Abstract:
The present invention is directed towards receiving removable media, and in some embodiments, providing tighter alignment tolerances between an inserted removable media member and a receiving device. The present invention is also directed towards providing one or more electrical or optical device on or in the removable media member itself, and for providing an electrical and/or optical link between the one or more electrical and/or optical devices on or in the removable media and the receiving device.

Description:
This application claims priority to U.S. provisional application No. 60/404,876, filed Aug. 21, 2002, entitled “CYTOMETER”, U.S. patent application Ser. No. 09/630,924, filed Aug. 2, 2000, and entitled “PORTABLE FLOW CYTOMETER”, U.S. patent application Ser. No. 09/630,927, filed Aug. 2, 2000, entitled “OPTICAL DETECTION SYSTEM FOR FLOW CYTOMETRY”, U.S. patent application Ser. No. 10/174,851, filed Jun. 19, 2002, entitled “ELECTROSTATICALLY ACTUATED VALVE”, and U.S. patent application Ser. No. 09/404,560, now U.S. Pat. No. 6,240,944, filed Sep. 23, 1999, entitled “ADDRESSABLE VALVE ARRAYS FOR PROPORTIONAL PRESSURE OR FLOW CONTROL”, all of which are incorporated herein by reference. 
    
    
     BACKGROUND 
     The present invention generally relates to removable media, and more particularly, to methods and apparatus for receiving a removable media member. 
     Over the past several decades there has been an ever increasing use of devices and systems that use, in one form or another, a removable media member. Some illustrative removable media members include, for example, removable or replaceable filters, removable ink and toner cartridges, removable data storage devices such as magnetic or optical disks, removable magnetic tape cartridges, removable memory sticks, etc. 
     A limitation of many of the existing systems is that the alignment tolerance between the inserted removable media member and the receiving device is often not very precise. In some cases, the receiving device simply includes a slot for receiving the removable media member. In other cases, a more complex mechanical mechanism is provided, such as the mechanical mechanism used in a conventional Video Cassette Recorder (VCR) for receiving VCR tapes. For some applications, the alignment tolerance that can be achieved using these existing systems is not adequate. 
     Another limitation with many existing systems is that provisions are typically not made for including one or more electrical or optical devices on or in the removable media member. For some applications, however, it may be desirable to provide one or more electrical and/or optical devices on or in the removable media member. In addition, it may be desirable to provide one or more electrical, optical and/or wireless links or connections between the electrical and/or optical devices on or in the removable media and the receiving device so that, for example, various functions may be performed by the removable media member. 
     SUMMARY 
     The present invention overcomes many of the disadvantages of the prior art by providing methods and apparatus for receiving a removable media member, and more specifically, for providing tighter alignment tolerances between an inserted removable media member and a receiving device. The present invention also provides methods and apparatus for providing one or more electrical or optical device on or in the removable media member itself, and for providing an electrical and/or optical link between the one or more electrical and/or optical devices on or in the removable media and the receiving device. 
     In a first illustrative embodiment, an apparatus is provided for accepting a removable media member. The apparatus includes a first member and a second member, wherein the first member and the second member are adapted to move away from each other to provide a space for receiving a removable media member. Once the removable media member is inserted into the space, the first member and second member can be moved toward each other to engage and/or secure the removable media member. 
     In one illustrative embodiment, the first member has one or more L-shaped cleats that provide a slot to receive the removable media member. The L-shaped cleats may include, for example, a first leg that extends away from the first member and toward the second member, and a second leg that extends from a distal end of the first leg and in a perpendicular direction relative to the first leg so that a channel or receiving slot is formed. The channel or receiving slot may then receive at least one side of the removable media member. 
     In some embodiments, two L-shaped cleats are provided for providing two spaced channels for receiving opposing sides of the removable media member. That is, the channel or slot of the first L-shaped cleat and the channel or slot of the second L-shaped cleat may be arranged so that the removable media member slides into both channels when it is inserted between the first member and the second member. In one embodiment, the two L-shaped cleats are secured to the first member. 
     During use, the first member and the second member may be moved away from one another, and the removable media member may be slid into the channel or receiving slots provided by the one or more L-shaped cleats. The L-shaped cleats are preferably positioned so that that when the removable media member is received by the one or more L-shaped cleats, the removable media member is at least roughly aligned with a desired position relative to the first member and/or second member. The first member and the second member may then be moved toward one another to engage and/or secure the removable media member therebetween. 
     To remove the removable media member, the first member and the second member may be moved away from each other. Because at least part of the removable media member is positioned in the channel or slot of the one or more L-shaped cleats, and when the one or more L-shaped cleats are secured to the first member, the removable media member may be pulled away from the second member by the L-shaped cleats as the first member and second member are moved away from each other. 
     To provide better alignment between the removable media member and the first and/or second members, the second member may include one or more alignment pins that extend toward the first member. The removable media member may then include one or more receiving holes for receiving the one or more alignment pins. The alignment pins and receiving holes may provide improved alignment between the removable media member and the first and/or second members when the removable media member is secured between the first member and the second member. 
