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    Measuring viscoelastic properties of Red Blood Cell using optical tweezers

    , Article Iranian Journal of Physics Research ; Volume 19, Issue 1 , 2019 , Pages 101-108 ; 16826957 (ISSN) Seyed Reihani, S. N ; Azadbakht, A ; Mirzahossein, E ; Mottaghian, M ; Babaei, M ; Sharif University of Technology
    Isfahan University of Technology  2019
    Abstract
    Efforts have been made to study the behavior of complex materials in micrometer dimensions with various techniques. One of these methods is the use of optical tweezers for biophysical applications. Red blood cells, as the most abundant blood-forming cells, play an important role in the life of living organisms, and their unique mechanical properties are important. In this report, the study of soft materials is done using light tweezers. This work investigates micrometer particle movements in the optical trap and also, when they are connected to a red blood cell. The tweezers allow the Newtonian fluid viscosity, such as water and glycerin, to measure the mechanical properties of viscoelastic... 

    Measuring viscoelastic properties of Red Blood Cell using optical tweezers

    , Article Iranian Journal of Physics Research ; Volume 19, Issue 1 , 2019 , Pages 101-108 ; 16826957 (ISSN) Seyed Reihani, S. N ; Azadbakht, A ; Mirzahossein, E ; Mottaghian, M ; Babaei, M ; Sharif University of Technology
    Isfahan University of Technology  2019
    Abstract
    Efforts have been made to study the behavior of complex materials in micrometer dimensions with various techniques. One of these methods is the use of optical tweezers for biophysical applications. Red blood cells, as the most abundant blood-forming cells, play an important role in the life of living organisms, and their unique mechanical properties are important. In this report, the study of soft materials is done using light tweezers. This work investigates micrometer particle movements in the optical trap and also, when they are connected to a red blood cell. The tweezers allow the Newtonian fluid viscosity, such as water and glycerin, to measure the mechanical properties of viscoelastic... 

    Non-Parametric Analysis of Positional data of a Micro-Nano Sphere Trapped by Optical Tweezers

    , M.Sc. Thesis Sharif University of Technology Mousavi Kolkasaraei, Mahdiyeh (Author) ; Reihani, Nader (Supervisor) ; Rahimi Tabar, Mohammad Reza (Supervisor)
    Abstract
    Optical tweezers consist of a tightly focused laser beam. A particle with refractive index greater than that of the surrounding medium can be trapped at the focus of the laser. The trapped object experiences a three-dimensional Hookean restoring force towards the focus. Nano (micron)-sized spheres can produce forces in the range of few pico-newton to few nano-newton. This range covers a large number of the forces, which contribute in biological processes; therefore, optical tweezers are very often used for micromanipulation of biological tissues. In a typical micromanipulation experiment it is crucial to perform proper positional calibration prior to use. There are several calibrate methods... 

    Study of Viscoelastic Property of Fluid with Optical Tweezers

    , M.Sc. Thesis Sharif University of Technology Mirzahossein, Elham (Author) ; Seyed Reihani, Nader (Supervisor)
    Abstract
    Viscoelastic properties of biological fluid play an important role on biological organs. As an example we all know that Red blood cells must have high flexibility to pass thorough thin capillary.This high flexibility come partially from cytoplasm and 2 dimensional membrane and partially from polymeric fluid inside the cell(hemoglobin). So, for recognizing mechanical properties of a whole cell we also need to study the same properties just for fluid inside the cell. for this general purpose through this project we are going to measure viscoelastic properties of any polymeric fluid by optical tweezers which has an ability for measuring displacement of micron particle with accuracy of nm. first... 

