Tube length-assisted optimized aerosol trapping

Optical Trapping of Gold Nanoparticles in Air

“…We trapped gold, polystyrene, and silica nanoparticles stably in air for several minutes. The trapping depth could be varied from 0 μm to more than 100 μm above the surface; however, as predicted with our choice of immersion media, 7,26 the trapping was measured to be optimal ∼12 μm above the surface (unpublished data by Taheri et al).…”

“…Such levitation of droplets has proven highly useful for Raman spectroscopy investigations. − In 1997 Omori et al reported optical trapping (as opposed to levitation) of a dielectric particle in air using a single tightly focused laser beam. Since then, more progress has been accomplished on optimizing optical control of dielectric particles, liquid droplets have been optically trapped in air, , and even multiple droplets have been trapped in air by holographic optical tweezers . Not just the translation but also the rotation of microparticles in air have been recently proven .…”

“…To minimize turbulence we used a chamber as suggested in ref consisting of three subchambers as shown in Figure : The nanoparticle aerosol is delivered by a nebulizer in the upper chamber, a small hole (1 mm in diameter drilled with a diamond drill) allows part of the airborne particles to fall in the gravitational field into the second chamber, which has less turbulence than the upper chamber. A small hole in the lower coverslip of the second chamber allows a certain fraction of these particles to fall into the third and final chamber, the trapping chamber, which is higher than the maximal working distance of the objective.…”

“…The ethanol–particle solution was pipetted into a nebulizer , for medical use (Omron micro air U22) and the aerosol was formed in the nozzle. Between each experiment, or after nebulizing 7 mL of ethanol solution, we cleaned the nebulizer filter by 20 min ultrasonication in Milli-Q water.…”

Optical Trapping in Air on a Single Interference Fringe

“…In a different work, large, absorbing particles were trapped and transported in free space using standard diffraction lenses and using vortex or bottle beams [9,10,11]. Single dielectric and metallic micro and nanoparticles were trapped in air by L. Jauffred and S. Taheri using a trapping chamber designed to minimize any turbulence [12,13]. In this context, the paramount influence of the surface of the trapped particle was revealed for gold nanoparticles [14].…”