In this paper, we present a portable single-cell analysis system with the hydrodynamic cell trapping and the broadband electrical impedance spectroscopy(EIS). Using the least flow resistance path principle, the hydrodynamic cell trapping in serpentine arrays can be carried out in a deterministic and automatic manner without the assistance of any external fields. The experimental results show that a cell trap rate of higher than 95% can be easily achieved in our cell trapping microdevices. Using the maximum length sequences(MLS) technique, our home-made EIS is capable of measuring the impedance spectrum ranging from 1.953 kHz to 1 MHz in approximately 0.5 ms. Finally, on the basis of the developed single-cell analysis system, we precisely monitor the trapping process of human breast tumor cells(MCF-7 cells) according to the changes of electrical impedance. The MCF-7 cells with different trapping conditions or sizes can also be clearly distinguished through the impedance signals. Our portable single-cell analysis system may provide a promising tool to monitor single cells for long periods of time or to discriminate cell types.
The inertial secondary flow is particularly important for hydrodynamic focusing and particle manipulation in biomedical research.In this paper,the development of the inertial secondary flow structure in a curved microchannel was investigated by the multi relaxation time lattice Boltzmann equation model with a force term.The numerical results indicate that the viscous and inertial competition dominates the development of secondary flow structure development.The Reynolds number,Dean number,and the cross section aspect ratio influence significantly on the development of the secondary vortexes.Both the intensity of secondary flow and the distance between the normalized vortex centers are functions of Dean numbers but independent of channel curvature radius.In addition,the competition mechanism between the viscous and inertial effects were discussed by performing the particle focusing experiments.The present investigation provides an improved understanding of the development of inertial secondary flows in curved microchannels.
