Systems and methods for sensing red blood cell hematocrit

A blood processing system comprising

• a device for processing blood to obtain a blood suspension containing a quantity of red blood cells, the quantity of red blood cells in the blood suspension being expressed as a percentage of red blood cells present in the blood suspension (% RBC).
• a sensing assembly outside the device including an incident light source and an optical sensor to optically sense presence of red blood cells, and
• a fluid circuit coupled to the device and including a blood inlet tube for conveying a flow of blood into the device and a component collection tube for conveying a flow of the blood suspension from the device, and a fixture including a holder to hold the blood inlet tube and the component collection tube in an adjacent, spaced-apart relationship for handling as a bundle, the holder also being movable into releasable engagement with the sensing assembly to hold the component collection tube within the holder at a predetermined radial distance from the incident light source where a linear relationship exists between sensed reflected light measured by the optical sensor and % RBC in a range of at least % RBC=10% to % RBC=90%.

A blood separation system comprising

• a device for separating whole blood into a blood suspension containing a quantity of red blood cells, the quantity of red blood cells in the blood suspension being expressed as a percentage of red blood cells present in the blood suspension (% RBC),
• a sensing assembly outside the device including an incident source of light having a wavelength of about 805 nm and an optical sensor to sense red blood cells, and
• a fluid circuit coupled to the device and including a component collection tube for conveying a flow of the blood suspension from the device, and a fixture movable into releasable engagement with the sensing assembly and including a holder to hold the component collection tube at a radial distance of about 7.5 mm from the incident source of light where a linear relationship exists between sensed reflected light measured by the optical sensor and % RBC in a range of at least % RBC=10% to % RBC=90%.