     Preferably, the one or more L-shaped cleats may be used to pull the removable media member away from the second member, thereby separating the one or more receiving holes of the removable media member from the one or more alignment pins that are extending from the second member. With the one or more receiving holes separated from the alignment pins, the removable media member then may be more easily removed from between the first member and the second member. 
     In some embodiments, the removable media member may include one or more electrical and/or optical devices. For example the removable media member may include one or more transistors, diodes, sensors such as optical, pressure, temperature and/or flow sensors, Vertical Cavity Surface Emitting Lasers (VCSELs), LEDs, electro-statically actuated actuators or pumps, micro-lenses or any other suitable electrical, mechanical and/or optical device. One illustrative removable media member that includes flow sensors is shown and described in U.S. patent application Ser. No. 10/150,851, issued as U.S. Pat. No. 6,794,981 on Sep. 21, 2004, which is incorporated herein by reference. To provide power and/or to communicate or control the one or more electrical, mechanical and/or optical devices, an electrical and/or optical interface may be provided between the first and/or second member and the removable media member. 
     In one illustrative embodiment, one or more electrical contact pads are provided on a surface of the removable media member. The one or more electrical contact pads may be electrically connected to the one or more electrical and/or optoelectronic devices of the removable media member, such as by a metal trace or the like. In one illustrative embodiment, the first member may include one or more spring biased probes that extend outward away from the first member and toward the second member. The one or more spring biased probes are preferably positioned to align with the one or more electrical contact pads of the removable media member when the removable media member is at a desired positioned between the first member and the second member. In some cases, the one or more alignment pins discussed above may help provide alignment between the one or more spring biased probes of the first member and the one or more electrical contact pads of the removable media member. When the first member and the second member are moved toward one another to secure and/or engage the removable media member, the one or more spring biased probes of the first member may make electrical contact with the one or more electrical contact pads of the removable media member. 
     To help separate the one or more spring biased probes of the first member from the one or more electrical contact pads when the first member is moved away from the second member, an outward or separating bias may be provided between the first member and the removable media member. This outward bias may be overcome when the first member and the second member are moved toward each other to secure and/or engage the removable media member. However, when the first member and the second member are moved away from each other to release the removable media member, the outward bias may separate the one or more spring biased probes of the first member from the one or more electrical contact pads, which may make the removal of the removable media member from between the first member and the second member easier and may help protect the spring bias probes from damage. 
     In another illustrative embodiment, one or more optical transmitters and/or receivers may be provided on a surface of the removable media member. The one or optical transmitters and/or receivers may be electrically connected to the one or more electrical and/or optoelectronic devices of the removable media member, such as by an optical waveguide, metal trace, or the like. In this embodiment, the first member and/or second member may include one or more optical transmitters and or optical receivers, which are preferably positioned to align with the one or more optical transmitters and/or receivers of the removable media member when the removable media member is at a desired positioned between the first member and the second member. In some cases, the one or more alignment pins discussed above may help provide alignment between the optical transmitters and/or optical receivers of the first and/or second members and the one or more optical transmitters and/or optical receivers of the removable media member. When the first member and the second member are moved toward one another to secure and/or engage the removable media member, the one or more optical transmitters and/or optical receivers of the first and/or second members become aligned with the one or more optical transmitters and/or optical receivers of the removable media member to provide a communications link therebetween. The one or more optical transmitters and/or optical receivers may be used to, for example, help provide optical communication between the removable media member and the receiving device that accepts or receives the removable media member. In another illustrative embodiment, one or more RF transmitters and/or receivers may be provided on or in the removable media member. The one or more RF transmitters and/or receivers may be used to, for example, help provide wireless communication between the removable media member and the receiving device that accepts or receives the removable media member. 
     In some cases, the removable media member may include one or more fluid ports for accepting or delivering fluid to and/or from the removable media member. In one illustrative embodiment, the removable media member may be a fluidic cartridge adapted for use in flow cytometry. The fluidic cartridge may include one or more flow channels. The one or more fluid ports may be in fluid communication with at least some of the flow channels. When so provided, one or more corresponding fluid ports may be provided on the first member and/or second member, as desired. Preferably, the one or more fluid ports of the first member and/or second member are positioned to align with at least selected ones of the fluid ports of the removable media member when the removable media member is secured and/or engaged by the first member and the second member. 
     In some cases, one or more alignment pins as discussed above may be provided to help provide alignment between the one or more fluid ports of the first member and/or second member and the one or more fluid ports of the removable media member. In addition, an outward bias may be provided between the removable media member and the first member and/or second member to help separate the one or more fluid ports of the first member and/or second member and the one or more fluid ports of the removable media member when the first member is moved away from the second member. 
