Gold nanoparticles are gaining increasing attention due to their biological and medical applications.In this letter,we experimentally demonstrate the optical manipulation of 250-nm-diameter gold nanoparticles along an...Gold nanoparticles are gaining increasing attention due to their biological and medical applications.In this letter,we experimentally demonstrate the optical manipulation of 250-nm-diameter gold nanoparticles along an optical nanofiber(550 nm in diameter) injected by an 808-nm laser light.The nanoparticles situated in the evanescent optical field are trapped by optical gradient force and move along the direction of light propagation due to optical scattering force.The velocities reach as high as 132 μm/s at an optical power of 80 mW.展开更多
Optogenetics is a new and rapidly evolving gene and neuroengineering technology that allows optical control of specific populations of neurons without affecting other neurons in the brain at high temporal and spatial ...Optogenetics is a new and rapidly evolving gene and neuroengineering technology that allows optical control of specific populations of neurons without affecting other neurons in the brain at high temporal and spatial resolution. By heterologous expression of the light-sensitive membrane proteins, cell type-specific depolarization or hyperpolarization can be optically induced on a millisecond time scale. Optogenetics has the higher selectivity and specificity compared to traditional electrophysiological techniques and pharmaceutical methods. It has been a novel promising tool for medical research. Because of easy handling, high temporal and spatial precision, optogenetics has been applied to many aspects of nervous system research, such as tactual neural circuit, visual neural circuit, auditory neural circuit and olfactory neural circuit, as well as research of some neurological diseases. The review highlights the recent advances of optogenetics in medical study.展开更多
Light carries energy and momentum,laying the physical foundation of optical manipulation that has facilitated advances in myriad scientific disciplines,ranging from biochemistry and robotics to quantum physics.Utilizi...Light carries energy and momentum,laying the physical foundation of optical manipulation that has facilitated advances in myriad scientific disciplines,ranging from biochemistry and robotics to quantum physics.Utilizing the momentum of light,optical tweezers have exemplified elegant light–matter interactions in which mechanical and optical momenta can be interchanged,whose effects are the most pronounced on micro and nano objects in fluid suspensions.In solid domains,the same momentum transfer becomes futile in the face of dramatically increased adhesion force.Effective implementation of optical manipulation should thereupon switch to the“energy”channel by involving auxiliary physical fields,which also coincides with the irresistible trend of enriching actuation mechanisms beyond sole reliance on light-momentum-based optical force.From this perspective,this review covers the developments of optical manipulation in schemes of both momentum and energy transfer,and we have correspondingly selected representative techniques to present.Theoretical analyses are provided at the beginning of this review followed by experimental embodiments,with special emphasis on the contrast between mechanisms and the practical realization of optical manipulation in fluid and solid domains.展开更多
We report on a method to achieve multiple microscopic particles being trapped and manipulated transversely by using a size-tunable Bessel beam generated by cross-phase modulation(XPM)based on the thermal nonlinear opt...We report on a method to achieve multiple microscopic particles being trapped and manipulated transversely by using a size-tunable Bessel beam generated by cross-phase modulation(XPM)based on the thermal nonlinear optical effect.The results demonstrate that multiple polystyrene particles can be stably trapped simultaneously,and the number of the trapped particles can be controlled by varying the trapping beam power.In addition,the trapped particles can be manipulated laterally with micron-level precision by changing the size of J_(0)Bessel beam.This work provides a simple but efficient way to trap and manipulate multiple particles simultaneously,which would have potential applications in many fields such as cell sorting and transportation.展开更多
The perfect hybrid vector vortex beam(PHVVB)with helical phase wavefront structure has aroused significant concern in recent years,as its beam waist does not expand with the topological charge(TC).In this work,we inve...The perfect hybrid vector vortex beam(PHVVB)with helical phase wavefront structure has aroused significant concern in recent years,as its beam waist does not expand with the topological charge(TC).In this work,we investigate the spatial quantum coherent modulation effect with PHVVB based on the atomic medium,and we observe the absorption characteristic of the PHVVB with different TCs under variant magnetic fields.We find that the transmission spectrum linewidth of PHVVB can be effectively maintained regardless of the TC.Still,the width of transmission peaks increases slightly as the beam size expands in hot atomic vapor.This distinctive quantum coherence phenomenon,demonstrated by the interaction of an atomic medium with a hybrid vector-structured beam,might be anticipated to open up new opportunities for quantum coherence modulation and accurate magnetic field measurement.展开更多
