The deformation of the biological cell relates to the biological function. An erythrocyte has a high flexibility to pass through the capillary in the micro circulation system for the blood in vivo. Several kinds of the flowing cells can pass through the narrow gap in vivo.The deformability of the biological cell plays an important role in vivo.&nbsp;A red blood cell, for example, has high flexibility. The elasticity of the membrane, and fatigue&nbsp;were evaluated in the previous studies.&nbsp;The aging effect on deformability&nbsp;and the sublethal damage were also detected in the shear flow in the previous studies.&nbsp;It also passes through micro-circulation, of which the dimension is smaller than the diameter of the red blood cell.&nbsp;After circulation through the blood vessels for days, the red blood cell is trapped in the micro-circulation systems.Several systems sort cells according to the deformability in vivo.&nbsp;One of the systems, which trap red blood cells, is a spleen.&nbsp;The spleen has special morphology at the blood flow path to sort injured red blood cells.&nbsp;A gap is one of the systems, which sorts biological cells in vivo.&nbsp;The sorting at the gap depends on the deformability of each cell.&nbsp;Some cells are able to pass through a very narrow gap.A photolithography technique enables manufacturing micro grooves&nbsp;or micro structures&nbsp;in the flow-channel for cell tests in vitro.&nbsp;Several micro-fabrication processes have been designed to simulate morphology of the microcirculation.&nbsp;The technique also has been applied to handle cells in diagnostics in vitro.&nbsp;The photolithography technique can be applied to make a micro gap.&nbsp;The gap between micro cylinders was made to sort cells in the previous study.&nbsp;The deformation of the depth direction between cylinders, however, cannot be observed by the conventional optical microscope.&nbsp;To observe the deformed cell at the direction perpendicular to the walls of the gap, another type of the gap is designed with the combination of micro ridges in the present study.In the present study, deformation of each cell during passing through a micro-gap in a flow channel has been investigated in vitro. At the middle part of the flow channel, the gap with the rectangular cross section (7 μm height, 0.4 mm width, and 0.1 mm length) has been made by the photolithography technique.A micro-gap has been designed between a transparent polydimethylsiloxane (PDMS) plate and a borosilicate glass (Tempax) plate. The upper plate of PDMS has a rectangular ridge of 0.05 mm height, 0.10 mm width, and 2 mm length. The lower plate of glass has a rectangular groove (the depth of 0.010 mm, the width of 2 mm, and the length of 20 mm), which has a narrow part of 0.8 mm width. These plates make contact to keep the gap (the width of 0.8 mm, the length of 0.1 mm and the height of 0.010 mm) between them.Myoblasts (C2C12: mouse myoblast cells) were used in the test. The flow rate of the medium, in which cells were suspended, was controlled by the pressure head between the inlet and the outlet. The deformation of cells passing through the micro-gap was observed with an inverted phase-contrast microscope. The experimental results show intermittent deformation of each cell quantitatively through the gap.During the intermittent movement of each cell passing through the gap, the cell shows deformation and rotation. Elongation of the cell tends to decrease the area of the cell facing the wall of the gap. In the present study, deformation of each cell during passing through a micro-gap in a flow channel has quantitatively been investigated in vitro.

Cell Behavior in Flow Passing Through Micro Machined Gap

Paper Proceedings: https://asmedigitalcollection.asme.org/IMECE/IMECE2021/volume/85543

ASME 2021 International Mechanical Engineering Congress and Exposition (IMECE2021)

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