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- Roelofs, S. H., et al.
(författare)
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Calibration of trap stiffness and viscoelasticity in polymer solutions
- 2008
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Ingår i: Proc SPIE Int Soc Opt Eng. - : SPIE. - 9780819472588
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Konferensbidrag (refereegranskat)abstract
- We present an experimental demonstration of a method using optical tweezers proposed by Fischer and Berg-Sorensen for measuring viscoelasticity using optical tweezers. It is based on a sinusoidal oscillation of the liquid in combination with force measurements using optical tweezers. We verify the method by applying it to measurements in water, glycerol and polyethylene oxide (PEO).
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| 5. |
- Roelofs, S. H., et al.
(författare)
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Calibration of trap stiffness and viscoelasticity in polymer solutions - art. no. 703823
- 2008
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Ingår i: Optical Trapping and Optical Micromanipulation V. - : SPIE. - 9780819472588 ; 7038, s. 3823-3823
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Konferensbidrag (refereegranskat)abstract
- We present an experimental demonstration of a method using optical tweezers proposed by Fischer and Berg-Sorensen for measuring viscoelasticity using optical tweezers. it is based on a sinusoidal oscillation of the liquid in combination with force measurements using optical tweezers. We verify the method by applying it to measurements in water, glycerol and polyethylene oxide (PEO).
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| 6. |
- Asavei, T., et al.
(författare)
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Engineering Optically Driven Micromachines. - art. no. 703816
- 2008
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Ingår i: Optical Trapping and Optical Micromanipulation V. - 9780819472588 ; 7038, s. 3816-3816
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Konferensbidrag (refereegranskat)abstract
- Optical forces and torques acting on microscopic objects trapped in focussed laser beams promise flexible methods of driving micromachines through a microscope cover slip or even a cell wall. We are endeavouring to engineer special purpose micro-objects for a range of tasks. Colloidal self assembly of calcium carbonate provides birefringent spheres which can exert considerable torque, while two photon polymerisation allows us to fabricate objects of arbitrary shape that can be designed to exchange both spin and orbital angular momentum. Numerical calculations of forces and torques can allow an optimal design, and optical measurements provide us with certain knowledge of the forces and torques which are actually exerted.
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- Midtvedt, Daniel, et al.
(författare)
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Deep learning in light-matter interactions
- 2022
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Ingår i: Nanophotonics. - : Walter de Gruyter GmbH. - 2192-8606 .- 2192-8614. ; 11:14, s. 3189-3214
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Tidskriftsartikel (refereegranskat)abstract
- The deep-learning revolution is providing enticing new opportunities to manipulate and harness light at all scales. By building models of light-matter interactions from large experimental or simulated datasets, deep learning has already improved the design of nanophotonic devices and the acquisition and analysis of experimental data, even in situations where the underlying theory is not sufficiently established or too complex to be of practical use. Beyond these early success stories, deep learning also poses several challenges. Most importantly, deep learning works as a black box, making it difficult to understand and interpret its results and reliability, especially when training on incomplete datasets or dealing with data generated by adversarial approaches. Here, after an overview of how deep learning is currently employed in photonics, we discuss the emerging opportunities and challenges, shining light on how deep learning advances photonics.
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- Nieminen, T. A., et al.
(författare)
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Tailoring particles for optical trapping and micromanipulation: An overview
- 2008
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Ingår i: Piers 2008 Hangzhou: Progress in Electromagnetics Research Symposium, Vols I and Ii, Proceedings. - 9781934142004 ; , s. 864-868
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Konferensbidrag (refereegranskat)abstract
- Optical trapping and micromanipulation has developed from an interesting novelty to a powerful and widely used tool, with the capability to move or trap microscopic live biological specimens and measure forces on the order of piconewtons, typical of forces in microbiological systems. Despite this, the range of particles typically trapped or manipulated is quite small, and it is unusual to see applications involving objects other than biological specimens or homogeneous isotropic microspheres, typically polymer or silica. However, particles can be modified or specially fabricated to expand the possible applications of optical tweezers. For example, while non-absorbing homogeneous isotropic spheres cannot be rotated, optically anisotropic spheres can, and can therefore function as microscopic torque sensors, extending the usual translational micromanipulation and force measurement to rotational manipulation and torque sensing. The development of such particles has led to applications in microscale metrology and biophysics, along with potential deployment of optically-driven micro-machines in lab-on-a-chip devices. We present an overview of our work on the tailoring of microparticles for versatile optical trapping and micromanipulation. This includes approaches based on controlled chemistry - nano-assembly - and optical microfabrication. Beginning with the production of anisotropic vaterite microspheres, we review some. of the applications, and difficulties encountered along the way. Some of these difficulties can be overcome by coating of the vaterite microspheres. We also discuss the use of anti-reflection coating to allow strong trapping of high refractive index particles. The alternative strategy of producing arbitrarily shaped polymer microstructures through two-photon photopolymerization is also discussed. This can be used to produce optically-driven microrotors or structurally anisotropic microspheres to replace vaterites for particular applications.
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- Parkin, S. J., et al.
(författare)
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Highly birefringent vaterite microspheres: production, characterization and applications for optical micromanipulation
- 2009
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Ingår i: Optics Express. - 1094-4087. ; 17:24, s. 21944-21955
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Tidskriftsartikel (refereegranskat)abstract
- This paper reports on a simple synthesis and characterization of highly birefringent vaterite microspheres, which are composed of 20-30 nm sized nanocrystalls. Scanning electron microscopy shows a quite disordered assembly of nanocrystals within the microspheres. However, using optical tweezers, the effective birefringence of the microspheres was measured to Delta n = 0.06, which compares to Delta n = 0.1 of vaterite single crystals. This suggests a very high orientation of the nanocrystals within the microspheres. A hyperbolic model of the direction of the optical axis throughout the vaterite spherulite best fits the experimental data. Results from polarized light microscopy further confirm the hyperbolic model. (C) 2009 Optical Society of America
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| 10. |
- Vogel, R., et al.
(författare)
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Synthesis and Surface Modification of Birefringent Vaterite Microspheres
- 2009
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Ingår i: Langmuir. - 0743-7463. ; 25:19, s. 11672-11679
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Tidskriftsartikel (refereegranskat)abstract
- This paper reports on the synthesis of birefringent vaterite microspheres with narrow size distribution using a seeded growth method. In a post-treatment the microspheres were stabilized and functionalized through coating with a combination of organosilica and silica. The coating vastly enhanced the stability of the vaterite microspheres in biological buffers and allowed the attachment of biomolecules such as DNA or proteins. As an example, streptavidin was attached to the surface of the functionalized microspheres. These results pave the way for the use of birefringent vaterite particles for the micromanipulation of single biological molecules such as DNA or specific proteins in an optical trap capable of exerting and measuring torques. The stabilized birefringent microspheres may also find use for biosensor and biological screening applications.
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