We show experimentally that when an unfocused continuous wave(CW) laser beam is obliquely incident onto the surface of a millimeter-sized mineral oil drop on sucrose solution, it will exert a pushing force on the oi...We show experimentally that when an unfocused continuous wave(CW) laser beam is obliquely incident onto the surface of a millimeter-sized mineral oil drop on sucrose solution, it will exert a pushing force on the oil drop, making it move forwards along the surface of the sucrose solution. However, after a period of time, the oil drop stops moving. This can be explained as the phenomenon caused by the change of Abraham momentum, the optical gradient force, and friction together.展开更多
Recently, numerous biological macromolecular experiments have been conducted with optical tweezers. For the single molecular stretching experiment with optical tweezers, three ways to determine the initial adhesion po...Recently, numerous biological macromolecular experiments have been conducted with optical tweezers. For the single molecular stretching experiment with optical tweezers, three ways to determine the initial adhesion point of DNA on the coverslip are described in this work. In addition, a new method through analyzing the displacement variance of the trapped particle to obtain the trap height is introduced. Using our proposed methods, the obtained force-extension curve for the operated dsDNA agrees well with the worm-like chain model. These improved methods are also applicable to other related biological macromolecular experiments requiring high precision.展开更多
An optical trap forms a restoring optical force field to immobilize and manipulate tiny objects.A fiber optical trap is capable of establishing the restoring optical force field using one or a few pieces of optical fi...An optical trap forms a restoring optical force field to immobilize and manipulate tiny objects.A fiber optical trap is capable of establishing the restoring optical force field using one or a few pieces of optical fiber,and it greatly simplifies the optical setup by removing bulky optical components,such as microscope objectives from the working space.It also inherits other major advantages of optical fibers:flexible in shape,robust against disturbance,and highly integrative with fiber-optic sys-tems and on-chip devices.This review will begin with a concise introduction on the principle of optical trapping techniques,followed by a comprehensive discussion on different types of fiber optical traps,including their structures,functionalities and associated fabrication techniques.A brief outlook to the future development and potential applications of fiber optical traps is given at the end.展开更多
Light carries linear momentum and can therefore exert a radiation force on the objects that it encounters. This established fact enabled optical manipulation of micro/nano-sized objects, as well as macroscopic objects...Light carries linear momentum and can therefore exert a radiation force on the objects that it encounters. This established fact enabled optical manipulation of micro/nano-sized objects, as well as macroscopic objects such as solar sails, among many other important applications. While these efforts benefit from the average value of light’s linear momentum, in this article, we propose exploiting the temporal variation of light’s linear momentum to achieve an oscillatory force of microNewton amplitude and picosecond period. We validate our proposal by analytical calculations and time domain simulations of Maxwell’s equations in the case of a high-index quarter-wave slab irradiated by a terahertz plane electromagnetic wave. In particular, we show that for plane wave terahertz light of electric field amplitude 5000 V/m and frequency 4.8 THz, an oscillatory radiation pressure of amplitude 1.8 × 10<sup>-4</sup> N/m<sup>2</sup> and 0.1 ps period can be achieved.展开更多
