Transport of airborne particles in straight and curved microchannels

Abstract

The measurement of airborne particles is important for environmental and exposure monitoring. Microfluidic technologies present potential advantages for aerosol monitoring but have been applied very little to the handling of airborne particles. In this paper, we examine the flow focusing and cross-streamline diffusion of aerosols in straight microchannels, and the size-based lateral displacement of aerosols caused by centrifugal forces in a curved channel. We present calculations, simulations, and experimental results verifying the models: measurements of the focusing and diffusion of 0.2 μm and 0.75 μm particles in straight channels and of the size-dependent lateral displacement of particles between 0.2 μm and 2 μm in curved channels are demonstrated and shown to match well with the simulations. We observe lateral dispersion of the particles: particles closer to the top and bottom wall of the channel experience less lateral displacement than particles near the center due to the flow velocity distribution across the channel cross section. These results confirm that the microchannel techniques presented are a viable method for the size-based manipulation of airborne particles.

Continuous aerosol size separator using inertial microfluidics and its application to airborne bacteria and viruses

“…The results indicated the possibility of separating viruses and bacteria simultaneously. [15][16][17] Our resent study showed that a microscale impactor successfully detected target bacteria using a mini-fluorescence microscope and SYBR green I dyestained microsized agar plates. 16 Kim and co-workers demonstrated a virtual impactor which can separate airborne bacteria from larger aerosols.…”

“…Therefore, an efficient aerosol size separator with low loss can allow obtainment of high purity of airborne bacteria and viruses simultaneously and continuously before sampling the targeted airborne microorganisms. 8,[15][16][17] Over the past few years, several studies have demonstrated the separation of submicron aerosols and bioaerosols on microchips according to their inertial differences. Such systems are relatively simple and inexpensive and lend themselves easily to the development of portable and rapid bioaerosol detectors.…”

Numerical study of airborne particle dynamics in vortices subject to electric field

“…Selective separation and collection of the airborne particulate based on their size (typically 5 − 10µm aerodynamic diameter) and inertia for further transfer is required in a variety of applications of bioaerosol detection and sampling [42][43][44] . Microfluidic device designs based on either particle inertia 45,46 or DEP force 47 for such real time detection of microorganism were reported, however developing active, reliable and rapid sampling techniques is still an active research problem 17 . Pharmaceutical aerosol drug delivery is another rapidly growing field in aerosol engineering, where the drug loaded on an excipient constitute a particulate of size about 5 micron 20,48 , is delivered through inhalation route to the patient's airways or lungs.…”

“…Leveraging air circulations to replace plasma arc ion injection in to air would be of crucial role in improving ESP adaptation under health and environmental impacts. Selective deposition of particles identified at the interplay of counter circulating air flow and electrostatic fields might be combined with microfluidic biosampling devices 45,46 , wet wall 64,65 and membrane wall 66,67 airborne particulate collectors for novel active, faster and reliable bioaerosol sampling techniques. Inertial limit cycle manipulation of airborne particles could be of importance in particulate flight through narrow irregular channels, such as aerosol drug delivery applications.…”

Inertial migration of aerosol particles in three-dimensional microfluidic channels

“…Microfluidics, a new technique rapidly developed since 1990s, becomes another prominent method to provide direct capture and downstream airborne pathogen analysis ( Metcalf et al, 2018 , Sui and Cheng, 2014 ). Over the past few years, several studies have demonstrated separation of submicron aerosols and bioaerosols on microchips according to their inertial differences, size differentiation and special structure ( Schaap, Chu, & Stoeber, 2012 ), which have shown significant advantages of being simple, rapid, portable and low-cost. For example, Chin et al ( Chin et al, 2011 ) used microfluidics to enable a single, easy-to-use point-of-care (POC) diagnostics and early detection of infectious diseases.…”