Determination of cell concentration and / or platelet mass index of fluid

Abstract

To provide a method of determining the concentration of one or more substances in a fluid and / or the platelet mass index of the fluid.SOLUTION: An optical detection assembly for monitoring a fluid includes a light source, a light detector array, and a controller. The controller receives signals from the light detector array that are indicative of intensity of light received by the light detector array after the light has passed through the fluid. The controller generates a scattering profile based on the signals, with the scattering profile including rising and falling edges each having a slope. The controller calculates one or both slopes and determines a platelet mass index (for a platelet-containing fluid) and / or a concentration of a substance in the fluid based on said slopes. The optical detection assembly may also be used to analyze a reference fluid having a known concentration of the substance, with signals received by the controller when analyzing the reference fluid being a factor when determining the concentration of the substance in the fluid of interest.SELECTED DRAWING: None

Description

Technical Field

[0001] [Cross - Reference to Related Applications] This application claims the benefit and priority of U.S. Provisional Patent Application No. 63 / 547,710, filed on November 8, 2023, and U.S. Provisional Patent Application No. 63 / 565,070, filed on March 14, 2024, which are incorporated herein by reference.

[0002] [Technical Field] The present disclosure relates to optical monitoring of fluids. More specifically, the present disclosure relates to determining the concentration of one or more substances in a fluid optically monitored using a light source and an array of photodetectors and / or the platelet mass index of the fluid.

Background Art

[0003] It is known to use an optical detection assembly to monitor the flow of blood, blood components, and other biological fluids through a fluid flow circuit and to determine various characteristics of the flow. A typical optical detection assembly includes a light source (e.g., a laser or a light - emitting diode) configured to emit light into a fluid - containing vessel of the fluid flow circuit and a photodetector (e.g., a photodiode) configured to receive light exiting the vessel. The photodetector transmits a signal to a control unit based on the received light, and the control unit uses that signal to determine one or more characteristics of the fluid.

[0004] Conventional optical detection assemblies may have any of several drawbacks depending on their exact configuration. For example, optical detection assemblies are generally used to monitor the flow of biological fluids through flexible plastic tubes of a fluid flow circuit. When light is incident on a plastic tube, the transmission of light into the lumen of the tube can vary according to Snell's law depending on the refractive index of the material and the angle of the incident light formed by the tube surface. The refractive index of air (about 1) and that of plastic (usually about 1.3 - 1.5) are quite different, the formation of the tube surface is not consistent from procedure to procedure, and the incident angle also varies, so the transmission of light into the tube varies from procedure to procedure, and the measured values of fluid characteristics lose consistency.

[0005] Another possible drawback is the configuration of the photodetector of the conventional optical detection assembly, which is often a single photodiode. In such a configuration, only the amplitude of the light exiting the container at a single location is known, but the light transmitted through a turbid medium (such as blood or blood components) is scattered rather than exiting along a single path that can be fully received by a single photodiode.

[0006] U.S. Patent Application Publication No. 2023 / 0243746A1 (the disclosure of which is incorporated herein by reference) describes an optical detection assembly that improves such a conventional optical detection assembly. The optical detection assembly described in U.S. Patent Application Publication No. 2023 / 0243746A1 is based on the principle that the light exiting a turbid medium (such as blood or blood components) is scattered and can be detected at multiple positions using an array of photodetectors rather than detecting the light at a single position by a single photodetector (such as an individual photodiode). For different fluids (e.g., fluids with different concentrations of the target substance), light rays with different scattering patterns are generated, and the individual photodetectors or light sensing elements of the photodetector array receive different amounts of light that have passed through the fluid. The control unit can determine the concentration of a substance (such as platelets) in the target fluid based on the maximum intensity of the light received by one of the individual photodetectors, the sum of the intensities of the light received by at least two of the individual photodetectors, or the width of the scattering pattern (corresponding to the number of individual photodetectors that received the minimum amount of light).

[0007] One characteristic of platelet-containing substances (e.g., whole blood, platelet-rich plasma, platelet concentrate) is the platelet mass index (PMI). This is a unit of platelet volume / fluid volume and can be calculated by multiplying the platelet concentration of the substance by the mean platelet volume (MPV). One conventional method for determining the PMI of a fluid is to use a cell counter. This is an invasive method of measuring the number and size of platelets in a sample and using those values to calculate the PMI of the fluid. One practical application example of the relationship between PMI, platelet concentration, and MPV is to determine the volume of the preservation solution to be used in platelet preparations. According to one conventional approach, the operator of a fluid processing system provides the system with the target platelet yield of the procedure and also inputs the MPV of the fluid to be mixed with the preservation solution (e.g., provided by a cell counter). Disadvantages of this approach include the inaccuracy of the MPV measured by the cell counter and the difference between the target platelet yield and the actual platelet yield, resulting in the possibility of using an inappropriate volume of the preservation solution.

[0008] Therefore, it is advantageous to provide an approach for determining the PMI of a fluid that improves on the conventional approach, which may include providing a non-invasive approach for determining the PMI. SUMMARY OF THE INVENTION

[0009] The subject matter of the present invention has several aspects that can be implemented separately or together in the devices and methods described and claimed below. These aspects can be used alone or in combination with other aspects of the subject matter described herein, and the fact that these aspects are described together is not intended to preclude the use of these aspects individually or the claiming of these aspects individually as set forth in the claims appended hereto.

[0010] In one aspect, an optical detection assembly for monitoring a fluid within a container includes a directionally oriented light source configured to emit light into the fluid within the container, an array of light detectors configured to receive at least a portion of the light exiting the container and including a plurality of light detectors, and a control unit. The control unit is programmed to receive from the array of light detectors a signal indicative of the intensity of the portion of light received by each light detector and to generate a scattering profile based at least in part on the signals from the array of light detectors. The control unit calculates the slope of the rising edge of the scattering profile and / or the slope of the falling edge of the scattering profile and uses one or both slopes to determine a platelet mass index and / or the concentration of a substance in the fluid within the container.

[0011] In another aspect, a biological fluid processing device includes a pump system, a valve system, a control unit programmed to control the operation of the pump system and the valve system to perform a biological fluid processing procedure, and an optical detection assembly. The optical detection assembly includes a directionally oriented light source configured to emit light into the fluid within a container and an array of light detectors configured to receive at least a portion of the light exiting the container and including a plurality of light detectors. The control unit is further programmed to receive from the array of light detectors a signal indicative of the intensity of the portion of light received by each light detector, and the scattering profile is generated based at least in part on the signals from the array of light detectors. The scattering profile includes a rising edge and a falling edge, the slope of the rising edge and / or the slope of the falling edge is calculated, and is then used to determine a platelet mass index and / or the concentration of a substance in the fluid within the container.

[0012] In yet another aspect, a method of determining a platelet mass index and / or a concentration of a substance in a fluid within a container includes irradiating the fluid within the container with light and receiving at least a portion of the light exiting the container with a plurality of photodetectors of a photodetector array. A scattering profile is generated, the scattering profile being at least partially based on the intensity of the portion of light received by each photodetector. The scattering profile includes a rising edge and a falling edge, and a slope of the rising edge and / or a slope of the falling edge is calculated. Next, the platelet mass index and / or the concentration of the substance in the fluid within the container is determined at least partially based on the slope.

[0013] In another aspect, an optical detection assembly for monitoring a fluid within a container includes a directed light source assembly configured to emit light into the fluid within the container, a photodetector assembly configured to receive at least a portion of the light exiting the container, and a control unit. The control unit is programmed to receive from the photodetector assembly a first signal indicative of the intensity of the portion of light received by the photodetector assembly when a reference fluid is within the container and a second signal indicative of the intensity of the portion of light received by the photodetector assembly when a target fluid is within the container. The control unit compares the first signal and the second signal and determines a concentration of a substance within the target fluid within the container at least partially based on a comparison of the first signal and the second signal.

[0014] In yet another aspect, a biological fluid processing apparatus includes a pump system, a valve system, a control unit programmed to control the operation of the pump system and the valve system to perform a biological fluid processing procedure, and an optical detection assembly. The optical detection assembly includes a light source assembly configured and oriented to emit light into a fluid within a container, and a photodetector assembly configured to receive at least a portion of the light exiting the container. The control unit is further programmed to receive from the photodetector assembly a first signal indicative of the intensity of the portion of the light received by the photodetector assembly when a reference fluid is within the container, and the control unit is programmed to receive from the photodetector assembly a second signal indicative of the intensity of the portion of the light received by the photodetector assembly when a target fluid is within the container. The control unit compares the first signal and the second signal and determines the concentration of a substance within the target fluid in the container based at least in part on the comparison of the first signal and the second signal.

[0015] In another aspect, a method of determining the concentration of a substance in a target fluid within a container includes irradiating a reference fluid within the container with a first light. At least a portion of the first light exiting the container is received by a photodetector assembly, generating a first signal, the first signal indicative of the intensity of a portion of the first light received by the photodetector assembly. A second light is radiated into the target fluid within the container, at least a portion of the second light exiting the container is received by the photodetector assembly, subsequently generating a second signal, the second signal indicative of the intensity of a portion of the second light received by the photodetector assembly. The first signal is compared to the second signal, and the concentration of the substance within the target fluid in the container is determined based at least in part on the comparison of the first signal and the second signal. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] FIG. 1 is a perspective view of exemplary hardware components of a biological fluid processing system according to one aspect of the present disclosure.

[0017] Figures 2 and 2A are schematic diagrams of exemplary disposable components that can be attached to the hardware components of FIG. 1 to complete a biological fluid processing system according to one aspect of the present disclosure.

[0018] FIG. 3 is a perspective view of an exemplary optical detection assembly of the hardware components of FIG. 1 with the lid in an open position.

[0019] FIG. 4 is a perspective view of the optical detection assembly of FIG. 3 with the lid in a closed position.

[0020] FIG. 5 is a perspective view of selected components of the optical detection assembly of FIG. 3.

[0021] FIG. 6 is a schematic diagram of the optical detection assembly of FIG. 3 monitoring a fluid with low cell concentration and PMI.

[0022] FIG. 7 is a schematic diagram of the optical detection assembly of FIG. 3 monitoring a fluid with high cell concentration and PMI.

[0023] FIG. 8 is a graph showing a scattering profile generated using signals from the photodetector array of the optical detection assembly of FIG. 3.

[0024] FIG. 9 is a graph showing a portion of the scattering profile generated using signals from the photodetector array of the optical detection assembly of FIG. 3.

[0025] FIG. 10 is a graph showing an exemplary correlation between the slope of a portion of the scattering profile and the concentration of platelets in a fluid.

[0026] FIG. 11 is a schematic diagram of the optical detection assembly of FIG. 3 monitoring a reference fluid having a known cell concentration.

[0027] FIG. 12 is a schematic diagram of the optical detection assembly of FIG. 3 monitoring a target fluid having an unknown cell concentration.

[0028] Figures 13 and 14 are a pair of graphs showing the scattering profiles generated when monitoring a reference fluid and a target fluid.

[0029] Figure 15 is a flowchart showing an approach for determining the cell concentration of a target fluid according to one aspect of the present disclosure.

[0030] Figures 16 and 17 show another embodiment of the optical detection assembly according to one aspect of the present invention, with its carriage in different positions.

[0031] Figure 18 is a graph showing an exemplary correlation between the slope of a part of the scattering profile and the PMI of the fluid.

DETAILED DESCRIPTION OF THE INVENTION

[0032] The embodiments disclosed herein are intended to provide an exemplary description of the subject matter of the present invention. However, these are merely examples, and the subject matter of the present invention may be embodied in various forms. Therefore, the specific details disclosed herein should not be construed as limiting the subject matter defined in the appended claims.

[0033] Figures 1 - 2A show the components of a biological fluid processing system embodying various aspects of the subject matter of the present invention. Although the use of a system for separating blood into two or more components and collecting at least one component is described herein, it should be understood that the systems according to the present disclosure can be used to process a variety of different biological fluids.

[0034] Generally speaking, this system includes two main components: a durable and reusable biological fluid processing device 10 (FIG. 1) and a disposable fluid flow circuit 12 (FIGS. 2 and 2A). The illustrated biological fluid processing device 10 includes a rotary membrane separator drive unit 14, a centrifuge or centrifugal separator 16, additional components for controlling the flow of fluid through the disposable fluid flow circuit 12, and a control unit 18 for controlling the operation of the other components of the biological fluid processing device 10 to perform a biological fluid processing procedure. The principles described herein can be employed when using the biological fluid processing device 10 of FIG. 1, but it should be understood that these same principles are also applicable to other biological fluid processing devices including devices that employ a single separation technique or approach.

[0035] I. Durable Biological Fluid Processing Device The biological fluid processing device 10 (FIG. 1) is configured to be durable for long-term use. It should be understood that the biological fluid processing device of FIG. 1 is merely an example of one possible configuration, and the biological fluid processing device according to the present disclosure may have a different configuration.

[0036] In the illustrated embodiment, the biological fluid processing device 10 is embodied within a single housing or case 20. The illustrated case 20 includes a substantially horizontal portion 22 (which may include inclined or angled surfaces or upper surfaces to improve visibility and ergonomics) and a substantially vertical portion 24. The rotary membrane separator drive unit 14 and the centrifuge 16 are shown as being incorporated into the substantially horizontal portion 22 of the case 20, while the control unit 18 is shown as being incorporated into the substantially vertical portion 24.

[0037] A. Rotary Membrane Separator Drive Unit The biological fluid treatment apparatus 10 includes a rotor support or a rotating membrane separator drive unit 14 for accommodating a generally cylindrical rotating membrane separator 26 of a fluid flow circuit 12. U.S. Patent No. 5,194,145 (incorporated herein by reference) describes an exemplary rotating membrane separator drive unit suitable for incorporation into the fluid treatment apparatus 10, but it should be understood that the rotating membrane separator drive unit 14 can be configured differently without departing from the scope of the present disclosure.

