Electrokinetic insect-bioinspired membrane pumping in a high aspect ratio bio-microfluidic system

Microscale flows utilizing stimulus-responsive working fluids are finding increasing applications in emerging areas in mechanical, biological and chemical engineering. Motivated by such applications, in the present article, an analytical study of the electrokinetic effect on insect bio-inspired rhythmic pumping is conducted for a high aspect ratio micro-tube. The membrane attached to the wall performs periodic compression and expansion phases during the complete contraction cycle. Thus, the micro-pump transports the fluid owing to wall deformation by virtue of membrane kinematics. Electroosmotic phenomena are simulated with the Poisson- Boltzmann equation. The impact of the membrane shape parameter is retained in the model. The effects of Helmholtz-Smoluchowski velocity (U-HS) and reciprocal of electrical double layer thickness (kappa) on the pressure distribution, radial and axial velocity distribution, volumetric flow rate pumping characteristic, wall shear stress, and vector field streamline patterns are visualized graphically and interpreted the physical significance. The simulations show that volumetric flow rate and wall shear stress are elevated for thinner EDL. A boost in wall shear stress accompanies an increment in positive U-HS in the vicinity of the membrane. The magnitude of the axial velocity is positive for U-HS = 1 (positive direction of axial electrical field) whereas negative values are computed for U-HS = -1 (reversed direction of axial electrical field). The present analysis furnishes some novel insights into membrane-based pumping mechanisms in electroosmotic microfluidics devices relevant to the manipulation of microscale internal flow in bio-medicine, soft robotics and other areas.

Automated summary

This article presents an analytical study of the electrokinetic effect on insect bio-inspired rhythmic pumping in a high aspect ratio micro-tube. The simulations reveal that thinner electrical double layer leads to higher volumetric flow rate and wall shear stress. This analysis provides novel insights into membrane-based pumping mechanisms in electroosmotic microfluidics devices and their applications in manipulating microscale internal flow.