2. Vortex Fluidic Technology
From manipulating single-cell organisms to processing advanced materials
and small molecule synthesis, these processing capabilities and many
more can be conducted through a VFD by accurately regulating the shear
force experienced by the fluid, among various other parameters that
affect the fluid dynamics. As shown in Figure 1, the VFD has noticeably
unique features and capabilities. Typically a VFD has a glass or quartz
tube with an external diameter of either 10 mm, 15 mm, or 20 mm, and can
be spun at speeds from 1000 to 10000 rpm while inclined at an angle θ
which can be varied from 90° to 0° with recent developments towards -45°
processing17. The inclination angle and rotational
speed control the management of shear rates at high magnitudes, with the
fluid dynamics being inherently complex when θ
>> 0°18. The formation of a
thin film from the liquid in the VFD witnesses high shear from the
interaction between gravitational and centrifugal forces. These forces
are accompanied by the appearance of Stewartson/Ekman layers as fluid
flows upwards on the rotating tube’s internal surface and downwards near
the liquid’s surface, parallel to the rotational axis of the rotating
tube.