Aerosol flow through a long micro-capillary: collimated aerosol beam

Abstract

A micro-capillary system capable of generating a focused collimated aerosol beam (CAB) is demonstrated both theoretically and experimentally. The approach is based on a manifestation of the Saffman force where high velocity (*100 m/s) aerosol particles, flowing through a micro-capillary (d * 100 lm and l * 1 cm), migrate perpendicular to the centerline of the capillary. Upon exiting the micro-capillary system, the particles maintain momentum, and when the aerosol is comprised of solid-inliquid dispersions such as Ag nanoparticle ink, the CAB approach enables printing of advanced materials features with linewidth B 10 lm.

Aerosol Flow Through a Converging-Diverging Micro-Nozzle

“…Brought to you by | Kungliga Tekniska Högskolan Authenticated Download Date | 7/6/15 9:59 AM This was shown in our previous work [2], and confirmed again here.…”

“…The challenge for this technology is to produce thin features, which may only be realized by the development of an aerosol nozzle that can both collimate and accelerate the aerosol particles to a high velocity. The use of micro-scale nozzles to improve the collimation of the aerosol has been modeled theoretically for liquid aerosols at lower velocities [2], but may prove quite challenging for MCS-DW applications due to the high velocities achieved. Further, a more robust understanding of the behavior of aerosols in higher particle Reynolds number flows is required.…”

“…The two forces relevant to this computational study are Stokes drag force and Saffman lift force [2,3] are given by equations…”

“…A variant of Aerosol Jet, termed Collimated Aerosol Beam Direct Write (CAB-DW), uses an improved nozzle design consisting of a converging-diverging-converging nozzle that makes the aerosol particle beam more focused and more collimated. The nozzle design was developed using a combination of theory and experiment to model aerosol particles, and has shown printed features as small as 5 µm wide [2,3]. Micro Cold Spray Direct Write (MCS-DW) is an aerosolbased direct-write process which deposits a dry aerosol generated from metal powders rather than liquid inks and is currently under development in our laboratory.…”

Aerosol penetration in microchannels

“…In the last few years, a number of researchers have investigated different applications involving aerosols in microchannels. Akhatov, Hoey, Swenson, and Schulz (2008) experimentally studied aerosol flow through a converging micro-capillary in order to focus an aerosol stream. The micro-capillary was of diameter 100 mm and of length 1 cm.…”