Theoretical Analytical Flow Model in Hollow Microneedles for Non-forced Fluid Extraction

In a hollow microneedles for non-force fluid extraction and transfer, under the viscosity and capillary force, the fluid flow velocity varied following time. The fluid mechanical analysis couldn´t apply the steady pipe flow model. In this paper, based on Newtonian fluid, a transient flow theoretical model was built to interpret microfluidic properties in the microneedle with the rectangular cross section for non-force fluid extraction and transfer, and the analytical solution for the marching position of fluid flow was obtained in order to study the relation between the flow variables and physical properties in pipe flow of a Newtonian fluid in the microneedle. The contact angles between the open surface of the microneedle and the different fluids, which were water, plasma, serum and whole blood, were measured using the CCD to approximate as the contact angles of the internal surface. For faster fluid filling into the microneedles, the length width ratio of the section of microchannel was optimized to radic 2 +1