     In some cases, the manufacture of the removable media member may create a ridge, a burr, or other imperfections, particularly around the outer perimeter of the removable media member. In one example, a fluidic cartridge may be manufactured by laminating several layers or sheets together, and then cutting individual fluidic cartridges from the laminated structure. At the cut lines, ridges, burrs, and other imperfections may arise. To help the removable media member seat correctly along the first and/or second member, a groove or other relief structure may provided in receiving surface of the first and/or second member to accommodate the one or more imperfections in the removable media member. In one illustrative embodiment, a groove may extend along a groove path that corresponds to, for example, the perimeter of the removable media member in anticipation of imperfections that might occur along the perimeter of the removable media member. It is contemplated, however, that a groove or other relief structure may be provided at any location where an anticipated imperfection might occur in the removable media member. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Other objects of the present invention and many of the attendant advantages of the present invention will be readily appreciated as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings, in which like reference numerals designate like parts throughout the figures thereof and wherein: 
         FIG. 1  is a perspective view of an illustrative portable cytometer in accordance with the present invention; 
         FIG. 2  is a schematic view of the illustrative portable cytometer of  FIG. 1 ; 
         FIG. 3  is a more detailed schematic diagram showing the portable cytometer of  FIG. 2  with the cover not yet depressed; 
         FIG. 4  is a more detailed schematic diagram showing the portable cytometer of  FIG. 2  with the cover depressed; 
         FIG. 5  is a perspective view of another illustrative portable cytometer in accordance with the present invention; 
         FIG. 6  is a perspective side view of the illustrative portable cytometer of  FIG. 5 ; 
         FIG. 7  is another perspective view of the illustrative portable cytometer of  FIG. 5 ; 
         FIG. 8  is a perspective view of the first plate or member of the illustrative portable cytometer of  FIG. 5 ; 
         FIG. 9  is a perspective view of the lower cleat of the first plate or member of  FIG. 8 ; 
         FIG. 10  is a perspective view of the upper cleat of the first plate or member of  FIG. 8 ; 
         FIG. 11  is a perspective view of the outward bias wedge of the first plate or member of  FIG. 8 ; and 
         FIG. 12  is a perspective view of the second plate or member of the illustrative portable cytometer of FIG.  5 . 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     For illustrative purposes, a portable flow cytometer system is described in detail below. However, it must be recognized that the present invention has wide applicability to numerous other removable media systems including, for example, removable or replaceable filters, removable ink and toner cartridges, removable data storage devices such as magnetic or optical disks, removable magnetic tape cartridges, removable memory sticks, as well as many other systems and/or devices that use removable media. 
       FIG. 1  is a perspective view of an illustrative portable cytometer. The portable cytometer is generally shown at  10 , and includes a housing  12  and a removable or replaceable cartridge  14 . The removable cartridge  14  may have a front side, a back side, and one or more lateral sides extending between the front side and the back side. The illustrative housing  12  includes a base  16 , a cover  18 , and a hinge  20  that attaches the base  16  to the cover  18 . The base  16  includes an array of light sources  22 , associated optics and the necessary electronics for operation of the cytometer. The cover  12  includes a manual pressurizing element, pressure-chambers with control microvalves, and an array of light detectors  24  with associated optics, as further described in U.S. patent application Ser. No. 09/630,924, filed Aug. 2, 2000, and entitled “PORTABLE FLOW CYTOMETER”, and U.S. patent application Ser. No. 09/630,927, filed Aug. 2, 2000, and entitled “OPTICAL DETECTION SYSTEM FOR FLOW CYTOMETRY”, both of which are incorporated herein by reference. 
     The removable member (e.g. cartridge)  14  preferably receives a sample fluid via a sample collector port  32 . A cap  38  may be used to protect the sample collector port  32  when the removable cartridge  14  is not in use. The removable cartridge  14  may perform blood dilution, red cell lysing, and hydrodynamic focusing for core formation. The removable cartridge  14  may be constructed similar to the fluidic circuits available from Micronics Inc., some of which are fabricated using a laminated structure with etched fluid channels. 
     The removable cartridge  14  is inserted into the housing when the cover  18  is in the open position. The removable cartridge  14  may include holes  26   a  and  26   b  for receiving registration pins  28   a  and  28   b  in the base  16 , which help provide alignment and coupling between the different parts of the instrument. The removable cartridge  14  also preferably includes a transparent flow stream window  30 , which is in alignment with the array of the light sources  22  and light detectors  24 . When the cover is moved to the closed position, and the system is pressurized, the cover  18  provides controlled pressures to pressure receiving ports  34   a ,  34   b , and  34   c  in the removable cartridge  14  via pressure providing ports  36   a ,  36   b  and  36   c , respectively. 
     To initiate a test, the cover  18  is lifted and a new cartridge  14  is placed and registered onto the base  16 . A blood sample is introduced into the sample collector  32 . The cover  18  is closed and the system is manually pressurized. Once pressurized, the instrument performs a white blood cell cytometry measurement. The removable cartridge  14  provides blood dilution, red cell lysing, and hydrodynamic focusing for core formation. The light sources  22 , light detectors  24  and associated control and processing electronics perform differentiation and counting of white blood cells based on light scattering signals received by the light detectors  24 . Rather than using a hinged construction for the housing  12 , it is contemplated that a sliding cartridge slot or any other suitable construction may be used, including that described further below with respect to  FIGS. 5-12 . 