    Efficient elimination of cross-talk in dual-beam optical tweezers by spatial filtering

    , Article Optical Molecular Probes, Imaging and Drug Delivery, OMP 2013, Waikoloa Beach, HI ; 14-18 April , 2013 ; 9781557529664 (ISBN) Ott, D ; Reihani, S. N. S ; Oddershede, L. B ; Sharif University of Technology
    2013
    Abstract
    In dual-beam optical traps, the precision of position/force measurements is often compromised by crosstalk, i.e. imperfect separation of the two signals. We devise a simple yet very efficient method to perform crosstalk eliminating spatial filtering  

    Axial position detection for optical tweezers based on Moiré Deflectometry

    , Article Optics Communications ; Volume 446 , 2019 , Pages 33-38 ; 00304018 (ISSN) Khorshad, A. A ; S. Reihani, S. N ; Sharif University of Technology
    Elsevier B.V  2019
    Abstract
    Optical tweezers are indispensable instruments for applying and measuring Pico-Newton range forces. The magnitude of the exerted force is determined by measuring the displacement of the trapped bead from the center of the trap. Recently, we developed a new detection system for optical tweezers based on Moiré Deflectometry (MD). In this work, we show, both theoretically and experimentally, that the introduced method can be used for detection in the axial direction, as well, with a significantly larger sensitivity compared to the commonly used QPD method. As an example, for a 2.17μm polystyrene bead this method could provide a sensitivity 285% larger than that of the QPD method. © 2019... 

    Measuring Dielectrophoresis Force Excerted on Polystyrene Micro-Beads using Optical Tweezers

    , M.Sc. Thesis Sharif University of Technology Mollaei, Parisa (Author) ; Seyyed Reihani, Nader (Supervisor)
    Abstract
    The base of dielectrophoresis(DEP) technique has been demonstrated through electro-dynamic interactions between an applied non-uniform AC electric field and induced distributed dipoles within a polarized. In particle manipulation and/or separation using the DEP method, knowledge of precise DEP force of a particle is essential in designing a DEP device and improving its separation efficiency and accuracy. In most DEP studies related to particle manipulation and/or separation, however their absolute DEP forces remain unknown[2]. Insufficient information regarding the DEP behavior of particles can result in preventing a strategic maneuver for efficient particle manipulation and/or separation... 

    Investigation of Mechanical Properties of Healthy Red Blood Cells using Optical Tweezers

    , M.Sc. Thesis Sharif University of Technology Azadbakht, Ali (Author) ; Seyed Reihani, Nader (Supervisor) ; Moosavi-Movahhedi, Ali Akbar (Co-Advisor)
    Abstract
    Red blood cells (RBC, erythrocytes) are cells with an average diameter of 8 microns, the thickness of 2-3 microns and the volume of 90 fl. The biconcave shape of red blood cells,together with cell membrane flexibility, enables them to pass the capillaries whose diameter is considerably less than 8 micrometers. Mechanical properties of RBC are related to their membrane and cytoskeleton, which consists of spectrin network. Optical tweezers is able to exert very precise forces to erythrocytes using beed as a handle. In this report, we studied mechanical properties of RBC such as elasticity and viscoelasticity using single trap optical tweezers with beads with antibody coated in order to attach... 

    Investigating the Effect of Hemoglobin on Viscoelastic Properties of RBC

    , M.Sc. Thesis Sharif University of Technology Felekary, Arash (Author) ; Seyed Reihani, Nader (Supervisor)
    Abstract
    Red blood cells are one of the most important parts of blood and their mechanical properties are so important in some diseases. Red blood cell is mostly consisted of membrane, cell skeleton, and cytoplasm which contains hemoglobin proteins. Studying these properties separately not only could give us pieces of information about cell mechanics, but also reveals a way to predict their behavior after illnesses. Optical tweezers as a tool, which can produce and measure Piconewton to Nanonewton forces, has been interesting in red blood cell parts' studying. In this thesis, at first hemoglobin is taken out gradually by using Saponin (which is enable to make some pores in the membrane) and the... 

    The Effect of Thyroid Hormones on The Viscoelastic Behavior of Red Blood Cells

    , M.Sc. Thesis Sharif University of Technology Laktarash, Shaghayegh (Author) ; Seyed Reihani, Nader (Supervisor)
    Abstract
    Blood is one of the most important fluids in the human body, consisting of three parts: red blood cells, white blood cells and platelets. The mechanical properties of red blood cells are important in many diseases. The study of viscosity and other mechanical properties of red blood cells in recent years has attracted the attention of scientists in this field. The mechanical properties of red blood cells are related to the outer membrane and its cytoskeleton, and the study of these components can predict the behavior of red blood cells in diseases. The thyroid gland is located in front of the neck and secretes hormones that control many chemical processes in different parts of the body.... 

