Abstract:
An optical sensor is disclosed for use in an interactive cell processing system that includes a plurality of sensors arranged for monitoring and providing sensor data to a control module that directs processing of biological cells. The sensors including an optical sensor for characterizing a fluid transferred in a sterile manner during the processing. The optical sensor includes a light source, a light detector, a cuvette and a control circuit. The light source is connected to a control circuit and is constructed and arranged to emit light of at least one selected wavelength directed toward the fluid. The cuvette is constructed as a part of a fluid distribution manifold that includes several conduits for transferring the sterile fluid during the processing, wherein the cuvette is constructed and arranged to convey the fluid. The light detector is connected to the control circuit and is constructed and arranged to detect light that was emitted from the source and has interacted with the fluid flowing inside the cuvette. The control circuit is constructed and arranged to characterize the fluid in the cuvette based on the detected light.

Description:
RELATED APPLICATIONS 
     This application claims the benefit under Title 35, U.S.C. §119(e) of U.S. Provisional Application Ser. No. 60/047,213, filed May 20, 1997, now abandoned, entitled “Cell Processing System”, incorporated herein by reference. This application is also related to co-pending U.S. patent applications entitled: “Rotating Seals for Cell Processing Systems”, application Ser. No. 09/081,733, filed on May 20, 1998; “Apparatus and Method for Expressing Fluid Materials”, application Ser. No. 09/082,200 filed May 20, 1998, now abandoned; “Fluid Management Systems”, application Ser. No. 09/082,201 filed on May 20, 1998; and “Cell Processing Systems”, application Ser. No. 09/082,341, filed on May 20, 1998, now abandoned, all of which are incorporated by reference. 
    
    
     FIELD OF THE INVENTION 
     The invention relates to an optical method and apparatus for use in an interactive cell processing system. 
     BACKGROUND OF THE INVENTION 
     Cell processing includes steps where cells or cell elements are treated with different process chemicals or are washed and then separated from a liquid phase. For example, when preparing frozen erythrocytes for transfusion, erythrocytes are separated from cryopreservatives and other blood components such as white cells, platelets and sub-cellular debris. The entire process must be performed under sterile conditions that minimize the risk of contamination. Furthermore, whole blood is separated into its various therapeutic components such as red blood cells, white blood cells, platelets and plasma which are later transfused. There are different cell processing systems that process biological cells in an automated or semi-automated way. These systems may use a controller connected to various sensors and valves for controlling the process and helping an operator to maximize the processing efficiency. However, these systems do not interactively adjust the process based on the amount or type of the processed cells or different processing conditions. 
     During the separation, for example, by expression of the processing fluid, it is desirable to accurately differentiate the supernatant (for example, a wash solution) from the harvested cells in order to avoid losing valuable cellular product into the expressed (and thereafter discarded) wash solution. Various optical detectors have been designed and described in the prior art. However, there are several features that needed to be resolved. For example, the means and location of the optic assembly housing can be problematic. A separate plastic cuvette is typically used to provide flat, parallel surfaces through which the object cells must pass. These flat surfaces minimize optical distortion but add a separate object, the cuvette, to the disposable set designed to contain the cells and washing reagents. This additional cuvette increases the complexity and requires an extra operator step during set up of the instrument, as this cuvette must be accurately positioned in the optical detector housing. Any operator interaction may potentially introduce an error. If the housing is located away from the centrifuge, such design leaves a length of tubing between its location and the centrifuge that is full of packed cells immediately after the first of the cells have been detected. These cells are typically lost to the waste supernatant of the next wash cycle. Finally, cell processing may involve separating one cell type from another (e.g., the buffy coat containing white blood cells and platelets must be separated from erythrocytes being prepared as packed red cells for transfusion; erythrocytes must be removed from bone marrow during the preparation of progenitor cells). 
     Therefore, there is a need for an optical sensor for use in an automated interactive cell processing system. Such optical sensor would need to have a practical design and would need to provide precise and reproducible data for different disposable elements, varying amounts of processed cells, different types of processed cells, or different operators and processing laboratories. 
     SUMMARY OF THE INVENTION 
     The present invention is a optical method and apparatus for characterizing a fluid transferred in a sterile manner during cell processing. 