Optical methods to manipulate and detect nanoscale objects are highly desired in both nanomaterials and molecular biology fields.Optical tweezers have been used to manipulate objects that range in size from a few hund...Optical methods to manipulate and detect nanoscale objects are highly desired in both nanomaterials and molecular biology fields.Optical tweezers have been used to manipulate objects that range in size from a few hundred nanometres to several micrometres.The emergence of near-field methods that overcome the diffraction limit has enabled the manipulation of objects below 100 nm.A highly free manipulation with signal-enhanced real-time detection,however,remains a challenge for single sub-100-nm nanoparticles or biomolecules.Here we show an approach that uses a photonic nanojet to perform the manipulation and detection of single sub-100-nm objects.With the photonic nanojet generated by a dielectric microlens bound to an optical fibre probe,three-dimensional manipulations were achieved for a single 85-nm fluorescent polystyrene nanoparticle as well as for a plasmid DNA molecule.Backscattering and fluorescent signals were detected with the enhancement factors up to~103 and~30,respectively.The demonstrated approach provides a potentially powerful tool for nanostructure assembly,biosensing and single-biomolecule studies.展开更多
Bacterial biofilms underlie many persistent infections,posing major hurdles in antibiotic treatment.Here we design and demonstrate‘tug-of-war’optical tweezers that can facilitate the assessment of cell–cell adhesio...Bacterial biofilms underlie many persistent infections,posing major hurdles in antibiotic treatment.Here we design and demonstrate‘tug-of-war’optical tweezers that can facilitate the assessment of cell–cell adhesion—a key contributing factor to biofilm development,thanks to the combined actions of optical scattering and gradient forces.With a customized optical landscape distinct from that of conventional tweezers,not only can such‘tug-of-war’tweezers stably trap and stretch a rod-shaped bacterium in the observing plane,but,more importantly,they can also impose a tunable lateral force that pulls apart cellular clusters without any tethering or mechanical movement.As a proof of principle,we examined a Sinorhizobium meliloti strain that forms robust biofilms and found that the strength of intercellular adhesion depends on the growth medium.This technique may herald new photonic tools for optical manipulation and biofilm study,as well as other biological applications.展开更多
Optical line tweezers have been an efficient tool for the manipulation of large micron particles. In this paper, we propose to create line traps with transformable configurations by using the transverse electromagneti...Optical line tweezers have been an efficient tool for the manipulation of large micron particles. In this paper, we propose to create line traps with transformable configurations by using the transverse electromagnetic mode-like laser source.We designed an optical path to simulate the generation of the astigmatic beams and line traps with a series of lenses to realize the rotational transformation with respect to the rotation angle of cylindrical lenses. It is shown that the spherical particles with diameters ranging from 5 μm to 20 μm could be trapped, aligned, and revolved in experiment. The periodical trapping forces generated by transformable line traps might open an alternative way to investigate the mechanical properties of soft particles and biological cells.展开更多
Optical tweezers that rely on laser irradiation to capture and manipulate nanoparticles have provided powerful tools for biological and biochemistry studies.However,the existence of optical diffraction-limit and the t...Optical tweezers that rely on laser irradiation to capture and manipulate nanoparticles have provided powerful tools for biological and biochemistry studies.However,the existence of optical diffraction-limit and the thermal damage caused by high laser power hinder the wider application of optical tweezers in the biological field.For the past decade,the emergence of optothermal tweezers has solved the above problems to a certain extent,while the auxiliary agents used in optothermal tweezers still limit their biocompatibility.Here,we report a kind of nanotweezers based on the sign transformation of the thermophoresis coefficient of colloidal particles in low-temperature environment.Using a self-made microfluidic refrigerator to reduce the ambient temperature to around 0℃in the microfluidic cell,we can control a single nanoparticle at lower laser power without adding additional agent solute in the solution.This novel optical tweezering scheme has provided a new path for the manipulation of inorganic nanoparticles as well as biological particles.展开更多
Leveraging developments in microfabrication open new possibilities for optical manipulation.With the structural design freedom from three-dimensional printing capabilities of two-photon polymerization,we are starting ...Leveraging developments in microfabrication open new possibilities for optical manipulation.With the structural design freedom from three-dimensional printing capabilities of two-photon polymerization,we are starting to see the emergence of cleverly shaped‘light robots’or optically actuated micro-tools that closely resemble their macroscopic counterparts in function and sometimes even in form.In this work,we have fabricated a new type of light robot that is capable of loading and unloading cargo using photothermally induced convection currents within the body of the tool.We have demonstrated this using silica and polystyrene beads as cargo.The flow speeds of the cargo during loading and unloading are significantly larger than when using optical forces alone.This new type of light robot presents a mode of material transport that may have a significant impact on targeted drug delivery and nanofluidics injection.展开更多
