We studied the lateral forces arising during the vertical indentation of the cell membrane by an optically trapped microbead, using back focal plane interferometry to determine force components in all directions. We analyzed the cell-microbead interaction and showed that indeed the force had also lateral components. Using the Hertz model, we calculated and compared the elastic moduli resulting from the total and vertical forces, showing that the differences are important and the total force should be considered. To confirm our results we analyzed cells from two breast cancer cell lines: MDA-MB-231 and HBL-100, known to have different cancer aggressiveness and hence stiffness.
Showing posts with label International Journal of Optomechatronics. Show all posts
Showing posts with label International Journal of Optomechatronics. Show all posts
Thursday, February 25, 2016
The Influence of Lateral Forces on the Cell Stiffness Measurement by Optical Tweezers Vertical Indentation
Fatou Ndoye, Muhammad Sulaiman Yousafzai, Giovanna Coceano, Serena Bonin, Giacinto Scoles, Oumar Ka, Joseph Niemela & Dan Cojoc
Thursday, December 17, 2015
Optical Trapping of Nanoparticles on a Silicon Subwavelength Grating and Their Detection by an Ellipsometric Technique
Naoya Taki, Yasuhiro Mizutan, Tetsuo Iwata, Takao Kojima, Hiroki Yamamoto & Takahiro Kozawa
A method and setup are proposed for trapping and detecting nanoparticles dispersed in a nanocomposite solution using periodically localized light generated by a subwavelength transmission grating. By numerical simulations, it is shown that there is an optimum duty ratio of the grating to produce the periodically localized light. Experimental results are presented for Au/γ-Fe2O3 composite nanoparticles having a diameter of 21.0 nm trapped on a silicon subwavelength rectangular grating and detected ellipsometrically. The technique should prove useful for evaluating optical and mechanical properties of nanocomposite materials.
DOI
A method and setup are proposed for trapping and detecting nanoparticles dispersed in a nanocomposite solution using periodically localized light generated by a subwavelength transmission grating. By numerical simulations, it is shown that there is an optimum duty ratio of the grating to produce the periodically localized light. Experimental results are presented for Au/γ-Fe2O3 composite nanoparticles having a diameter of 21.0 nm trapped on a silicon subwavelength rectangular grating and detected ellipsometrically. The technique should prove useful for evaluating optical and mechanical properties of nanocomposite materials.
DOI
Thursday, April 30, 2015
Wide-range Axial Position Measurement for Jumping Behavior of Optically Trapped Microsphere Near Surface Using Chromatic Confocal Sensor
Shin-ichi Ueda, Masaki Michihata, Terutake Hayashi & Yasuhiro Takaya
When a microsphere is trapped near a surface by single-beam gradient force trapping, the standing wave is generated between the microsphere and the surface, where abrupt motion along the optical axis (jumping) is observed corresponding to displacement of the surface. This jumping distance is on the order of a few hundred nanometers. In the vicinity of the surface, intensity of retro-reflected light is increased so that the averaged position of the jumping is shifted up on the order of several micrometers. Therefore wide-range and high-resolution position measurement technique is required. In this article, we proposed to apply a chromatic confocal sensor to measure the axial position of the microsphere in the standing wave. It was experimentally validated that the position of the microsphere could be measured with a resolution of 10 nm and a measuring range of 3 µm.
DOI
When a microsphere is trapped near a surface by single-beam gradient force trapping, the standing wave is generated between the microsphere and the surface, where abrupt motion along the optical axis (jumping) is observed corresponding to displacement of the surface. This jumping distance is on the order of a few hundred nanometers. In the vicinity of the surface, intensity of retro-reflected light is increased so that the averaged position of the jumping is shifted up on the order of several micrometers. Therefore wide-range and high-resolution position measurement technique is required. In this article, we proposed to apply a chromatic confocal sensor to measure the axial position of the microsphere in the standing wave. It was experimentally validated that the position of the microsphere could be measured with a resolution of 10 nm and a measuring range of 3 µm.
