Systems and methods for fluid separation interface control using color-based optical measurements

A blood separation system, comprising:

• a centrifugal separator configured to receive a centrifugal blood separation chamber of a disposable fluid flow circuit, the centrifugal separation chamber having an annular channel and a ramp extending from a high-G side wall portion toward a low-G side wall portion across at least a portion of the annular channel of the centrifugal separation chamber and to process blood to separate at least one cellular component from plasma;
• a pump system configured to move the plasma in the disposable fluid flow circuit;
• an outlet associated with the blood separation chamber for removing at least a portion of the plasma from the blood separation chamber;
• a color-based interface monitoring system configured to directly monitor the interior of the blood separation chamber and to determine an interface position between the separated component and the plasma during a centrifugal separation procedure;
• wherein the color-based interface monitoring system further comprises a light source directed toward the ramp in the centrifugal separation chamber and a color measurement device which measures colors of dominant wavelengths of reflected light over time;
• and
• a controller configured to:
• control the pump system to convey a fluid into the centrifugal separation chamber;
• control the centrifugal separator to separate the blood in the centrifugal separation chamber into layers of plasma and the separated at least one cellular component with the interface position located between the layers;
• utilize the light source and color measurement device to measure a color of each layer via a dominant wavelength of reflected light;
• calculate as a color time a duration of time over which the reflected light is present for each measured dominant wavelength associated with the respective layers;
• set a predetermined target color time as a setpoint for a selected layer;
• calculate an error signal equal to the target color time minus the calculated color time for the selected layer;
• calculate proportional-integral-derivative terms and a control signal;
• and
• utilize the error signal and calculate proportional-integral-derivative terms and a control signal that changes a pump system setting so as to adjust the interface position.