fig1 is a perspective view of an illustrative miniaturized portable cytometer in accordance with the present invention . the cytometer is generally shown at 10 , and includes a housing 12 and a removable or replaceable cartridge 14 . 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 light sources 22 a and 22 b , 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 light detectors 24 a and 24 b with associated optics . the removable 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 preferably performs 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 technologies , some of which are fabricated using a laminated structure with etched channels . the removable structure or 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 transparent flow stream windows 30 a and 30 b , which are in alignment with the arrays of the light sources 22 a and 22 b , and light detectors 24 a and 24 b . 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 a and 22 b , light detectors 24 a and 24 b and associated control and processing electronics perform differentiation and counting of white blood cells based on light scattering fluorescent signals . 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 . fig2 is a schematic view of the illustrative cytometer of fig1 . as above , the base 16 may include light sources 22 a and 22 b , 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 light detectors 24 a and 24 b 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 the present device . once formed , the core is provided down a flow stream path 50 , which passes the flow stream windows 30 a and 30 b of fig1 . the light sources 22 a and 22 b , and associated optics in the base provide light through and to the core stream via the flow stream windows 30 a and 30 b . the light detectors 24 a and 24 b , and associated optics receive scattered and non - scattered light from the core , also via the flow stream windows 30 a and 30 b , respectively . the controller or processor 40 receives output signals from the detectors 24 a and 24 b , and differentiates , identifies 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 control the velocity of each of the fluids . in the illustrative example , the fluid control block 48 includes flow sensors for sensing the velocity of the various fluids and reports 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 . because blood and other biological waste can spread disease , the removable cartridge 14 preferably has a waste reservoir 52 downstream of the flow stream windows 30 a and 30 b . 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 . fig3 is a more detailed schematic diagram showing the cytometer of fig2 with the cover 18 not yet depressed . fig4 is a more detailed schematic diagram showing the cytometer of fig2 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 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 example , 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 . 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 is sucked 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 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 , 050429 , 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 . 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 valves 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 illustrative example of the invention , downstream valves 110 are opened by mechanical action when the cover is closed . fig5 is a schematic diagram showing an illustrative manual fluid driver having a bulb 100 and check valve 102 . the check valve 102 is preferably a one way valve that allows air in but not out of the first pressure chamber 104 . when the bulb 100 is depressed , the air in the interior 106 of the bulb 100 is forced through the check valve 102 and into the first pressure chamber 104 . preferably , another one - way vent valve 105 is provided that allows air in from the atmosphere but not out of the interior 106 of the bulb 100 . thus , when the bulb is released , the one - way vent valve 105 may allow replacement air to flow into bulb 100 . rather than using a manually operated fluid driver , it is contemplated that any relatively small pressure source may be used including , for example , an electrostatically actuated meso - pump . one such meso - pump is described in , for example , u . s . pat . no . 5 , 836 , 750 to cabuz , which is incorporated herein by reference . fig6 is a graph showing proportional pressure control produced by an 8 × 7 addressable array of microvalves . to create the graph shown in fig6 , 6 . 5 psi was applied to a first pressure chamber 120 . a small opening was provided to a second pressure chamber 122 . the microvalves are shown at 124 , and vent the pressure in the second pressure chamber 122 . by changing the number of addressable microvalves that are closed , the pressure in the second pressure chamber can be changed and controlled . in the graph shown , the pressure in the second pressure chamber 122 could be changed from about 0 . 6 psi , when zero of the 8 × 7 array of microvalves close , to about 6 . 5 psi , when all of the 8 × 7 array of microvalves are closed . these low power , micromachined silicon microvalves can be used for controlling pressures up to 10 psi and beyond . fig7 is a schematic diagram showing the formation of a flow stream and core by the hydrodynamic focusing block 88 of fig3 . the hydrodynamic focusing block 88 receives blood , lyse and sheath at controlled velocities from the fluid driver . the blood is mixed with the lyse , causing the red blood cells to be removed . the lysing solution may have a ph lower than that of the red blood cells . this is often referred to as red cell lysing or lyse - on - the - fly . the remaining white blood cells are provided down a central lumen 150 , which is surrounded by sheath fluid to produce a flow stream 50 . the flow stream 50 includes a core stream 160 surrounded by the sheath fluid 152 . the dimensions of the channel are reduced as shown so that the white blood cells 154 and 156 are in single file . the velocity of the sheath fluid is preferably about 9 times that of the core stream 160 . however , the velocity of the sheath fluid and core stream 160 remain sufficiently low to maintain laminar flow in the flow channel . light emitters 22 a and 22 b , and associated optics are preferably provided adjacent one side of the flow stream 50 . light detectors 24 a and 24 b , and associated optics are provided on another side of the flow stream 50 for receiving the light from the light emitters 22 a and light from fluorescing particles via the flow stream 50 . the output signals from the light detectors 24 a and 24 b are provided to controller or processor 40 , wherein they are analyzed to identify and / or count selected white blood cells in the core stream 160 . fig8 is a schematic diagram showing an array 22 a of light sources and an array 24 b of light detectors for analysis of the core stream 160 via scattering of fig7 . the light sources are shown as “+” signs and the detectors are shown at boxes . in the example shown , the array of light sources is provided adjacent one side of the flow stream 50 , and the array of light detectors is provided adjacent the opposite side of the flow stream . each of the light detectors is preferably aligned with a corresponding one of the light sources . the array of