Supernatant decanting on a centrifugal platform

Abstract

This study presents a novel approach to decant supernatant on a centrifugal platform. By manipulating the centrifugally induced pressure and the elastic deformation of the plastic lids in the decanting chamber, fixed amounts of the supernatant can be decanted into the detection chamber at lower rotational speeds. The experimental results showed that decanted volume is affected by the volume of deformation and the operating parameters. Factors that influence the decanting ratio are also discussed. This approach has the advantages of simple design and low manufacturing cost; further, it has no need of surface modification. It has been applied to on-disk separation of plasma from whole blood, and the results showed good stability and repeatability.

Figure 1

(a) Schematic illustration of a rectangular chamber on a centrifugal platform. (b) Photograph of the chamber at a high rotational speed (4000 rpm) and still image of the chamber (0 rpm). (c) The measured height of the deformed chamber along the radial direction, as estimated by curing UV glue at a rotational speed of 4000 rpm.

Figure 2

Schematic of the supernatant decanting scheme for plasma separation and decanting: (1) filling stage, (2) sedimentation stage, and (3) decanting stage. The platform rotated in counterclockwise direction.

Figure 3

(a) The schematic of the chamber lid deformation analyzed by ANSYS. (b) Quantification of the volume of deformation by image analysis.

Figure 4

Comparison of the volume of deformation between the experimental results measured by image analysis (exp) and calculation by ANSYS simulation (sim) for a platform made of polycarbonate disks and pressure-sensitive adhesive.

Figure 5

Comparison of the volume of deformation between the experimental results measured by image analysis (exp) and calculation by ANSYS simulation (sim) for a platform made by polycarbonate disks and dry film photoresist.

Figure 6

The decanted liquid volume under various decelerations.