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Golden nanoparticle in optical tweezers: influence of shape and orientation on optical trapping
Šiler, Martin ; Brzobohatý, Oto ; Chvátal, Lukáš ; Karásek, Vítězslav ; Paták, Aleš ; Pokorná, Zuzana ; Mika, Filip ; Zemánek, Pavel
Noble metal nanoparticles (NPs) have attracted increased attention in recent years due to various applications of resonant collective oscillations of free electrons excited with light (plasmon resonance). In contrast to bulk metal materials, where this plasmon resonance frequency depends only on the free electron number density, the optical response of gold and silver NPs can be tuned over the visible and near-infrared spectral region by the size and shape of the NP. Precise and remote placement and orientation of NPs inside cells or tissue would provide another degree of control for these applications. A single focused laser beam – optical tweezers – represents the most frequently used arrangement which provides threedimensional (3D) contact-less manipulation with dielectric objects or living cells ranging in size from tens of nanometers to tens of micrometers. It was believed that larger metal NPs behave as tiny mirrors that are pushed by the light beam radiative force along the direction of beam propagation, without a chance to be confined. However, recently several groups have reported successful optical trapping of gold and silver particles as large as 250 nm. We\noffer an explanation based on the fact that metal nanoparticles naturally occur in various nonspherical\nshapes, and their optical properties differ significantly due to changes in localized plasmon excitation.
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From the mere pushing to sorting of microparticles and assembly of microrobots by light
Zemánek, Pavel ; Arzola, Alejandro V. ; Brzobohatý, Oto ; Chvátal, Lukáš ; Jákl, Petr ; Kaňka, Jan ; Karásek, Vítězslav ; Šerý, Mojmír ; Šiler, Martin
We demonstrate the recent progress in the field of optical micromanipulation. We start with the classical applications of solar sail propelled by the radiation pressure and approach the recent ones dealing with optical tractor beams, optical binding and sorting of microobjects. The pioneering attempts to assemble a microrobot by light is presented.
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Classical and advanced methods of optical micromanipulations and their applications
Zemánek, Pavel ; Brzobohatý, Oto ; Šiler, Martin ; Karásek, Vítězslav ; Samek, Ota ; Jákl, Petr ; Šerý, Mojmír ; Ježek, Jan
Optical micro-manipulation techniques have been using for more than 30 years to transfer the momentum from light to microparticles or nanoparticles and influence their movement in liquid, on the surface, or in the air. These days such techniques become more developed and frequently used in physics, chemistry and biology to manipulate, trap, rotate, or sort various types of objects, including living cells in a contactless and gentle way.
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Pokročilé techniky optických mikromanipulací
Zemánek, Pavel ; Čižmár, Tomáš ; Šiler, Martin ; Jákl, Petr ; Šerý, Mojmír ; Karásek, Vítězslav ; Brzobohatý, Oto
Nowadays the classical tool of optical micro-manipulations - optical tweezers - found numerous applications in physics, biology and chemistry. However new techniques were developed that used more sophisticated laser beam tailoring and enable to modify positions and number of manipulated objects dynamically, to sort optically objects according to their properties, to deliver them over millimetre long distances or even to let them self-organize after light illumination. We present several results dealing with the above mentioned advanced techniques developed in our laboratory.
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