Controlled deposition of nanoparticle clusters by electrohydrodynamic atomization

A suspension containing 20 nm silica particles in ethylene glycol was subjected to electrohydrodynamic atomization (EHDA) in the stable cone-jet mode using a ring-shaped ground electrode. The droplets produced were sized by laser diffraction and were in the range 0.5-20 mum. Immediately after deposition, droplet relics were analysed by optical microscopy and were found to be in the size range 1-80 mum. Subsequently, using a pointed rod-electrode (rather than a ring), and by increasing the intensity of the electric field and by reducing the flow rate of suspension subjected to EHDA, relics of similar to50 mum in size were deposited using a patterning device. In both of the above instances, the relics contained two distinct zones, an outer ring of ethylene glycol and a much smaller dense inner region of silica nanoparticles. These results show that, by using EHDA, a novel controlled deposition method of nanosuspensions has been developed.