     In one aspect, an optical sensor is used in an interactive cell processing system that includes a plurality of sensors arranged for monitoring and providing sensor data to a control module that directs processing of biological cells. The sensors including an optical sensor for characterizing a fluid transferred in a sterile manner during the processing. The optical sensor includes a light source, a light detector, a cuvette and a control circuit. The light source is connected to a control circuit and is constructed and arranged to emit light of at least one selected wavelength directed toward the fluid. The cuvette is constructed as a part of a fluid distribution manifold that includes several conduits for transferring the sterile fluid during the processing, wherein the cuvette is constructed and arranged to convey the fluid. The light detector is connected to the control circuit and is constructed and arranged to detect light that was emitted from the source and has interacted with the fluid flowing inside the cuvette. The control circuit is constructed and arranged to characterize the fluid in the cuvette based on the detected light. 
     The optical sensor may include one or several of the following features: 
     The light source and the light detector may be arranged in a transmission geometry. The light source, the light detector and the control circuit are enclosed in a housing. The housing is suitable for sterilization by gama rays or by other means. 
     The fluid distribution manifold includes an integral component constructed to be placed in close proximity to the housing and arranged to define uniquely the position of the cuvette relative to the light source and the light detector. 
     The cuvette is made of an optical material suitable for sterilization. The cuvette is made of an optical material suitable for sterilization using gama radiation. The cuvette and the fluid distribution manifold may be disposable. 
     The light source and the light detector are located in a sealed housing constructed and arranged for wet cleaning. 
     The light source includes a light emitting diode (LED) constructed and arranged to emit light of about 560 nm and about 640 nm. The light detector includes a silicon diode. The optical sensor is arranged to detect red blood cells in the fluid. 
     The control circuit is constructed to activate the light source and the light detector to perform repeated measurements over a short period of time to increase precision of the characterization. The control circuit is constructed to calibrate operation of the optical sensor after placement of the cuvette. 
     The optical sensor is further arranged to provide data to the control module to actuate re-distribution of fluids flowing in the conduits. 
     Another aspect is a method of characterizing a fluid transferred in a sterile manner in a conduit during processing of biological cells in a cell processing system. The method includes conveying the fluid in a cuvette during operation of a cell processing system, wherein the conveying includes distributing the fluid in a fluid distribution manifold that includes several conduits for transferring sterile fluid during the processing, and wherein at least one of the conduits is permanently connected to the cuvette. The method also includes emitting light of at least one selected wavelength generated by a light source; detecting light that was emitted from the source and has interacted with the fluid flowing inside the cuvette; and characterizing the fluid in the cuvette based on the detected light. 
     Another aspect is a method of controlling operation of a cell processing system comprising a control module, a processing module connected in a sterile manner by a set of conduits to a cell module and to a supply module for providing selected process chemicals, and a plurality of sensors providing process data to the control module also arranged to actuate a plurality of valves regulating flow of the cells and the chemicals in the conduits during the operation. The method includes processing biological cells in the processing module by employing process chemicals including saline; expressing the process chemicals from the processing module; transferring a flow the expressed process chemicals to a waste container via the conduits, wherein at least one of the conduits is permanently connected to and in communication with a cuvette. The method also includes emitting light of at least one selected wavelength generated by a light source; detecting light that was emitted from the source and has interacted with the fluid flowing inside the cuvette; characterizing the fluid in the cuvette based on the detected light; and upon detecting presence of the processed biological cells during the characterization, redirecting the flow to transfer the processed biological cells to a cell container. 
     Any of the above methods may include one or several of the following: 
     The emitting includes generating light of about 560 nm and about 640 nm. The re-directing includes temporarily reversing the expressing action performed by the processing module to draw back the detected biological cells, and actuating a valve by the control module. The biological cells include red blood cells. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of an interactive cell processing system. 
     FIG. 2 is a conceptual flow diagram displaying operation of an interactive cell processing system. 
     FIG. 3 is a block diagram of the interactive cell processing system of FIG.  1 . 
     FIGS. 4 and 4A show a flow diagram of a process for enzymatic conversion of red blood cells. 
     FIG. 5 is a perspective view of an optical sensor used in the cell processing system of FIG.  1 . 
     FIG. 6 is a schematic diagram of the elements used in optical sensor of FIG.  5 . 
     FIG. 7 is a perspective view of a fluid distribution module including a partial view the optical sensor of FIG.  5 . 
