Background: Effective micromixers represent essential components for micro total analysis systems or lab-on-a-chip. Indeed, mixing is a key process for the success of all chemical or biochemical reactions. Most microfluidic systems operate in a laminar flow regime dominated by molecular diffusion, which is not favorable to mixing. In the present work, numerical analyses of mixing in 3-dimensional channels with obstacles on the walls were performed to investigate mixing behavior and flow characteristics with geometric parameters as well as Reynolds number. Methods: Several channel wall geometries were numerically modeled, and the influence of obstacle height, phase shift between the walls, channel cross-section shape (aspect ratio) and Reynolds number on mixer performances was investigated. Wall geometries were evaluated comparatively in terms of index of mixing and pressure drops caused. Results: Results indicated that furrowed channels with proper triangle-shaped obstacles show good performances in terms of achieving complete mixing in a very short length of channel, and at the same time offer low pressure losses. Convective motions are the main influences responsible for successful mixing, and micromixers with triangle-shaped obstacles show an improvement in the mixing performances for increasing Reynolds numbers. Moreover, short times are required for the mixing process. Finally, depending on the Reynolds number that one works at, there is also some flexibility in the choice of the channel geometry, as the occurrence of effective chaotic advection was obtained for several conformations of the channels proposed in this study. Conclusions: Mixing enhancement can be achieved by optimizing the shape of the furrowed channel.

Computational modeling of passive furrowed channel micromixers for lab-on-a-chip applications

NASON, FRANCESCA;PENNATI, GIANCARLO;DUBINI, GABRIELE ANGELO
2014-01-01

Abstract

Background: Effective micromixers represent essential components for micro total analysis systems or lab-on-a-chip. Indeed, mixing is a key process for the success of all chemical or biochemical reactions. Most microfluidic systems operate in a laminar flow regime dominated by molecular diffusion, which is not favorable to mixing. In the present work, numerical analyses of mixing in 3-dimensional channels with obstacles on the walls were performed to investigate mixing behavior and flow characteristics with geometric parameters as well as Reynolds number. Methods: Several channel wall geometries were numerically modeled, and the influence of obstacle height, phase shift between the walls, channel cross-section shape (aspect ratio) and Reynolds number on mixer performances was investigated. Wall geometries were evaluated comparatively in terms of index of mixing and pressure drops caused. Results: Results indicated that furrowed channels with proper triangle-shaped obstacles show good performances in terms of achieving complete mixing in a very short length of channel, and at the same time offer low pressure losses. Convective motions are the main influences responsible for successful mixing, and micromixers with triangle-shaped obstacles show an improvement in the mixing performances for increasing Reynolds numbers. Moreover, short times are required for the mixing process. Finally, depending on the Reynolds number that one works at, there is also some flexibility in the choice of the channel geometry, as the occurrence of effective chaotic advection was obtained for several conformations of the channels proposed in this study. Conclusions: Mixing enhancement can be achieved by optimizing the shape of the furrowed channel.
File in questo prodotto:
File Dimensione Formato  
A98 Nason micromixer JABFM2015.pdf

Accesso riservato

Descrizione: Articolo completo
: Publisher’s version
Dimensione 1.02 MB
Formato Adobe PDF
1.02 MB Adobe PDF   Visualizza/Apri
Computational modeling of passive furrowed channel_11311-959994_Pennati.pdf

accesso aperto

: Post-Print (DRAFT o Author’s Accepted Manuscript-AAM)
Dimensione 1.01 MB
Formato Adobe PDF
1.01 MB Adobe PDF Visualizza/Apri

I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.

Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11311/959994
Citazioni
  • ???jsp.display-item.citation.pmc??? ND
  • Scopus 2
  • ???jsp.display-item.citation.isi??? 1
social impact