       FIG. 2  is a schematic view of the illustrative portable cytometer of FIG.  1 . As above, the base  16  may include an array of light sources  22 , associated optics and the necessary control and processing electronics  40  for operation of the cytometer. The base  16  may also include a battery  42  for powering the cytometer. The cover  12  is shown having a manual pressurizing element  44 , pressure-chambers  46   a ,  46   b  and  46   c  with control microvalves, and an array of light detectors  24  with associated optics. 
     The removable cartridge  14  may receive a sample fluid via the sample collector port  32 . When pressurized by the cover  18 , the removable cartridge  14  performs blood dilution, red cell lysing, and hydrodynamic focusing for core formation in a preferred embodiment. Once formed, the core is provided down a flow stream path  50 , which passes the flow stream window  30  of FIG.  1 . The array of light sources  22  and associated optics in the base provide light through the core stream via the flow stream window  30 . The array of light detectors and associated optics receive scattered and non-scattered light from the core, also via the flow stream window  30 . The controller or processor  40  receives output signals from the array of detectors, and differentiates and counts selected white blood cells that are present in the core stream. 
     It is contemplated that the removable cartridge  14  may include a fluid control block  48  for helping to control the velocity of each of the fluids. In the illustrative embodiment, the fluid control block  48  includes flow sensors for sensing the velocity of the various fluids and report the velocities to the controller or processor  40 . The controller or processor  40  may then adjust the microvalves associated with pressure-chambers  46   a ,  46   b  and  46   c  to achieve the desired pressures and thus desired fluid velocities for proper operation of the cytometer. In some embodiments, and as further described below, one or more electrical, optical and/or wireless connections may be provided between the processor  40  in the base  16  and the flow sensors on the removable cartridge  14 . 
     Because blood and other biological waste can spread disease, the removable cartridge  14  preferably has a waste reservoir  52  downstream of the flow stream window  30 . The waste reservoir  52  receives and stores the fluid of the flow stream in the removable cartridge  14 . When a test is completed, the removable cartridge may be removed and disposed of, preferably in a container compatible with biological waste. 
       FIG. 3  is a more detailed schematic diagram showing the portable cytometer of  FIG. 2  with the cover  18  not yet depressed.  FIG. 4  is a more detailed schematic diagram showing the portable cytometer of  FIG. 2  with the cover depressed. The cover  18  is shown having a manual pressurizing element  44 , pressure-chambers  46   a ,  46   b  and  46   c , and control microvalves generally shown at  60 . The array of light sources and detectors are not shown in these Figures. 
     There are three pressure chambers  46   a ,  46   b  and  46   c , one for each fluid to be pressurized. In the illustrative embodiment, pressure chamber  46   a  provides pressure to a blood sample reservoir  62 , pressure chamber  46   b  provides pressure to a lyse reservoir  64 , and pressure chamber  46   c  provides pressure to a sheath reservoir  66 . The size and shape of each pressure chamber  46   a ,  46   b  and  46   c  may be tailored to provide the desired pressure characteristics to the corresponding fluid. 
     Pressure chamber  46   a  includes a first pressure chamber  70  and a second pressure chamber  72 . A first valve  74  is provided between the first pressure chamber  70  and the second pressure chamber  72  for controllably releasing the pressure in the first pressure chamber  70  to a second pressure chamber  72 . A second valve  76 , in fluid communication with the second pressure chamber  72 , controllably vents the pressure in the second pressure chamber  72 . Each valve is preferably an array of electrostatically actuated microvalves that are individually addressable and controllable, as described in, for example, co-pending U.S. patent application Ser. No. 09/404,560, entitled “ADDRESSABLE VALVE ARRAYS FOR PROPORTIONAL PRESSURE OR FLOW CONTROL”, and incorporated herein by reference. Pressure chambers  46   b  and  46   c  include similar valves to control the pressures applied to the lyse reservoir  64  and sheath reservoir  66 , respectively. Alternatively, each valve may be an array of electrostatically actuated microvalves that are pulse modulated with a controllable duty cycle to achieve a controlled “effective” flow or leak rate. Alternatively, each valve may be a similar to that described in co-pending U.S. patent application Ser. No. 10/174,851, entitled “ELECTROSTATICALLY ACTUATED VALVE”, which is incorporated herein by reference. 
     The removable cartridge  14  has pressure receiving ports  34   a ,  34   b , and  34   c  for receiving the controlled pressures from the cover  18 . The controlled pressures are provided to the blood reservoir  62 , lyse reservoir  64  and sheath reservoir  66 , as shown. The lyse reservoir  64  and sheath reservoir  66  are preferably filled before the removable cartridge  14  is shipped for use, while the blood reservoir  62  is filled from sample collector port  32 . A blood sample may be provided to the sample collector port  32 , and through capillary action, the blood sample may be drawn into the blood reservoir  62 . Once the blood sample is in the blood reservoir  62 , the cover  18  may be closed and the system may be pressurized. 
