*The deformability of the biological cell plays an important role in biomicrofluidics in vivo. An erythrocyte, for example, has high flexibility, and deforms in the shear flow. The deformed cell also passes through the capillary in the micro-circulation, of which the dimension is smaller than the diameter of the biconcave disc shape of erythrocyte. After circulation through the blood vessels for days, the erythrocyte is trapped in the micro-circulation systems. A slit is one of the systems, which sorts biological cells in vivo. The sorting at the slit depends on the deformability of the cell. Several cells are able to pass through very narrow slits: cancer cells, or white blood cells.* *The photolithography technique enables manufacturing the micro-morphology in the flow channel. The slit between micro cylinders was made to sort cells in the previous study. The deformation of the depth direction between cylinders, however, cannot be observed by the conventional optical microscope. To observe the deformed cell at the direction perpendicular to the walls of the slit, the slit is designed with the combination of micro-ridge and micro-groove in the present study.*

*A micro-slit has been designed to measure the deformation of* *a floating biological single cell passing through the slit, which has been fabricated in a flow channel by the photolithography technique. Through the micro slit, deformation of a biological cell has been observed in vitro.*

*At the middle part of the flow channel, the slit (7 μm height, 0.4 mm width, and 0.1 mm length) has successfully been made by photolithography technique: the combination of micro-ridge on the transparent polydimethylsiloxane plate and micro-groove on the borosilicate glass plate. The upper plate of PDMS has a rectangular groove of 0.03 mm depth, 0.6 mm width, and 16 mm length (separated in to two half parts with the interval of 0.1 mm length). The lower plate of glass has a rectangular groove of 7 μm depth, 0.4 mm width, and 1 mm length.  These plates keep contact to make slits between them.* *C2C12 (mouse myoblast cell line) was used in the test. The flow of the suspension of cells was controlled by the pressure head between the inlet and the outlet. The deformation of cells passing through the micro slit was observed with an inverted phase-contrast microscope. At the video images, the outline of each cell was traced, and the projected area was calculated: before the slit, in the slit, and after the slit. Some cells deform partially to project the part of the body into the slit at the edge of the entry of the slit. The projected length at the direction of downstream in the slit was measured.*

*The experimental results show that a cell deforms to the flat circular disk and passes through the micro-slit. Although the smaller cells tend to pass the micro-slit easily, some bigger cells also passed the micro-slit. The deformation ratio, which is calculated by the change of the projected area, is independent of the size of the cell (16 μm \< equivalent diameter \< 24 μm). The designed slit has capability to detect quantitative deformability of each single biological cell. The methodology would be applied to several technology: sorting cells for regenerative medicine, or diagnostics.*


Micro Machined Slit Between Ridge and Groove in Micro Fluid-Channel to Measure Floating Cell Deformability

Division / Sponsors: 
Heat Transfer Division (HTD), Fluids Engineering Division (FED)

Heat Transfer Summer Conference
Paper Proceedings: https://asmedigitalcollection.asme.org/HT/HT2020/volume/83709

18th International Conference on Nanochannels, Microchannels, and Minichannels
Paper Proceedings: https://asmedigitalcollection.asme.org/ICNMM/ICNMM2020/volume/83693

Fluids Engineering Division Summer Meeting
Paper Proceedings: https://asmedigitalcollection.asme.org/FEDSM/FEDSM2020/volume/83716

HT-ICNMM2020 - Virtual Conference, SHTC - Virtual Conference, FEDSM2020 - Virtual Conference

Supporting the need among researchers worldwide for additional online and multimedia content, ASME now offers the ASME Conference Video Collection. This platform will collect and provide long-term access to conference presentation videos, encompassing all technology areas within ASME's technical conference and events program. About 30,000-40,000 engineers across all mechanical engineering and related disciplines participate in ASME conferences each year. This includes authors of approximately 6,000 to 8,000 technical papers published by ASME, the majority of whom also submit video presentations for our virtual conferences. The video collection will be available as an add-on to existing product packages or as a separate subscription.