Vortex-based microfluidics has received significant attention
for
its unique characteristics of high efficiency, flexible control, and
label-free properties for the past decades. Herein, we present a vortex-based
acousto-inertial chip that allows both fluid and particle manipulation
within a significantly wider flow range and lower excitation voltage.
Composed of contraction–expansion array structures and vibrating
microstructures combined with bubbles and sharp edges, such a configuration
results in more vigorous vortical fluid motions. The overall improvement
in device performance comes from the synergistic effect of acoustics
and inertia, as well as the positive feedback loop formed by vibrating
bubbles and sharp edges. We characterize flow patterns in the microchannels
by fluorescence particle tracer experiments and uncover single- and
double-vortex modes over a range of sample flow rates and excitation
voltages. On this basis, the ability of rapid and efficient sample
homogenization up to a flow rate of 200 μL/min under an excitation
voltage of 15 Vpp is verified by a two-fluid fluorescence
mixing experiment. Moreover, the recirculation motion of particles
in microvortices is investigated by using a high-speed imaging system.
We also quantitatively measure the particle velocity variation on
the trajectory and illustrate the capturing mechanism, which results
from the interaction of the microvortices, particle dynamics, and
composite microstructure perturbations. Further utilizing the shear
forces derived by microvortices, our acousto-inertial chip is demonstrated
to lysis red blood cells (RBCs) in a continuous, reagent-free manner.
The high controllability and multifunction of this technology allow
for the development of multistep miniaturized “lab-on-chip”
analytical systems, which could significantly broaden the application
of microvortex technology in biological, chemical, and clinical applications.