DOI
Wednesday, February 11, 2015
The Manipulation and Combustion of Carbon-Based Micro Particles by Optical Tweezers
Sheng-ji Li & Xue-feng Huang
This article presents the manipulation and combustion of carbon-based micro particles (polystyrene, active carbon) by optical tweezers. Trap, ignition, and combustion of micro particles are well demonstrated. For polystyrene in water, polystyrene micro particles of 2.9 µm are trapped with increasing laser power. The polystyrene takes reaction and combusts as the laser power of 520 mW. For active carbon in air, both single active carbon and active carbon bundle can be trapped, dragged, oxidized, ignited, and combusted. The drag speed and burning rate of single active carbon of 7.0 µm are 103.7 µm/s and 14.0 µm/s as the minimum ignition power of 3.2 mW. Combustions of single active carbon and bundle are flameless at minimum ignition power. As the power is further enhanced, strenuous oxidation and combustion flame can be observed. For active carbon bundle of 215.7 µm, combustion process sustains 0.72 s as the laser power of 90 mW.
DOI
This article presents the manipulation and combustion of carbon-based micro particles (polystyrene, active carbon) by optical tweezers. Trap, ignition, and combustion of micro particles are well demonstrated. For polystyrene in water, polystyrene micro particles of 2.9 µm are trapped with increasing laser power. The polystyrene takes reaction and combusts as the laser power of 520 mW. For active carbon in air, both single active carbon and active carbon bundle can be trapped, dragged, oxidized, ignited, and combusted. The drag speed and burning rate of single active carbon of 7.0 µm are 103.7 µm/s and 14.0 µm/s as the minimum ignition power of 3.2 mW. Combustions of single active carbon and bundle are flameless at minimum ignition power. As the power is further enhanced, strenuous oxidation and combustion flame can be observed. For active carbon bundle of 215.7 µm, combustion process sustains 0.72 s as the laser power of 90 mW.
DOI
Tuesday, February 26, 2013
New Technique for Single-Beam Gradient-Force Laser Trapping in Air
Masaki Michihata, Tada-aki Yoshikane, Terutake Hayashi and Yasuhiro Takaya
Laser trapping is becoming an important technique for microsystem technologies. To apply it to industrial uses, it should be developed to function in air. However, there is not much research about laser trapping in air. One of the reasons is the difficulty of trapping micro-objects. Therefore, we have proposed a new technique to trap micro-objects in air. In particular, we focused our attention on the substrate where the micro-object is set. By applying a textured surface and employing tungsten carbide as the substrate material, the trapping probability was improved by a remarkable amount. Although a certain degree of improvement was attained, the trapping was still not perfect. To ascertain the forces working on the micro-object, an analytical calculation of the adhesion forces and an electromagnetic simulation of the optical forces were implemented. Based on these calculations, we discuss what the most important factor is for successful laser trapping in air.
DOI
Laser trapping is becoming an important technique for microsystem technologies. To apply it to industrial uses, it should be developed to function in air. However, there is not much research about laser trapping in air. One of the reasons is the difficulty of trapping micro-objects. Therefore, we have proposed a new technique to trap micro-objects in air. In particular, we focused our attention on the substrate where the micro-object is set. By applying a textured surface and employing tungsten carbide as the substrate material, the trapping probability was improved by a remarkable amount. Although a certain degree of improvement was attained, the trapping was still not perfect. To ascertain the forces working on the micro-object, an analytical calculation of the adhesion forces and an electromagnetic simulation of the optical forces were implemented. Based on these calculations, we discuss what the most important factor is for successful laser trapping in air.
DOI
Monday, June 18, 2012
Optical Trapping Forces on Non-Spherical Particles in Fluid Flows
Dewan Hasan Ahmed & Hyung Jin Sung
The optical stability of particles above a waveguide surface depends on the forces induced by fluid drag and the electromagnetic field. The optical trapping forces on non-spherical particles were examined for various flow conditions. A three-dimensional finite element method was employed to calculate the electromagnetic field and the fluid flow. It was found that the stability of non-spherical particles is significantly affected by the fluid velocity and the orientation of the particles. The downward trapping force meant that non-spherical particles are more stable at higher Reynolds numbers. The length of the particle in the transverse direction also had a significant impact on particle stability. The present model was tested against previously reported results.