Usually,an unfocused light beam,such as a paraxial Gaussian beam,can exert a force on an object along the direction of light propagation,which is known as light pressure.Recently,however,it was found that an unfocused...Usually,an unfocused light beam,such as a paraxial Gaussian beam,can exert a force on an object along the direction of light propagation,which is known as light pressure.Recently,however,it was found that an unfocused light beam can also exert an optical pulling force(OPF)on an object toward the source direction;the beam is accordingly named an optical tractor beam.In recent years,this intriguing force has attracted much attention and a huge amount of progress has been made both in theory and experiment.We briefly review recent progress achieved on this topic.We classify the mechanisms to achieve an OPF into four different kinds according to the dominant factors.The first one is tailoring the incident beam.The second one is engineering the object’s optical parameters.The third one is designing the structured material background,in which the light–matter interaction occurs,and the fourth one is utilizing the indirect photophoretic force,which is related to the thermal effect of light absorption.For all the methods,we analyze the basic principles and review the recent achievements.Finally,we also give a brief conclusion and an outlook on the future development of this field.展开更多
Optical manipulation of micro/nanoscale objects is of importance in life sciences,colloidal science,and nanotechnology.Optothermal tweezers exhibit superior manipulation capability at low optical intensity.However,our...Optical manipulation of micro/nanoscale objects is of importance in life sciences,colloidal science,and nanotechnology.Optothermal tweezers exhibit superior manipulation capability at low optical intensity.However,our implicit understanding of the working mechanism has limited the further applications and innovations of optothermal tweezers.Herein,we present an atomistic view of opto-thermo-electro-mechanic coupling in optothermal tweezers,which enables us to rationally design the tweezers for optimum performance in targeted applications.Specifically,we have revealed that the non-uniform temperature distribution induces water polarization and charge separation,which creates the thermoelectric field dominating the optothermal trapping.We further design experiments to systematically verify our atomistic simulations.Guided by our new model,we develop new types of optothermal tweezers of high performance using low-concentrated electrolytes.Moreover,we demonstrate the use of new tweezers in opto-thermophoretic separation of colloidal particles of the same size based on the difference in their surface charge,which has been challenging for conventional optical tweezers.With the atomistic understanding that enables the performance optimization and function expansion,optothermal tweezers will further their impacts.展开更多
Micromachining based on femtosecond lasers usually requires accurate control of the sample movement,which may be very complex and costly.Therefore,the exploration of micromachining without sample movement is valuable....Micromachining based on femtosecond lasers usually requires accurate control of the sample movement,which may be very complex and costly.Therefore,the exploration of micromachining without sample movement is valuable.Herein,we have illustrated the manipulation of optical fields by controlling the polarization or phase to vary periodically and then realized certain focal traces by real-time loading of the computer-generated holograms(CGHs) on the spatial light modulator.The focal trace is composed of many discrete focal spots,which are generated experimentally by using the real-time dynamically controlled CGHs.With the designed focal traces,various microstructures such as an ellipse,a Chinese character "Nan",and an irregular quadrilateral grid structure are fabricated in the z-cut LiNbO_(3) wafers,showing good qualities in terms of continuity and homogeneity.Our method proposes a movement free solution for micromachining samples and completely abandons the high precision stage and complex movement control,making microstructure fabrication more flexible,stable,and cheaper.展开更多
文摘Gold nanoparticles are gaining increasing attention due to their biological and medical applications.In this letter,we experimentally demonstrate the optical manipulation of 250-nm-diameter gold nanoparticles along an optical nanofiber(550 nm in diameter) injected by an 808-nm laser light.The nanoparticles situated in the evanescent optical field are trapped by optical gradient force and move along the direction of light propagation due to optical scattering force.The velocities reach as high as 132 μm/s at an optical power of 80 mW.