     A flow sensor is provided in-line with each fluid prior to hydrodynamic focussing. Each flow sensor  80 ,  100  and  102  measures the velocity of the corresponding fluid. The flow sensors are preferably thermal anemometer type flow sensors, and more preferably microbridge or microbrick type flow sensor. Microbridge flow sensors are described in, for example, U.S. Pat. No. 4,478,076, U.S. Pat. No. 4,478,077, U.S. Pat. No. 4,501,144, U.S. Pat. No. 4,651,564, U.S. Pat. No. 4,683,159, and U.S. Pat. No. 5,050,429, all of which are incorporated herein by reference. An output signal from each flow sensor  80 ,  100  and  102  is provided to controller or processor  40  via one or more electrical connection between the removable cartridge and the base. Alternatively, or in addition, one or more optical transmitters and/or optical receivers may be provided on the removable cartridge  14 . The one or more optical transmitters and/or optical receivers may be used to, for example, help provide optical communication between the removable cartridge  14  and the controller or processor  40  in the base  16 . Likewise, and in some embodiments, one or more RF transmitters and/or receivers may be provided on or in the removable cartridge. The one or more RF transmitters and/or receivers may be used to, for example, help provide wireless communication between the removable cartridge and the base  16 . 
     The controller or processor  40  opens the first valve  74  when the velocity of the blood sample drops below a first predetermined value and opens the second valve  76  when the velocity of the blood sample increases above a second predetermined value. Valves  84 ,  86 ,  94  and  96  operate in a similar manner to control the velocities of the lyse and sheath fluids. 
     During operation, and to pressurize the system, the manual pressurizing element  44  is depressed. In the example shown, the manual pressurizing element  44  includes three plungers, with each plunger received within a corresponding one of the first pressure chambers. The plungers create a relatively high non-precision pressure in the first pressure chambers. Lower, controlled pressures are built in the secondary chambers by opening the first valves  70 ,  84  and  94 , which produce a controllable leak into the secondary chambers. If too much pressure builds up in the secondary pressure chambers, the corresponding vent valve  76 ,  86  and  96  are opened to relieve the pressure. 
     When closing the cover  18 , the normally open first valves  74 ,  84  and  94  are closed while the vent valves  76 ,  86  and  96  are open. When a predetermined pressure P is achieved in the first pressure chambers, the vent valves  76 ,  86  and  96  are closed, and the first valves  74 ,  84  and  94  are opened to build a lower pressure P′ in the secondary pressure chambers. The controlled pressure in the secondary pressure chambers provide the necessary pressures to the fluidic circuit of the removable cartridge  14  to produce fluid flow for the blood, lyse and sheath. The velocity of the fluid flow is then measured by the downstream flow sensors  80 ,  100  and  102 . Each flow sensor provides an output signal that is used by the controller or processor  40  to control the operation of the corresponding first valve and vent valve to provide a desired and constant flow rate for each fluid. 
     Downstream valves generally shown at  110  may also be provided. Controller or processor  40  may close downstream valves  110  until the system is pressurized. This may help prevent the blood, lyse and sheath from flowing into the fluid circuit before the circuit is pressurized. In another embodiment, downstream valves  110  are opened by mechanical action when the cover is closed. 
     In some embodiments, pressure generated in pressure-chambers  46   a ,  46   b  or  46   c , or some other pressure chamber (not shown), may be used to control one or more pneumatic valves placed on or in the removable cartridge  14 . The one or more pneumatic valves may be used to control, for example, a flow path, a flow rate or some other flow property associated with a fluid or gas on or in the removable cartridge  14 . Alternatively, or in addition, the pressure generated in pressure-chambers  46   a ,  46   b  or  46   c , or some other pressure chamber (not shown), may be used to control one or more pneumatically controlled elements that provide some other mechanical movement on or in the removable cartridge  14 , such as a pneumatically controlled pump, plunger, gear, etc. 
       FIG. 5  is a perspective view of another illustrative portable cytometer in accordance with the present invention. The basic operation of the portable cytometer of  FIG. 5  is similar to that described above with respect to  FIGS. 1-4  above. The portable cytometer of  FIG. 5  is generally shown at  120 , and includes a base  122 , a first member  124 , a second member  126 , a clamp frame  128  with clamp lever  130 , an air buffer module  132 , a valve module assembly  134  with polymer microvalves, an air accumulator module  136 , and an optics assembly  140 . 
     In the illustrative embodiment, the second member  126  is fixed to the base  122 . A number of shoulder screws  142   a ,  142   b ,  142   c  and  142   d  ( 142   d  not shown in  FIG. 5 ) pass through holes in the first member  124  and are secured to the second member  126 . Springs  144   a ,  144   b ,  144   c  and  144   d  ( 144   d  not shown in  FIG. 5 ) are placed between the first member  124  and the head of the corresponding shoulder screw  142   a ,  142   b ,  142   c  and  142   d . The springs  144   a ,  144   b ,  144   c  and  144   d  provide a bias force to the first member  124  toward the second member  126 . 
