scholarly journals Enhanced Signal-to-Noise and Fast Calibration of Optical Tweezers Using Single Trapping Events

Micromachines ◽  
2021 ◽  
Vol 12 (5) ◽  
pp. 570
Author(s):  
Alexander B. Stilgoe ◽  
Declan J. Armstrong ◽  
Halina Rubinsztein-Dunlop
Keyword(s):  
Brownian Motion ◽  
Optical Tweezers ◽  
Optical Trap ◽  
Force Transducer ◽  
Signal To Noise ◽  
Likelihood Estimator ◽  
Micro Fluidics ◽  
Large Numbers ◽  
Force Reconstruction ◽  
Micron Particle

The trap stiffness us the key property in using optical tweezers as a force transducer. Force reconstruction via maximum-likelihood-estimator analysis (FORMA) determines the optical trap stiffness based on estimation of the particle velocity from statistical trajectories. Using a modification of this technique, we determine the trap stiffness for a two micron particle within 2 ms to a precision of ∼10% using camera measurements at 10 kfps with the contribution of pixel noise to the signal being larger the level Brownian motion. This is done by observing a particle fall into an optical trap once at a high stiffness. This type of calibration is attractive, as it avoids the use of a nanopositioning stage, which makes it ideal for systems of large numbers of particles, e.g., micro-fluidics or active matter systems.

Measurement of Trap Stiffness of Holographic Optical Tweezers with Power Spectrum Method

2013 ◽  
Vol 787 ◽  
pp. 423-426
Author(s):  
Kai Xu ◽  
Jing Li ◽  
Gang Du ◽  
Chun Li Zhu ◽  
Peng Fei Li ◽  
...  
Keyword(s):  
Brownian Motion ◽  
Power Spectrum ◽  
Optical Tweezers ◽  
Laser Power ◽  
Optical Trap ◽  
Bottom Surface ◽  
Sample Cell ◽  
Spectrum Method ◽  
Holographic Optical Tweezers ◽  
Power Spectrum Method

A microsphere trapped by optical tweezers moves according to the Brownian motion law, which can be described by the Langevin equation. Based on it, a quadrant photodiode (QD) is used to track the displacement of the microsphere with a diameter of 2.5um trapped by holographic optical tweezers, and power spectrum method is adopted to obtain radial trap stiffness. Experiments show that the trap stiffness increases with the increase of the laser power, and decreases as the distance between the optical trap and the inside bottom surface of the sample cell increases.

scholarly journals Dynamic Analysis and Simulation of an Optically Levitated Rotating Ellipsoid Rotor in Liquid Medium

2021 ◽  
Author(s):  
Qi Zhu ◽  
Nan Li ◽  
Heming Su ◽  
Wenqiang Li ◽  
Huizhu Hu
Keyword(s):  
Dynamic Analysis ◽  
Liquid Medium ◽  
Optical Tweezers ◽  
Incident Light ◽  
Optical Trap ◽  
Future Research ◽  
Rotational Axis ◽  
Micron Particle ◽  
Three Degree Of Freedom ◽  
And Control

AbstractOptical trap, a circularly polarized laser beam can levitate and control the rotation of microspheres in liquid medium with high stiffness. Trapping force performs as confinement while the trapped particle can be analog to a liquid floated gyroscope with three degree-of-freedom. In this work, we analyzed the feasibility of applying optically levitated rotor in the system. We presented the dynamic analysis and simulation of an ellipsoid micron particle. The precession motion and nutation motion of a rotating ellipsoid probe particle in optical tweezers were performed. We also analyzed the attitude changes of an optically levitated ellipsoid when there was variation of the external torque caused by deviation of the incident light that was provided. Furthermore, the trail path of the rotational axis vertex and the stabilization process of a particle of different ellipticities were simulated. We compared the movement tendencies of particles of different shapes and analyzed the selection criteria of ellipsoid rotor. These analytical formulae and simulation results are applicable to the analysis of the rotational motion of particles in optical tweezers, especially to the future research of the gyroscope effect.