基金National Natural Sciences Foundation of China (No.81070749)Chongqing Science and Technology Project,China (No.CSTC,2010AB5118)
文摘Optogenetics is a new and rapidly evolving gene and neuroengineering technology that allows optical control of specific populations of neurons without affecting other neurons in the brain at high temporal and spatial resolution. By heterologous expression of the light-sensitive membrane proteins, cell type-specific depolarization or hyperpolarization can be optically induced on a millisecond time scale. Optogenetics has the higher selectivity and specificity compared to traditional electrophysiological techniques and pharmaceutical methods. It has been a novel promising tool for medical research. Because of easy handling, high temporal and spatial precision, optogenetics has been applied to many aspects of nervous system research, such as tactual neural circuit, visual neural circuit, auditory neural circuit and olfactory neural circuit, as well as research of some neurological diseases. The review highlights the recent advances of optogenetics in medical study.
基金supported by the National Natural Science Foundation of China (Nos.61927820,61905201,and 62275221).
文摘Light carries energy and momentum,laying the physical foundation of optical manipulation that has facilitated advances in myriad scientific disciplines,ranging from biochemistry and robotics to quantum physics.Utilizing the momentum of light,optical tweezers have exemplified elegant light–matter interactions in which mechanical and optical momenta can be interchanged,whose effects are the most pronounced on micro and nano objects in fluid suspensions.In solid domains,the same momentum transfer becomes futile in the face of dramatically increased adhesion force.Effective implementation of optical manipulation should thereupon switch to the“energy”channel by involving auxiliary physical fields,which also coincides with the irresistible trend of enriching actuation mechanisms beyond sole reliance on light-momentum-based optical force.From this perspective,this review covers the developments of optical manipulation in schemes of both momentum and energy transfer,and we have correspondingly selected representative techniques to present.Theoretical analyses are provided at the beginning of this review followed by experimental embodiments,with special emphasis on the contrast between mechanisms and the practical realization of optical manipulation in fluid and solid domains.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.61805200,51927804,and12104365)the Natural Science Foundation of Shaanxi Province,China(Grant No.2020JM-432)+1 种基金the Fund for Young Star in Science and Technology of Shaanxi Province,China(Grant No.2021KJXX-27)the Fund from the Education Department of Shaanxi Province,China(Grant No.21JK0915)。
文摘We report on a method to achieve multiple microscopic particles being trapped and manipulated transversely by using a size-tunable Bessel beam generated by cross-phase modulation(XPM)based on the thermal nonlinear optical effect.The results demonstrate that multiple polystyrene particles can be stably trapped simultaneously,and the number of the trapped particles can be controlled by varying the trapping beam power.In addition,the trapped particles can be manipulated laterally with micron-level precision by changing the size of J_(0)Bessel beam.This work provides a simple but efficient way to trap and manipulate multiple particles simultaneously,which would have potential applications in many fields such as cell sorting and transportation.