     The clamp frame  128  is secured to the second member  126  as shown. The clamp lever  130  interacts with the clamp frame to provide an outward bias force to the first member away from the second member  126 . By moving the clamp lever  130  in a first direction, the first member  124  is moved away from the second member  126  by overcoming the inward bias force provided of spring  144   a ,  144   b ,  144   c  and  144   d . By moving the clamp lever  130  in a second opposite direction, the first member  124  is moved toward the second member  126 , assisted by the inward bias force provided of spring  144   a ,  144   b ,  144   c  and  144   d.    
     During operation, the clamp lever  130  may be moved in the first direction to move the first member  124  away from the second member  126 , leaving a space therebetween. A removable media member, such as a removable fluidic cartridge  150 , may then be slid into the space. The removable cartridge  150  may have a front side, a back side, and one or more lateral sides extending between the front side and the back side, as shown. The clamp lever  130  may then be moved in the second direction to move the first member  124  toward the second member  136  to secure and/or engage the removable media member  150 , as shown in FIG.  5 .  FIG. 6  is a perspective side view of the illustrative portable cytometer of FIG.  5 . 
     In one illustrative embodiment, the removable media member  150  has one or more fluid ports in the front and/or back sides, similar to that described above with respect to  FIGS. 1-4 . It is contemplated that the one or more fluid ports may be adapted to accept either a gas or a liquid, depending on the application. The second member  126  of the illustrative embodiment includes corresponding fluid ports that align with the one or more fluid ports of the removable media member  150 . One such fluid port is shown at  160  in  FIG. 6. A  fluid port gasket (see  FIG. 12  below) may be secured to the second member  126  to help provide a better seal, if desired. 
     A fluid control module may then be fluidly coupled to the fluid ports of the second member  126 . In the illustrative embodiment, the fluid control module includes the air accumulator module  136 , the valve module assembly  134  with polymer microvalves, and the air buffer module  132 . The air accumulator module  136  includes an internal chamber for accumulating an pressure. A port (not shown) may be provided from the internal chamber of the air accumulator  136  to an air pressure source. The accumulated air pressure may be supplied to the valve module assembly  134 . The valve module assembly may include one or more microvalves, such as polymer microvalves as disclosed in U.S. patent application Ser. No. 10/174.851, entitled “ELECTROSTATICALLY ACTUATED VALVE”, which is incorporated herein by reference. In the illustrative embodiment, the valve module assembly  134  may provide three separate pressure channels including a blood channel, a lyse channel and a sheath channel, as shown and described above with respect to  FIGS. 1-4 . The valve module assembly  134  is preferably controlled by a controller in base  122  to provide three separate controlled pressures to air buffer module  132 . Air buffer module  132  buffers the controlled pressures, and delivers the pressurized air to the fluid ports of the removable media member  150  via the fluid ports that pass in or through the second member  126 . 
     In some cases, the removable media member  150  may include one or more electrical and/or optical devices. For example, and in the illustrative embodiment, the removable media member  150  may include three flow sensors, with each flow sensor measuring the flow rate of the pressurized fluid through one of the three separate pressure channels of the removable media member  150 . Like above, the flow sensors are preferably thermal anemometer type flow sensors, and more preferably microbridge or microbrick type flow sensor, commercially available from Honeywell International. Microbridge flow sensors are described in, for example, U.S. Pat. No. 4,478,076, U.S. Pat. No. 4,478,077, U.S. Pat. No. 4,501,144, U.S. Pat. No. 4,651,564, U.S. Pat. No. 4,683,159, and U.S. Pat. No. 5,050,429, all of which are incorporated herein by reference. An output signal from each flow sensor is provided to controller or processor in base  122 , preferably via an electrical, optical and/or wireless coupling between the removable media member and the second member  126 . 
     The optical assembly module  140  preferably includes one or more light sources (e.g. VCSELs) on one side of the removable cartridge  150 , one or more light detectors on the opposite side of the removable cartridge  150 , and associated optics. When so provided, the removable cartridge  150  may include a transparent flow stream window, which is in alignment with the one or more light sources and one or more light detectors. The air buffer module  132 , valve module assembly  134 , and air accumulator module  136  are preferably controlled to form a core stream down a flow stream path that passes the flow stream window in the removable cartridge  150 . The light sources, when activated, provide light through the core stream via one side of the flow stream window. The optical detectors receive scattered and non-scattered light from the core stream via the opposite side of the flow stream window. A controller or processor in the base  122  then receives output signals from the detectors, and differentiates and counts selected white blood cells that are present in the core stream. 
       FIG. 7  is another perspective view of the illustrative portable cytometer of  FIG. 5 , further illustrating additional detail.  FIG. 7  shows a hole  170  through the first member  124  and second member  126 . The hole  170  may allow the one or more light sources and one or more light detectors of the optical assembly module  140  to directly access the flow stream window of the removable cartridge (not shown in FIG.  7 ). 
