Optical manipulation of aerosols using surface acoustic wave nebulisation

High density micron sized aerosols from liquid surfaces were generated using surface acoustic wave (SAW) nebulisation. The SAWs are made from a set of interdigitated electrodes (IDT) deposited on a lithium niobate (LiNbO ₃) substrate and are designed to operate around 10MHz. RF powers of ∼235mW are used to achieve nebulisation. Power below this results in droplet motion across the substrate surface. The nebulisation process generated aerosols of a narrow size distribution with diameter ranging from 0.5-2 μm. We consider ways in which these aerosols can be loaded into optical traps for further study. In particular we look at how SAW nebulisation can be used to load particles into a trap in a far more robust manner than a conventional nebuliser device. We demonstrate trapping of a range of particle types and sizes and analyse the size distribution of particles as a function of the applied frequency to the SAW device. We show that it is simpler to load, in particular, solid particles into optical traps using this technique compared to conventional nebulisation. We also consider the possibilities for loading nanoparticles into aerosol optical tweezers.