     FIG. 8 is a partially exploded view of the fluid distribution module of FIG. 7 with another view of the optical sensor of FIG.  5 . 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring to FIGS. 1 and 3, an interactive cell processing system  10  includes a cell module  12 , a supply module  20 , a fluid distribution module  40 , a processing module  60 , a collection module  70  (not shown in FIG. 1) and a control module  80 . These modules are operatively interconnected for processing biological cells in a sterile environment. Cell module  12  is constructed for a short term or long term storage of biological cells for processing. Supply module  20  includes several containers for storing different process chemicals including saline, or other fluids used for washing the processed cells and also includes sterile air. The containers are connected to fluid distribution module  40  by a set of conduits. Fluid distribution module  40  includes several valves and sensors for dispensing controlled amounts of the process chemicals from supply module  20  to processing module  60  and for dispensing a known amount of the biological cells from cell module  12  to processing module  60 . Furthermore, fluid distribution module  40  is constructed to direct the process waste from processing module  60  to a waste container  72  and the processed cells to a cell storage container  74 , both of which are located in collection module  70 , while maintaining the purity and sterility of the cells. Control module  80  directs the entire process according to a selected algorithm. 
     In general, the operation of cell processing system  10  is shown in FIG.  2 . Control module  80  executes a processing algorithm selected initially ( 98 ). Control module  80  includes a logic controller that receives real-time data from several in-line sensors arranged in a processing loop. A mass sensor (or a volume sensor) measures an initial amount of the provided biological cells ( 94 ) and sends the data to control module  80 . Control module  80  controls the amount of cells dispensed to processing module  60  in accordance with the processing algorithm. Based on the provided amount of the biological cells, control module  80  also calculates the individual doses of the process chemicals ( 100 ) and directs a set of control valves to dispense the chemicals ( 102 ) in a selected order to processing module  60 , again in accordance with the processing algorithm. 
     Control module  80  executes iteratively the processing algorithm. Control module  80  receives data from the individual sensors (e.g., a weight sensor, a volume sensor, a temperature sensor, an optical sensor, a resistance or capacitance sensor, a flow sensor, a pressure sensor or another sensor arranged to monitor the transferred matter in a liquid, gaseous or solid state). After dispensing the selected amount of one or several processing chemicals to processing module  60 , control module  80  regulates the temperature and the time of processing and directs the processing module to agitate, mix or otherwise treat the cells with the process chemicals. Depending on the processing algorithm, control module  80  may manage one or several processing cycles. At the end of each cycle, processing module  60  may separate the processed cells from intermediate products and from the process waste. During the separation process, fluid distribution module  40  detects the fluid component being expressed from processing module  60  and directs the separated components to different containers for disposal ( 110 ) or for storage ( 112 ). Each processing cycle may use a different processing chemical and different processing conditions. Cell processing system  10  can also process different types of cells at the same time or sequentially. Furthermore, cell processing system  10  may also partially process biological cells and then store them in cell storage container  74  (shown in FIG.  3 ), which may include a temperature control system. The processed cells may be later automatically dispensed from cell storage container  74  and processed using another processing algorithm. The processed cells may also be grown in culture prior to another use. 
     Based on the starting weight of the biological cells, the controller calculates the dosage of the processing chemicals. Supply module  20  includes a weight sensor  29  for providing the weight of each process chemical to the controller. During the process, the controller confirms that correct amount of each process chemical has been transferred by measuring the change in the weight of the process chemical stored in supply module  20  and the initial weight of the chemical. The process chemicals in a fluid state are pumped through a 0.2 micron filter to assure sterility. A pressure transducer is mounted up-stream from the filter. If the fluids being pumped through the filter have a variable viscosity, the controller will adjust the pumping speed to yield a constant pressure drop across the filter membrane. 
     Processing module  60  is designed to assure identical processing conditions (e.g., pressure, temperature, mixing, processing time or other) for large and small amounts of the biological cells provided for processing. For this purpose, processing module  60  includes a processing chamber that has a variable volume design. Depending on the volume of the processed cells and other processing chemicals transferred into the processing chamber, the controller changes the chamber volume. The volume change is achieved by a movable wall that may be a membrane. Processing module  60  includes another pressure sensor for measuring the pressure inside the processing chamber and also includes a temperature sensor for measuring the temperature inside the processing chamber. Based on the data from the temperature sensor, a heat transfer system can provide or remove heat from the processing chamber. 