基金Project supported by the Youth Innovation Promotion Association CASState Key Laboratory of Transient Optics and Photonics Open Topics (Grant No. SKLST202222)
文摘The perfect hybrid vector vortex beam(PHVVB)with helical phase wavefront structure has aroused significant concern in recent years,as its beam waist does not expand with the topological charge(TC).In this work,we investigate the spatial quantum coherent modulation effect with PHVVB based on the atomic medium,and we observe the absorption characteristic of the PHVVB with different TCs under variant magnetic fields.We find that the transmission spectrum linewidth of PHVVB can be effectively maintained regardless of the TC.Still,the width of transmission peaks increases slightly as the beam size expands in hot atomic vapor.This distinctive quantum coherence phenomenon,demonstrated by the interaction of an atomic medium with a hybrid vector-structured beam,might be anticipated to open up new opportunities for quantum coherence modulation and accurate magnetic field measurement.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.90921009 and 11274401)
文摘We show experimentally that when an unfocused continuous wave(CW) laser beam is obliquely incident onto the surface of a millimeter-sized mineral oil drop on sucrose solution, it will exert a pushing force on the oil drop, making it move forwards along the surface of the sucrose solution. However, after a period of time, the oil drop stops moving. This can be explained as the phenomenon caused by the change of Abraham momentum, the optical gradient force, and friction together.
基金Supported by the National Natural Science Foundation of China under Grant No 91023049the National Basic Research Program of China under Grant No 2012CB937500
文摘Recently, numerous biological macromolecular experiments have been conducted with optical tweezers. For the single molecular stretching experiment with optical tweezers, three ways to determine the initial adhesion point of DNA on the coverslip are described in this work. In addition, a new method through analyzing the displacement variance of the trapped particle to obtain the trap height is introduced. Using our proposed methods, the obtained force-extension curve for the operated dsDNA agrees well with the worm-like chain model. These improved methods are also applicable to other related biological macromolecular experiments requiring high precision.
基金from National Natural Science Foundation of China(Grant number:11874164)the Innovation Fund of Wuhan National Laboratory for Optoelectronics and 1000 Talent Youth Program.
文摘An optical trap forms a restoring optical force field to immobilize and manipulate tiny objects.A fiber optical trap is capable of establishing the restoring optical force field using one or a few pieces of optical fiber,and it greatly simplifies the optical setup by removing bulky optical components,such as microscope objectives from the working space.It also inherits other major advantages of optical fibers:flexible in shape,robust against disturbance,and highly integrative with fiber-optic sys-tems and on-chip devices.This review will begin with a concise introduction on the principle of optical trapping techniques,followed by a comprehensive discussion on different types of fiber optical traps,including their structures,functionalities and associated fabrication techniques.A brief outlook to the future development and potential applications of fiber optical traps is given at the end.
文摘Light carries linear momentum and can therefore exert a radiation force on the objects that it encounters. This established fact enabled optical manipulation of micro/nano-sized objects, as well as macroscopic objects such as solar sails, among many other important applications. While these efforts benefit from the average value of light’s linear momentum, in this article, we propose exploiting the temporal variation of light’s linear momentum to achieve an oscillatory force of microNewton amplitude and picosecond period. We validate our proposal by analytical calculations and time domain simulations of Maxwell’s equations in the case of a high-index quarter-wave slab irradiated by a terahertz plane electromagnetic wave. In particular, we show that for plane wave terahertz light of electric field amplitude 5000 V/m and frequency 4.8 THz, an oscillatory radiation pressure of amplitude 1.8 × 10<sup>-4</sup> N/m<sup>2</sup> and 0.1 ps period can be achieved.
基金supported by the Program for Changjiang Scholars and Innovative Research Team in University(IRT13042)the National Natural Science Foundation of China(No.61205165).
文摘Optical methods to manipulate and detect nanoscale objects are highly desired in both nanomaterials and molecular biology fields.Optical tweezers have been used to manipulate objects that range in size from a few hundred nanometres to several micrometres.The emergence of near-field methods that overcome the diffraction limit has enabled the manipulation of objects below 100 nm.A highly free manipulation with signal-enhanced real-time detection,however,remains a challenge for single sub-100-nm nanoparticles or biomolecules.Here we show an approach that uses a photonic nanojet to perform the manipulation and detection of single sub-100-nm objects.With the photonic nanojet generated by a dielectric microlens bound to an optical fibre probe,three-dimensional manipulations were achieved for a single 85-nm fluorescent polystyrene nanoparticle as well as for a plasmid DNA molecule.Backscattering and fluorescent signals were detected with the enhancement factors up to~103 and~30,respectively.The demonstrated approach provides a potentially powerful tool for nanostructure assembly,biosensing and single-biomolecule studies.