[0038] The illustrated rotating membrane separator drive unit 14 includes a base 28 configured to accommodate a lower portion of the rotating membrane separator 26 and an upper end cap 30 configured to accommodate an upper portion of the rotating membrane separator 26. Preferably, the upper end cap 30 is disposed directly above the base 28, vertically orients the rotating membrane separator 26 received by the rotating membrane separator drive unit 14, and defines a vertical axis about which the rotating membrane separator 26 rotates. While it is advantageous for the rotating membrane separator drive unit 14 to orient the rotating membrane separator 26 in the vertical direction, it is also within the scope of the present disclosure for the rotating membrane separator 26 to be oriented in a different direction when attached to the biological fluid treatment apparatus 10.

[0039] In one embodiment, one of the base 28 and the upper end cap 30 of the rotating membrane separator drive unit 14 is movable relative to the other, thereby enabling rotating membrane separators 26 of different sizes to be accommodated by the rotating membrane separator drive unit 14. For example, the upper end cap 30 is moved vertically relative to the base 28 and locked in a plurality of different positions, each lock position corresponding to a rotating membrane separator 26 of a different size.

[0040] At least one of the base 28 and the upper end cap 30 is configured to rotate one or more components of the rotary membrane separator 26 about an axis defined by the rotary membrane separator drive unit 14. The mechanism by which the rotary membrane separation device drive unit 14 rotates one or more components of the rotary membrane separation device 26 can be changed without departing from the scope of the present disclosure. In one embodiment, the components of the rotary membrane separator 26 to be rotated include at least one element configured to be acted upon by a magnet (e.g., a metallic material), while the rotary membrane separator drive unit 14 includes a magnet (e.g., a series of magnetic coils or semi-circular arcs). By modulating the magnetic field acting on the aforementioned elements of the rotary membrane separator 26, the components of the rotary membrane separator 26 can be rotated in different directions and at different speeds. In other embodiments, different mechanisms may be employed to rotate the components of the rotary membrane separator 26.

[0041] Regardless of the mechanism by which the rotary membrane separator drive unit 14 rotates one or more components of the rotary membrane separator 26, one or more components of the rotary membrane separator 26 preferably rotate at a speed sufficient to generate Taylor vortices in the gap between the rotating components and the fixed components (or components rotating at different speeds) of the rotary membrane separator 26. The fluid separated within the rotary membrane separator 26 flows through this gap, and the generation of Taylor vortices may dramatically improve filtration.

[0042] B. Centrifugal Separator Regarding the centrifugal separator 16, it includes a centrifugal separation chamber 36 of the fluid flow circuit 12 and a centrifugal separation section 32 that houses other components of the centrifugal separator 16. Further details regarding the centrifugal separator are described in International Publication No. WO2018 / 053217A1 of the PCT application, which is incorporated herein by reference.

[0043] A fluid (e.g., anticoagulated whole blood) is introduced into the centrifugation chamber 36 by the umbilical cord (umbilicus), and as a result of the rotating centrifugal force, within the centrifugation chamber 36, the fluid separates into a layer of less dense components (e.g., platelet-rich plasma when separating blood) and a layer of more dense components (e.g., red blood cell concentrate). The components of the interface monitoring system can be arranged within the centrifugation section 32 to monitor the separation of the fluid within the centrifugation chamber 36. The interface monitoring system may include a light source 50 and a photodetector 52 arranged and oriented to receive at least a portion of the light emitted by the light source 50.

[0044] The orientation of the various components of the interface monitoring system is determined, at least in part, by the particular configuration of the centrifugation chamber 36. However, generally, the light source 50 emits a light beam (e.g., a laser beam) through the separated fluid components within the centrifugation chamber 36 (which can be formed of a material that does not absorb light or substantially transmits light of at least a particular wavelength). A portion of the light reaches the photodetector 52, and the photodetector 52 transmits a signal indicating the position of the interface between the separated fluid components to the control unit 18. If the control unit 18 determines that the interface is in the wrong position (which may affect the separation efficiency of the centrifuge 16 and / or the quality of the separated fluid components), it can issue commands to the appropriate components of the biological fluid processing device 10 to change their operation to move the interface to the appropriate position.

[0045] C. Other Components of the Biological Fluid Processing Device In addition to the rotary membrane separator drive unit 14 and the centrifuge 16, the biological fluid processing device 10 can include other components compactly arranged to assist with fluid processing.

[0046] In a substantially horizontal portion 22 of the case 20 of the illustrated fluid processing apparatus 10, there is included a cassette station 54 that houses a flow control cassette of the fluid flow circuit 12. In one embodiment, the cassette station 54 is configured similarly to the cassette station of U.S. Patent No. 5,868,696 (incorporated herein by reference), but is adapted to include additional components and functions. The illustrated cassette station 54 includes a plurality of clamps or valves V1-V9 (collectively referred to herein as the "valve system" of the biological fluid processing system 10), and these clamps or valves move between a plurality of positions (e.g., a retracted or lowered position and an actuated or raised position) to selectively contact or interact with corresponding valve stations of the flow control cassette of the fluid flow circuit 12. Depending on the configuration of the fluid flow circuit 12, the cassette may not include valve stations for each of the valves V1-V9 of the cassette station 54, in which case fewer valves than all of the valves V1-V9 will be used in the fluid processing procedure.

[0047] In the actuated position, valves V1-V9 engage with the associated valve stations to prevent fluid flow through those valve stations (e.g., by closing one or more ports associated with the valve station to prevent fluid flow through that port). In the stored position, valves V1-V9 disengage from (or the force of contact with) the associated valve stations becomes weaker than when in the actuated position, allowing fluid flow through those valve stations (e.g., by opening one or more ports associated with the valve station, thereby allowing fluid flow through that port or ports). Additional clamps of the valve system or valves V10 and V11 are disposed outside of cassette station 54 and interact with a portion (which may be the length of a tube) of the valve stations of fluid flow circuit 12 to selectively permit or prevent fluid flow therethrough. Valves V1-V9 and the corresponding valve stations and cassettes of cassette station 54 may have a different configuration and different operation from valves V10 and V11 and the valve stations located away from cassette station 54.

[0048] Cassette station 54 may be provided with additional components such as pressure sensors A1-A4 that interact with the sensor stations of the cassette to monitor the pressures at various locations in fluid flow circuit 12. For example, if the fluid source is a human donor, one or more of pressure sensors A1-A4 may be configured to monitor the pressure in the donor's vein during blood collection and blood return. Other pressure sensors A1-A4 may monitor the pressures of rotary membrane separator 26 and centrifugation chamber 36. Control unit 18 receives signals indicating the pressures within fluid flow circuit 12 from pressure sensors A1-A4, and if the signals indicate a low or high pressure condition, control unit 18 can warn the operator of that condition and / or initiate an alarm or error condition to attempt to reduce the pressure to an acceptable level without operator intervention.

[0049] The biological fluid processing apparatus 10 may include a plurality of pumps P1 to P6 (collectively referred to herein as the "pump system" of the biological fluid processing apparatus 10) for flowing fluid through the fluid flow circuit 12. The pumps P1 to P6 may have different configurations or similar configurations and / or may have similar or different functions from each other. In the illustrated embodiment, the pumps P1 to P6 are configured as peristaltic pumps, which can be configured generally as described in U.S. Patent No. 5,868,696. Each of the pumps P1 to P6 engages with a different tube loop extending from the side of the flow control cassette and is selectively operated based on commands from the control unit 18 to allow fluid to flow through a portion of the fluid flow circuit 12. In one embodiment, all or part of the cassette station 54 is capable of translational movement in and out of the case 20, thereby enabling the tube loops to be automatically loaded onto the associated pumps P1 to P6. In another exemplary embodiment, instead of using peristaltic pumps, pneumatic pumps are used and actuators incorporated into the cassette station 54 interact with appropriately configured portions of the fluid flow circuit 12 (e.g., the pump stations of the cassette attached to the cassette station 54) to convey fluid through the fluid flow circuit 12.

[0050] The illustrated biological fluid processing apparatus 10 also includes a rotor inlet sensor M1 for determining one or more characteristics of the fluid flowing into the rotary membrane separator 26 mounted within the rotary membrane separator drive unit 14. When the fluid flowing into the rotary membrane separator 26 is whole blood (which may include anticoagulated whole blood), the rotor inlet sensor M1 may be configured to determine the hematocrit value of the blood flowing into the rotary membrane separator 26. When the fluid flowing into the rotary membrane separator 26 is platelet-rich plasma, the rotor inlet sensor M1 may be configured to determine the platelet concentration and / or PMI of the platelet-rich plasma flowing into the rotary membrane separator 26. The rotor inlet sensor M1 can detect one or more characteristics of the fluid by optically monitoring the fluid as it flows through the tubing of the fluid flow circuit 12 or by other suitable means. The control unit 18 receives a signal from the rotor inlet sensor M1 indicating one or more characteristics of the fluid flowing into the rotary membrane separator 26 and uses that signal to optimize the fluid processing procedure based on that characteristic. If the characteristic is outside the acceptable range, the control unit 18 may initiate an alarm or error condition to alert the operator of that condition. Suitable devices and methods for monitoring hematocrit and / or platelet concentration are described in U.S. Patent No. 6,419,822 (incorporated herein by reference), but it should be understood that different approaches may also be employed to monitor one or more characteristics of the fluid or fluid components flowing into the rotary membrane separator 26.

[0051] The illustrated biological fluid processing apparatus 10 further includes a rotor outlet sensor M2, which houses a tube of the fluid flow circuit 12 that allows the fluid components separated from the rotary membrane separator 26 to flow out. The rotor outlet sensor M2 monitors the separated fluid components and determines one or more of their characteristics. This determination can be made optically as the separated fluid components flow through the tube, or by other suitable methods. In one embodiment (shown in FIG. 2), the separated plasma flows through the tube, in which case the rotor outlet sensor M2 can be configured to determine the amount of cellular blood components in the plasma and / or whether the plasma is hemolytic and / or lipemic. This can be done using an optical monitor of the type described in U.S. Patent No. 8,556,793, which is incorporated herein by reference, to measure the optical density of the fluid in the associated tube, or by other suitable devices and / or methods. In another embodiment (illustrated in FIG. 2A), the rotor outlet sensor M2 is associated with a tube that receives the flow of separated platelets or platelet concentrate discharged from the rotary membrane separator 26, in which case the rotor outlet sensor M2 may be configured to determine its PMI, as will be described in more detail.

[0052] The illustrated fluid processing apparatus also includes an air detector M3 (e.g., an ultrasonic bubble detector) that houses the piping of the fluid flow circuit 12 that flows the fluid to the receiving part. Since it may be advantageous to prevent air from reaching the recipient, whether the recipient is a human recipient (e.g., the same human being that is the blood source) or a non-human recipient (e.g., a storage bag or container), the air detector M3 can send a signal indicating the presence or absence of air in the tube to the control unit 18. If the signal indicates that air is present in the tube, the control unit 18 initiates an alarm or error state to warn the operator of that state and / or executes corrective actions so that air does not reach the recipient (e.g., reverses the flow of fluid through the tube or diverts the flow to a vent location).

[0053] In the substantially vertical portion 24 of the case 20, a plurality of volume measurement systems W1 - W6 (six are shown, but more or fewer are possible) are included, and each volume measurement system is configured to be associated with one or more fluid containers F1 - F7 of the fluid flow circuit 12 (FIGS. 2 and 2A). Each of the volume measurement systems W1 - W6 operates in combination with the control unit 18 and is configured to measure the current volume of the fluid in the associated fluid containers F1 - F7 and calculate the change in that volume between two or more points in time. The individual volume measurement systems W1 - W6 can be configured in various ways without departing from the scope of the invention, including the possibility that two or more of the volume measurement systems W1 - W6 have different configurations. As an example, the volume measurement systems W1 - W6 can be configured as, or can include, a weighing scale configured to support and measure the weight of the fluid in the associated fluid containers F1 - F7 (the measured weight is converted to volume by a component of the volume measurement systems W1 - W6 or by the control unit 18). In another exemplary embodiment, the volume measurement systems W1 - W6 can include one or more sensors configured to detect the volume and / or change in volume of the fluid in the associated fluid containers F1 - F7. Volume measurement systems including additional components (e.g., both a weighing scale and a sensor) and / or alternative components can also be employed without departing from the scope of the present disclosure.

[0054] Regardless of their respective configurations, each of the volume measurement systems W1 - W6 transmits a signal indicating the volume of the fluid in the associated containers F1 - F7 to the control unit 18 and tracks the change in volume during the course of the treatment. Thereby, the control unit 18 can process the incremental volume change to derive the fluid treatment volume and flow rate, and then generate a signal to control the treatment event based at least in part on the derived treatment volume. For example, the control unit 18 can diagnose leaks or malfunctions in the fluid flow circuit 12 and issue a warning to the operator.

[0055] The illustrated case 20 is also provided with a plurality of hooks or supports H1 and H2 that can support various components of the fluid flow circuit 12 or other suitable sized and configured objects.

[0056] D. Control Unit According to one aspect of the present disclosure, the biological fluid processing apparatus 10 includes a control unit 18 that is appropriately configured and / or programmed to control the operation of the biological fluid processing apparatus 10. In one embodiment, the control unit 18 includes a main processing unit (MPU), which can be configured, for example, with a Pentium (trademark) type microprocessor manufactured by Intel Corporation, but other types of conventional microprocessors can also be used. In one embodiment, the control unit 18 may be disposed inside a substantially vertical portion 24 of the case 20, adjacent to or incorporated into an operator interface station (e.g., a touch screen). In other embodiments, the control unit 18 and the operator interface station may be associated with a substantially horizontal portion 22, or may be incorporated into another device connected (physically, such as by a cable or wirelessly) to the biological fluid processing apparatus 10.

[0057] The control unit 18 is configured and / or programmed to execute at least one biological fluid processing procedure, and more preferably, is configured and / or programmed to execute various different biological fluid processing procedures. For example, the control unit 18 may be configured and / or programmed to execute one or more of a two-unit red blood cell collection procedure, a plasma collection procedure, a plasma / red blood cell collection procedure, a red blood cell / platelet / plasma collection procedure, a platelet collection procedure, and a platelet / plasma collection procedure.