     Cell processing system  10  may process or separate cells and/or cell elements from different liquids or solids. Such cells and cell elements include, but are not limited to, erythrocytes (i.e., red blood cells); leukocytes (i.e., white blood cells, including lymphocytes, granulocytes, and monocytes); blood cell progenitors (e.g., primitive stem cells, burst forming units, reticulocytes, megakaryocytes, etc.); cell fragments (e.g., platelets, subcellular elements such as nuclei, debris, etc.); epithelial cells; endothelial cells; mesothelial cells; cells of normal tissues (e.g., liver cells, kidney cells, bladder cells, lung cells, pancreatic cells, embryonic cells, fetal cells, etc.); cells of abnormal tissues (e.g., malignant cells), and other. 
     Referring again to FIG. 3, in one preferred embodiment of the cell processing system, cell module  12  includes a weight sensor  14  arranged to weigh red blood cells provided in a PVC bag  16 . Tubing  17  connects bag  16  to a leuko filter  18  and to fluid distribution module  40 . Supply module  20  includes a bag  21  with enzyme Al/B, a bag  22  with enzyme A2, a bag  23  with 140 mMolar potassium phosphate dibasic (DPP), a bag  24  with polyethylene glycol (PEG), a bag  25  with storage solution, and a bag  26  with phosphate citrate isotonic (PCI). Fluid bags  21 ,  22 , . . . ,  26  are made of cryovac M312. Each bag is connected by tubing  28  to fluid distribution module  40 . Weight sensor  29  is constructed to weigh any of the above-mentioned fluids located in supply module  20 . Supply module  20  also includes a compressor  30  connected via a filter  31  and a check valve  32  to air reservoir  33 , which stores sterile air used for cell processing. Pressure switch and sensor  34  is in communication with air tubing  36 , which delivers sterile air to an air filter located in fluid distribution module  40 . A regulator  37 , connected to a solenoid valve  36 , regulates the air pressure provided to fluid distribution module  40  and to processing module  60 . Fluid distribution module  40  includes a peristaltic pump  42 , and twelve plunger valves  43 ,  44 , . . . , and  54  connected to a set of conduits for distributing the process chemicals and the cells during the automated process. The logic controller can close or open any combination of the twelve valves to redirect the fluid flowing inside the conduits. A pressure sensor  55  measures the fluid pressure during the process, and a optical sensor  58  monitors the fluid to and from processing module  60 . Processing module  60  includes a centrifuge  62  and an expressor system  64 . An IR temperature sensor  68  monitors the temperature of the process chemicals or the cells located inside centrifuge  62 . Collection module  70  includes a waste bag  72 , a saline solution bag  74 , and a product bag  76 . Collection module  70  also includes a weight sensor  76  connected to product bag  76  and arranged to weigh the processed red blood cells. 
     The controller controls the volume of the processing chamber of centrifuge  62  to assure identical processing conditions for large or small amounts of the red blood cells. The processing chamber includes a flexible wall for containing expresser fluid inside the processing chamber. For small volumes, expresser system  64  pumps expressor fluid into the chamber until the pressure transducer at the chamber signals a full condition. This pre-filling step assures that different amounts of red blood cells are subjected to the same accumulated centrifugal force and mechanical stresses due to packing. Otherwise, smaller amounts would spin longer and pack harder as the expresser fluid fills the processing chamber during the expression step. 
     During the process, the controller receives input from IR temperature sensor  66 , which measures the temperature of the red blood cells and the process chemicals. If the temperature is less than the set point, expressor of system  64  increases the temperature of the expressor fluid. Conversely, if the temperature is greater than the set point, expresser of system  64  decreases the temperature of the expressor fluid. A control loop continuously monitors the temperature of the processed cells. 
     Processing module  60  also includes a second pressure transducer that monitors the pressure of the sterile air on the rotating seal. If the seal is working, this pressure only fluctuates slightly between established limits. If the pressure drops below the established threshold, a warning condition is initiated that calls for a check of the rotating seal as well as other possible causes of failure. 
