Aerosol Flow Through a Micro-Capillary

A combined theoretical/experimental study of micron size aerosol flows through micro-capillaries of diameter about 100 μm and length about 1 cm is presented. It is shown that under proper conditions at a relatively high velocity of about 100 m/s such an aerosol flow reveals a new manifestation of microfluidics: the Saffman force acting on aerosol particles in gas flowing through a micro-capillary becomes significant thereby causing noticeable migration of particles toward the center line of the capillary. This finding opens up new opportunities for aerosol focusing, which is in stark contrast to the classical aerodynamic focusing methodologies where only particle inertia and the Stokes force of gas-particle interaction are typically used to control particle trajectories. A mathematical model for aerosol flow through a micro-capillary accounting for complicated interactions between particles and carrier gas is presented. This model describes the experimental observables obtained via shadowgraphy for aerosol beams exiting micro-capillaries. It is further shown that it is possible to design a micro-capillary system capable of generating a Collimated Aerosol Beam (CAB) in which aerosol particles stay very close to a capillary center line. The performance of such a CAB system for direct-write fabrication on a substrate is demonstrated. The lines deposited by CAB for direct-write fabrication are shown to exhibit widths of less than 5 μm — superior to ink-jet. Materials deposition based upon directed aerosol flow has the potential of finding application in the fields of flexible electronics, sensors, and solar cells. In this paper, the genesis of a new materials deposition method termed Collimated Aerosol Beam Direct-Write (CAB-DW) is discussed.

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High-Speed Aerosol Flow Through Micro-Nozzles for Direct-Write Processes

Volume 10: Micro- and Nano-Systems Engineering and Packaging ◽

10.1115/imece2013-65271 ◽

2013 ◽

Cited By ~ 1

Author(s):

Justin M. Hoey ◽

Sourin Bhattacharya ◽

Artur Lutfurakhmanov ◽

Michael Robinson ◽

Orven F. Swenson ◽

...

Keyword(s):

High Speed ◽

Aerosol Particles ◽

Particle Interaction ◽

Direct Write ◽

Particle Rotation ◽

High Speed Flow ◽

Magnus Force ◽

Aerosol Flow ◽

Speed Flow ◽

Flow Through

Aerosol direct-write printing for mesoscale features has been commercially available since around 2002 from Optomec®. We have developed variances to this process first in Collimated Aerosol Beam-Direct Write (CAB-DW) for printing sub-10 μm features and in Micro Cold Spray for printing with solid metallic aerosols. These deposition tools offer extensive uses, but are still limited in certain applications by either line widths or the amount of overspray. Modeling of aerosol flow through micro-nozzles used in these applications yields a greater understanding of the focusing of these aerosol particles, and may provide a vehicle for new nozzle designs which will further enhance these tools. Recent modeling applied both Stokes and Saffman force to the aerosol particles. Under certain conditions particle rotation and Magnus force may also be necessary to accurately predict the aerosol particles. In this paper we will present our recent results of high-speed flow of 1–10 μm diameter aerosol particles through micro-nozzles in which the model includes all three forces (Stokes, Saffman, Magnus) of fluid-particle interaction, and a comparison of these results to experiments.

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Experimental Characterization of Aerosol Flow Through a Micro-Capillary

ASME 2010 8th International Conference on Nanochannels, Microchannels, and Minichannels: Parts A and B ◽

10.1115/fedsm-icnmm2010-30794 ◽

2010 ◽

Author(s):

Zakaria Mahmud ◽

Justin M. Hoey ◽

Artur Lutfurakhmanov ◽

Jason Daugs ◽

Orven F. Swenson ◽

...

Keyword(s):

Coming Out ◽

Experimental Validation ◽

Direct Write ◽

Particle Sizing ◽

Experimental Characterization ◽

Small Particles ◽

Aerosol Flow ◽

Geometric Convergence ◽

Flow Through

Aerosol flow through a long and tapered micro-capillary (MC) for direct write (DW) technology is typically used with small particles of sizes ranging from 0.2 μm to 10 μm at velocities up to 100 m/s. Earlier research showed that the particles coming through a long MC experience Saffman force that moves the particles towards the center of the beam other than the geometric convergence (due to Stokes drag); thus creating a collimated aerosol beam. It was also established that the additional Saffman force becomes more effective with certain particle diameters and velocities. Therefore, for experimental validation, it is important to accurately measure the particle size distribution and velocities coming out of the long MC. However, the current sizing methods are incapable of measuring particles less than 5 μm due to optical limitations. The current paper presents results using a micro-shadowgraphy system from LaVision Inc. to characterize the flow field. A modification of the particle-sizing algorithm is proposed to measure particles of sub-micron sizes. The modified algorithm can be used to accurately size particles of 1μm diameter.

