Openfoam Simulations for Development of a Mist Flow Diverter in Aerosol Jet Printing

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The Aerosol Jet® (AJ) direct-write technology enables material deposition for producing micron-scale fine features on various substrates with almost arbitrary geometry, which is of particular interest in manufacturing 3D conformal electronics among other applications. It operates by delivering an aerosol mist stream consisting of micron-size “ink” droplets, through an aerodynamic focusing nozzle with co-flowing sheath gas in a tapered channel, to the substrate several millimetres away with an impinging jet flow [1]. The ink pattern produced with AJ printing is essentially controlled in a “vector drawing mode” by the relative motion of the substrate with respect to the deposition nozzle. When a constant mist flow rate is fed into the deposition head, a mechanism for stopping the mist flow toward substrate must be implemented to prevent ink deposition in places where ink is undesired along the substrate moving toolpath. In other words, the mist stream toward substrate needs to be switched off at the time when the places of substrate where ink deposition is unwanted are moved under the AJ deposition nozzle, and to be switched on at the time when ink deposition is wanted. For the mist flow toward substrate, it can be considered as a function of time with on or off at certain time points. Here we describe a vacuum-boost diverter for rapid mist flow on-and-off switching in AJ printing, with OpenFOAM® simulations to aid its development and to offer fundamental understanding of its operational behaviour.