[0058] More specifically, when executing these fluid processing procedures, the control unit 18 is configured and / or programmed to control one or more of the following tasks. Draw fluid into the fluid flow circuit 12 attached to the biological fluid processing apparatus 10, convey the fluid through the fluid flow circuit 12 to a separation location (i.e., the rotary membrane separator 26 or the centrifugal separation chamber 36 of the fluid flow circuit 12), separate the fluid into two or more components as needed, convey the separated components to a storage container, and further convey them to a second location for further separation (e.g., either of the rotary membrane separator 26 and the centrifugal separation chamber 36 that was not used in the first separation stage), or convey them to a recipient (which may be the source from which the fluid was initially drawn).

[0059] This includes instructing the rotary membrane separator drive unit 14 and / or the centrifuge 16 to operate at a specific rotational speed, and instructing the pumps P1 - P6 to transport fluid through a part of the fluid flow circuit 12 at a specific flow rate. Therefore, although in this specification, a specific component of the biological fluid processing apparatus 10 (e.g., the rotary membrane separator drive unit 14 or the centrifuge 16) is described as performing a specific function, it is necessary to understand that the component is controlled by the control unit 18 to perform that function.

[0060] Before, during, and after the treatment, the control unit 18 can receive signals from various components of the biological fluid processing apparatus 10 (e.g., the pressure sensors A1 - A4) to monitor various aspects of the operation of the biological fluid processing apparatus 10, and the characteristics of the fluid flowing through the fluid flow circuit 12 and the separated fluid components. If the operation of any component and / or one or more characteristics of the fluid or the separated fluid components are outside the allowable range, the control unit 18 initiates an alarm or error state to warn the operator, and / or executes actions to correct the state. Appropriate corrective measures vary depending on the specific error state and may include measures that are executed with or without operator involvement.

[0061] For example, the control unit 18 may include an interface control module that receives signals from the photodetector 52 of the interface monitoring system. The signal received by the control unit 18 from the photodetector 52 indicates the position of the interface between the separated fluid components in the centrifugation chamber 36. If the control unit 18 determines that the interface is at an incorrect position, it can issue commands to appropriate components of the biological fluid processing apparatus 10 to change their operations to move the interface to the appropriate position. For example, the control unit 18 can instruct one of the pumps P1 - P6 to cause fluid to flow into the centrifugation chamber 36 at different speeds, and / or to remove the separated fluid components from the centrifugation chamber 36 at different speeds, and / or to instruct the centrifuge 16 to rotate the centrifugation chamber 36 at different speeds.

[0062] When an operator interface station associated with the control unit 18 is provided, the operator can view information regarding the operation of the system on a screen or display, and / or display it (in alphanumeric form and / or as a graphic image). At the operator interface station, the operator can also select the applications executed by the control unit 18 and change specific functions and performance criteria of the system. When configured as a touch screen, the screen of the operator interface station can receive input from the operator by touch operations. Otherwise, if the screen is not a touch screen, the operator interface station may receive input from the operator via another input device such as a computer mouse or keyboard. It is also within the scope of the present disclosure for the operator interface station to receive input from both a touch screen and another input device such as a keypad.

[0063] II. Disposable fluid flow circuit The fluid flow circuit or flow set 12 (Figs. 2 and 2A) is intended to be a sterilized, single-use, disposable item. Prior to initiating a predetermined fluid processing procedure, the operator loads the various components of the fluid flow circuit 12 associated with the biological fluid processing apparatus 10 into the case 20. The control unit 18 executes the procedure based on a pre-set protocol taking into account other inputs from the operator. When the procedure is complete, the operator removes the fluid flow circuit 12 from the biological fluid processing apparatus 10. The portion of the fluid flow circuit 12 that holds the collected fluid components (such as a collection container or bag) is removed from the case 20 and retained for storage, infusion, or further processing. The remaining portion of the fluid flow circuit 12 is removed from the case 20 and discarded.

[0064] In the illustrated embodiment, the fluid flow circuit 12 includes a cassette, and the other components of the fluid flow circuit 12 are connected to the cassette by flexible tubing. The other components may include a plurality of fluid containers F1 - F7. In the context of the present disclosure, these containers include an anticoagulant container F1, a saline container F2, an intermediate container F3, a return container F4, a plasma collection container F5, a platelet collection container F6, and (optionally) an additive container F7. The illustrated flow circuit 12 further includes one or more fluid source access devices (e.g., connectors or bleeding needles for accessing blood within the fluid containers), a rotary membrane separator 26, and a centrifugation chamber 36.

[0065] The flow control cassette provides a centralized programmable integrated platform for all the pump functions and many of the valve functions required for a predetermined fluid processing procedure. In one embodiment, the cassette is configured similarly to the cassette of U.S. Patent No. 5,868,696 but is adapted to include additional components (e.g., more tubing loops) and functions.

[0066] In use, the cassette is attached to the cassette station 54 of the biological fluid processing apparatus 10 such that each sensor station is aligned with the associated pressure sensors A1 - A4 of the cassette station 54 and its valve station is aligned with the associated valves V1 - V9. Each valve station can define one or more ports that enable fluid communication between the valve station and another internal cavity (e.g., a flow path) of the cassette. As described above, each of the valves V1 - V9 is movable in accordance with instructions from the control unit 18 and moves between a plurality of positions (e.g., between a stored or lowered position and an actuated or raised position) to selectively contact the valve stations of the cassette. In the actuated position, the valves V1 - V9 engage the associated valve stations to close one or more ports and prevent fluid flow therethrough. In the stored position, the valves V1 - V9 are disengaged from the associated valve stations (or the force of contact with the associated valve stations is weaker than when in the actuated position), and one or more ports associated with the valve stations open to allow fluid to flow therethrough.

[0067] A plurality of tube loops extend from the side of the cassette and interact with the pumps P1 - P6 of the biological fluid processing apparatus 10. Different pumps P1 - P6 interact with the tube loops of the cassette to perform different tasks during the procedure. In the context of the present disclosure, different ones of the pumps P1 - P6 may be configured to function as an anticoagulant pump P1, a source pump P2, a centrifugal pump P3, an outlet pump P4, a recirculation pump P5, and a plasma pump P6. When the pumps P1 - P6 are configured differently (e.g., configured as pneumatic pumps), the cassette is also configured differently (e.g., the pump stations are aligned with pneumatic pump actuators) such that the pumps P1 - P6 can convey fluid through the cassette.

[0068] Additional tubing extends from the sides of the cassette and connects to various fluid containers F1 - F7, the rotary membrane separator 26, and other components of the fluid flow circuit 12 such as the centrifugal separation chamber 36. The tubing connected to the centrifugal separator chamber 36 (including one inlet tube and two outlet tubes) may converge at an umbilical-like structure (umbilicus).

[0069] Various additional components can be incorporated within the tubing exiting the cassette or within one of the cavities of the cassette. For example, a manual clamp 56 can be associated with the line leading to the fluid source, a return line filter 58 (e.g., a microaggregate filter) can be associated with the line leading to the fluid recipient, and / or an air trap 62 can be placed on the line upstream of the centrifugal separation chamber 36.

[0070] III. Exemplary Biological Fluid Processing Procedures Here, an exemplary biological fluid processing procedure according to the present disclosure will be described.

[0071] Prior to processing, the operator selects the desired protocol (e.g., using an operator interface station if provided), thereby notifying the control unit 18 of how to control the other components of the biological fluid processing apparatus 10 during processing. This includes first selecting one of the multiple procedures executable by the system, then selecting the nature of the procedure, and then selecting one or more parameters that will be valid during the procedure. For example, selecting a platelet collection procedure from among various blood separation procedures, and then selecting the total volume of blood to be processed or the target volume of platelets to be collected during that procedure. If the fluid source is a biological source (such as a donor or patient), the operator can input various parameters such as the gender, height, and weight of the fluid source. In one embodiment, the operator can also input one or more characteristics of the fluid to be processed, such as a pre - count of platelets.

[0072] When the control unit 18 receives the necessary inputs, it can instruct the operator to attach the fluid flow circuit 12 to the biological fluid processing apparatus 10. If there are fluid containers (e.g., platelet additive solution containers) that are not integrally formed with the fluid flow circuit 12, those fluid containers are connected to the fluid flow circuit 12 (e.g., by piercing the septum of the tubing of the fluid flow circuit 12 or via a Luer connector), and then the fluid flow circuit 12 is attached to the biological fluid processing apparatus 10 (optionally including fluid containers F1 - F7 associated with the volume measurement systems W1 - W6). As an example, each of the volume measurement systems W1 - W6 includes a weighing scale associated with a hook that can suspend the fluid container. In another exemplary embodiment, at least one of the volume measurement systems W1 - W6 includes a weighing scale associated with a horizontal platform or surface, the container is placed on the platform or surface for support, and the weighing scale transmits a signal indicating the weight of the container (and its contents) to the control unit 18 throughout the course of the procedure. In other embodiments, the fluid container may be associated with a volume measurement system that omits the weighing scale but includes other means (e.g., one or more sensors) for measuring the volume of the fluid within the container.

[0073] When the fluid flow circuit 12 is fully attached to the biological fluid processing apparatus 10, the control unit 18 proceeds with an integrity check of the fluid flow circuit 12 to confirm that the various components of the fluid flow circuit 12 are properly connected and functioning. When the integrity check is successfully completed, a fluid source is connected to the fluid flow circuit 12 (e.g., by connecting to a container of previously collected fluid or by bleeding a donor), and the fluid flow circuit 12 is primed (e.g., using physiological saline pumped from the physiological saline container F2 by the operation of one or more of the pumps P1 - P6 of the biological fluid processing apparatus 10).

[0074] After the fluid flow circuit 12 is primed, fluid processing is initiated. In the first step of an exemplary platelet collection procedure, blood is drawn from a blood source into the fluid flow circuit 12. If the blood source is a donor, the blood can be drawn into the fluid flow circuit 12 through a single needle connected to the cassette by line L1. Line L1 can include a manual clamp 56 that is initially in a closed position to prevent fluid flow through line L1. When starting the process, the operator moves the manual clamp 56 from the closed position to the open position to allow fluid flow through line L1.

[0075] Blood is drawn into line L1 by the supply pump P2 of the biological fluid processing device 10. Anticoagulant from the anticoagulant container F1 is drawn through line L2 by the action of the anticoagulant pump P1 and added to the blood at the junction of line L1 and line L2.

[0076] In the illustrated embodiment, valve V10 is open to permit the anticoagulated blood to flow through line L3 and the cassette sensor station associated with pressure sensor A1, while valve V11 is closed to prevent fluid from flowing through line L4. If the blood source is a living body (e.g., a donor), pressure sensor A1 can communicate with the control unit 18 to monitor the pressure within the vein of the blood source.

[0077] The cassette is provided with two valve stations downstream of the supply pump P2. Valve V2 is closed to prevent flow through line L5, and valve V1 is open to permit flow through line L6. A portion of the blood is sent through line L7 and the cassette sensor station associated with pressure sensor A3 to the processing container F3 during processing, and the remaining blood is sent through line L8 to the centrifuge pump P3. The centrifuge pump P3 controls the amount of blood sent to the centrifuge chamber 36 rather than the processing container F3. In particular, the flow rate of the supply pump P2 is greater than the flow rate of the centrifuge pump P3, and the difference is equal to the flow rate of blood to the processing container F3. The flow rate can be selected such that at the end of the collection phase, the processing container F3 is partially or fully filled with blood.

[0078] The blood delivered through line L8 by the centrifugal pump P3 passes through line L19, the air trap 62, and the cassette sensor station associated with the pressure sensor A2 (which monitors the pressure within the centrifugal chamber 36 in conjunction with the control unit 18 of the biological fluid processing device 10) before reaching the centrifugal chamber 36 of the fluid flow circuit 12. The centrifuge 16 of the biological fluid processing device 10 operates the centrifugal chamber 36 to separate the blood within the centrifugal chamber 36 into platelet-rich plasma and red blood cell concentrate. In one embodiment, the centrifugal chamber 36 rotates at a nominal 4,500 rpm, although the specific rotational speed varies depending on the flow rate of the fluid entering and leaving the centrifugal chamber 36.

[0079] The concentrated red blood cells exit the centrifugal chamber 36 via line L10, flow back through line L11, and into the return container F4. The platelet-rich plasma is withdrawn from the centrifugal chamber 36 via line L12 by the combined operation of the recirculation pump P5 and the outlet pump P4 of the biological fluid processing device 10. The platelet-rich plasma passes through line L12 and reaches a junction where it branches into lines L13 and L14. The recirculation pump P5 is connected to line L13, redirecting a portion of the platelet-rich plasma towards the junction where it mixes with the blood in line L8 being conveyed to the centrifugal chamber 36 by the centrifugal pump P3. By recirculating a portion of the platelet-rich plasma along with the incoming blood into the centrifugal chamber 36, the hematocrit value of the blood entering the centrifugal chamber 36 may be reduced, potentially improving the separation efficiency. With such an arrangement, the flow rate of the fluid entering the centrifugal chamber 36 is equal to the sum of the flow rates of the centrifugal pump P3 and the recirculation pump P5. Since the platelet-rich plasma drawn from the centrifugal chamber 36 into line L13 by the recirculation pump P5 is immediately returned to the centrifugal chamber 36, the bulk flow rate or net flow rate of the platelet-rich plasma flowing out of the centrifugal chamber 36 is equal to the flow rate of the outlet pump P4.

[0080] Line L14 ends at the junction where it merges with lines L15 and L16. Valve V6 is closed to prevent the flow of fluid through line L16 and send the separated platelet-rich plasma through line L15 to the rotary membrane separator 26. A part of the platelet-rich plasma conveyed through line L15 passes through the rotor inlet sensor M1 and the cassette sensor station associated with the pressure sensor A4 before reaching the rotary membrane separator 26. The rotor inlet sensor M1 can detect the PMI or platelet concentration in the platelet-rich plasma entering the rotary membrane separator 26, and the pressure sensor A4 can monitor the pressure of the rotary membrane separator 26.

[0081] Valve V6 is normally closed but can be selectively opened as needed to divert all or part of the platelet-rich plasma from line L14 into line L16 and send it back to the return container F4 via line L16. An example is at the start of a procedure where separation is initiated and the platelets have not yet exited the centrifugation chamber 36. In this case, the fluid conveyed through line L14 by the outlet pump P4 may be diverted to the return container F4.