DOI
The optical stability of particles above a waveguide surface depends on the forces induced by fluid drag and the electromagnetic field. The optical trapping forces on non-spherical particles were examined for various flow conditions. A three-dimensional finite element method was employed to calculate the electromagnetic field and the fluid flow. It was found that the stability of non-spherical particles is significantly affected by the fluid velocity and the orientation of the particles. The downward trapping force meant that non-spherical particles are more stable at higher Reynolds numbers. The length of the particle in the transverse direction also had a significant impact on particle stability. The present model was tested against previously reported results.
DOI
Friday, October 7, 2011
Integration of Optical Manipulation and Electrophysiological Tools to Modulate and Record Activity in Neural Networks
F. Difato, L. Schibalsky, F. Benfenati & A. Blau
We present an optical system that combines IR (1064 nm) holographic optical tweezers with a sub-nanosecond-pulsed UV (355 nm) laser microdissector for the optical manipulation of single neurons and entire networks both on transparent and non-transparent substrates in vitro. The phase-modulated laser beam can illuminate the sample concurrently or independently from above or below assuring compatibility with different types of microelectrode array and patch-clamp electrophysiology. By combining electrophysiological and optical tools, neural activity in response to localized stimuli or injury can be studied and quantified at sub-cellular, cellular, and network level.
DOI
We present an optical system that combines IR (1064 nm) holographic optical tweezers with a sub-nanosecond-pulsed UV (355 nm) laser microdissector for the optical manipulation of single neurons and entire networks both on transparent and non-transparent substrates in vitro. The phase-modulated laser beam can illuminate the sample concurrently or independently from above or below assuring compatibility with different types of microelectrode array and patch-clamp electrophysiology. By combining electrophysiological and optical tools, neural activity in response to localized stimuli or injury can be studied and quantified at sub-cellular, cellular, and network level.
DOI
Custom-Built Optical Tweezers for Locally Probing the Viscoelastic Properties of Cancer Cells
Federica Tavano, Serena Bonin, Giulietta Pinato, Giorgio Stanta & Dan Cojoc
We report a home built optical tweezers setup to investigate the mechanism of the membrane tether formation from single cells in vitro. Using an optically trapped microbead as probe, we have determined the force-elongation curve during tether formation and extracted several parameters characterizing the viscoelastic behavior of the cell membrane: tether stiffness, force, and viscosity. Breast cancer MDA-MB-231 cells have been studied in two different conditions, at room and physiological temperatures, showing a strong temperature dependence of the visoelastic properties of the cell membrane. To get detailed inside information about the tether formation mechanism we have extended the analysis of the force-elongation curves fitting them with a Kelvin model. These preliminary results are part of a larger project of whose goal is to compare the viscoelastic properties of several types of cancer cell lines, characterized by different aggressiveness and metastatic potential.
DOI
We report a home built optical tweezers setup to investigate the mechanism of the membrane tether formation from single cells in vitro. Using an optically trapped microbead as probe, we have determined the force-elongation curve during tether formation and extracted several parameters characterizing the viscoelastic behavior of the cell membrane: tether stiffness, force, and viscosity. Breast cancer MDA-MB-231 cells have been studied in two different conditions, at room and physiological temperatures, showing a strong temperature dependence of the visoelastic properties of the cell membrane. To get detailed inside information about the tether formation mechanism we have extended the analysis of the force-elongation curves fitting them with a Kelvin model. These preliminary results are part of a larger project of whose goal is to compare the viscoelastic properties of several types of cancer cell lines, characterized by different aggressiveness and metastatic potential.
