In this study,we adopted a microchip with three micropillars arranged in a triangular configuration and an xyz piezoelectric actuator to apply the circular vibration.At the centre of the micropillars,the interference of the vibration-induced flows originating from the individual micropillars induces rotational flow.Consequently,a biological cell placed at this centre rotates under the influence of the flow.Under three-plane circular vibrations in the xy,xz or yz plane,the cell can rotate in both the focal and vertical planes of the microscope.Applying this 3D cell rotation method,we measured the rotational speeds of mouse oocytes in the focal and vertical planes as 63.7±4.0°s^(−1) and 3.5±2.1°s^(−1),respectively.Furthermore,we demonstrated the transportation and rotation of the mouse oocytes and re-positioned their nuclei into a position observable by microscope.
基金financially supported by the National Natural Science Foundation of China(No.51675130)the Key Program of the National Natural Science Foundation of China(No.51435004)。
文摘The pulsed power ultrasonic-assisted gas metal arc welding(PU-GMAW)is a new development hybrid welding method.The influences of the pulsed power ultrasonic on the microstructure evolution of the welded joint of Al-Cu alloy were investigated by using scanning electron microscopy,transmission electron microscope and electron back scattering diffraction.The results showed that the efficient heat input in the PU-GMAW was increased by above 100%compared with the traditional GMAW.The grain and eutectic of the PU-GMAW weld seam were refined compared with that of the GMAW.Cavitation and acoustic streaming induced the dendrite fragmentation(α-Al)and heterogeneous nucleation,which were the main reasons for the grain refinement.The microhardness of the PU-GMAW welded joint was improved compared with that of the GMAW owing to the change of the eutectic and grain.
