Micro-Dumbbells—A Versatile Tool for Optical Tweezers

Author(s):

Weronika Lamperska, Sławomir Drobczyński, Michał Nawrot, Piotr Wasylczyk, Jan Masajada

Abstract:

“Manipulation of micro- and nano-sized objects with optical tweezers is a well-established, albeit still evolving technique. While many objects can be trapped directly with focused laser beam(s), for some applications indirect manipulation with tweezers-operated tools is preferred. We introduce a simple, versatile micro-tool operated with holographic optical tweezers. The 40 µm long dumbbell-shaped tool, fabricated with two-photon laser 3D photolithography has two beads for efficient optical trapping and a probing spike on one end. We demonstrate fluids viscosity measurements and vibration detection as examples of possible applications.”

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Publication: Micromachines
Issue/Year: Micromachines Volume 9, Issue 6
DOI: 10.3390/mi9060277

Particle trapping and conveying using an optical Archimedes’ screw

Author(s):

Barak Hadad and Sahar Froim and Harel Nagar and Tamir Admon and Yaniv Eliezer and Yael Roichman and Alon Bahabad

Abstract:

“Trapping and manipulation of particles using laser beams has become an important tool in diverse fields of research. In recent years, particular interest has been devoted to the problem of conveying optically trapped particles over extended distances either downstream or upstream of the direction of photon momentum flow. Here, we propose and experimentally demonstrate an optical analog of the famous Archimedes’ screw where the rotation of a helical-intensity beam is transferred to the axial motion of optically trapped micrometer-scale, airborne, carbon-based particles. With this optical screw, particles were easily conveyed with controlled velocity and direction, upstream or downstream of the optical flow, over a distance of half a centimeter. Our results offer a very simple optical conveyor that could be adapted to a wide range of optical trapping scenarios.”

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Publication: Optica
Issue/Year: Optica Vol. 5, Issue 5, pp. 551-556 (2018)
DOI: 10.1364/OPTICA.5.000551

Investigation of albumin-derived perfluorocarbon-based capsules by holographic optical trapping

Author(s):

Jannis Köhler and Jegor Ruschke and Katja Bettina Ferenz and Cemal Esen and Michael Kirsch and Andreas Ostendorf

Abstract:

“Albumin-derived perfluorocarbon-based capsules are promising as artificial oxygen carriers with high solubility. However, these capsules have to be studied further to allow initial human clinical tests. The aim of this paper is to provide and characterize a holographic optical tweezer to enable contactless trapping and moving of individual capsules in an environment that mimics physiological (in vivo) conditions most effectively in order to learn more about the artificial oxygen carrier behavior in blood plasma without recourse to animal experiments. Therefore, the motion behavior of capsules in a ring shaped or vortex beam is analyzed and optimized on account of determination of the optical forces in radial and axial direction. In addition, due to the customization and generation of dynamic phase holograms, the optical tweezer is used for first investigations on the aggregation behavior of the capsules and a statistical evaluation of the bonding in dependency of different capsule sizes is performed. The results show that the optical tweezer is sufficient for studying individual perfluorocarbon-based capsules and provide information about the interaction of these capsules for future use as artificial oxygen carriers.”

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Publication: Biomed. Opt. Express
Issue/Year: Biomedical Optics Express Vol. 9,Issue 2, pp. 743-754(2018)
DOI: 10.1364/BOE.9.000743

Rotating of low-refractive-index microparticles with a quasi-perfect optical vortex

Author(s):

Yansheng Liang and Ming Lei and Shaohui Yan and Manman Li and Yanan Cai and Zhaojun Wang and Xianghua Yu and Baoli Yao

Abstract:

“Low-refractive-index microparticles, such as hollow microspheres, have shown great significance in some applications, such as biomedical sensing and targeted drug delivery. However, optical trapping and manipulation of low-refractive-index microparticles are challenging, owing to the repelling force exerted by typical optical traps. In this paper, we demonstrated optical trapping and rotating of large-sized low-refractive-index microparticles by using quasi-perfect optical vortex (quasi-POV) beams, which were generated by Fourier transform of high-order quasi-Bessel beams. Numerical simulation was carried out to characterize the focusing property of the quasi-POV beams. The dynamics of low-refractive-index microparticles in the quasi-POV with various topological charges was investigated in detail. To improve the trapping and rotating performances of the vortex, a point trap was introduced at the center of the ring. Experimental results showed that the quasi-POV was preferable for manipulation of large-sized low-refractive-index microparticles, with its control of the particles’ rotating velocity dependent only on the topological charge due to the unchanged orbital radius.”

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Publication: Applied Optics
Issue/Year: Applied Optics Volume 57, Issue 1 pp. 79-84
DOI: 10.1364/ao.57.000079

Fast label-free microscopy technique for 3D dynamic quantitative imaging of living cells

Author(s):

José A. Rodrigo, Juan M. Soto, and Tatiana Alieva

Abstract:

“The refractive index (RI) is an important optical characteristic that is often exploited in label-free microscopy for analysis of biological objects. A technique for 3D RI reconstruction of living cells has to be fast enough to capture the cell dynamics and preferably needs to be compatible with standard wide-field microscopes. To solve this challenging problem, we present a technique that provides fast measurement and processing of data required for real-time 3D visualization of the object RI. Specifically, the 3D RI is reconstructed from the measurement of bright-field intensity images, axially scanned by a high-speed focus tunable lens mounted in front of a sCMOS camera, by using a direct deconvolution approach designed for partially coherent light microscopy in the non-paraxial regime. Both the measurement system and the partially coherent illumination, that provides optical sectioning and speckle-noise suppression, enable compatibility with wide-field microscopes resulting in a competitive and affordable alternative to the current holographic laser microscopes. Our experimental demonstrations show video-rate 3D RI visualization of living bacteria both freely swimming and optically manipulated by using freestyle laser traps allowing for their trapping and transport along 3D trajectories. These results prove that is possible to conduct simultaneous 4D label-free quantitative imaging and optical manipulation of living cells, which is promising for the study of the cell biophysics and biology.”

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Publication: Optics Express
Issue/Year: Optics Express Volume 8, Issue 12
DOI: 10.1364/BOE.8.005507

In situ single-atom array synthesis using dynamic holographic optical tweezers.

Author(s):

Kim, Hyosub and Lee, Woojun and Lee, Han-gyeol and Jo, Hanlae and Song, Yunheung and Ahn, Jaewook

Abstract:

“Establishing a reliable method to form scalable neutral-atom platforms is an essential cornerstone for quantum computation, quantum simulation and quantum many-body physics. Here we demonstrate a real-time transport of single atoms using holographic microtraps controlled by a liquid-crystal spatial light modulator. For this, an analytical design approach to flicker-free microtrap movement is devised and cold rubidium atoms are simultaneously rearranged with 2N motional degrees of freedom, representing unprecedented space controllability. We also accomplish an in situ feedback control for single-atom rearrangements with the high success rate of 99% for up to 10?µm translation. We hope this proof-of-principle demonstration of high-fidelity atom-array preparations will be useful for deterministic loading of N single atoms, especially on arbitrary lattice locations, and also for real-time qubit shuttling in high-dimensional quantum computing architectures.”

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Publication: Nature Communications
Issue/Year: Nature Communications, volume 7, Article number: 13317 (2016)
DOI: 10.1038/ncomms13317

Dark-hollow optical beams with a controllable shape for optical trapping in air

Author(s):

Porfirev, A. P. & Skidanov, R. V.

