Plasmon-Enhanced Optothermal Manipulation

Abstract

AbstractPlasmon-enhanced optical heating can synergize optics and thermal fields to offer a versatile platform for optothermal manipulation of colloidal particles and living cells. By exploiting entropically favorable photon-phonon conversion and universal heat-directed migration, various optothermal tweezing techniques have been developed. Under the thermal gradient field enabled by plasmonic heating, opto-thermophoretic tweezers harness the permittivity gradient at particle-solvent interfaces to direct particles and cells toward the plasmonic hotspot via thermophoresis. Opto-thermoelectric tweezers can manipulate charged colloidal particles with various sizes, materials, and shapes in a localized electric field that is generated by the plasmon-enhanced electrolyte Seebeck effect. In addition, conventional plasmonic trapping can be significantly improved by three types of plasmon-enhanced optothermal-hydrodynamics, i.e., thermo-plasmonic convection, Marangoni convection, and electrothermoplasmonic flow. These plasmon-enhanced optothermal convective flows can rapidly transport or concentrate free-dispersed objects to the plasmonic nanostructures, which significantly enhance the trapping efficiency of micro-and nano-objects. With their low operational power, simple optics, and wide applicability, plasmon-enhanced optothermal manipulation techniques can be applied to optothermal assembly of colloidal matter, non-invasive manipulation of cells and biological objects, and in-situ characterization of optical coupling in colloidal superstructures for a wide range of applications in photonics, materials science, colloidal science, biology, and medical engineering.KeywordsPlasmonic heatingThermophoresisElectrolyte thermoelectricityThermo-plasmonic convectionMarangoni convectionElectrothermoplasmonic flowColloidal particlesCells