The inertial secondary flow is particularly important tbr hydrodynamic lbcusing and particle manipulation m biomed- ical research. In this paper, the development of the inertial secondary flow structure in a curved microchannel was investi- gated 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 vor- texes. 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.
Nanopores are emerging sensitive sensors that can detect and analyze single charged molecule.Nanopores present a promising approach for sequencing human genome below US$1,000 because of its superior performance,such as high throughput and low cost.However,a dominant bottleneck,that is,the high translocation speed of DNA molecules,has to be overcome.This property decreases accuracy of nanopore sensors to the single-base level.In this review,we mainly introduce the recent research works of retarding and manipulating of DNA motion through nanopores by actively control of three forces,which are the driving force,interaction force between nanopore and molecule,and exterior drag force.Lastly,conclusion and further outlook are presented on future directions of nanopore-based DNA sequencing technology.
Solid-state nanopore is found to be a promising tool to detect proteins and their complexes. Nanopore-protein interaction is a fundamental and ubiquitous process in biology and medical biotechnology. By translocating phi29 connector protein through silicon nitride nanopores, we demonstrate preliminarily probing the surface hydrophobicity of individual protein at single-molecule resolution. The unique 'double-level event' observed in the translocation and the ratio of two current drop levels suggest that the position where the interaction occurs is the hydrophobic surface of the protein. We provide a potential method to locate the hydrophobic region of a specific protein surface. This study is of fundamental significance in revealing the important role that hydrophobic interaction plays in nanopore-protein interaction and holds great potential for detecting local surface chemical property of individual protein using solid-state nanopores.
