Comparative study of methods to calibrate the stiffness of a single-beam gradient-force optical tweezers over various laser trapping powers

Sarshar, Mohammad Amin; Wong, Winson T.; Anvari, Bahman

doi:10.1117/1.jbo.19.11.115001

Cited by 72 publications

(58 citation statements)

References 98 publications

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“…In this work, we used three different position detection methods, namely fiber based, PSD based, and camera based methods, to obtain the position data of a trapped bead. These data were processed by the power spectrum analysis method [23][24][25][26] (for the fiber based detection mechanism and PDS methods) and equipartition method 10,[27][28][29][30][31] (for camera based methods), in order to calibrate the trap stiffness. More details of three different position detection methods can be found in Methods section and Supplementary information.…”

Section: Resultsmentioning

confidence: 99%

Objective-lens-free Fiber based Position Detection with Nanometer Resolution in a Fiber Optical Trapping System

Ti¹,

Shen²,

Thanh³

et al. 2017

Frontiers in Optics 2017

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Position detection with high accuracy is crucial for force calibration of optical trapping systems. Most existing position detection methods require high-numerical-aperture objective lenses, which are bulky, expensive, and difficult to miniaturize. Here, we report an affordable objective-lens-free, fiber-based position detection scheme with 2 nm spatial resolution and 150 MHz bandwidth. This fiber based detection mechanism enables simultaneous trapping and force measurements in a compact fiber optical tweezers system. In addition, we achieved more reliable signal acquisition with less distortion compared with objective based position detection methods, thanks to the light guiding in optical fibers and small distance between the fiber tips and trapped particle. As a demonstration of the fiber based detection, we used the fiber optical tweezers to apply a force on a cell membrane and simultaneously measure the cellular response.

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Section: Resultsmentioning

confidence: 99%

Objective-lens-free Fiber based Position Detection with Nanometer Resolution in a Fiber Optical Trapping System

Ti¹,

Shen²,

Thanh³

et al. 2017

Frontiers in Optics 2017

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“…When the inertial force can be neglected compared with the viscous force, Eq. (2) can be described by a simpli ed equation as follows [16,20,23]:…”

Section: Theory Of Force Calibrationmentioning

confidence: 99%

“…By solving the Fourier transform of the above equation, the power spectrum of the captured microsphere is expressed as [16] …”

Section: Theory Of Force Calibrationmentioning

confidence: 99%

“…The transverse trap sti ness k i can be obtained by substituting the calculated roll-o frequency into Eq. (5) [16,20].…”

Section: Theory Of Force Calibrationmentioning

confidence: 99%

“…The aim of the study is to experimentally investigate this relationship. In this paper, we used the power spectral density (PSD) method [16][17][18][19][20] to demonstrate the relationship between the transverse gradient force and the topological charge of the vortex beam.…”

Section: Introductionmentioning

confidence: 99%

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Experimental investigation on optical vortex tweezers for microbubble trapping

et al. 2018

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Abstract:In this paper, we investigated the microbubble trapping using optical vortex tweezers. It is shown that the microbubble can be trapped by the vortex optical tweezers, in which the trapping light beam is of vortex beam. We studied a relationship between the transverse capture gradient force and the topological charges of the illuminating vortex beam. For objective lenses with numerical aperture of 1.25 (100×), the force measurement was performed by the power spectral density (PSD) roll-o method. It was shown that transverse trapping forces of vortex optical tweezers increase with the increment of the laser power for xed topological charge. Whereas, the increase in the topological charges of vortex beam for the same laser power results in the decrease of the transverse trapping forces. The experimental results demonstrated that the laser mode (topological charge) has signi cant in uence on the lateral trapping force.

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Quantitative analysis of the three‐dimensional trap stiffness of a dielectrophoretic corral trap

et al. 2021

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Dielectrophoresis is a robust approach for the manipulation and separation of (bio)particles using microfluidic platforms. We developed a dielectrophoretic corral trap in a microfluidic device that utilizes negative dielectrophoresis to capture single spherical polystyrene particles. Circular‐shaped micron‐size traps were employed inside the device and the three‐dimensional trap stiffness (restoring trapping force from equilibrium trapping location) was analyzed using 4.42 μm particles and 1 MHz of an alternating electric field from 6 VP‐P to 10 VP‐P. The trap stiffness increased exponentially in the x‐ and y‐direction, and linearly in the z‐direction. Image analysis of the trapped particle movements revealed that the trap stiffness is increased 608.4, 539.3, and 79.7% by increasing the voltage from 6 VP‐P to 10 VP‐P in the x‐, y‐, and z‐direction, respectively. The trap stiffness calculated from a finite element simulation of the device confirmed the experimental results. This analysis provides important insights to predict the trapping location, strength of the trapping, and optimum geometry for single particle trapping and its applications such as single‐molecule analysis and drug discovery.

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Comparative study of methods to calibrate the stiffness of a single-beam gradient-force optical tweezers over various laser trapping powers

Cited by 72 publications

References 98 publications

Objective-lens-free Fiber based Position Detection with Nanometer Resolution in a Fiber Optical Trapping System

Objective-lens-free Fiber based Position Detection with Nanometer Resolution in a Fiber Optical Trapping System

Experimental investigation on optical vortex tweezers for microbubble trapping

Quantitative analysis of the three‐dimensional trap stiffness of a dielectrophoretic corral trap

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