文摘Bacterial biofilms underlie many persistent infections,posing major hurdles in antibiotic treatment.Here we design and demonstrate‘tug-of-war’optical tweezers that can facilitate the assessment of cell–cell adhesion—a key contributing factor to biofilm development,thanks to the combined actions of optical scattering and gradient forces.With a customized optical landscape distinct from that of conventional tweezers,not only can such‘tug-of-war’tweezers stably trap and stretch a rod-shaped bacterium in the observing plane,but,more importantly,they can also impose a tunable lateral force that pulls apart cellular clusters without any tethering or mechanical movement.As a proof of principle,we examined a Sinorhizobium meliloti strain that forms robust biofilms and found that the strength of intercellular adhesion depends on the growth medium.This technique may herald new photonic tools for optical manipulation and biofilm study,as well as other biological applications.
基金This work was supported by the National Natural Science Foundation of China(No.61965008)Guangxi Natural Science Foundation(No.AD21220086)+1 种基金Scientific Research Project for Guangxi University(No.2020KY05022)Guangxi Key Laboratory(Nos.YQ21109 and GD21103).
文摘Optical line tweezers have been an efficient tool for the manipulation of large micron particles. In this paper, we propose to create line traps with transformable configurations by using the transverse electromagnetic mode-like laser source.We designed an optical path to simulate the generation of the astigmatic beams and line traps with a series of lenses to realize the rotational transformation with respect to the rotation angle of cylindrical lenses. It is shown that the spherical particles with diameters ranging from 5 μm to 20 μm could be trapped, aligned, and revolved in experiment. The periodical trapping forces generated by transformable line traps might open an alternative way to investigate the mechanical properties of soft particles and biological cells.
基金the National Natural Science Foundation of China(Nos.62275164,61905145,and 62275168)National Key Research and Development Program of China(No.2022YFA1200116)+1 种基金Guangdong Natural Science Foundation and Province Project(No.2021A1515011916)Shenzhen Science and Technology Planning Project(No.ZDSYS20210623092006020).
文摘Optical tweezers that rely on laser irradiation to capture and manipulate nanoparticles have provided powerful tools for biological and biochemistry studies.However,the existence of optical diffraction-limit and the thermal damage caused by high laser power hinder the wider application of optical tweezers in the biological field.For the past decade,the emergence of optothermal tweezers has solved the above problems to a certain extent,while the auxiliary agents used in optothermal tweezers still limit their biocompatibility.Here,we report a kind of nanotweezers based on the sign transformation of the thermophoresis coefficient of colloidal particles in low-temperature environment.Using a self-made microfluidic refrigerator to reduce the ambient temperature to around 0℃in the microfluidic cell,we can control a single nanoparticle at lower laser power without adding additional agent solute in the solution.This novel optical tweezering scheme has provided a new path for the manipulation of inorganic nanoparticles as well as biological particles.
基金supported by the Enhanced Spatial Light Control in Advanced Optical Fibres(e-space)project,financed by Innovation Fund Denmark(Grant No.0603-00514B).
文摘Leveraging developments in microfabrication open new possibilities for optical manipulation.With the structural design freedom from three-dimensional printing capabilities of two-photon polymerization,we are starting to see the emergence of cleverly shaped‘light robots’or optically actuated micro-tools that closely resemble their macroscopic counterparts in function and sometimes even in form.In this work,we have fabricated a new type of light robot that is capable of loading and unloading cargo using photothermally induced convection currents within the body of the tool.We have demonstrated this using silica and polystyrene beads as cargo.The flow speeds of the cargo during loading and unloading are significantly larger than when using optical forces alone.This new type of light robot presents a mode of material transport that may have a significant impact on targeted drug delivery and nanofluidics injection.
