Tools of Nanotechnology: Electrospray

Liquids can readily interact with electric fields. Field-induced or injected charges in liquids interact with an external electric field causing liquids to move, break into drops or spray into jets or strings of fine droplets. One important case of liquid in the capillary deserves special mentioning as it serves as a basis of many and varied technological applications. An electric field acts on a liquid meniscus, counteracted by surface tension. In a strong enough field a cone is formed that emits a jet of liquid from its tip. This effect is used, for example, to coat car bodies by a thin uniform layer of paint. At the other end of the scale nano-electrospray has revolutionised mass-spectroscopy of bio-molecules. The ability of electrospray to repeatedly generate very small and uniform volumes of liquid makes it into one of the important tools of nanotechnology.

Electrospray has been used to deposit ultra-thin films of inorganic, organic and biological materials, to generate nanoparticles and quantum dots, to sort them according to their sizes, and to help with dispersion and delivery of nanomaterials. This mini-review introduces basics of electrospray technology and summarises the diverse applications of electrospray in nano-sciences.