Impulse acoustics based ejection of ferrofluid grains from a ferrofluid: the blueprint of a concept for a nozzle-free inkjet printer

Abstract

We present numerical simulations to demonstrate that it may be possible to eject ferrofluid grains from a ferrofluid using non-linear acoustic impulses. The study considers a container with some dilute ferrofluid that is placed in a strong, vertical, homogeneous magnetic field. The field induces the formation of magnetic dipoles into vertical chains that approximately span the region between the base and the surface of the container. We use particle dynamical simulations to show that an impulse generated at the base of any chain, will typically travel as a weakly dispersive bundle of energy. When the impulse magnitudes are appropriate (typically ~60 m/s or more) the ferrofluid grain nearest to the surface of the liquid may be ejected by the impulse. Since all ferrofluid grains possess a coating of the liquid host, the ejected grain can be used as an ink-drop, with typical diameter of 15 or so nanometers. The velocities of the ejecting grains can be controlled and hence the method, if experimentally feasible, may have wide ranging applications. One of these applications is likely to be in designing special-purpose nozzle-free inkjet printers of unprecedented resolution.