       FIG. 7  also shows one or more spring biased probes secured to the first member  124 . The one or more spring biased probes are preferably positioned to align with the one or more electrical contact pads on the removable cartridge when the removable cartridge is at a desired positioned between the first member  124  and the second member  126 . In the illustrative embodiment, three arrays of spring biased probes  174   a ,  174   b  and  174   c  are provided, with each array mounted via a small PC board and secured within a corresponding hole in the first member  124 . The holes in the first member  124  may provide access to the reverse side of the spring bias probes, which in some embodiments, may provide a convenient location to make an electrical connection between a controller in the base  122  and each spring bias probe. 
     In addition, or alternatively, it is contemplated that one or more optical transmitters and/or optical detectors may be secured to the first and/or second member. The one or more optical transmitters and/or optical detectors are preferably positioned to align with the one or more optical detectors and/or optical transmitters on the removable cartridge when the removable cartridge is at a desired positioned between the first member  124  and the second member  126 . This may provide an optical link between the removable cartridge and the first member and/or second member  126 , as desired. 
       FIG. 8  is a perspective view of the first member  124  of the illustrative portable cytometer of FIG.  5 .  FIG. 8  shows the opposite side of the three arrays of spring biased probes  174   a ,  174   b  and  174   c  of FIG.  7 . As can be seen, each spring bias probes is biased by a spring in an outward direction away from the first member  124  and toward the removable cartridge (not shown in FIG.  8 ). The spring biased probes are preferably positioned to align with the one or more electrical contact pads on the removable cartridge when the removable cartridge is at a desired positioned between the first member  124  and the second member  126 . When the first member  124  and the second member  126  are moved toward one another to secure and/or engage the removable cartridge, the spring biased probes preferably make electrical contact with the one or more electrical contact pads on the removable cartridge. 
     To help separate the spring biased probes from the one or more electrical contact pads on the removable cartridge when the first member  124  is moved away from the second member  126 , an outward or separating bias  178  may be provided between the first member  124  and the removable cartridge. Referring momentarily to  FIG. 11 , the outward bias  178  may include a wedge  180  and a spring  182 . The spring  182  may be positioned in a recess  184  in the first member  124 , with the wedge  180  biased in an outward direction by the spring  182 . 
     Referring back to  FIG. 8 , the outward bias  178  may be overcome when the first member  124  and the second member  126  are moved toward each other to secure and/or engage the removable cartridge. However, when the first member  124  and the second member  126  are moved away from each other to release the removable cartridge, the outward bias  178  may separate the one or more spring biased probes  174   a ,  174   b  and  174   c  from the one or more electrical contact pads of the removable cartridge, which may make the removal of the removable cartridge from between the first member  124  and the second member  126  easier and may help protect the spring bias probes from damage during the removal process. 
     The first member  124  may also have one or more L-shaped cleats that provide a slot to receive the removable cartridge. In the illustrative embodiment of  FIG. 8 , an upper L-shaped cleat  190  and a lower L-shaped cleat  192  are provided. The L-shaped cleats  190  and  192  may each include, for example, a first leg  194  that extends away from the first member  124  and toward the second member, and a second leg  196  that extends from a distal end of the first leg  194  and in a perpendicular direction relative to the first leg  194  so that a channel or receiving slot  198  is formed. The channel or receiving slot  198  may then receive one side of the removable media member. In the illustrative embodiment, the upper L-shaped cleat  190  includes a second leg  196  that extends in a downward direction, and the lower L-shaped cleat  192  includes a second leg that extends in an upward direction. In addition, the upper L-shaped cleat  190  and the lower L-shaped cleat  192  are spaced so that two spaced channels  196  are provided for receiving opposing sides (e.g. upper side and lower side) of the removable cartridge. That is, the channel or slot of the upper L-shaped cleat  190  and the channel or slot of the lower L-shaped cleat  192  are arranged so that the removable cartridge slides into both channels when it is inserted between the first member  124  and the second member  126 . In the illustrative embodiment, the two L-shaped cleats are secured to the first member  124 . 
     An alignment pin  200  may be provided toward the back of the first member  124  to engage the back of the removable cartridge. The alignment pin  200  is preferably positioned to stop the removable cartridge at or near the desired insertion position between the first member  124  and the second member  126 . 
     During use, the first member  124  and the second member  126  may be moved away from one another, and the removable cartridge may be slid into the channel or receiving slots  198  provided by the L-shaped cleats  190  and  192  until the removable cartridge engages the alignment pin  200 . The L-shaped cleats  190  and  192  are preferably positioned so that that when the removable cartridge is received by the L-shaped cleats  190  and  192 , the removable cartridge is at least roughly aligned with a desired position relative to the first member  124  and/or second member  126 . The first member  124  and the second member  126  may then be moved toward one another to engage and/or secure the removable cartridge therebetween. 
