Nanoscale liquid droplet deposition using the ultrasmall aperture on a dynamic mode AFM tip.

We have developed a novel method for nanometer-sized droplet deposition of electrically conductive liquids based on the dynamic mode atomic force microscopy (AFM). We succeeded in depositing liquid droplets with a volume of ten zeptoliters or smaller and in making arrays of the droplets with a spacing of several tens of nanometers using the AFM cantilever with a small aperture fabricated by a focused ion beam. The liquid droplets were deposited through the aperture by applying an electric field between the liquid and a conductive surface.