[0082] The rotary membrane separator drive unit 14 of the biological fluid treatment device 10 operates the rotary membrane separator 26 to separate the platelet-rich plasma into platelet-poor plasma ("plasma") and platelet concentrate ("platelets"). The plasma is sent out from the rotary membrane separator 26 via line L17 by the plasma pump P6 of the biological fluid treatment device 10. Valves V5, V6, V8, and V9 are closed, and the separated plasma passes through valve V4 along line L18 and is sent to the return container F4 (which contains the separated red blood cells). In the direction of Figure 2, the plasma passes through the rotor outlet sensor M2 on its way to the return container F4. The rotor outlet sensor M2 cooperates with the control unit 18 to determine one or more characteristics of the plasma, such as the amount of cellular blood components in the plasma and / or whether the plasma is hemolytic and / or lipemic.

[0083] The platelet concentrate is conveyed from the rotary membrane separator 26 via line L19. Since no pump is associated with line L19, instead, the flow rate at which platelets are discharged from the rotary membrane separator 26 is equal to the difference between the flow rates of outlet pump P4 and plasma pump P6. Valve V8 is closed to prevent the flow of fluid through line L20, and the platelet flow is directed along line L19 through valve V7 to the platelet collection container F6. In the direction of Figure 2A, on the way towards the platelet collection container F6, the platelets pass through the rotor outlet sensor M2. The rotor outlet sensor M2 cooperates with the control unit 18 to determine one or more characteristics of the platelets, such as PMI and / or platelet concentration. Valve V8 is selectively opened, and the fluid flows through line L20 to the junction, and the plasma that flows through line L18 as required is combined with the return container F4.

[0084] Depending on the volume of platelets to be collected, the above collection steps can be repeated, and the collection steps and return steps can also be performed alternately. In the return step, the blood from the processing container F3 is separated in the centrifugation chamber 36, and the blood components previously collected in the return container F4 are returned to the blood source. In such a return step, the separated red blood cells and platelet-rich plasma may be sent through various paths via the fluid flow circuit 12, and usually, an additional volume of platelets is separated from the platelet-poor plasma by the rotary membrane separator 26 (similar to the case of the collection step) and then collected in the platelet collection container F6. Before ending the procedure, the platelet additive solution from the additive container F7 can be added to the platelets collected in the platelet collection container F6.

[0085] IV. Determination of Cell Concentration As described above, the rotor inlet sensor M1 can be used in combination with the control unit 18 to determine one or more characteristics of the fluid flowing into the rotary membrane separator 26, and the rotor outlet sensor M2 can be used to determine one or more characteristics of the fluid flowing out of the rotary membrane separator 26. FIGS. 3-5 show an exemplary optical detection assembly 100 that can be incorporated into the biological fluid processing apparatus 10 to perform the functions of the rotor inlet sensor M1 or the rotor outlet sensor M2. In one embodiment, two such optical detection assemblies 100 can be incorporated into the biological fluid processing apparatus 10, one functioning as the rotor inlet sensor M1 and the other functioning as the rotor outlet sensor M2. The optical detection assembly 100 of FIGS. 3-5 is described herein as a component of the biological fluid processing apparatus 10 of FIG. 1, but it should be understood that the optical detection assembly according to the present disclosure may be incorporated into biological fluid processing apparatuses of different configurations or provided as a stand-alone device not incorporated into a biological fluid processing apparatus.

[0086] In the illustrated embodiment, the optical detection assembly 100 includes a light source 102 and a photodetector array 104, which are spaced apart to accommodate a container "B" therebetween. When the optical detection assembly 100 is used as the rotor inlet sensor M1, the container B may be line L15 of the fluid flow circuit 12, and when the optical detection assembly 100 is used as the rotor outlet sensor M2, the container B may be line L17 (FIG. 2) or line L19 (FIG. 2A) of the fluid flow circuit 12. It should be understood that the configuration of the container B used in combination with the optical detection assembly 100 can be changed without departing from the scope of the present disclosure as long as the container B is suitable for containing the fluid (including the case where the container B is configured to accommodate the fluid flow therethrough) and is formed of a material configured to transmit the light emitted by the light source 102.

[0087] The illustrated optical detection assembly 100 includes a base 106 that defines a slot or channel 108 configured to receive a container B. The channel 108 is configured to hold the container B in a desired orientation with respect to the light source 102 and the photodetector array 104. The optical detection assembly 100 may also include a lid 110 (shown in FIGS. 3 and 4 as being hingedly or pivotally associated with the base 106) to prevent external light from interfering with the analysis of the fluid within the container B.

[0088] Light D emitted from the light source 102 (which can have various configurations without departing from the scope of the present invention) enters the container B, passes through the fluid within the container B, and then exits the container B. FIGS. 6 and 7 show the transmitted light exiting the container B, and the photodetector array 104 is arranged and oriented to receive at least a portion of the transmitted light. The photodetector array 104 is composed of a plurality of photodetectors or light sensing elements (e.g., 256 photodiodes in a linear array). As explained above, since light emerging from a turbid medium (such as blood or blood components) is scattered, the light can be detected at multiple positions rather than at a single position by a single photodetector (such as an individual photodiode). It has been found that different fluids (e.g., fluids with different concentrations of the analyte) can generate light rays with different scattering patterns. For example, FIG. 6 shows a fluid "f" with a relatively low platelet concentration, and FIG. 7 shows a fluid "F" with a high platelet concentration. The light D (e.g., a narrowly focused laser beam) transmitted through the fluid within the container B is scattered, and different individual photodetectors receive different portions of the transmitted light.

[0089] The control unit associated with the photodetector array 104 (which may be the control unit 18 of the biological fluid processing apparatus 10 or another dedicated control unit) receives signals from each of the individual photodetectors of the photodetector array 104, and each signal indicates the intensity of the light received by the individual photodetector that transmitted the signal to the control unit. Figures 6 and 7 include charts (herein referred to as "scattering profiles") generated by the control unit based on the signals from the photodetector array 104, which charts reflect the intensity of the signals received by the control unit from each individual photodetector, and the results are ordered by the relative positions of the individual photodetectors (i.e., the signal from the photodetector at the left end of the photodetector array 104 is displayed at the left end of each chart, and the signal from an adjacent photodetector is displayed immediately to the right of the signal from the first photodetector, continuing until the signal from the photodetector at the right end of the photodetector array 104 is displayed at the right end of each chart). As can be seen from Figures 6 and 7, the photodetectors in the center of the photodetector array 104 tend to receive the strongest light, and the photodetectors at both ends of the photodetector array 104 tend to receive little or no light.

[0090] In the illustrated embodiment, platelets in the fluid cause light to scatter rather than pass straight through the fluid and vessel B (along its initial path). Since there are many cells in the fluid F of Figure 7, there is more light scattering, and more individual photodetectors receive at least some light, but the maximum intensity is relatively low compared to the maximum intensity of the light received by the individual photodetectors of Figure 6. In other words, the light passing through the low-concentration fluid f of Figure 6 is narrowly distributed or dispersed, whereas the light passing through the high-concentration fluid F of Figure 7 is more widely distributed or dispersed. Thus, by providing the photodetector array 104, the intensity of the light received by a plurality of individual photodetectors (i.e., the light distribution or scattering profile) can be evaluated to determine one or more characteristics of the target fluid (such as the concentration of substances (e.g., platelets) in the fluid). This may improve the measurement accuracy compared to a conventional optical detection assembly comprising a single photodetector and a control unit configured only to evaluate the intensity of the light received by the single photodetector.

[0091] When the control unit generates a scattering profile, various approaches can be employed to extract data from the scattering profile that can be used to determine the characteristics of the target fluid. For example, the scattering profile has a peak at a position corresponding to the individual photodetector that received the most light passing through container B and the fluid within container B. The scattering profile has a "rising edge" to the left of the peak and a "falling edge" to the right of the peak. The rising edge includes signals from individual photodetectors that are to the left of the central photodetector, and the falling edge includes signals from individual photodetectors that are to the right of the central photodetector. As explained above, photodetectors closer to the center of the photodetector array 104 tend to receive more light than photodetectors at positions farther from the center. Therefore, the rising edge has a positive slope (which may vary at different points along the scattering profile), and the falling edge has a negative slope (which may vary at different points along the scattering profile).

[0092] Since the slopes of the rising edge and the falling edge tend to change at different points along the scattering profile, the control unit can adopt different methods to calculate the slope of one section of the rising edge or the falling edge. For example, FIG. 6 shows a section of the rising edge of the scattering profile that can be analyzed to calculate the slope of the rising edge, and FIG. 7 shows a section of the falling edge of the scattering profile that can be analyzed to calculate the slope of the falling edge. As an example, the control unit selects two points on the rising edge or two points on the falling edge of the scattering profile corresponding to the signals from two individual photodetectors in the photodetector array 104. Next, the control unit divides the change in detector response (the voltage of the signal transmitted by the rightmost detector among the two detectors minus the voltage of the signal transmitted by the leftmost detector among the two detectors) by the change in detector position (the difference in the relative positions of the two detectors within the photodetector array 104) to calculate the slope of the edge. In the example shown in FIG. 8, the falling edge of the scattering profile is analyzed by the control unit and its slope is calculated. The voltage of the signal "L" from the left end (detector position is 290) among the two selected detectors is 2.1 dV, and the voltage of the signal "R" from the right end (detector position is 350) among the two selected detectors is 0.7 dV. In this example, the slope of the falling edge is approximately -0.023 ((0.7 dV - 2.1 dV) / (350 - 290)).

[0093] According to another approach, the control unit can use linear regression to calculate the slope of the rising edge or the slope of the falling edge. FIG. 9 shows the regression lines for calculating the slope of the section of the rising edge (line "C") of the scattering profile and the slope of the section of the falling edge (line "E") of the scattering profile.

[0094] When calculating the slope of a selected edge, any two points on the rising edge of the scatter profile or any two points on the falling edge of the scatter profile can be selected. According to one exemplary approach, the two points correspond to individual photodetectors that generated a signal that is one of two selected percentages of the signal at the peak "A" of the scatter profile. In one example, the two selected percentages are 35% of the signal at the peak of the scatter profile and 65% of the signal at the peak of the scatter profile. When analyzing the rising edge of the scatter profile, the leftmost photodetector of the two selected photodetectors has a signal that is 35% of the signal at the peak of the scatter profile, and the rightmost photodetector of the two selected photodetectors has a signal that is 65% of the signal at the peak. When analyzing the falling edge of the scatter profile (as in Figure 8), the leftmost detector of the two selected detectors has a signal that is 65% of the signal at the peak, and the rightmost detector has a signal that is 35% of the signal at the peak.

[0095] According to another exemplary approach, the two points on the scatter profile selected to calculate the slope of the rising edge or the falling edge of the scatter profile correspond to signals generated by two pre-selected or predetermined photodetectors of the photodetector array 104. When implementing this approach, the signals generated by the same two photodetectors are used regardless of the maximum voltage of the signal or the percentage of the maximum voltage represented by the signals generated by each of the two photodetectors (e.g., the signal generated by the photodetector at detector position 280 is always used, and the signal generated by the photodetector at detector position 350 is always used). The two photodetectors used can be changed without departing from the scope of the present disclosure, but it is advantageous to select two photodetectors that are likely to generate signals located within the rising edge of the scatter profile or two photodetectors that are likely to generate signals located within the falling edge of the scatter profile, and there is sufficient spacing between the positions of the two photodetectors to provide an accurate approximation of the slope of the corresponding edge of the scatter profile.

[0096] Regardless of the method for calculating the slope of the rising edge or the slope of the falling edge, it has been found that the magnitudes of the slopes of the rising edge and the falling edge of the scatter profile each indicate the cell concentration of the fluid being monitored by the optical detection assembly 100. A library or database of substance concentrations, each of which correlates with the slope of the rising edge and / or the slope of the falling edge, can be programmed into the control unit or stored elsewhere and remotely accessed by the control unit. For example, FIG. 10 is a graph showing an empirically derived correlation between the slope of the rising edge or the slope of the falling edge and the platelet concentration of the fluid. In the example shown in FIG. 8, the magnitude of the slope of the falling edge is approximately 0.023, which corresponds to a platelet concentration of approximately 2,250×10 3 cells / μL.

[0097] Since the scatter profile has both a rising edge and a falling edge, either slope can be calculated and compared to a library or database of correlations to determine the properties of the fluid that correlate with the slope. The scatter profile is often approximately symmetric about its peak, and the slope of the rising edge section tends to be approximately equal to the slope of the corresponding section of the falling edge, in which case each slope correlates with the same approximate fluid property value. However, it is also within the scope of the present disclosure to employ both slopes when determining the fluid property value. As an example, there is a method of calculating both the slope of the rising edge and the slope of the falling edge, with the control unit calculating the average of the two slopes and comparing the average value to a library or database of correlations to determine the fluid property value. According to another exemplary approach, both the slope of the rising edge and the slope of the falling edge are calculated, and the control unit can compare each slope to a library or database to determine the fluid property value that correlates with each slope. Next, the control unit calculates the average of these two fluid property values and determines that the fluid property value of the target fluid is equal to the calculated average. Other approaches (e.g., giving one slope a greater weight than the other) for determining the fluid property value using both the slopes of the rising edge and the falling edge of the scatter profile can also be employed without departing from the scope of the present disclosure.

[0098] According to another aspect of the present disclosure, an optical detection assembly can be used to analyze both a reference fluid having a known fluid property value (e.g., cell concentration) and a target fluid having an unknown value for the same fluid property, and determine the fluid property value of the target fluid. The target fluid may have a composition that affects the optical analysis as described above, which may result in an incorrect determination of the target fluid property value. For example, plasma may contain proteins and lipids that affect its color and optical transparency. Since lipids can scatter light and disperse it throughout the fluid similar to cells, optical analysis of lipemic plasma may overestimate the platelet concentration in the plasma (because the light transmitted through the plasma is scattered by both platelets and lipids before reaching the photodetector assembly). By analyzing the reference fluid, such effects can be taken into account, enabling a more accurate determination of the target fluid property value (such as cell concentration) of the target fluid.