     Expressor fluid system  64  included a third pressure transducer that measures the pressure of the expressor fluid which is an indirect measure of the pressure on the red blood cells. The controller adjusts the expressor pump speed to assure that pressure is within accepted limits and cells are protected from damage. If the pressure is too low, the pump rate is increased to speed up the expression cycle. If the pressure is too high, the controller sends control signals to the pump to slow down in order to protect the processed cells from excessive pressure. This procedure also protects the “sterility” seal of processing module  60  from excessive pressure. 
     Referring to FIGS. 4 and 4A, in the preferred embodiment, the cell processing system of FIG. 3 is used for enzymatic conversion of red blood cells to type O red blood cells. The enzymatic conversion process starts in step  115  by weighting the provided amount of red blood cells. In step  117 , based on the starting weight of the provided red blood cells, the system dilutes the red blood cells dispensed to the processing bag located inside centrifuge  62 , shown in FIG. 3, with saline in the 1:1 ratio, and also flushes the bag with 100 ml of saline (step  119 ). In step  121 , the controller calculates the correct dosage of PCI to obtain the ratio of 65 ml of PCI for 100 ml of red blood cells. The controller also calculates the correct dosage of DPP to obtain the ratio of 110 ml of DPP for 100 mls of red blood cells. Prior to executing step  123 , the controller confirms that the correct amount of saline was transferred to centrifuge  62 . In step  123 , the centrifuge spins at 3000 RPM for about 2.5 minutes and then slows down to about 1500 RPM and expresses the saline waste while the washed red blood cells are left in the processing bag. 
     Next, in step  127 , the system purges the tubing with PCI and dispenses the dose calculated in step  121 , of PCI to the processing bag. PCI (Phosphate Citrate Isotonic) includes citric acid monohydrate 10.7 g/L, sodium phosphate dibasic (anhydrous) 2.7 g/L, sodium chloride 6.4 g/L suspended in one liter of sterile water having pH=2.8±0.05. The required dose is 65 mls of 2.8 pH PCI Buffer for every 100 mls of the 85 crit cell mass. In step  129 , the centrifuge thoroughly mixes the solution during addition of PCI and them occasionally agitates the red blood cells and PCI mixture for about 10 minutes for equilibration to reduce the pH of the packed red blood cells from approx 7.0 to 5.5. Then, in step  123 , the centrifuge expresses the separated waste (also called supernatant) while the red blood cells are left in the processing bag. 
     In step  131 , the system purges the tubing with PEG and dispenses the calculated dose to the processing bag. In step  133 , the system also adds enzymes to the processing bag, based on the amount of red blood cells measured in step  115 . The enzyme includes 12.5 ml of rB-zyme or 25 ml of a suspension of exo- and endo- rA-zyme and the PEG dose is 23 ml per 250 ml of 85 crit cell suspension. The centrifuge agitates for 60 minutes at the incubation temperature of 26° C. for rB-zyme and at 37° C. for rA-zymes. The enzyme is suspended in 5.5 pH PCI Buffer, PEG is 1450 MW suspended in 5.5 pH PCI. The system also verifies the dose, the time and the temperature according to the algorithm (step  135 ) and continues the red blood cells conversion if all parameters are satisfied. Then, the system purges the tubing with saline and fills up the processing bag with saline. In step  123 , the centrifuge spins the solution at 3000 RPM for about 2.5 minutes and then slows down to about 1500 RPM and expresses the supernatant waste while the washed red blood cells are left in the processing bag. 
     After the red blood cell conversion, the centrifuge expresses the supernatant (step  123 ). Next, in step  141 , the system dispenses saline to the processing bag, agitates the mixture and spins the mixture at about 3000 RPM for about 2.5 minutes. The centrifuge expresses the waste, and the system restores the 85 crit cell mass. In step  145 , purges the tubing with DPP to restore subsequently pH of converted red blood cells. In step  147 , the system dispenses DPP by metering 110 ml of DPP Buffer for every 100 ml of the 85 cri cell suspension. The system dispenses 140 mM potassium phosphate dibasic with pH 9.0±0.1 (DPP) that includes potassium phosphate dibasic (anhydrous) 24.4 g/L suspended in one liter of sterile water. The centrifuge mixes thoroughly the liquid during addition of the buffer and equilibriates at 26° C. for 10 minutes also mixing occasionally during the equilibration. Next, in step  141 , the system fills the processing bag with saline, agitates the mixture, and expresses the waste while the red blood cells are left in the processing bag. 
