Fluid flow driven along microchannel by its upper stretching wall with electrokinetic effects

We develop a mathematical model to describe the flow in a microchannel driven by the upper stretching wall of the channel in the presence of electrokinetic effects. In this model, we avoid imposing any unphysical boundary condition, for instance, the zero electrostatic potential in the middle of the channel. Using the similarity transformation, we employ the homotopy analysis method （HAM） to get the analytical solution of the model. In our approach, the unknown pressure constant and the integral constant related to the electric potential are solved spontaneously by using the proper boundary conditions on the channel walls, which makes our model consistent with the commonly accepted models in the field of fluid mechanics. It is expected that our model can offer a general and proper way to study the flow phenomena in microchannels.

A new numerical technique for simulating the coupled seismic and electromagnetic waves in layered porous media

Chen＇s technique of computing synthetic seismograms, which decomposes every vector with a set of basis of orthogonality and completeness before applying the Luco-Apsel-Chen （LAC） generalized reflection and transmission coefficients method, is confirmed to be efficient in dealing with elastic waves in multi-layered media and accurate in any frequency range. In this article, we extend Chen＇s technique to the computation of coupled seismic and electromagnetic （EM） waves in layered porous media. Expanding the involved mechanical and electromagnetic fields by a set of scalar and vector wave-function basis, we obtain the fundamental equations which are subsequently solved by using a recently developed version of the LAC generalized reflection and transmission coefficients method. Our approach and corresponding program is validated by reciprocity tests. We also show a numerical example of a two-layer model with an explosion source. The P-to-EM conversion waves radiated from the interface may have potential application.

Discontinuous streaming potential via liquid gate

Streaming potential is mainly related to electrokinetic energy conversion,which has been considered to show promising potential for advanced technologies,especially sensing.The inherent property of streaming potential is that the energy conversion process is always a continuous state.However,practical applications include many cases of discontinuous states,such as nonlinear sensing.Here,we report a discontinuous streaming potential electrokinetic energy conversion fluid system.Experiments and theoretical calculations reveal that this system exhibits a discontinuous electrokinetic effect and provides a gating liquid slip in micropores,offering the advantages of gating liquid charge coupling and interfacial drag reduction.Moreover,the system is demonstrated in a wearable fall-down alert application.We expect this liquid gating energy conversion system to open up a platform for the design and application of autonomous health monitoring devices,seismic sea wave warning systems,and beyond.