    Axial potential mapping of optical tweezers for biopolymer stretching: The bead size matters

    , Article Optics Letters ; Volume 38, Issue 5 , 2013 , Pages 685-687 ; 01469592 (ISSN) Ahmadi, A ; Reihani, S. N. S ; Sharif University of Technology
    2013
    Abstract
    Optical tweezers (OT) are widely used for pico (and femto)-Newton range force measurements. The appropriate choice of the bead size is not well understood for biopolymer stretching applications of OT. We have shown, both by theory and experiment, that wrong choice of the bead size could cause errors as large as 295% in the measured force. We provide a simple map for correct choice of the bead size and the direction of pulling for such applications. There is a good agreement between our theoretical and experimental results  

    Enhancement of axial force of optical tweezers by utilizing a circular stop at the back focal plane of the objective

    , Article Journal of the Optical Society of America B: Optical Physics ; Volume 35, Issue 11 , 2018 , Pages 2654-2660 ; 07403224 (ISSN) Gorjizadeh Alinezhad, H ; Meydanloo, S ; Reihani, S. N ; Sharif University of Technology
    OSA - The Optical Society  2018
    Abstract
    Optical tweezers are indispensable force spectroscopes. The trap stiffness and the linear force range of the instrument determine the working force range of the instrument. Here we show both theoretically and experimentallythat utilizing a circular obstruction at the back focal plane of the objective can significantly increase the maximumlinear force. For instance, utilizing a disk with an obstruction ratio of 0.773 could increase the maximum linearforce by a factor of ∼39 when a 3.4 μm polystyrene bead is trapped. We also show that this simple beam shapingmethod can significantly improve the maximum applicable force per unit power of the laser entering the objectivelens. © 2018 Optical... 

    Evaluating the toxic effect of an antimicrobial agent on single bacterial cells with optical tweezers

    , Article Biomedical Optics Express ; Volume 6, Issue 1 , 2015 , Pages 112-117 ; 21567085 (ISSN) Samadi, A ; Zhang, C ; Chen, J ; Reihani, S. N. S ; Chen, Z ; Sharif University of Technology
    OSA - The Optical Society  2015
    Abstract
    We implement an optical tweezers technique to assess the effects of chemical agents on single bacterial cells. As a proof of principle, the viability of a trapped Escherichia coli bacterium is determined by monitoring its flagellar motility in the presence of varying concentrations of ethyl alcohol. We show that the “killing time” of the bacterium can be effectively identified from the correlation statistics of the positional time series recorded from the trap, while direct quantification from the time series or associated power spectra is intractable. Our results, which minimize the lethal effects of bacterial photodamage, are consistent with previous reports of ethanol toxicity that used... 

    Passive Measurement of Viscoelastic Properties of the Healthy Red Blood Cell by Optical Tweezers

    , M.Sc. Thesis Sharif University of Technology Motaghian, Melika (Author) ; Seyyed Reihani, Nader (Supervisor)
    Abstract
    Blood is one of the most important biological organs. Red blood cell (RBC), as the most abundant cell of blood, plays an important role at life of the living bodies. Unique mechanical properties of RBCs enable them to pass through very narrow vessels. Any abnormality in these mechanical properties will disorder the function of the cell and many diseases affect these properties too. Studying the mechanical properties of RBCs is very importantin that it could result in a disease diagnostic method in a single-cell level. In this thesis we have tried to measure the viscoelastic properties of a single RBC by an optical trap through a passive method. This measurement is made through studying the... 

    Creating Double Optical Trap Using Fresnel Lens

    , M.Sc. Thesis Sharif University of Technology Farajian, Mahboubeh (Author) ; Seyed Reihani, Nader (Supervisor)
    Abstract
    Intensity or phase Modulation of a wavefront is possible by means of optical devices. Placing a grating or lens on the way of a wavefront, will alter the phase or intensity of it and this will make a diffraction pattern. Spatial Light Modulator (SLM) is an optical device which is the most important part of a video projector. One can apply grating, lens and other phases on the wavefront using this device.In this project we used SLM to modify phase of laser beam and then we made many focal points such that they could displace independently. The result of this project can be used in designing and creating a holographic optical tweezers.Moreover, A. Einstein proved that the light could be... 