     Next, this system purges the lines with saline and washes the red blood cells several times by filling the processing bag with saline and subsequently expressing the waste (steps  141 ,  143  and  149 ). These steps remove the residual buffer, enzyme, PEG and phosphate to a level approximately equivalent to 99.9999%. After expressing the used saline in the last washing cycle (step  153 ), the system restores the 85 crit cell mass. 
     The controller directs fluid distribution module  40  to switch the tubing to collect the processed red blood cells in storage bag  74 . This process is controlled by optical sensor  58  (shown in FIG.  3 ). After the optical sensor detects red blood cells, in step  155 , the expresser pump reverses its pumping direction to draw back into the processing bag the red blood cells from the tubing located between the processing bag and the optical sensor. This is done to minimize the loss of red blood cells. Then, fluid distribution system  40  redirects the expressed red blood cells to storage bag  74 . When the processing cycle is completed (step  157 ) the controller meters 100 mls of nutracell storage solution for 250 ml of the 85 crit cell suspension. This solution is then stored in the storage bag made from a material approved for 42-day storage (step  163 ). 
     This embodiment of the cell processing system is used for enzymatically converting blood type as described, for example, in U.S. Pat. Nos. 4,330,619, 4,427,777 and 4,609,627 by Goldstein. 
     Optical sensor  58  sensor monitors the color and the turbidity of the transferred fluids. Specifically, optical sensor  58  also monitors the supernatant expressed from the centrifuge chamber. In step  153 , when red cells are detected in the supernatant, the controller responds by stopping the expressor pump to avoid losing any cells to waste. In step  155 , the controller switches valves to collect the cells in cell storage container  74 . 
     Optical sensor  58  is constructed and arranged to optically characterize a fluid being transferred within fluid distribution system  40 . Since the processed cells must be maintained in a sterile environment during the entire process, the optical sensor has to satisfy the corresponding requirements. The requirements include a sterile and easily replaceable optical chamber. The entire design is waterproof and enables easy sterilization of all outside surfaces in accordance with the corresponding regulations. 
     In general, optical sensor  58  is constructed and arranged to perform in-line characterization of fluids being transferred during the operation of cell processing system  10 . Optical sensor  58  periodically samples fluids flowing through an optical chamber and provides data to control module  80 . When optical sensor  58  detects a selected quality of the optically sampled fluid, it provides the corresponding data to control module  80 , which, in turn, activates a selected valve within fluid distribution system  40 . The activated valve redirects the flow of the fluid in accordance with the process. 
     A specific, currently preferred embodiment of optical sensor  58  is shown in FIG.  5 . Referring to FIG. 5, optical sensor  200  includes a circuit board  202 , a plastic mount  204 , a source cover  206 , a detector cover  208  and a soft gasket  210 . A two-color light emitting diode  212  (shown in FIG. 6) is mounted on a source mount  214  and placed inside source cover  206 . A silicon diode detector  216  (shown in FIG. 6) is mounted on a detector mount  218  and is located within the detector cover  208 . Also, mounted within source cover  206  is a source aperture having a 1 mm size hole. Source aperture  213 , located in front of LED  212 , is aligned with a detector aperture, also having a 1 mm hole, located in front of silicon diode detector  216 . 
     The light emitting diode is constructed to emit light of about 560 nm and about 640 nm. Preferably, the LED is AND176RAG made by Purdy Electronics Corp., 720 Palomar Ave., Sunnyvale, Calif. The silicon diode detector is OPT210 made by Burr-Brown Corp., 6730 S. Tucson Blvd., Tucson, Ariz. 85706. Located on circuit board  202  is electronics  225  shown in FIG.  6 . 
     After each power-up, control module  80  calibrates optical sensor  200  by taking the transmission data either without the cuvette or with the cuvette empty and comparing this to calibration data stored in the memory. Furthermore, a local controller  230  calibrates source  212  or detector  216  each time when a new cassette is located in fluid distribution system  40 . 
     FIGS. 7 and 8 show the arrangement of optical sensor  200  relative to fluid distribution module  40 . The fluid distribution module is part of a fluid management system that coordinates the delivery of biological cells, process chemicals, solutions, fluids, reagents, etc. to conform with a processing algorithm executed by control module  80 . Generally, the fluid distribution module controls the delivery of fluids from supply module  20  and cell module  12  to the processing module  60  (see FIGS.  1  and  3 ), as well as the expression of fluids from the processing module  60 . The fluid distribution module is a device comprised of pumps, valves, pressure management devices, and other components useful in the management of a multiplicity of fluids. 