基金This work was supported by the National Natural Science Foundation of China(Grant Nos.11874134 and 11474077).
文摘Usually,an unfocused light beam,such as a paraxial Gaussian beam,can exert a force on an object along the direction of light propagation,which is known as light pressure.Recently,however,it was found that an unfocused light beam can also exert an optical pulling force(OPF)on an object toward the source direction;the beam is accordingly named an optical tractor beam.In recent years,this intriguing force has attracted much attention and a huge amount of progress has been made both in theory and experiment.We briefly review recent progress achieved on this topic.We classify the mechanisms to achieve an OPF into four different kinds according to the dominant factors.The first one is tailoring the incident beam.The second one is engineering the object’s optical parameters.The third one is designing the structured material background,in which the light–matter interaction occurs,and the fourth one is utilizing the indirect photophoretic force,which is related to the thermal effect of light absorption.For all the methods,we analyze the basic principles and review the recent achievements.Finally,we also give a brief conclusion and an outlook on the future development of this field.
基金the National Science Foundation(No.NSF-CMMI-1761743)the National Aeronautics and Space Administration Early Career Faculty Award(No.80NSSC17K0520)+2 种基金the National Institute of General Medical Sciences of the National Institutes of Health(No.DP2GM128446)L.H.L.acknowledges financial support from the National Natural Science Foundation of China(No.62075111)the State Key Laboratory of Precision Measurement Technology and Instruments.The authors are grateful to Prof.Brian A.Korgel and Dr.Taizhi Jiang for providing Si particles.They also thank Yaoran Liu,Jingang Li,Kan Yao and Zhihan Chen for useful discussions。
文摘Optical manipulation of micro/nanoscale objects is of importance in life sciences,colloidal science,and nanotechnology.Optothermal tweezers exhibit superior manipulation capability at low optical intensity.However,our implicit understanding of the working mechanism has limited the further applications and innovations of optothermal tweezers.Herein,we present an atomistic view of opto-thermo-electro-mechanic coupling in optothermal tweezers,which enables us to rationally design the tweezers for optimum performance in targeted applications.Specifically,we have revealed that the non-uniform temperature distribution induces water polarization and charge separation,which creates the thermoelectric field dominating the optothermal trapping.We further design experiments to systematically verify our atomistic simulations.Guided by our new model,we develop new types of optothermal tweezers of high performance using low-concentrated electrolytes.Moreover,we demonstrate the use of new tweezers in opto-thermophoretic separation of colloidal particles of the same size based on the difference in their surface charge,which has been challenging for conventional optical tweezers.With the atomistic understanding that enables the performance optimization and function expansion,optothermal tweezers will further their impacts.
基金supported by the National Key R&D Program of China (Nos. 2017YFA0303800 and 2017YFA0303700)National Natural Science Foundation of China (Nos. 11534006, 11774183, 12074196, and 11904152)
文摘Micromachining based on femtosecond lasers usually requires accurate control of the sample movement,which may be very complex and costly.Therefore,the exploration of micromachining without sample movement is valuable.Herein,we have illustrated the manipulation of optical fields by controlling the polarization or phase to vary periodically and then realized certain focal traces by real-time loading of the computer-generated holograms(CGHs) on the spatial light modulator.The focal trace is composed of many discrete focal spots,which are generated experimentally by using the real-time dynamically controlled CGHs.With the designed focal traces,various microstructures such as an ellipse,a Chinese character "Nan",and an irregular quadrilateral grid structure are fabricated in the z-cut LiNbO_(3) wafers,showing good qualities in terms of continuity and homogeneity.Our method proposes a movement free solution for micromachining samples and completely abandons the high precision stage and complex movement control,making microstructure fabrication more flexible,stable,and cheaper.