[0099] Figures 11 and 12 show an optical detection assembly 100 equipped with a light source 102 and a photodetector array 104 of the type shown in FIGS. 3 - 5, and the optical detection assembly 100 is used to analyze a reference fluid "J" (FIG. 11) and a target fluid "K" (FIG. 12). The principle of analyzing the reference fluid to improve the analysis of the target fluid is described with reference to an optical detection assembly using a photodetector array, but it should be understood that it is not limited to the use of such an optical detection assembly. In fact, this principle can be employed in optical detection assemblies with different configurations, such as those equipped with a single photodetector instead of a photodetector array.

[0100] The reference fluid J is selected to have a composition (and thus optical properties) similar to that of the target fluid K, but the reference fluid J has known values for the fluid properties of interest. Thus, the properties of the reference fluid J can vary depending on the properties of the target fluid K. If the target fluid K is a platelet concentrate or platelet-rich plasma having an unknown platelet concentration measured using an optical detection assembly, the reference fluid J may be platelet-poor plasma or a supernatant substantially free of platelets (i.e., having a known platelet concentration of zero). This can be carried out during the course of the blood separation procedure of the above type using a biological fluid processing apparatus 10 of the type shown in FIG. 1. More specifically, in such an exemplary procedure, blood is separated into a red blood cell concentrate and platelet-rich plasma using a centrifuge 16, and the platelet-rich plasma is conveyed via line L15 to a rotary membrane separation drive unit 14 where the platelet-rich plasma is optically analyzed by a rotor inlet sensor M1. The platelet-rich plasma is separated by the rotary membrane separation drive unit 14 into a platelet concentrate and platelet-poor plasma (supernatant), and the platelet-poor plasma is conveyed from the rotary membrane separation drive unit 14 via line L17 and optically analyzed by a rotor outlet sensor M2 (FIG. 2).

[0101] Signals generated by the rotor inlet sensor M1 and the rotor outlet sensor M2 are received by a control unit 18, which compares the signal from the rotor inlet sensor M1 (indicating the composition of the platelet-rich plasma) with the signal from the rotor outlet sensor M2 (indicating the composition of the platelet-poor plasma or supernatant) to more accurately determine the platelet concentration of the platelet-rich plasma. This improvement is because the signals from the two sensors M1 and M2 represent the same two fluids (including non-cellular plasma components such as lipids that affect optical analysis) except for the cell composition, which is the fluid property of interest. Otherwise, if the control unit 18 determines the platelet concentration of the platelet-rich plasma using only the signal from the rotor inlet sensor M1, the presence of various non-cellular components within the platelet-rich plasma can affect the optical analysis, resulting in inaccurate results.

[0102] The nature of the comparison between the signal representing the composition of the reference fluid and the signal representing the composition of the target fluid can vary without departing from the scope of the present disclosure. For example, when a signal is transmitted from a photodetector assembly configured as an array of photodetectors, a scattering profile may be generated by the control unit as described above. FIG. 13 shows the scattering profiles of the target fluid (upper graph) and the corresponding reference fluid (lower graph). As described above, since the slope of the rising edge and / or the slope of the falling edge of the scattering profile are correlated with fluid characteristic values (e.g., cell concentration), the control unit can determine the fluid characteristic values for each of the target fluid and the reference fluid by comparing the slope of the rising edge and / or the slope of the falling edge with a library or database of correlations. Next, the control unit subtracts the fluid characteristic value obtained for the reference fluid from the fluid characteristic value obtained for the target fluid to obtain the final value or corrected value of the target fluid.

[0103] According to another approach, the maximum voltage of the signal from the optical detection assembly may indicate the composition of the fluid, in which case the maximum voltage of the signal indicating the composition of the reference fluid may be correlated with the fluid characteristic value by the control unit. The control unit performs the same for the maximum voltage of the signal representing the composition of the target fluid, and subsequently the control unit subtracts the fluid characteristic value of the reference fluid from the fluid characteristic value of the target fluid to arrive at the final value or corrected value of the target fluid. Alternatively, the control unit subtracts the maximum voltage of the signal representing the composition of the target fluid from the maximum voltage of the signal representing the composition of the reference fluid, and then the control unit accesses a library or database of values to correlate the voltage difference with the fluid characteristic value that constitutes the final value or corrected value of the target fluid. For example, FIG. 13 shows a target fluid scattering profile with a maximum signal voltage of 4V and a reference fluid scattering profile with a maximum signal voltage of 5V. The difference between the two maximum voltages is 1V, and the control unit can correlate this with the final or corrected fluid characteristic value (such as cell concentration) of the target fluid.

[0104] Comparing FIGS. 13 and 14 reveals the impact of the fluid composition on optical analysis and a method for separating the characteristics of the target fluid using the principles described herein. As previously mentioned, FIG. 13 shows the scattering profile of a target fluid with a maximum signal voltage of 4V and the scattering profile of a reference fluid with a maximum signal voltage of 5V. FIG. 14 shows the scattering profiles of the target fluid (upper graph) and the corresponding reference fluid (lower graph). The target fluids in FIGS. 13 and 14 have the same cell concentration but different fluid compositions (e.g., the target fluid in FIG. 14 is platelet-rich plasma with a higher lipid content than the sample of platelet-rich plasma shown in FIG. 13). It can be seen that the target fluids in FIGS. 13 and 14 have the same cell concentration, but the maximum voltage of the scattering profile of the target fluid in FIG. 14 is 3V compared to the maximum voltage of 4V of the scattering profile of the target fluid in FIG. 13. A direct comparison of the scattering profiles of these two target fluids would lead to the incorrect conclusion that the cell concentrations of the fluids are different. In contrast, when considering the scattering profile of each target fluid in combination with the scattering profile of the corresponding reference fluid, the same 1V voltage difference is obtained, leading to the correct determination that the target fluids in FIGS. 13 and 14 have the same cell composition.

[0105] According to one embodiment, light having different intensities can be used to analyze the target fluid and the corresponding reference fluid. When analyzing the cell concentration of a fluid, since the reference fluid without cells does not contain cells that significantly reduce the amount of light transmitted through the fluid, the relatively high light intensity required to analyze the fluid containing cells may be too high for the reference fluid, and the signal may saturate. Conversely, the light intensity required to obtain an unsaturated signal for the reference fluid without cells is usually too low to analyze the target fluid containing cells, resulting in a low signal intensity or the signal becoming unmeasurable. Therefore, it may be advantageous for the light intensity used to analyze the reference fluid to be lower than the light intensity used to analyze the target fluid. An exemplary routine for practicing this principle is shown in FIG. 15.

[0106] Without departing from the scope of the present disclosure, any method for realizing incident light of different intensities can be adopted. As an example, a single light source 102 is configured to selectively emit light of different intensities. When analyzing the reference fluid J, a low intensity is used (see FIG. 11), and when analyzing the target fluid K, a high intensity is used (see FIG. 12). In such an embodiment, a single optical detection assembly 100 and a single container B can be used to analyze both the reference fluid J and the target fluid K. In another exemplary embodiment, two separate fixed-intensity light sources configured to emit light of different intensities can be used in combination with separate fluid paths or containers and separate optical detection assemblies (for example, the rotor inlet sensor M1 is provided with a single light source configured to emit relatively high-intensity light, and the rotor outlet sensor M2 is provided with a single light source configured to emit lower-intensity light). Alternatively, instead of using two optical detection assemblies each having one light source, a single optical detection assembly provided with a light source assembly including a first light source and a second light source can be provided. In such an embodiment, first, one of the fluids is analyzed by the optical detection assembly using an appropriate light source, and then the other fluid is analyzed using the other light source. This includes passing the target fluid and the reference fluid through the same container at different times during the procedure, or using a single optical detection assembly configured to analyze the fluids in two different containers (one container is associated with one of the light sources and is used for the flow of the target fluid, and the other container is associated with the other light source and is used for the flow of the reference fluid).

[0107] Figures 16 and 17 show alternative embodiments of an optical detection assembly 150 suitable for analyzing a reference fluid J and a target fluid K using light of different intensities. In the embodiments of Figures 16 and 17, the optical detection assembly 150 includes, in addition to an optical filter assembly 152 including an actuator 154 (e.g., a linear actuator) and a carriage 156, a single light source 102 (configured to emit light having a constant intensity) and a light detector array 104 of the type described above. At least one optical filter is incorporated into the carriage 156, and this optical filter reduces the intensity of light from the container B and the fluid present therein. In the illustrated embodiment, the carriage 156 has a first optical filter 158 and a second optical filter 160, and each optical filter is configured such that light of different intensities reaches the container B and the fluid present therein.

[0108] In such an embodiment, the actuator 154 is controlled by a control unit, and depending on the fluid present in the container B, moves an appropriate optical filter into the path of the light from the light source 102. If the carriage 156 includes two optical filters (as in Figures 16 and 17), the control unit commands the actuator 154 to move the carriage 156 such that when the reference fluid J is present in the container B, the more light-restricting optical filter 158 is aligned with the light source 102 (as in Figure 16). When the target fluid K is present in the container B and more intense light is appropriate, the control unit commands the actuator 154 to move the carriage 156 such that the less light-restricting optical filter 160 is aligned with the light source 102 (see Figure 17). If the carriage 156 includes only one optical filter, the control unit commands the actuator 154 to move the carriage 156 such that when the reference fluid J is present in the container B, the single optical filter is aligned with the light source 102, and when the target fluid K is present in the container B, the control unit moves the optical filter to a position where it is not aligned with the light source 102 (e.g., aligns the opening defined by the carriage 156 with the light source 102), enabling the target fluid to be analyzed with more intense light.

[0109] When analyzing a reference fluid and a target fluid, it may be advantageous for some optical detection assemblies to apply light of different intensities, but it is necessary to understand that some photodetectors may be able to receive more light without saturation. Therefore, when using such a photodetector assembly, both the reference fluid and the target fluid can be analyzed using incident light of the same intensity.

[0110] Determination of V.PMI As described above, data can be extracted from the scattering profile to determine various characteristics of the target fluid. For example, in addition to the cell concentration of the fluid, one of the other characteristics of a platelet-containing fluid that can be determined by analyzing the scattering profile is the PMI of the fluid.

[0111] Similar to FIGS. 6 and 7 showing fluids with relatively low and relatively high platelet concentrations, respectively, FIGS. 6 and 7 show fluids with relatively low PMI (FIG. 6) and relatively high PMI (FIG. 7). According to the above description of the scattering profiles generated for fluids having different platelet concentrations, the scattering profiles generated for fluids having different PMI have different maximum signals, different slopes of the rising edges, and different slopes of the falling edges, and have different shapes. More specifically, in the illustrated embodiment, the platelets in the fluid scatter the light rather than transmitting it straight through the fluid and container B (along its initial path). Since the volume of platelets in fluid F in FIG. 7 is large, more light scattering occurs and more individual photodetectors receive at least some of the light, but the maximum intensity is relatively low compared to the maximum intensity of the light received by the individual photodetectors in FIG. 6. In other words, the light passing through the lower PMI fluid f in FIG. 6 is narrowly distributed or dispersed, whereas the light passing through the higher PMI fluid F in FIG. 7 is more widely or broadly distributed or dispersed. Therefore, by providing the photodetector array 104, the intensity of the light received by the plurality of individual photodetectors (i.e., the light distribution or scattering profile) can be evaluated to determine the PMI of the substance.

[0112] In accordance with the above description regarding the determination of the cell concentration of a fluid, when the control unit generates a scattering profile, the control unit can adopt various approaches to extract data from the scattering profile that can be used to determine the PMI of the target fluid. In particular, it has been found that the slope of the rising edge of the scattering profile and / or the slope of the falling edge of the scattering profile indicate the PMI of the fluid.

[0113] The control unit can adopt different techniques to calculate the slope of the section of the rising edge of the scattering profile or to calculate the slope of the section of the falling edge of the scattering profile, and the same techniques described above in the description of the determination of the cell concentration of the fluid are equally applicable to the determination of the PMI of the fluid. A library or database of PMIs, each of which correlates with the slope of the rising edge and / or the slope of the falling edge, can be programmed into the control unit or stored elsewhere and accessed remotely from the control unit. For example, FIG. 18 is a graph showing an empirically derived correlation between the slope of the rising edge or the slope of the falling edge and the PMI of the fluid, and this graph is created using data from a type of cell counter sold by Sysmex Corporation of Kobe. When the control unit calculates the relevant slope, the control unit can refer to the library or database to correlate that slope with the PMI of the fluid under monitoring.

[0114] According to the above description regarding the determination of the cell concentration of a fluid, since the scattering profile has both a rising edge and a falling edge, either slope can be calculated and compared with a correlation library or database to determine the PMI associated with the slope. The scattering profile often becomes approximately symmetric about its apex, and the slope of the section of the rising edge tends to be approximately equal to the slope of the corresponding section of the falling edge, in which case each slope correlates with the same approximate PMI. However, it is within the scope of the present disclosure to use both slopes when determining the PMI of a substance. As an example, both the slope of the rising edge and the slope of the falling edge are calculated, and the control unit calculates the average of the two slopes and compares the average value with a correlation library or database to determine the PMI. According to another exemplary approach, both the slope of the rising edge and the slope of the falling edge are calculated, and the control unit can compare each slope with a library or database to determine the PMI associated with each slope. Next, the control unit calculates the average of these two PMI values and determines that the PMI of the target fluid is equal to the calculated average. Other approaches to determining the PMI using both the slopes of the rising edge and the falling edge of the scattering profile (for example, giving one slope a greater weight than the other) can also be employed without departing from the scope of the present disclosure.

[0115] Once the PMI of a substance is determined, the control unit can use it in various ways. For example, as described above, the PMI of a substance may be used as a factor in determining the appropriate volume of a preservation solution to be added to the substance. In another example, if the control unit also determines the platelet concentration of the substance (according to the above approach, or using a different optical detection assembly, or according to other suitable approaches), the control unit can calculate the MPV of the substance by dividing the PMI by the platelet concentration. If the MPV is abnormally high or low (which may indicate various diseases and disorders), the control unit may generate a warning or add an appropriate note to the profile of the blood source.