     To remove the removable cartridge, the first member  124  and the second member  126  may be moved away from each other. Because the upper and lower edges of the removable cartridge are positioned in the channel or slot  198  of the L-shaped cleats  190  and  192 , the removable cartridge is pulled away from the second member  126  by the second legs  196  of the L-shaped cleats  190  and  192  as the first member  124  and second member  126  are moved away from each other. 
     To provide better alignment between the removable media member and the first member  124  and/or the second members  126 , the second member  126  may include one or more alignment pins  200   a - 200   c  that extend toward the first member (see FIG.  12 ). The removable media member  150  may then include one or more receiving holes for receiving the one or more alignment pins  200   a - 200   c . The alignment pins  200   a - 200   c  and receiving holes may provide improved alignment between the removable media member  150  and the first member  124  and/or second member  126  when the removable media member  150  is secured between the first member  124  and the second member  126 . 
     Preferably, the L-shaped cleats  190  and  192  may be used to pull the removable media member  150  away from the second member  126 , thereby separating the one or more receiving holes of the removable media member  150  from the one or more alignment pins  200   a - 200   c  that are extending from the second member  126 . With the one or more receiving holes separated from the alignment pins  200   a - 200   c , the removable media member  150  then may be more easily removed from between the first member  124  and the second member  126 . 
       FIG. 9  is a perspective view of the lower cleat  192  of FIG.  8 . The illustrative lower cleat  192  includes a first leg  194   a  and a second leg  196   a , wherein the second leg  196   a  extends from a distal end of the first leg  194   a  and in a perpendicular direction to form a channel or receiving slot  198   a . A mounting leg  202   a  may extend from the first leg  194  as shown, for mounting the lower cleat  192  to the first member  124 . 
       FIG. 10  is a perspective view of the upper cleat  190  of FIG.  8 . The illustrative upper cleat  190  includes a first leg  194   b  and a second leg  196   b , wherein the second leg  196   b  extends from a distal end of the first leg  194   b  and in a perpendicular direction to form a channel or receiving slot  198   b . A mounting leg  202   b  may extend from the first leg  194   b  as shown, for mounting the upper cleat  190  to the first member  124 . 
       FIG. 12  is a perspective view of the second plate or member  126  of the illustrative portable cytometer of FIG.  5 . The second member  126  may be fixed to the base  122  by screws that are threaded into screw holes  210   a  and  210   b . As detailed above, the second member  126  may further include a hole  170  that may allow the one or more light sources and one or more light detectors of the optical assembly module  140  to directly access the flow stream window of the removable cartridge. 
     In the illustrative embodiment, the second member  126  includes a flat major surface with a recessed portion for receiving the removable cartridge. To provide better alignment between the removable cartridge and the first member  124  and/or the second members  126 , the second member  126  may include one or more alignment pins  200   a - 200   c  that extend toward the first member. The removable cartridge  150  may then include one or more receiving holes for receiving the one or more alignment pins  200   a - 200   c . The alignment pins  200   a - 200   c  and receiving holes may provide improved alignment between the removable cartridge and the first member  124  and/or second member  126  when the removable cartridge is secured between the first member  124  and the second member  126 . 
     Additional recesses  212  and  214  may be included to receive the second legs  196   a  and  196   b  of the upper L-shaped cleat  190  and lower L-shaped cleat  192 , respectively (see FIGS.  8 - 10 ). By providing relief for the second legs  196   a  and  196   b  of the upper L-shaped cleat  190  and lower L-shaped cleat  192 , the removable cartridge may directly engage the surface of the second member  126 . 
     In some cases, the manufacture of the removable cartridge may create a ridge, a burr, or other imperfections, particularly around the outer perimeter of the removable cartridge. In one example, a fluidic cartridge may be manufactured by laminating several layers or sheets together, and then cutting individual fluidic cartridges from the laminated structure. At the cut lines, ridges, burrs, and/or other imperfections may arise. To help the removable cartridge seat flush with the surface of second member  126 , a groove  216  or other relief structure may be provided in the receiving surface of the second member  126  to accommodate the one or more imperfections in the removable cartridge. In the illustrative embodiment of  FIG. 12 , a groove  216  may extend along a groove path that extends around the perimeter of the removable cartridge. It is contemplated, however, that a groove or other relief structure may be provided at any location where an anticipated imperfection might occur in the removable cartridge. It is also contemplated that a groove or other relief structure may be provided in the receiving surface of the first member  124 , if desired. 
     In one illustrative embodiment, the removable cartridge has one or more fluid ports, similar to that described above with respect to  FIGS. 1-4 . It is contemplated that the one or more fluid ports may be adapted to accept either a gas or a liquid, depending on the application. The second member  126  of the illustrative embodiment includes corresponding fluid ports  220   a - 220   c  that align with the one or more fluid ports of the removable cartridge. A fluid port gasket  222  may be secured to the second member  126  to help provide a better seal, if desired. 
     Having thus described the preferred embodiments of the present invention, those of skill in the art will readily appreciate that the teachings found herein may be applied to yet other embodiments within the scope of the claims hereto attached.