Particle Manipulation Based on Optically Controlled Free Surface Hydrodynamics

Varanakkottu, Subramanyan Namboodiri; George, Sajan D.; Baier, Tobias; Hardt, Steffen; Ewald, Martina; Biesalski, Markus

doi:10.1002/anie.201302111

Cited by 59 publications

(58 citation statements)

References 25 publications

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“…Several techniques have been developed to control bead motion, based on optical tweezers, [1][2][3] electromagnetic tweezers, 4,5 dielectrophoresis, 6,7 acoustic traps, 8,9 and on-chip micromagnets. [10][11][12][13][14][15] In particular, the ability to control large numbers of beads in parallel, by employing an external field and magnetizable features patterned in substrates, shows high potential for remotely organizing single particles and cells on on-chip.…”

Section: Introductionmentioning

confidence: 99%

Dynamic trajectory analysis of superparamagnetic beads driven by on-chip micromagnets

Abedini-Nassab

Lim

et al. 2015

Journal of Applied Physics

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We investigate the non-linear dynamics of superparamagnetic beads moving around the periphery of patterned magnetic disks in the presence of an in-plane rotating magnetic field. Three different dynamical regimes are observed in experiments, including (1) phase-locked motion at low driving frequencies, (2) phase-slipping motion above the first critical frequency f c1 , and (3) phase-insulated motion above the second critical frequency f c2 . Experiments with Janus particles were used to confirm that the beads move by sliding rather than rolling. The rest of the experiments were conducted on spherical, isotropic magnetic beads, in which automated particle position tracking algorithms were used to analyze the bead dynamics. Experimental results in the phase-locked and phaseslipping regimes correlate well with numerical simulations. Additional assumptions are required to predict the onset of the phase-insulated regime, in which the beads are trapped in closed orbits; however, the origin of the phase-insulated state appears to result from local magnetization defects. These results indicate that these three dynamical states are universal properties of bead motion in non-uniform oscillators. V C 2015 AIP Publishing LLC. [http://dx

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Section: Introductionmentioning

confidence: 99%

Dynamic trajectory analysis of superparamagnetic beads driven by on-chip micromagnets

Abedini-Nassab

Lim

et al. 2015

Journal of Applied Physics

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“…As the paper reported by S.N. Varanakkottu, et al, the inward flow are induced when Az compound are dissolved in water and irradiated with UV light, which is supported by the gradient in surface tension between the difference of trans-form and cis-form Az [9]. Similarly, the gradient in surface tension can also be used to control the motion of glass rods in Az-doped polyethylene glycol films, as found by Su Ma et al [10].…”

Section: Introductionmentioning

confidence: 67%

“…In addition, the moved glass rods dispersed around the irradiated area could almost move back to the original position when being exposed to dark condition for some time, whose reversible motion behavior was not available for the glass rods dispersed in the irradiated area. According to our previous work [8,9,12], it was suggested that the phase transition supported the main driving force for the motion behavior of glass rods placed around the irradiated area. Since monodirectional cis-trans isomerization can be induced by UV light, irradiation with UV light was carried out to investigate the viscosity changes.…”

Section: Tab1 Effects Ofmentioning

confidence: 92%

See 1 more Smart Citation

Light-induced Phase Transition of Lyotropic Liquid Crystals and Motion Behavior of Micron Objects via Photochemical Azobenzene Molecules

Ma¹,

Kuwahara²,

Ogata³

et al. 2014

Proceedings of the 2015 International Conference on Material Science and Applications

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Abstract. Ternary lyotropic liquid crystal (LLC), was prepared by mixing tetradecyltrimethylamonium bromide (MTAB), water and azobenzene (Az). The phase transition of the LLC was induced from LC phase to isotropic (I) one upon Ar+ laser, which was owing to the trans-cis-trans phoisomerizaion cycle of Az during the irradiation. After that, the LC phase gradually recovered from I phase to nematic (N) phase when being exposed to dark condition. It was also suggested that the recovery time from I to N was different with the Az structures, temperature and ratio of MTAB/Az in the ternary system. Then, the effect of light irradiation on the motion behavior of micron objects dispersed in the ternary LLC film was studied. It was found that the micron objects which dispersed in the irradiated area moved toward the center of the irradiated area, while the micron objects which dispersed around the irradiated area moved away from the irradiated area.

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“…We thus conclude that the colloidal structure was not controlled by the relative composition of cis/trans AzoTAB isomers in the bulk, instead we propose that it was mediated by the adsorption/desorption dynamics of AzoTAB.Upon UV-induced trans-to-cis isomerization, AzoTAB became more polar [35,36] and desorbed from the air/water interface in an analogous way to what was reported for similar photosensitive surfactants. [29] This lightinduced desorption of surfactants could induce aM arangoni stress toward the irradiated area, [31,33,[37][38][39] increasing particle confinement and promoting their crystallization. When irradiation smaller than the particle patch was used, some particle motion towards the irradiated area was observed and crystallization occurred on al arger area than the spot size ( Figure S6), confirming that Marangoni-induced confinement could contribute to particle crystallization.…”

Section: Angewandte Chemiementioning

confidence: 99%