     Referring to FIGS. 7 and 8, the main components of the fluid distribution module are a housing  250 , a pump valve assembly  252  mounted in the housing, and a distribution manifold  256  mounted on the housing on platen  262 . The housing  252  can be formed from sheet metal. Also mounted on the housing  250  is peristaltic (“roller”) pump  42 . A connector  260  is attachable to the distribution manifold and receives tubing from different sources of fluids to be transferred to the manifold. The distribution manifold  256  includes a plurality of ports connected to interior runner channels for transferring fluid from one place to another. The manifold includes a series of interior channels connecting the ports in an arrangement for transference of the fluids from one port to another. 
     The distribution module  40  is arranged so that the distribution manifold  256  is easily attachable to the housing  252  so that it may be a single use disposable device which can be replaced after the processing cycle is complete for a bag  16  of biological cells. The distribution manifold  256  is easily attachable and detachable to the housing through the use of spring knobs  258  (see FIG.  8 ). To attach the manifold, the spring knobs are rotated horizontally, the manifold is placed on platen  262 , the spring knobs are pulled out, rotated vertically and released to bias the manifold against the platen. 
     The platen  262  is seated in a recess  264  of housing  250 . The platen  262  is an intermediary between the distribution manifold  256  and the pump valve assembly  252 . The pump valve assembly includes a series of solenoids which can be energized to retract normally extended plungers associated with corresponding ports on the distribution manifold used to transfer fluids to and from the manifold  256 , as explained in detail in the above-referenced co-pending U.S. patent application entitled “Fluid Management Systems”. 
     Also supported by the pump valve assembly  252  are: load cells  288  and  290  which are used to sense the fluid pressure at two points within the distribution manifold  256 ; a sterile air hose and filter  293 ; and optical sensor  200  including a source housing  206  and a detector housing  208 . Hall effect sensors  298  are used to detect the position of the plungers. 
     Platen  262  includes variously shaped holes  300  to accommodate the plungers  264 - 286 , load cells  288  and  290 , a source housing  206  and detector housing  208  of the optical sensor, and sterile air hose  293  (see FIGS.  7  and  8 ). To prevent fluids from possibly entering the pump valve assembly  252 , individual silicon plunger membranes can be placed over each plunger, as well as the two load cells, and will seal the respective holes of the platen  262 . Thus, the plungers  264  and  266  seen in FIG. 8 are covered by such membranes. In FIG. 8, plungers  264  and  266  are shown in the normal (i.e., non-energized) position in which the ports associated with the plungers  264 - 266  would be shut off. When attaching distribution manifold  256  to the platen  262  all of the solenoids are energized so the plungers do not interfere with the placement of the manifold. Furthermore, distribution manifold  256  provides a standardized position for optical cuvette  348  of optical sensor  200 . Source housing  206  is received in cover  338  of distribution manifold  256 , and detector housing  208  is received in recess  340  on the other side of cuvette  348 . 
     All materials of distribution manifold  256  and optical sensor  200  are gamma stabile and resist color shift and physical property breakdown during gamma sterilization and have USP VI classification. The plastic components are made of an amorphous clear polymer with high flexural modulus and good impact strength because acrylic is not the only plastic with these properties. The possible materials include: polycarbonate (PC), styrene acrylonitrile (SAN), polyester and copolyester, clear acrylonitrile butadiene styrene (ABS), polystyrene (PC), polymethylpentene (TPX).) In the preferred embodiment, the plastic components are made of acrylic for its excellent light transmission, stiffness, and its ease of molding. They are processed by method of thermoplastic injection molding (IM). The optical cuvette  348  of distribution manifold  256  is molded to a finish standard of SPI A-1 (optical finish) as defined by The Society of Plastics Industry. Likewise, the mold cavity and core must have no draft in this area. The internal fluid channels require a finish of SPI B-3 or finer. 
     The sterility of all components is maintained during processing by aseptic methods and sterile pyrogen-free equipment and solutions. The transfer of all components is done without breakage of the seal. 
     Additional embodiments are within the following claims.