Abstract:

“A technique for generating dark-hollow optical beams (DHOBs) with a controllable cross-sectional intensity distribution is proposed and studied both theoretically and experimentally. Superimposed Bessel beams were used to generate such DHOBs. Variation of individual beam parameters enables the generation of Bessel-like non-diffracting beams. This technique allows the design of transmission functions for elements that shape both non-rotating and rotating DHOBs. We demonstrate photophoresis-based optical trapping and manipulation of absorbing air-borne nanoclusters with such beams.”

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Publication: Optics Express
Issue/Year: Optics Express, Volume 23; Number 7; Pages 8373; 2015
DOI: 10.1364/oe.23.008373

Optically driven pumps and flow sensors for microfluidic systems

Author(s): H Mushfique, J Leach, R Di Leonardo, M J Padgett, J M Cooper

Abstract:

“This paper describes techniques for generating and measuring fluid flow in microfluidic devices. The first technique is for the multi-point measurement of fluid flow in microscopic geometries. The flow sensing method uses an array of optically trapped microprobe sensors to map out the fluid flow. The optical traps are alternately turned on and off such that the probe particles are displaced by the flow of the surrounding fluid and then retrapped. The particles’ displacements are monitored by digital video microscopy and directly converted into velocity field values. The second is a method for generating flow within a microfluidic channel using an optically driven pump. The optically driven pump consists of two counter-rotating birefringent vaterite particles trapped within a microfluidic channel and driven using optical tweezers. The transfer of spin angular momentum from a circularly polarized laser beam causes the particles to rotate at up to 10 Hz. The pump is shown to be able to displace fluid in microchannels, with flow rates of up to 200 m-3 s-1 (200 fL s-1). In addition a flow sensing method, based upon the technique mentioned above, is incorporated into the system in order to map the magnitude and direction of fluid flow within the channel.”

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Publication: Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science
Issue/Year: Journal of Mechanical Engineering Science, Volume 222, Number 5 / 2008, Pages 829-837
DOI: 10.1243/09544062JMES760

Optical tweezers of programmable shape with transverse scattering forces

Author(s): Alexander Jesacher, Christian Maurer, Severin Fuerhapter, Andreas Schwaighofer, Stefan Bernet, Monika Ritsch-Marte

Abstract:

“We propose a non-holographic method to create line traps of arbitrary shape in the sample plane. Setting the phase gradient along theses lines gives control over the transverse forces acting on the confined particles. Phase structures, displayed on a spatial light modulator, are optically processed by a spiral phase filter and imaged onto the object plane of a microscope objective. The resulting bright line structures can be used to trap microparticles. Additionally, they exert transverse scattering forces, which can be exploited for inducing orbital motions or for creating “attracting” or “repelling” points, respectively. We give theoretical and experimental evidence that these scattering forces are proportional to the curvature of the line tweezers.”

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Publication:Optics Communications
Issue/Year: Optics Communications, Volume 281, Issue 8, 15 April 2008, Pages 2207-2212
DOI: 10.1016/j.optcom.2007.12.042

Full phase and amplitude control of holographic optical tweezers with high efficiency

Author(s): Alexander Jesacher, Christian Maurer, Andreas Schwaighofer, Stefan Bernet, and Monika Ritsch-Marte

Abstract:

“Recently we demonstrated the applicability of a holographic method for shaping complex wavefronts to spatial light modulator (SLM) systems. Here we examine the potential of this approach for optical micromanipulation. Since the method allows one to shape both amplitude and phase of a trapping light field independently and thus provides full control over scattering and gradient forces, it extends the possibilities of commonly used holographic tweezers systems. We utilize two cascaded phase-diffractive elements which can actually be display side-by-side on a single programmable phase modulator. Theoretically the obtainable light efficiency is close to 100%, in our case the major practical limitation arises from absorption in the SLM. We present data which demonstrate the ability to create user-defined “light pathways” for microparticles driven by transverse radiation pressure.”

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Publication: Optics Express
Issue/Year: Optics Express, Vol. 16, Issue 7, pp. 4479-4486, 2008
DOI: 10.1364/OE.16.004479