[0116] VI. Aspects Aspect 1 An optical detection assembly for monitoring a fluid within a container, comprising: a light source configured and oriented to emit light into the fluid within the container; an array of light detectors configured to receive at least a portion of the light exiting the container; and a control unit. The control unit receives from the array of light detectors signals indicative of at least a portion of the intensity of the light received by each of the plurality of light detectors, generates a scattering profile based at least in part on the signals from the array of light detectors, the scattering profile including a rising edge and a falling edge, calculates a slope of the rising edge or the falling edge of the scattering profile, and is programmed to determine a platelet mass index and / or a concentration of a substance in the fluid within the container based at least in part on the slope.

[0117] Aspect 2 The optical detection assembly according to aspect 1, wherein a library of substance concentrations and / or a library of platelet mass indices correlated with slopes of respective different rising edges and / or slopes of respective different falling edges are programmed into the control unit.

[0118] Aspect 3 The optical detection assembly according to aspect 1, wherein the control unit is programmed to remotely access a library of substance concentrations and / or a library of platelet mass indices correlated with slopes of respective different rising edges and / or slopes of respective different falling edges.

[0119] Aspect 4 The optical detection assembly according to any one of aspects 1 to 3, wherein the control unit is programmed to determine a platelet mass index and / or a concentration of a substance in the fluid within the container based on the slope of the rising edge without relying on the slope of the falling edge, or based on the slope of the falling edge without relying on the slope of the rising edge.

[0120] Aspect 5 The control unit is programmed to determine the platelet mass index and / or the concentration of a substance in the fluid within the container based on both the slope of the rising edge and the slope of the falling edge, according to any one of aspects 1 to 3 of the optical detection assembly described above.

[0121] Aspect 6 The control unit is programmed to calculate the slope of the rising edge or the slope of the falling edge by dividing the difference between the first voltage of the first signal from the first photodetector and the second voltage of the second signal from the second photodetector by the difference in the relative positions of the first photodetector and the second photodetector within the photodetector array, according to any one of aspects 1 to 5 of the optical detection assembly described above.

[0122] Aspect 7 The first photodetector and the second photodetector are predetermined or preselected based on the positions of the first photodetector and the second photodetector within the photodetector array, according to the optical detection assembly described in aspect 6.

[0123] Aspect 8 The first voltage is the first percentage of the maximum voltage of the signal received by the control unit from the photodetector array, The second voltage is the second percentage of the maximum voltage of the signal received by the control unit from the photodetector array, according to the optical detection assembly described in aspect 6.

[0124] Aspect 9 One of the first voltage and the second voltage is 35% of the maximum voltage, and the other of the first voltage and the second voltage is 65% of the maximum voltage, according to the optical detection assembly described in aspect 8.

[0125] Aspect 10 The control unit is programmed to calculate the slope of the rising edge or the slope of the falling edge using linear regression, according to any one of aspects 1 to 6 of the optical detection assembly described above.

[0126] Aspect 11 A biological fluid processing device, comprising a pump system, a valve system, a control unit programmed to control the operation of the pump system and the valve system to execute a fluid processing procedure, and an optical detection assembly. The optical detection assembly is configured to emit light into the fluid in the container, and includes an oriented light source and an array of light detectors configured to receive at least a portion of the light exiting the container. The control unit further receives from the array of light detectors a signal indicative of the intensity of at least a portion of the light received by each of the plurality of light detectors, generates a scattering profile based at least in part on the signal from the array of light detectors, the scattering profile including a rising edge and a falling edge, calculates the slope of the rising edge or the falling edge of the scattering profile, and is programmed to determine the platelet mass index and / or the concentration of a substance in the fluid in the container based at least in part on the slope.

[0127] Aspect 12 The biological fluid processing device according to aspect 11, wherein a library of substance concentrations and / or a library of platelet mass indices correlated with the slopes of different rising edges and / or the slopes of falling edges are programmed into the control unit.

[0128] Aspect 13 The biological fluid processing device according to aspect 11, wherein the control unit is programmed to remotely access a library of substance concentrations and / or a library of platelet mass indices correlated with the slopes of different rising edges and / or the slopes of falling edges.

[0129] Aspect 14 The biological fluid processing device according to any one of aspects 11 to 13, wherein the control unit is programmed to determine the platelet mass index and / or the concentration of a substance in the fluid in the container based on the slope of the rising edge without relying on the slope of the falling edge, or based on the slope of the falling edge without relying on the slope of the rising edge.

[0130] Aspect 15 The control unit is programmed to determine the platelet mass index and / or the concentration of a substance in the fluid within the container based on both the slope of the rising edge and the slope of the falling edge, for the biological fluid processing apparatus according to any one of aspects 11 to 13.

[0131] Aspect 16 The control unit is programmed to calculate the slope of the rising edge or the slope of the falling edge by dividing the difference between the first voltage of the first signal from the first photodetector and the second voltage of the second signal from the second photodetector by the difference in the relative positions of the first photodetector and the second photodetector within the photodetector array, for the biological fluid processing apparatus according to any one of aspects 11 to 15.

[0132] Aspect 17 The first photodetector and the second photodetector are predetermined or preselected based on the positions of the first photodetector and the second photodetector within the photodetector array, for the biological fluid processing apparatus according to aspect 16.

[0133] Aspect 18 The first voltage is the first percentage of the maximum voltage of the signal received by the control unit from the photodetector array, The second voltage is the second percentage of the maximum voltage of the signal received by the control unit from the photodetector array, for the biological fluid processing apparatus according to aspect 16.

[0134] Aspect 19 One of the first voltage and the second voltage is 35% of the maximum voltage, and the other of the first voltage and the second voltage is 65% of the maximum voltage, for the biological fluid processing apparatus according to aspect 18.

[0135] Aspect 20 The control unit is programmed to calculate the slope of the rising edge or the slope of the falling edge using linear regression, for the biological fluid processing apparatus according to any one of aspects 11 to 16.

[0136] Aspect 21 A method for determining the platelet mass index and / or the concentration of a substance in a fluid within a container, comprising: irradiating light onto the fluid within the container; receiving at least a portion of the light exiting the container by a plurality of photodetectors of a photodetector array; generating a scattering profile based at least in part on the intensity of at least a portion of the light received by each of the plurality of photodetectors, the scattering profile including a rising edge and a falling edge; calculating the slope of the rising edge or the falling edge of the scattering profile; and determining the platelet mass index and / or the concentration of the substance in the fluid within the container based at least in part on the slope.

[0137] Aspect 22 Determining the platelet mass index and / or the concentration of a substance in the fluid within the container comprises The method according to aspect 21, comprising accessing a local library of platelet mass indices and / or a local library of substance concentrations that correlate with the slopes of different rising edges and / or falling edges respectively.

[0138] Aspect 23 Determining the platelet mass index and / or the concentration of a substance in the fluid within the container comprises The method according to aspect 21, comprising accessing a remote library of platelet mass indices and / or a remote library of substance concentrations that correlate with the slopes of different rising edges and / or falling edges respectively.

[0139] Aspect 24 Determining the platelet mass index and / or the concentration of a substance in the fluid within the container is the method according to any one of aspects 21 to 23, based on the slope of the rising edge and not based on the slope of the falling edge, or based on the slope of the falling edge and not based on the slope of the rising edge.

[0140] Aspect 25 Determining the concentration of a substance in the fluid within the container is the method according to any one of aspects 21 to 23, based on both the slope of the rising edge and the slope of the falling edge.

[0141] Aspect 26 The slope of the rising edge or the slope of the falling edge is calculated by dividing the difference between the first voltage of the first signal from the first photodetector and the second voltage from the second photodetector by the difference in the relative positions of the first photodetector and the second photodetector in the photodetector array, according to the method of any one of Aspects 21 to 25.

[0142] Aspect 27 The first photodetector and the second photodetector are predetermined or preselected based on the positions of the first photodetector and the second photodetector in the photodetector array, according to the method of Aspect 26.

[0143] Aspect 28 The first voltage is the first percentage of the maximum voltage of the signal from the photodetector array having a scattering profile, The second voltage is the second percentage of the maximum voltage of the signal from the photodetector array having a scattering profile, according to the method of Aspect 26.

[0144] Aspect 29 One of the first voltage and the second voltage is 35% of the maximum voltage, and the other of the first voltage and the second voltage is 65% of the maximum voltage, according to the method of Aspect 28.

[0145] Aspect 30 The slope of the rising edge or the slope of the falling edge is calculated using linear regression, according to the method of any one of Aspects 21 to 26.

[0146] Aspect 31 An optical detection assembly for monitoring a fluid within a container, comprising a light source assembly configured and oriented to emit light into the fluid within the container, a light detector assembly configured to receive at least a portion of the light exiting the container, and a control unit. The control unit receives from the light detector assembly a first signal indicative of the intensity of at least a portion of the light received by the light detector assembly when a reference fluid is within the container, and a second signal indicative of the intensity of at least a portion of the light received by the light detector assembly when a target fluid is within the container. The control unit compares the first signal and the second signal, and is programmed to determine the concentration of a substance in the target fluid within the container based at least in part on a comparison of the first signal and the second signal.

[0147] Aspect 32 The optical detection assembly according to aspect 31, wherein the reference fluid has a known concentration of the substance.

[0148] Aspect 33 The optical detection assembly according to aspect 31 or aspect 32, wherein the reference fluid does not contain the substance.

[0149] Aspect 34 The optical detection assembly according to any one of aspects 31 to 33, wherein the reference fluid contains platelet-poor plasma or supernatant, the target fluid contains platelet-rich plasma or platelet concentrate, and the substance contains platelets.

[0150] Aspect 35 The optical detection assembly according to any one of aspects 31 to 34, wherein the light entering the reference fluid has a first intensity, the light entering the target fluid has a second intensity, and the first intensity is different from the second intensity.

[0151] Aspect 36 The optical detection assembly according to aspect 35, wherein the concentration of the substance in the reference fluid is lower than the concentration of the substance in the target fluid, and the second intensity is greater than the first intensity.

[0152] Aspect 37 The light source assembly includes a first light source and a second light source, and the control unit is programmed to control the first light source to emit light when the reference fluid is in the container, and the control unit is programmed to control the second light source to emit light when the target fluid is in the container. The optical detection assembly according to any one of aspects 31 to 36.

[0153] Aspect 38 The light source assembly includes a single light source, and the control unit is programmed to control the single light source to emit light of different intensities. The optical detection assembly according to any one of aspects 31 to 36.

[0154] Aspect 39 The light source assembly includes a single light source, and the optical detection assembly further includes an optical filter assembly including an optical filter incorporated in the carriage and an actuator associated with the carriage. The control unit is programmed to control the actuator to move the carriage so as to selectively place and remove the optical filter in the path of the light emitted by the light source assembly. The optical detection assembly according to any one of aspects 31 to 36.

[0155] Aspect 40 The optical filter assembly includes a first optical filter and a second optical filter, and the control unit is programmed to control the actuator to move the carriage so as to place the first optical filter in the path of the light emitted by the light source assembly when the reference fluid is in the container, and the control unit is programmed to control the actuator to move the carriage so as to place the second optical filter in the path of the light emitted by the light source assembly when the target fluid is in the container. The optical detection assembly according to aspect 39.

[0156] Aspect 41 The photodetector assembly includes a photodetector array including a plurality of photodetectors. The first signal indicates at least a part of the intensity of the light received by each of the plurality of photodetectors when the reference fluid is in the container. The second signal indicates at least a part of the intensity of the light received by each of the plurality of photodetectors when the target fluid is in the container. The control unit is programmed to generate a first scattering profile based at least in part on the first signal, generate a second scattering profile based at least in part on the second signal, and determine the concentration of the substance in the target fluid in the container based at least in part on a comparison between the first scattering profile and the second scattering profile. The optical detection assembly according to any one of aspects 31 to 40.

[0157] Aspect 42 The control unit is programmed to compare the voltage difference between the first signal and the second signal and determine the concentration of the substance in the target fluid in the container. The optical detection assembly according to any one of aspects 31 to 41.

[0158] Aspect 43 The control unit is programmed to calculate a first slope of the rising edge of the first scattering profile, calculate a second slope of the rising edge of the second scattering profile, and determine the concentration of the substance in the target fluid in the container based at least in part on a comparison between the first slope and the second slope. The optical detection assembly according to aspect 41.

[0159] Aspect 44 The control unit is programmed to calculate a first slope of the falling edge of the first scattering profile, calculate a second slope of the falling edge of the second scattering profile, and determine the concentration of the substance in the target fluid in the container based at least in part on a comparison between the first slope and the second slope. The optical detection assembly according to aspect 41.

[0160] Aspect 45 The control unit calculates the slope of the first rising edge and the slope of the first falling edge of the first scattering profile, calculates the slope of the second rising edge and the slope of the second falling edge of the second scattering profile, and is programmed to determine the concentration of a substance in a target fluid within a container based at least in part on a comparison of the slope of the first rising edge and the slope of the second rising edge, and a comparison of the slope of the first falling edge and the slope of the second falling edge, the optical detection assembly according to aspect 41.

[0161] Aspect 46 A biological fluid processing apparatus comprising a pump system, a valve system, a control unit programmed to control the operation of the pump system and the valve system to perform a fluid processing procedure, and an optical detection assembly, the optical detection assembly comprising a light source assembly configured and oriented to emit light into a fluid within a container, and a light detector assembly configured to receive at least a portion of the light exiting the container, the control unit further receiving from the light detector assembly a first signal indicative of the intensity of at least a portion of the light received by the light detector assembly when a quasi-fluid is within the container, receiving from the light detector assembly a second signal indicative of the intensity of at least a portion of the light received by the light detector assembly when a target fluid is within the container, comparing the first signal and the second signal, and being programmed to determine the concentration of a substance in the target fluid within the container based at least in part on a comparison of the first signal and the second signal, the biological fluid processing apparatus.

[0162] Aspect 47 The biological fluid processing apparatus according to aspect 46, wherein the reference fluid has a known concentration of the substance.

[0163] Aspect 48 The biological fluid processing apparatus according to aspect 46 or aspect 47, wherein the reference fluid does not contain the substance.

[0164] Aspect 49 The reference fluid contains platelet-poor plasma or supernatant, the target fluid contains platelet-rich plasma or platelet concentrate, and the substance contains platelets. The biological fluid treatment device according to any one of aspects 46 to 48.