ORIENTATING MANIPULATION OF CYLINDRICAL PARTICLES WITH OPTICAL TWEEZERS

2008 ◽  
Vol 17 (04) ◽  
pp. 387-394 ◽  
Author(s):  
XIUDONG SUN ◽  
XUECONG LI ◽  
JIANLONG ZHANG
Keyword(s):  
Escherichia Coli ◽  
Carbon Nanotubes ◽  
Laser Beam ◽  
Optical Tweezers ◽  
Optical Trap ◽  
Polarization Direction ◽  
Beam Shape ◽  
E Coli ◽  
Potential Applications ◽  
Cylindrical Particles

Orientating manipulations of cylindrical particles were performed by optical tweezers. Vertical and horizontal manipulations of Escherichia coli (E. coli) were carried out by changing the trapping depth and the focused laser beam shape. It was found that carbon nanotubes bundles (CNTBs) could be rotated in the linear polarized optical trap until it orientated its long axis along the linear polarization direction of the laser beam. However, E.coli could not be orientated in this way. Corresponding mechanisms were discussed based on the anisomeric electric characters of CNTBs. These orientation technologies of cylindrical objects with optical trap have potential applications in assembling nano-electric devices.

Large deviations and Berry–Esseen inequalities for estimators in nonhomogeneous diffusion driven by fractional Brownian motion

2020 ◽  
Vol 28 (3) ◽  
pp. 183-196
Author(s):  
Kouacou Tanoh ◽  
Modeste N’zi ◽  
Armel Fabrice Yodé
Keyword(s):  
Differential Equation ◽  
Brownian Motion ◽  
Maximum Likelihood ◽  
Large Deviations ◽  
Stochastic Differential Equation ◽  
Fractional Brownian Motion ◽  
Maximum Likelihood Estimator ◽  
Bayes Estimator ◽  
Likelihood Estimator

AbstractWe are interested in bounds on the large deviations probability and Berry–Esseen type inequalities for maximum likelihood estimator and Bayes estimator of the parameter appearing linearly in the drift of nonhomogeneous stochastic differential equation driven by fractional Brownian motion.

scholarly journals Myosin VI: cellular functions and motor properties

2004 ◽  
Vol 359 (1452) ◽  
pp. 1931-1944 ◽  
Author(s):  
K. C. Holmes ◽  
D. R. Trentham ◽  
R. Simmons ◽  
Rhys Roberts ◽  
Ida Lister ◽  
...  
Keyword(s):  
Optical Tweezers ◽  
Leading Edge ◽  
Force Transducer ◽  
Myosin Vi ◽  
Cellular Functions ◽  
Electron Microscopic ◽  
Coated Pits ◽  
Microscopic Studies ◽  
Golgi Network

Myosin VI has been localized in membrane ruffles at the leading edge of cells, at the trans–Golgi network compartment of the Golgi complex and in clathrin–coated pits or vesicles, indicating that it functions in a wide variety of intracellular processes. Myosin VI moves along actin filaments towards their minus end, which is the opposite direction to all of the other myosins so far studied (to our knowledge), and is therefore thought to have unique properties and functions. To investigate the cellular roles of myosin VI, we identified various myosin VI binding partners and are currently characterizing their interactions within the cell. As an alternative approach, we have expressed and purified full–length myosin VI and studied its in vitro properties. Previous studies assumed that myosin VI was a dimer, but our biochemical, biophysical and electron microscopic studies reveal that myosin VI can exist as a stable monomer. We observed, using an optical tweezers force transducer, that monomeric myosin VI is a non–processive motor which, despite a relatively short lever arm, generates a large working stroke of 18 nm. Whether monomer and/or dimer forms of myosin VI exist in cells and their possible functions will be discussed.

Myosin VI: a multifunctional motor

2004 ◽  
Vol 32 (5) ◽  
pp. 685-688 ◽  
Author(s):  
I. Lister ◽  
R. Roberts ◽  
S. Schmitz ◽  
M. Walker ◽  
J. Trinick ◽  
...  
Keyword(s):  
Optical Tweezers ◽  
Actin Filaments ◽  
Biochemical Characterization ◽  
Force Transducer ◽  
The Other ◽  
Myosin Vi ◽  
Coated Pits ◽  
Binding Partners ◽  
Alternative Approach

Myosin VI moves towards the minus end of actin filaments unlike all the other myosins so far studied, suggesting that it has unique properties and functions. Myosin VI is present in clathrin-coated pits and vesicles, in membrane ruffles and in the Golgi complex, indicating that it has a wide variety of functions in the cell. To investigate the cellular roles of myosin VI, we have identified a variety of myosin VI-binding partners and characterized their interactions. As an alternative approach, we have studied the in vitro properties of intact myosin VI. Previous studies assumed that myosin VI existed as a dimer but our biochemical characterization and electron microscopy studies reveal that myosin VI is a monomer. Using an optical tweezers force transducer, we showed that monomeric myosin VI is a non-processive motor with a large working stroke of 18 nm. Potential roles for myosin VI in cells are discussed.

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