Airborne particle generation through acoustic ejection of particles-in-droplets

This article reports a method to produce airborne particles by generating uniformly sized droplets that contain particles, where the droplets are made with an acoustic ejector that does not need any small orifice or nozzle which might become clogged. We demonstrate stable and continuous ejection for more than 10 minutes of 14-μm droplets containing 1-μm polystyrene latex (PSL) particles at a concentration of 1% solids. There was no indication of clogging. We have demonstrated ejection of droplets containing PSL at rates up to 3,000 droplets/s (90,000 1-μm-PSL particles/s). This method should produce, at a known rate, (1) uniform particles of known volume when the particles are soluble in the liquid and/or (2) particles with a statistical distribution (e.g., Poisson distribution) when the particles are aggregates of primary particles. The method should be useful for aerosol generation systems requiring no volatile organic compounds (VOC).