[0165] Aspect 50 The light entering the reference fluid has a first intensity, the light entering the target fluid has a second intensity, and the first intensity is different from the second intensity. The biological fluid treatment device according to any one of aspects 46 to 49.

[0166] Aspect 51 The concentration of the substance in the reference fluid is lower than the concentration of the substance in the target fluid, and the second intensity is greater than the first intensity. The biological fluid treatment device according to aspect 50.

[0167] Aspect 52 The light source assembly includes a first light source and a second light source, and the control unit is programmed to control the first light source to emit light when the reference fluid is in the container, and the control unit is programmed to control the second light source to emit light when the target fluid is in the container. The biological fluid treatment device according to any one of aspects 46 to 51.

[0168] Aspect 53 The light source assembly includes a single light source, and the control unit is programmed to control the single light source to emit light of different intensities. The biological fluid treatment device according to any one of aspects 46 to 51.

[0169] Aspect 54 The light source assembly includes a single light source, and the optical detection assembly further includes an optical filter assembly including an optical filter incorporated in the carriage and an actuator associated with the carriage, and the control unit is programmed to control the actuator to move the carriage so as to selectively dispose and non-dispose the optical filter in the path of the light emitted by the light source assembly. The biological fluid treatment device according to any one of aspects 46 to 51.

[0170] Aspect 55 The optical filter assembly includes a first optical filter and a second optical filter, and the control unit is programmed to control the actuator to move the carriage so as to place the first optical filter in the path of the light emitted by the light source assembly when the reference fluid is in the container, and the control unit is programmed to control the actuator to move the carriage so as to place the second optical filter in the path of the light emitted by the light source assembly when the target fluid is in the container. The biological fluid processing apparatus according to aspect 54.

[0171] Aspect 56 The photodetector assembly includes a photodetector array including a plurality of photodetectors. The first signal indicates at least a part of the intensity of the light received by each of the plurality of photodetectors when the reference fluid is in the container, and the second signal indicates at least a part of the intensity of the light received by each of the plurality of photodetectors when the target fluid is in the container. The control unit is programmed to generate a first scattering profile based at least in part on the first signal, generate a second scattering profile based at least in part on the second signal, and determine the concentration of a substance in the target fluid in the container based at least in part on a comparison between the first scattering profile and the second scattering profile. The biological fluid processing apparatus according to any one of aspects 46 to 55.

[0172] Aspect 57 The control unit is programmed to compare the voltage difference between the first signal and the second signal and determine the concentration of a substance in the target fluid in the container. The biological fluid processing apparatus according to any one of aspects 46 to 56.

[0173] Aspect 58 The control unit is programmed to calculate a first slope of the rising edge of a first scattering profile, calculate a second slope of the rising edge of a second scattering profile, and determine the concentration of a substance in a target fluid within the container based at least in part on a comparison of the first slope and the second slope, of the biological fluid processing apparatus according to aspect 56.

[0174] Aspect 59 The control unit is programmed to calculate a first slope of the falling edge of a first scattering profile, calculate a second slope of the falling edge of a second scattering profile, and determine the concentration of a substance in a target fluid within the container based at least in part on a comparison of the first slope and the second slope, of the biological fluid processing apparatus according to aspect 56.

[0175] Aspect 60 The control unit is programmed to calculate the slope of the first rising edge and the slope of the first falling edge of a first scattering profile, calculate the slope of the second rising edge and the slope of the second falling edge of a second scattering profile, and determine the concentration of a substance in a target fluid within the container based at least in part on a comparison of the slope of the first rising edge and the slope of the second rising edge, and a comparison of the slope of the first falling edge and the slope of the second falling edge, of the biological fluid processing apparatus according to aspect 56.

[0176] Aspect 61 A method for determining the concentration of a substance in a target fluid within a container, comprising irradiating light onto a reference fluid within the container, receiving at least a portion of a first light exiting the container by a photodetector assembly, generating a first signal indicative of the intensity of at least a portion of the first light received by the photodetector assembly, irradiating a second light onto the target fluid within the container, receiving at least a portion of a second light exiting the container by the photodetector assembly, generating a second signal indicative of the intensity of at least a portion of the second light received by the photodetector assembly, comparing the first signal and the second signal, and determining the concentration of a substance in the target fluid within the container based at least in part on a comparison of the first signal and the second signal.

[0177] Aspect 62 The reference fluid has a known concentration of the substance, and the method according to aspect 61.

[0178] Aspect 63 The reference fluid does not contain the substance, and the method according to aspect 61 or aspect 62.

[0179] Aspect 64 The reference fluid contains platelet-poor plasma or supernatant, the target fluid contains platelet-rich plasma or platelet concentrate, and the substance contains platelets, and the method according to any one of aspects 61 to 63.

[0180] Aspect 65 The light entering the reference fluid has a first intensity, the light entering the target fluid has a second intensity, and the first intensity is different from the second intensity, and the method according to any one of aspects 61 to 64.

[0181] Aspect 66 The concentration of the substance in the reference fluid is lower than the concentration of the substance in the target fluid, and the second intensity is greater than the first intensity, and the method according to aspect 65.

[0182] Aspect 67 The first light is emitted from a first light source, and the second light is emitted from a second light source, and the method according to any one of aspects 61 to 66.

[0183] Aspect 68 The first light and the second light have different intensities and are emitted from a single light source, and the method according to any one of aspects 61 to 66.

[0184] Aspect 69 The first light and the second light are emitted from a single light source, and emitting the first light and emitting the second light include moving an optical filter within the path of the light emitted from the single light source, and the method according to any one of aspects 61 to 66.

[0185] Aspect 70 Emitting the first light includes moving a first optical filter into the path of the first light, and emitting the second light includes moving a second optical filter into the path of the second light, the method according to aspect 69.

[0186] Aspect 71 A part of the first light and a part of the second light are received by a photodetector array including a plurality of photodetectors, the first signal indicates the intensity of at least a part of the first light received by each of the plurality of photodetectors, the second signal indicates the intensity of at least a part of the second light received by each of the plurality of photodetectors, and comparing the first signal and the second signal includes generating a first scattering profile based at least in part on the first signal, generating a second scattering profile based at least in part on the second signal, and comparing the first scattering profile and the second scattering profile, the method according to any one of aspects 61 to 70.

[0187] Aspect 72 Comparing the first signal and the second signal includes comparing the voltage difference between the first signal and the second signal, the method according to any one of aspects 61 to 71.

[0188] Aspect 73 Comparing the first scattering profile and the second scattering profile includes calculating a first slope of the rising edge of the first scattering profile, calculating a second slope of the rising edge of the second scattering profile, and comparing the first slope and the second slope, the method according to aspect 71.

[0189] Aspect 74 Comparing the first scattering profile and the second scattering profile includes calculating a first slope of the falling edge of the first scattering profile, calculating a second slope of the falling edge of the second scattering profile, and comparing the first slope and the second slope, the method according to aspect 71.

[0190] Aspect 75 Comparing the first scattering profile with the second scattering profile includes calculating the slope of the first rising edge and the slope of the first falling edge of the first scattering profile, calculating the slope of the second rising edge and the slope of the second falling edge of the second scattering profile, comparing the slope of the first rising edge with the slope of the second rising edge, and comparing the slope of the first falling edge with the slope of the second falling edge, the method according to aspect 71.

[0191] It will be understood that the above-described embodiments are illustrative of some applications of the principles of the present invention. Those skilled in the art can make numerous modifications without departing from the spirit and scope of the claimed subject matter, including combinations of features individually disclosed or claimed herein. For these reasons, the scope of the present invention is not limited to the above description, but is as set forth in the following claims, which may be directed to features of the present invention, including combinations of features individually disclosed or claimed herein.

Claims

1. 1. An optical detection assembly for monitoring a fluid in a container, comprising: a light source configured and oriented to emit light into the fluid in the container; a photodetector array comprising a plurality of photodetectors and configured to receive at least a portion of the light exiting the vessel; A control unit. The control unit is receiving a signal from the photodetector array indicative of an intensity of the at least a portion of the light received by each of the plurality of photodetectors; generating a scattering profile based at least in part on the signals from the photodetector array, the scattering profile including rising edges and falling edges; Calculating the slope of the rising edge or the falling edge of the scattering profile; an optical detection assembly programmed to determine a platelet mass index and / or a concentration of a substance in fluid within the container based at least in part on the slope.

2. The optical detection assembly of claim 1 , wherein the controller is programmed with a library of substance concentrations and / or a library of platelet mass indices that correlate with different rising edge slopes and / or falling edge slopes, respectively.

3. 2. The optical detection assembly of claim 1, wherein the control unit is programmed to remotely access a library of substance concentrations and / or a library of platelet mass indices that correlate with different rising edge slopes and / or falling edge slopes, respectively.

4. 4. The optical detection assembly of claim 1, wherein the control unit is programmed to determine a platelet mass index and / or a concentration of a substance in the fluid in the container based on a slope of a rising edge and / or a slope of a falling edge and / or a slope of a rising edge and / or a slope of a falling edge and / or a slope of a rising edge and / or a slope of a falling edge and / or a slope of a rising edge and / or a slope of a falling edge and / or a slope of a rising edge and / or a slope of a falling edge and / or a slope of a rising edge and / or a slope of a falling edge and / or a slope of a rising edge and / or a slope of a rising edge and / or a slope of a falling edge and / or a slope of a rising edge and / or a slope of a rising edge and / or a slope of a falling edge and / or a slope of a rising edge and / or a slope of a rising edge and / or a slope of a falling edge and / or a slope of a rising edge and / or a slope of a rising edge and / or a slope of a falling edge and / or a slope of a rising edge and / or a slope of a rising edge and / or a slope of a rising edge and / or a falling ... falling edge and / or a rising edge and / or a

5. 4. The optical detection assembly of claim 1, wherein the control unit is programmed to determine a platelet mass index and / or a concentration of a substance in the fluid in the container based on both the slope of the rising edge and the slope of the falling edge.

6. 6. The optical detection assembly of claim 1, wherein the controller is programmed to calculate the slope of the rising edge or the slope of the falling edge by dividing a difference between a first voltage of a first signal from a first photodetector and a second voltage from a second photodetector by a difference in relative positions of the first photodetector and the second photodetector within the photodetector array.

7. 7. The optical detection assembly of claim 6, wherein the first and second photodetectors are predetermined or preselected based on positions of the first and second photodetectors in the photodetector array.

8. the first voltage being a first percentage of a maximum voltage of the signal received by the controller from the photodetector array; The optical detection assembly of claim 6 , wherein the second voltage is a second percentage of the maximum voltage of the signal received by the controller from the photodetector array.

9. 9. The optical detection assembly of claim 8, wherein one of the first voltage and the second voltage is 35% of the maximum voltage and the other of the first voltage and the second voltage is 65% of the maximum voltage.

10. The optical detection assembly of claim 1 , wherein the controller is programmed to calculate the slope of the rising edge or the slope of the falling edge using linear regression.

11. 1. A biological fluid treatment apparatus comprising: A pump system; A valve system; a controller programmed to control operation of the pump system and the valve system to perform a fluid processing procedure; an optical detection assembly; The optical detection assembly includes: a light source configured and oriented to emit light into the fluid in the container; a photodetector array comprising a plurality of photodetectors and configured to receive at least a portion of the light exiting the vessel; The control unit further includes: receiving a signal from the photodetector array indicative of an intensity of the at least a portion of the light received by each of the plurality of photodetectors; generating a scattering profile based at least in part on the signals from the photodetector array, the scattering profile including rising edges and falling edges; Calculating the slope of the rising edge or the falling edge of the scattering profile; The biological fluid treatment device is programmed to determine a platelet mass index and / or a concentration of a substance in fluid within the container based at least in part on the slope.

12. 12. The biological fluid treatment device of claim 11, wherein the controller is programmed with a library of substance concentrations and / or a library of platelet mass indices that correlate with different rising edge slopes and / or falling edge slopes.

13. 12. The biological fluid treatment device of claim 11, wherein the controller is programmed to remotely access a library of substance concentrations and / or a library of platelet mass indices correlating to different rising edge slopes and / or falling edge slopes, respectively.

14. 14. The biological fluid treatment device of claim 11, wherein the control unit is programmed to determine the platelet mass index and / or the concentration of a substance in the fluid in the container based on the slope of a rising edge and not based on the slope of a falling edge, or based on the slope of a falling edge and not based on the slope of a rising edge.

15. The biological fluid treatment device of claim 11 , wherein the control unit is programmed to determine a platelet mass index and / or a concentration of a substance in the fluid in the container based on both the slope of the rising edge and the slope of the falling edge.

16. 16. The biological fluid treatment device of claim 11, wherein the controller is programmed to calculate the slope of the rising edge or the slope of the falling edge by dividing the difference between a first voltage of a first signal from a first photodetector and a second voltage from a second photodetector by the difference in relative positions of the first photodetector and the second photodetector within the photodetector array.

17. 17. The biological fluid treatment device of claim 16, wherein the first and second photodetectors are predetermined or preselected based on positions of the first and second photodetectors within the photodetector array.

18. the first voltage being a first percentage of a maximum voltage of the signal received by the controller from the photodetector array; 17. The biological fluid treatment device of claim 16, wherein the second voltage is a second percentage of the maximum voltage of the signal received by the controller from the photodetector array.

19. 20. The biological fluid treatment device of claim 18, wherein one of the first voltage and the second voltage is 35% of the maximum voltage and the other of the first voltage and the second voltage is 65% of the maximum voltage.

20. 17. The biological fluid treatment device of claim 11, wherein the controller is programmed to calculate the slope of the rising edge or the slope of the falling edge using linear regression.

21. 1. A method for determining a platelet mass index and / or a concentration of a substance in a fluid in a container, comprising: emitting light onto a fluid within the container; receiving at least a portion of the light exiting the vessel with a plurality of photodetectors of a photodetector array; generating a scattering profile based at least in part on an intensity of the at least a portion of the light received by each of the plurality of light detectors, the scattering profile including a rising edge and a falling edge; calculating a slope of the rising edge or the falling edge of the scattering profile; and determining a platelet mass index and / or a concentration of a substance in fluid within the container based at least in part on the slope.