    Trapping, Levitation, and Optomechanics of Nanoparticles

    , Ph.D. Dissertation Sharif University of Technology Jazayeri, Amir Mohammad (Author) ; Mehrany, Khashayar (Supervisor)
    Abstract
    The electromagnetic (EM) force is the pivot on which this thesis revolves. We inspect different formulations of the distribution of the EM force (and momentum) inside matter, and show that the Einstein-Laub force density is incompatible with special relativity. We study the exerted EM force on small particles in depth, and explain when the conventional dipole approximation fails to yield accurate results. We propose an all-dielectric structure which is able to trap very small dielectric particles (of diameters as small as 10 nm). One of the achievements of this thesis is an explanation for an adverse phenomenon observed in many experiments on the optomechanical systems employing... 

    Designing and Developing an Active Micromixer Based on Optical Tweezers for Microfluidics

    , M.Sc. Thesis Sharif University of Technology Taheri, Saeed (Author) ; Seyed Reihani, Nader (Supervisor)
    Abstract
    Microfluidics is a field of science that studies micron-scale characteristics of fluids. In this scale fluids show fascinating behavior far beyond our expectation compared to their large-scale counterparts. One of such peculiar behavior is the mixing of two different liquids flowing inside a microchannel. Due to low Reynolds number, the flow inside such a channel would be dominated by laminar behavior. In this regime mixing of the fluids is only mediated by molecular diffusion which is a rather slow process. In the current thesis, we utilized the rotating ability of optical tweezers to construct an active micromixer for Microfluidics. In order to do this we used birefringent microbeads. The... 

    Study of Viscoelastic Properties of Biopolymer Solutions

    , M.Sc. Thesis Sharif University of Technology Shahmoradi, Mohammad Reza (Author) ; Seyed Reihani, Nader (Supervisor)
    Abstract
    Properties of viscoelastic of biopolymers have important role in cells structure; for example: cell motility depends on viscoelastic propertie of Actin polymer. therefore according to its importance ,in this thesis we intend to examine the viscoelastic modulus using Optical tweezers and dissipation theorem.this method is benefits than methods of active microrheology. for example this method can be used for low concentrations; because in the low concentrations, the exerting force will cause changing in the state of matter that here we investigate destructive force effect. we investigate viscoelastic of water for method accuracy then obtain viscoelastic of Kelcogel  

    Tube length-assisted optimized aerosol trapping

    , Article Optics Communications ; Vol. 329, issue , 2014 , pp. 196-199 ; ISSN: 00304018 Taheri, S. M. R ; Sadeghi, M ; Madadi, E ; S. Reihani, S. N ; Sharif University of Technology
    Abstract
    Trapping a single aerosol using optical tweezers could be of great importance for environmental sciences. Though a single nanoparticle as small as 10 nm is successfully trapped in aqueous media using optical tweezers, due to spherical aberration only large clusters of nanoparticles were stably trapped in air. In this paper we provide our theoretical and experimental results on optimized trapping of aerosols as small as 400 nm in radius by the introduction of an extra spherical aberration source in order to minimize the total spherical aberration of the system. Our method allows for trapping of high refractive index particles such as polystyrene beads in air. It also provides considerably... 

    Crosstalk elimination in the detection of dual-beam optical tweezers by spatial filtering

    , Article Review of Scientific Instruments ; Volume 85, Issue 5 , May , 2014 ; ISSN: 00346748 Ott, D ; Reihani, S. N. S ; Oddershede, L. B ; Sharif University of Technology
    Abstract
    In dual-beam optical tweezers, the accuracy of position and force measurements is often compromised by crosstalk between the two detected signals, this crosstalk leading to systematic and significant errors on the measured forces and distances. This is true both for dual-beam optical traps where the splitting of the two traps is done by polarization optics and for dual optical traps constructed by other methods, e.g., holographic tweezers. If the two traps are orthogonally polarized, most often crosstalk is minimized by inserting polarization optics in front of the detector; however, this method is not perfect because of the de-polarization of the trapping beam introduced by the required...