Particle alignment in a viscoelastic liquid flowing in a square-shaped microchannel.
We demonstrate the possibility to achieve 3D particle focusing in a straight microchannel with a square cross-section by exploiting purely viscoelastic effects. Experiments are carried out by considering an elastic, constant-viscosity aqueous solution of PVP (polyvinylpyrrolidone) as the suspending liquid. Several flow rates and two channel dimensions (with a fixed particle size to channel dimension ratio) are investigated. A novel technique combining particle tracking measurements and numerical simulations is used to reconstruct the position of the flowing particles over the channel cross-section. The results show that, for all the investigated experimental conditions, particles migrate towards the channel centerline. Flow-focusing is enhanced by higher flow rates. The measured particle fractions can be rescaled according to a single dimensionless parameter, as already reported in the literature for the case of cylindrical channels. The so-obtained master curve can be used as a guide to predict the required focusing length. The effect of the entrance on the focusing channel length is also addressed. Finally, analogies and discrepancies with similar previous works are discussed.
Center for Advanced Biomaterials for Health Care @CRIB, Istituto Italiano di Tecnologia, P.le Tecchio 80, 80125 Naples, Italy. francesco.delgiudice@me.com.
Francesco
F
Del Giudice
Giovanni
G
Romeo
Gaetano
G
D'Avino
Francesco
F
Greco
Paolo A
PA
Netti
Pier Luca
PL
Maffettone
D004548:Elasticity; D046210:Microfluidic Analytical Techniques / Q000295:instrumentation*; D010316:Particle Size; D011205:Povidone / Q000737:chemistry; D014783:Viscosity
D011205:Povidone