Interface dynamics in a centrifugal cell separator

Abstract

Experiments were performed with bovine blood to study the response of the plasma/cell interface position to pumping rate adjustments in two single‐stage (SS I and SS II) cell separation chambers. Standard clinical instrumentation and equipment and on‐line computer interfacing were used to monitor and control the interface position. The data provided a quantitative description of its dynamics in the SS I and the SS II chambers. In the SS I chamber, adjustments in the flow rate caused the interface to move very slowly and in a complex manner from one steady‐state operation position to another. Such behavior made both manual and computer‐controlled operation very difficult. By contrast, the SS II chamber was inherently unstable for most operating conditions. We demonstrated, however, that a feedback controller could be used easily to adjust or maintain the interface position, and this system moved from one steady‐state operating condition to another 10 times as fast as the system using the SS I chamber. Also, the manner in which the controller allowed the system to respond to operator requests was much simplier than that for the SS I system. 1988 AABB