DOI
Thursday, October 7, 2010
A Prototype Optical Tweezer System Employing Adaptive Optics Technology
R. Nash; S. Bowman; C. Bradley; R. Conan
This article describes the design, implementation and characterization of a novel optical tweezer system. The system utilizes a deformable mirror, wavefront sensor and controller to manipulate an optically trapped micro-particle within a small chamber. This method for optical trapping employs technology adopted from astronomical instrumentation; in particular, adaptive optics. A deformable mirror is employed to control the wavefront phase of a laser beam before it is imaged into a chamber by a high numerical aperture microscope objective lens. The wavefront phase is measured by a Shack-Hartman wavefront sensor and the particle's position monitored by a video camera. The goals of the work presented here are to trap particles ranging in size from 1 μm to 10 μm; create a suitable controller for moving trapped particles in three dimensions; image the trapped particle; determine the prototype system's performance specifications; and determine the trap stiffness.
DOI
This article describes the design, implementation and characterization of a novel optical tweezer system. The system utilizes a deformable mirror, wavefront sensor and controller to manipulate an optically trapped micro-particle within a small chamber. This method for optical trapping employs technology adopted from astronomical instrumentation; in particular, adaptive optics. A deformable mirror is employed to control the wavefront phase of a laser beam before it is imaged into a chamber by a high numerical aperture microscope objective lens. The wavefront phase is measured by a Shack-Hartman wavefront sensor and the particle's position monitored by a video camera. The goals of the work presented here are to trap particles ranging in size from 1 μm to 10 μm; create a suitable controller for moving trapped particles in three dimensions; image the trapped particle; determine the prototype system's performance specifications; and determine the trap stiffness.
DOI
Wednesday, December 23, 2009
Laser Manipulation by Using Liquid Crystal Devices with Variable-Focusing and Beam-Steering Functions
Marenori Kawamura; Junji Onishi; Susumu Sato
A laser manipulation system for trapping and controlling the positions of microscopic transparent particles by using liquid crystal (LC) devices is developed. The LC device has functions of variable-focusing and beam-steering by controlling the applied voltages to the LC device without mechanical movements. The trapped particles suspended in deionized water can easily be shifted along the position of the focused laser spot. The microscopic rod-like particles can also be shifted and rotated in the clockwise or anticlockwise along the direction of the major axis of the elliptically distributed beam intensity. In addition, the multiple microscopic particles at the bright region of the linear interference fringe patterns of the LC device with comb-shaped electrodes can be trapped and shifted along the fringe patterns.
A laser manipulation system for trapping and controlling the positions of microscopic transparent particles by using liquid crystal (LC) devices is developed. The LC device has functions of variable-focusing and beam-steering by controlling the applied voltages to the LC device without mechanical movements. The trapped particles suspended in deionized water can easily be shifted along the position of the focused laser spot. The microscopic rod-like particles can also be shifted and rotated in the clockwise or anticlockwise along the direction of the major axis of the elliptically distributed beam intensity. In addition, the multiple microscopic particles at the bright region of the linear interference fringe patterns of the LC device with comb-shaped electrodes can be trapped and shifted along the fringe patterns.
Thursday, December 17, 2009
Spatial Stability of Particles Trapped by Time-Division Optical Tweezers
Johtaro Yamamoto; Toshiaki Iwai
We developed an on-demand multiple-spot holographic optical tweezers (HOT) system based on quasi-simultaneous generation of two intensity-spot patterns by alternately sending the two corresponding hologram patterns to a spatial light modulator. This switching operation reduces the spatial stability of a Brownian particle trapped inside the generated intensity spot. In this study, numerical analysis of the conditions for stable particle trapping in the time-division HOT is conducted using the Smoluchowski equation under the Rayleigh scattering approximation. The relationship between the particle size, the switching rate, and the focused laser beam power is obtained. Experiments confirm the validity of the numerical analysis.
We developed an on-demand multiple-spot holographic optical tweezers (HOT) system based on quasi-simultaneous generation of two intensity-spot patterns by alternately sending the two corresponding hologram patterns to a spatial light modulator. This switching operation reduces the spatial stability of a Brownian particle trapped inside the generated intensity spot. In this study, numerical analysis of the conditions for stable particle trapping in the time-division HOT is conducted using the Smoluchowski equation under the Rayleigh scattering approximation. The relationship between the particle size, the switching rate, and the focused laser beam power is obtained. Experiments confirm the validity of the numerical analysis.
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