22. Determining a platelet mass index and / or a concentration of a substance in a fluid in the container comprises:

22. The method of claim 21, comprising accessing a local library of platelet mass indices and / or local libraries of substance concentrations that correlate with different rising edge slopes and / or falling edge slopes, respectively.

23. Determining a platelet mass index and / or a concentration of a substance in a fluid in the container comprises:

22. The method of claim 21, comprising accessing a remote library of platelet mass indices and / or a remote library of substance concentrations that correlate with different rising edge slopes and / or falling edge slopes, respectively.

24. 24. The method of claim 21, wherein determining the platelet mass index and / or the concentration of a substance in the fluid in the container is based on the slope of a rising edge and not based on the slope of a falling edge, or based on the slope of a falling edge and not based on the slope of a rising edge.

25. 24. The method of any one of claims 21 to 23, wherein determining the concentration of a substance in the fluid in the vessel is based on both the slope of a rising edge and the slope of a falling edge.

26. 26. The method of claim 21, wherein the slope of the rising edge or the slope of the falling edge is calculated by dividing a difference between a first voltage of a first signal from a first photodetector and a second voltage from a second photodetector by a difference in relative positions of the first photodetector and the second photodetector within the photodetector array.

27. 27. The method of claim 26, wherein the first photodetector and the second photodetector are predetermined or preselected based on positions of the first photodetector and the second photodetector in the photodetector array.

28. the first voltage being a first percentage of a maximum voltage of a signal from the photodetector array comprising the scattering profile; 27. The method of claim 26, wherein the second voltage is a second percentage of the maximum voltage of the signal from the photodetector array that comprises the scattering profile.

29. 30. The method of claim 28, wherein one of the first voltage and the second voltage is 35% of the maximum voltage and the other of the first voltage and the second voltage is 65% of the maximum voltage.

30. 27. The method of any one of claims 21 to 26, wherein the slope of the rising edge or the slope of the falling edge is calculated using linear regression.

31. 1. An optical detection assembly for monitoring a fluid in a container, comprising: a light source assembly configured and oriented to emit light into the fluid in the container; a light detector assembly configured to receive at least a portion of the light exiting the vessel; A control unit. The control unit is receiving a first signal from the photodetector assembly indicative of an intensity of the at least a portion of the light received by the photodetector assembly when a reference fluid is in the container; receiving a second signal from the photodetector assembly indicative of an intensity of the at least a portion of the light received by the photodetector assembly when a fluid of interest is within the vessel; comparing the first signal with the second signal; an optical detection assembly programmed to determine a concentration of a substance in the fluid of interest within the vessel based at least in part on a comparison of the first signal and the second signal;

32. 32. The optical detection assembly of claim 31, wherein the reference fluid has a known concentration of the substance.

33. 33. The optical detection assembly of claim 31 or claim 32, wherein the reference fluid is free of the substance.

34. the reference fluid comprises platelet poor plasma or supernatant; the subject fluid comprises platelet-rich plasma or platelet concentrate; 34. The optical detection assembly of claim 31, wherein the substance comprises blood platelets.

35. the light entering the reference fluid has a first intensity; the light entering the target fluid has a second intensity; 35. The optical detection assembly of claim 31, wherein the first intensity is different from the second intensity.

36. the concentration of the substance in the reference fluid is lower than the concentration of the substance in the subject fluid; 36. The optical detection assembly of claim 35, wherein the second intensity is greater than the first intensity.

37. the light source assembly comprises a first light source and a second light source; the control unit is programmed to control the first light source to emit light when the reference fluid is in the container; 37. The optical detection assembly of claim 31, wherein the control unit is programmed to control the second light source to emit light when the target fluid is in the container.

38. the light source assembly comprises a single light source; 37. The optical detection assembly of claim 31, wherein the controller is programmed to control the single light source to emit light of different intensities.

39. the light source assembly includes a single light source; the optical detection assembly further includes an optical filter assembly including an optical filter integrated into a carriage and an actuator associated with the carriage; 37. The optical detection assembly of claim 31, wherein the control unit is programmed to control the actuator to move the carriage to selectively position and unposition the optical filter in the path of light emitted by the light source assembly.

40. the optical filter assembly includes a first optical filter and a second optical filter; the control unit is programmed to control the actuator to move the carriage to position the first optical filter in a path of light emitted by the light source assembly when the reference fluid is in the container; 40. The optical detection assembly of claim 39, wherein the control unit is programmed to control the actuator to move the carriage to position the second optical filter in a path of light emitted by the light source assembly when the target fluid is in the container.

41. the photodetector assembly comprises a photodetector array including a plurality of photodetectors; the first signal is indicative of an intensity of the at least some of the light received by each of the plurality of photodetectors when the reference fluid is in the container; the second signal is indicative of an intensity of the at least some of the light received by each of the plurality of light detectors when the fluid of interest is in the vessel; The control unit is generating a first scattering profile based at least in part on the first signal; generating a second scattering profile based at least in part on the second signal; 41. The optical detection assembly of claim 31, programmed to determine the concentration of the substance in the target fluid in the container based at least in part on a comparison of the first scattering profile and the second scattering profile.

42. 42. The optical detection assembly of claim 31, wherein the control unit is programmed to compare a voltage difference between the first signal and the second signal to determine the concentration of the substance in the target fluid in the container.

43. The control unit is Calculating a first slope of a rising edge of the first scattering profile; calculating a second slope of a rising edge of the second scattering profile; 42. The optical detection assembly of claim 41, programmed to determine the concentration of the substance in the target fluid in the container based at least in part on a comparison of the first slope and the second slope.

44. The control unit is Calculating a first slope of a descending edge of the first scattering profile; calculating a second slope of a descending edge of the second scattering profile; 42. The optical detection assembly of claim 41, programmed to determine the concentration of the substance in the target fluid in the container based at least in part on a comparison of the first slope and the second slope.

45. The control unit is calculating a slope of a first rising edge and a slope of a first falling edge of the first scattering profile; calculating a slope of a second rising edge and a slope of a second falling edge of the second scattering profile; 42. The optical detection assembly of claim 41, programmed to determine the concentration of the substance in the target fluid in the container based at least in part on a comparison of a slope of the first rising edge to a slope of the second rising edge and a comparison of a slope of the first falling edge to a slope of the second falling edge.

46. 1. A biological fluid treatment apparatus comprising: A pump system; A valve system; a controller programmed to control operation of the pump system and the valve system to perform a fluid processing procedure; an optical detection assembly; The optical detection assembly includes: a light source assembly configured and oriented to emit light into the fluid in the container; a photodetector assembly configured to receive at least a portion of the light exiting the vessel; The control unit further includes: receiving a first signal from the photodetector assembly indicative of an intensity of the at least a portion of the light received by the photodetector assembly when a reference fluid is in the container; receiving a second signal from the photodetector assembly indicative of an intensity of the at least a portion of the light received by the photodetector assembly when a fluid of interest is within the vessel; comparing the first signal with the second signal; The biological fluid treatment device is programmed to determine a concentration of a substance in the subject fluid within the vessel based at least in part on a comparison of the first signal and the second signal.

47. 47. The biological fluid treatment apparatus of claim 46, wherein the reference fluid has a known concentration of the substance.

48. 48. The biological fluid treatment apparatus of claim 46 or claim 47, wherein the reference fluid is free of the substance.

49. the reference fluid comprises platelet poor plasma or supernatant; the subject fluid comprises platelet-rich plasma or platelet concentrate; 49. The apparatus of any one of claims 46 to 48, wherein the material comprises platelets.

50. the light entering the reference fluid has a first intensity; the light entering the target fluid has a second intensity; 50. The biological fluid treatment device of any one of claims 46-49, wherein the first intensity is different from the second intensity.

51. the concentration of the substance in the reference fluid is lower than the concentration of the substance in the subject fluid; 51. The biological fluid treatment device of claim 50, wherein the second intensity is greater than the first intensity.

52. the light source assembly comprises a first light source and a second light source; the control unit is programmed to control the first light source to emit light when the reference fluid is in the container; 52. The biological fluid treatment device of any one of claims 46 to 51, wherein the control unit is programmed to control the second light source to emit light when the subject fluid is in the container.

53. the light source assembly comprises a single light source; 52. The biological fluid treatment device of any one of claims 46-51, wherein the control unit is programmed to control the single light source to emit light of different intensities.

54. the light source assembly includes a single light source; the optical detection assembly further includes an optical filter assembly including an optical filter integrated into a carriage and an actuator associated with the carriage; 52. A biological fluid treatment device as described in any one of claims 46 to 51, wherein the control unit is programmed to control the actuator to move the carriage to selectively position and unposition the optical filter in the path of light emitted by the light source assembly.

55. the optical filter assembly includes a first optical filter and a second optical filter; the control unit is programmed to control the actuator to move the carriage to position the first optical filter in a path of light emitted by the light source assembly when the reference fluid is in the container; 55. The biological fluid treatment device of claim 54, wherein the control unit is programmed to control the actuator to move the carriage to position the second optical filter in a path of light emitted by the light source assembly when the target fluid is in the container.

56. the photodetector assembly comprises a photodetector array including a plurality of photodetectors; the first signal is indicative of an intensity of the at least some of the light received by each of the plurality of photodetectors when the reference fluid is in the container; the second signal is indicative of an intensity of the at least some of the light received by each of the plurality of light detectors when the fluid of interest is in the vessel; The control unit is generating a first scattering profile based at least in part on the first signal; generating a second scattering profile based at least in part on the second signal; 56. The biological fluid treatment device of claim 46, further comprising: a programmable controller configured to determine the concentration of the substance in the target fluid in the vessel based at least in part on a comparison of the first scattering profile to the second scattering profile.

57. 57. The biological fluid treatment device of any one of claims 46 to 56, wherein the control unit is programmed to compare a voltage difference between the first signal and the second signal to determine the concentration of the substance in the target fluid in the container.

58. The control unit is Calculating a first slope of a rising edge of the first scattering profile; calculating a second slope of a rising edge of the second scattering profile; 57. The biological fluid treatment device of claim 56, programmed to determine the concentration of the substance in the subject fluid in the vessel based at least in part on a comparison of the first slope and the second slope.

59. The control unit is Calculating a first slope of a descending edge of the first scattering profile; calculating a second slope of a descending edge of the second scattering profile; 57. The biological fluid treatment device of claim 56, programmed to determine the concentration of the substance in the subject fluid in the vessel based at least in part on a comparison of the first slope and the second slope.

60. The control unit is calculating a slope of a first rising edge and a slope of a first falling edge of the first scattering profile; calculating a slope of a second rising edge and a slope of a second falling edge of the second scattering profile; 57. The biological fluid treatment device of claim 56, programmed to determine the concentration of the substance in the subject fluid in the container based at least in part on a comparison of a slope of the first rising edge to a slope of the second rising edge and a comparison of a slope of the first falling edge to a slope of the second falling edge.

61. 1. A method for determining a concentration of a substance in a fluid of interest in a container, comprising: irradiating a reference fluid in a container with light; receiving, with a photodetector assembly, at least a portion of the first light exiting the vessel; generating a first signal indicative of an intensity of the at least a portion of the first light received by the photodetector assembly; emitting a second light onto the target fluid in the container; receiving, with a photodetector assembly, at least a portion of the second light exiting the vessel; generating a second signal indicative of an intensity of the at least a portion of the second light received by the photodetector assembly; comparing the first signal and the second signal; and determining a concentration of a substance in the fluid of interest within the vessel based at least in part on a comparison of the first signal and the second signal.

62. 62. The method of claim 61 , wherein the reference fluid has a known concentration of the substance.

63. 63. The method of claim 61 or claim 62, wherein the reference fluid is free of the substance.

64. the reference fluid comprises platelet poor plasma or supernatant; the subject fluid comprises platelet-rich plasma or platelet concentrate; 64. The method of any one of claims 61 to 63, wherein the substance comprises platelets.

65. the light entering the reference fluid has a first intensity; the light entering the target fluid has a second intensity; 65. The method of any one of claims 61 to 64, wherein the first intensity is different from the second intensity.

66. the concentration of the substance in the reference fluid is lower than the concentration of the substance in the subject fluid; 66. The method of claim 65, wherein the second intensity is greater than the first intensity.

67. 67. The method of any one of claims 61 to 66, wherein the first light is emitted from a first light source and the second light is emitted from a second light source.

68. 67. The method of any one of claims 61 to 66, wherein the first light and the second light have different intensities and are emitted from a single light source.

69. the first light and the second light are emitted from a single light source; 67. The method of any one of claims 61 to 66, wherein emitting the first light and emitting the second light comprises moving an optical filter into a path of light emitted from the single light source.

70. emitting the first light includes moving a first optical filter into a path of the first light; 70. The method of claim 69, wherein emitting the second light comprises moving a second optical filter into a path of the second light.

71. a portion of the first light and a portion of the second light are received by a photodetector array including a plurality of photodetectors; the first signal is indicative of an intensity of the at least a portion of the first light received by each of the plurality of photodetectors; the second signal is indicative of an intensity of the at least a portion of the second light received by each of the plurality of photodetectors; Comparing the first signal and the second signal includes: generating a first scattering profile based at least in part on the first signal; generating a second scattering profile based at least in part on the second signal; 71. A method according to any one of claims 61 to 70, comprising comparing the first scattering profile with the second scattering profile.

72. 72. The method of any one of claims 61 to 71, wherein comparing the first signal and the second signal comprises comparing a difference in voltage between the first signal and the second signal.

73. Comparing the first scattering profile and the second scattering profile includes: Calculating a first slope of a rising edge of the first scattering profile; calculating a second slope of a rising edge of the second scattering profile; 72. The method of claim 71, comprising comparing the first slope and the second slope.

74. Comparing the first scattering profile and the second scattering profile includes: Calculating a first slope of a descending edge of the first scattering profile; calculating a second slope of a descending edge of the second scattering profile; 72. The method of claim 71, comprising comparing the first slope and the second slope.

75. Comparing the first scattering profile and the second scattering profile includes: calculating a slope of a first rising edge and a slope of a first falling edge of the first scattering profile; calculating a slope of a second rising edge and a slope of a second falling edge of the second scattering profile; 72. The method of claim 71, comprising comparing a slope of the first rising edge to a slope of the second rising edge, and comparing a slope of the first falling edge to a slope of the second falling edge.

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