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Optical-Trapping Laser Techniques for Characterizing Airborne Aerosol Particles and Its Application in Chemical Aerosol Study

Micromachines ◽

10.3390/mi12040466 ◽

2021 ◽

Vol 12 (4) ◽

pp. 466

Author(s):

Aimable Kalume ◽

Chuji Wang ◽

Yongle Pan

Keyword(s):

Light Scattering ◽

High Speed ◽

Optical Trapping ◽

Aerosol Particles ◽

Particle Interaction ◽

Raman Laser ◽

General Description ◽

Sample Collection ◽

Laser Technologies ◽

Laser Induced Breakdown

We present a broad assessment on the studies of optically-trapped single airborne aerosol particles, particularly chemical aerosol particles, using laser technologies. To date, extensive works have been conducted on ensembles of aerosols as well as on their analogous bulk samples, and a decent general description of airborne particles has been drawn and accepted. However, substantial discrepancies between observed and expected aerosols behavior have been reported. To fill this gap, single-particle investigation has proved to be a unique intersection leading to a clear representation of microproperties and size-dependent comportment affecting the overall aerosol behavior, under various environmental conditions. In order to achieve this objective, optical-trapping technologies allow holding and manipulating a single aerosol particle, while offering significant advantages such as contactless handling, free from sample collection and preparation, prevention of contamination, versatility to any type of aerosol, and flexibility to accommodation of various analytical systems. We review spectroscopic methods that are based on the light-particle interaction, including elastic light scattering, light absorption (cavity ring-down and photoacoustic spectroscopies), inelastic light scattering and emission (Raman, laser-induced breakdown, and laser-induced fluorescence spectroscopies), and digital holography. Laser technologies offer several benefits such as high speed, high selectivity, high accuracy, and the ability to perform in real-time, in situ. This review, in particular, discusses each method, highlights the advantages and limitations, early breakthroughs, and recent progresses that have contributed to a better understanding of single particles and particle ensembles in general.

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The Rate of Deposition of Aerosol Particles from Turbulent Flow through Ducts

The Annals of Occupational Hygiene ◽

10.1093/annhyg/8.3.239 ◽

1965 ◽

Cited By ~ 11

Keyword(s):

Turbulent Flow ◽

Aerosol Particles ◽

Flow Through

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Flexible Electronics Fabrication for Missile Wiring Interconnects

Additional Conferences (Device Packaging HiTEC HiTEN & CICMT) ◽

10.4071/2012dpc-tp34 ◽

2012 ◽

Vol 2012 (DPC) ◽

pp. 001096-001114

Author(s):

Michael R. Whitley ◽

Tracy D. Hudson

Keyword(s):

Unmanned Aerial Vehicles ◽

Flexible Electronics ◽

Printed Circuit Board ◽

Circuit Board ◽

Polyimide Films ◽

Passive Components ◽

Printed Circuit ◽

Data Formats ◽

Aerial Vehicles ◽

Ink Jet

The increased usage of unmanned aerial vehicles has driven the desire for smaller and lighter missile bodies. The wiring harnesses required to connect the missile subsystems constitute a significant portion of the missile weight and cost. We have been exploring the development of flexible electronics substrates manufactured using ink jet technology on polyimide films. This technology has an advantage over traditional flex circuit manufacturing because in addition to creating traditional wiring patterns the ink jet technology enables the creation of passive components such as resistors and capacitors. The Dimatix DMP-2831 ink jet system uses individually controllable piezoelectric driven MEMS nozzles to precisely deposit nanoparticle inks. These inks are then annealed to form wiring patterns. We will present the process for converting traditional printed circuit board data formats to inkjet printable data, the process for depositing the ink, annealing and testing.

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