Relaxation of microparticles exposed to hydrodynamic forces in microfluidic conduits

Abstract

The behavior of microparticles exposed to gravitational and lift forces and to the velocity gradient in flow velocity profile formed in microfluidic conduits is studied from the viewpoint of the transient period (the relaxation) between the moment at which a particle starts to be transported by the hydrodynamic flow and the time at which it reaches an equilibrium position, characterized by a balance of all active forces. The theoretical model allowing the calculation of the relaxation time is proposed. The numerical calculus based on the proposed model is compared with the experimental data obtained under different experimental conditions, namely, for different lengths of microfluidic channels, different average linear velocities of the carrier liquid, and different sizes and densities of the particles used in the study. The results are important for the optimization of microfluidic separation units such as microthermal field-flow fractionation channels in which the separation or manipulation of the microparticles of various origin, synthetic, natural, biological, etc., is performed under similar experimental conditions but by applying an additional thermodynamic force.

Integrated microfluidic device for single-cell trapping and spectroscopy

“…Furthermore, hydrodynamic forces in a laminar flow have the same order of magnitude of forces produced by optical tweezers (tens of picoNewton)13.…”

Trapping bacteria and fungi using microfluidic design

“…At the present, most of the trapping designs are governed by external factors, however, in our study, we are creating designs that would automatically trap E. coli and C. auris under fluid flow even without the presence of external factors like optical tweezers. The laminar flow produced by the optical tweezers has the same magnitude of hydrodynamic forces (Janča et al, 2011). The trapping execution supported by hydrodynamic concepts is achieved even in the absence of optical tweezers.…”

Optofluidics for handling and analysis of single living cells

“…This approach is motivated by a full geometrical and hydrodynamic compatibility between optical tweezers and microfluidics. The forces produced by optical tweezers (tens of picoNewton) are in the same order of magnitude of hydrodynamic forces in a laminar flow [16]. However, the use of OT inside a lab-on-chip apparatus presents some issues, and it is mainly implemented with bulky microscope s6,7,10 or by counter-propagating beams [18][19][20].…”