Large-scale optothermal assembly of colloids mediated by a gold microplate

Sharma, Vandana; Paul, Diptabrata; Chaubey, Shailendra K.; Tiwari, Sunny; Kumar, G. V. Pavan

doi:10.1088/1361-648x/ab8552

Cited by 20 publications

(22 citation statements)

References 52 publications

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“…A plot of the temperature distribution at the top of the wire at z=317 nm is plotted in figure 2 (e) which shows that the temperature is highest at the excitation point of the wire and gradually decreases along the length of the nanowire. As reported previously, 34 silica colloids show thermophoretic migration from a lower temperature to a higher temperature. When the silver nanowire is excited, a temperature gradient is set up in the nanowire as well as its surroundings.…”

Section: Resultssupporting

confidence: 82%

Optothermal pulling, trapping, and assembly of colloids using nanowire plasmons

Sharma,

Tiwari,

Paul

et al. 2021

Preprint

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Optical excitation of colloids can be harnessed to realize soft matter systems that are out of equilibrium. In this paper, we present our experimental studies on the dynamics of silica colloids in the vicinity of a silver nanowire propagating surface plasmon polaritons (SPPs). Due to the optothermal interaction, the colloids make a transition from a diffusive to superdiffusive behaviour, and are directionally pulled towards the excitation point of the nanowire. Having reached this point, they are spatio-temporally trapped around the excitation location. By increasing the concentration of colloids in the system, we observe multi-particle assembly around the nanowire. This process is thermophoretically driven and assisted by SPPs. Furthermore, we find such an assembly to be sensitive to the excitation polarization at input of the nanowire.Numerically-simulated temperature distribution around an illuminated nanowire corroborates sensitivity to the excitation polarization. Our study will find relevance in exploration of SPPs-assisted optothermal pulling, trapping and assembly of colloids, and can serve as test-beds of plasmon-driven active matter.

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Section: Resultssupporting

confidence: 82%

Optothermal pulling, trapping, and assembly of colloids using nanowire plasmons

Sharma,

Tiwari,

Paul

et al. 2021

Preprint

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“…There have been several reports of harnessing the plasmonically-generated thermal forces for trapping and assembly of nano as well as micro particles. Recently a large-scale assembly of silica microbeads using gold platelets have been demonstrated 26 , 39 . In our case, the photothermal effect of GO structure is responsible for the local heat generation and the colloidal assembly process.…”

Section: Resultsmentioning

confidence: 99%

“…In order to compare the efficiency of photothermal capability of GO with plasmonic metals such as gold, we performed similar opto-thermophoretic experiments using gold microplatelets as reported by Sharma et al 39 . Unlike their work where the gold structure was illuminated under Kretchmann geometry, we used direct illumination of the gold structure to generate the temperature gradient.…”

Section: Resultsmentioning

confidence: 99%

“…A low power laser based plasmon-enhanced thermophoretic technique to generate reversible assembly of plasmonic nanoparticles on gold was reported 38 . More recently, it was shown that large-scale assembly of silica beads was possible by optically assisted heating of gold microplates 39 . By illuminating the gold microplatelet using evanescent waves, joule heating of the gold structure caused a thermal gradient that generated the assembly of the micron sized beads into hexagonal packing structures.…”

Section: Introductionmentioning

confidence: 99%

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Optically-assisted thermophoretic reversible assembly of colloidal particles and E. coli using graphene oxide microstructures

Joby

Das

Pinapati

et al. 2022

Sci Rep

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Optically-assisted large-scale assembly of nanoparticles have been of recent interest owing to their potential in applications to assemble and manipulate colloidal particles and biological entities. In the recent years, plasmonic heating has been the most popular mechanism to achieve temperature hotspots needed for extended assembly and aggregation. In this work, we present an alternative route to achieving strong thermal gradients that can lead to non-equilibrium transport and assembly of matter. We utilize the excellent photothermal properties of graphene oxide to form a large-scale assembly of silica beads. The formation of the assembly using this scheme is rapid and reversible. Our experiments show that it is possible to aggregate silica beads (average size 385 nm) by illuminating thin graphene oxide microplatelet by a 785 nm laser at low intensities of the order of 50–100 µW/µm2. We further extend the study to trapping and photoablation of E. coli bacteria using graphene oxide. We attribute this aggregation process to optically driven thermophoretic forces. This scheme of large-scale assembly is promising for the study of assembly of matter under non-equilibrium processes, rapid concentration tool for spectroscopic studies such as surface-enhanced Raman scattering and for biological applications.

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“…Plasmonic tweezers [48][49][50][51][52][53][54] have emerged as an alternative to trap nanoscale entities with low power budget. 55,56 In recent times, the thermoplasmonic fields around a metal film 41,57 or other designed nanostructures [58][59][60] have been utilized to optically trap nano and micro objects at extremely low powers.…”

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confidence: 99%

Single Molecule SERS in a Single Gold Nanoparticle-driven Thermoplasmonic Tweezer

Tiwari¹,

Khandelwal²,

Sharma³

et al. 2021

Preprint

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Surface enhanced Raman scattering (SERS) is optically sensitive and chemically specific to detect single molecule spectroscopic signatures. Facilitating this capability in optically-trapped nanoparticles at low laser power remains a significant challenge.In this letter, we show single molecule SERS signatures in reversible assemblies of trapped plasmonic nanoparticles using a single laser excitation (633 nm). Importantly, this trap is facilitated by the thermoplasmonic field of a single gold nanoparticle dropcasted on a glass surface. We employ bi-analyte SERS technique to ascertain the single molecule statistical signatures, and identify the critical parameters of the thermoplasmonic tweezer that provide this sensitivity. Furthermore, we show the utility of this low power (≈0.1mW/µm 2 ) tweezer platform to trap single gold nanoparticle and transport assembly of nanoparticles. Given that our configuration is based on a dropcasted gold nanoparticle, we envisage its utility to create reconfigurable plasmonic metafluids in physiological and catalytic environments, and can be potentially adapted as an in-vivo plasmonic tweezer.Optical confinement and interrogation of single molecules in a fluid remains one of the vital goals of nanoscience and technology. [1][2][3][4][5][6] This letter discusses how single molecule surface 1

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Large-scale optothermal assembly of colloids mediated by a gold microplate

Cited by 20 publications

References 52 publications

Optothermal pulling, trapping, and assembly of colloids using nanowire plasmons

Optothermal pulling, trapping, and assembly of colloids using nanowire plasmons

Optically-assisted thermophoretic reversible assembly of colloidal particles and E. coli using graphene oxide microstructures

Single Molecule SERS in a Single Gold Nanoparticle-driven Thermoplasmonic Tweezer

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