Abstract
Inertial particle focusing in curved channels has enormous potential for lab-on-a-chip applications. This paper compares a zigzag channel, which has not been used previously for inertial focusing studies, with a serpentine channel and a square wave channel to explore their differences in terms of focusing performance and separation possibilities. The particle trajectories and fluid fields in the curved channels are studied by a numerical simulation. The effects of different conditions (structure, Reynolds number, and particle size) on the competition between forces and the focusing performance are studied. The results indicate that the zigzag channel has the best focusing effect at a high Reynolds number and that the serpentine channel is second in terms of performance. Regarding the particle separation potential, the zigzag channel has a good performance in separating 5 μm and 10 μm particles at ReC = 62.5. In addition, the pressure drop of the channel is also considered to evaluate the channel performance, which has not been taken into account in the literature on inertial microfluidics. This result is expected to be instructive for the selection and optimization of inertial microchannel structures.
Highlights
The development of inertial microfluidics[1] has enabled particle manipulation with improved performance over sheath flow control[2] and external force generators[3] and has made it possible to miniaturize the devices and simplify the operation[4]
Since the relationship between the driving force and ReC is calculated from Poiseuille’s law, which is defined for a straight channel, ReC in the simulation is higher than the actual value
When the majority of small particles are focused at the channel center at higher ReC, a small portion of particles are focused closed to the sidewalls, which causes an increase in the deviation in the focusing position
Summary
The development of inertial microfluidics[1] has enabled particle manipulation with improved performance over sheath flow control[2] and external force generators[3] and has made it possible to miniaturize the devices and simplify the operation[4]. In addition to straight channels, there are three basic types of microchannel structures: expansion-shrink array channels, spiral channels and serpentine channels These structures were created to introduce extra inertial effects, such as Dean flow, to achieve more precise manipulation of particles. The interaction of the inertial lift force and dielectrophoretic force in a square wave channel was studied[20], and a tunable separation method was proposed by an innovative hybrid DEP-inertial microfluidic platform[21] All of these studies investigated the application of curved channels in inertial particle focusing, but it should be noted that the above experimental studies could not adequately study the interaction between particles and flows by showing the focusing behavior of the particles.
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