light sources and the array of light detectors are shown arranged along a light source axis 200 that is slightly rotated relative to the axis 202 of the flow stream 50 . the array 22 a of light sources is preferably an array of lasers such as vertical cavity surface emitting lasers ( vcsels ) fabricated on a common substrate . because of their vertical emission , vcsels are ideally suited for packaging in compact instruments such as a miniaturized portable cytometer . such cytometer may be wearable on a person &# 39 ; s body . preferably , the vcsels are “ red ” vcsels that operate at wavelengths that are less than the conventional 850 nm , and more preferably in the 670 nm to 780 nm range . red vcsels may have a wavelength , power and polarization characteristic that is ideally suited for scatter measurements . some prior art cytometer bench models use a single 9 mw edge - emitting laser with a wavelength of 650 nm . the beam is focussed to a 10 × 100 micron elongated shape to cover the uncertainty in particle position due to misalignment and width of the core stream . in contrast , the output power of the red vcsels of the present invention , operating at 670 nm , is typically around 1 mw for a 10 × 10 micron emitter and 100 - micron spacing . thus , the total intensity of the light from a linear array of ten red vcsels may be essentially the same as that of some prior art bench models . using a linear array of lasers oriented at an angle with respect to the flow axis 202 offers a number of important advantages over the single light source configuration of the prior art . for example , a linear array of lasers may be used to determining the lateral alignment of the path of the particles in the core steam . one source of uncertainty in the alignment of the particle stream is the width of the core flow , which leads to statistical fluctuations in the particle path position . these fluctuations can be determined from analysis of the detector data and can be used by the controller or processor 40 to adjust the valves of the fluid driver in order to change the relative pressures that are applied to the sample fluid and the supporting fluids to change the alignment of the selected particles in the flow stream . to determine the lateral alignment of the cells in the fluid stream 50 , the cells pass through several focussed spots produced by the linear array of vcsels . the cells produce a drop in signal in the corresponding in - line reference detectors . the relative strengths of the signals are used by the controller or processor 40 to determine the center of the particle path and a measure of the particle width . for determining particle path and size , the lasers 22 a are preferably focussed to a series of gaussian spots 214 ( intensity on the order of 1000 w / cm 2 ) in the plane of the core flow . the spots 214 are preferably about the same size as a white blood cell ( 10 - 12 um ). illustrative gaussian spots 214 are shown in fig9 . arrays 24 a of detectors and their focussing optics are provided on the opposite side of the fluid stream 50 . lenses with fairly large f - numbers are used to provide a working space of several hundred microns for the cytometer section of the removable cartridge . another advantage of using a linear array 22 a of lasers rather than a single laser configuration is that the velocity of each cell may be determined . particle velocity can be an important parameter in estimating the particle size from light scatter signals . in conventional cytometry , the particle velocity is extrapolated from the pump flow rates . a limitation of this approach is that the pumps must be very precise , the tolerance of the cytometer flow chambers must be tightly controlled , no fluid failures such as leaks can occur , and no obstructions such as microbubbles can be introduced to disturb the flow or core formation . to determine the velocity of each cell , the system may measure the time required for each cell to pass between two adjacent or successive spots . for example , and with reference to fig8 , a cell may pass detector 208 and then detector 210 . by measuring the time required for the cell to travel from detector 208 to detector 210 , and by knowing the distance from detector 208 to detector 210 , the controller or processor 40 can calculate the velocity of the cell . this would be an approximate velocity measurement . this is often referred to as a time - of - flight measurement . once the velocity is known , the time of travel through the spot on which the particle is centered ( a few microseconds ) may provide a measure of particle length and size . it is contemplated that the particle velocity can also be used to help control the fluid driver . to reduce the size , cost and complexity of the present invention , the replaceable cartridge of fig1 may be manufactured from a plastic laminate or molded parts . while such manufacturing techniques may provide inexpensive parts , they are typically less dimensionally precise and repeatable , with asymmetrical dimensions and wider tolerance cross - sections . these wider tolerances may produce variations in particle velocity , particularly from cartridge to cartridge . to help compensate for these wider tolerances , the time - of - flight measurement discussed above can be used by the controller or processor 40 to adjust the controlled pressures applied to the blood , lyse and sheath fluid streams such that the particles in the core stream have a relatively constant velocity . to further evaluate the cell size , it is contemplated that laser beams may be focused both along the cell path and across the cell path . additionally , multiple samples across the cell may be analyzed for texture features , to correlate morphological features to other cell types . this may provide multiple parameters about cell size that may help separate cell types from one another . another advantage of using a linear array 22 a of lasers rather than a single layer configuration is that a relatively constant light illumination may be provided across the flow channel . this is accomplished by overlapping the gaussian beams 214 from adjacent vcsels 22 a , as shown in fig9 . in prior art single laser systems , the light illumination across the flow channel typically varies across the channel . thus , if a particle is not in the center of the flow channel , the accuracy of subsequent measurements may be diminished . to perform the above described measurements , each detector 24 a in fig8 may be a single in - line detector . to measure fals and sals scatter , however , each detector 24 a may further include two annular detectors disposed around the in - line detector , as shown in fig1 . referring to fig1 , a vcsel 218 is shown providing light in an upward direction . the light is provided through a lens 220 , which focuses the light to a gaussian spot in the plane of the core flow . lens 220 may be a microlens or the like , which is either separate from or integrated with the vcsel 218 . the light passes through the core flow , and is received by another lens 222 , such as a diffractive optical element . lens 222 provides the light to in - line detector 226 and annular detectors 228 and 230 . the in - line detector 226 detects the light that is not significantly scattered by the particles in the core stream . annular detector 228 detects the forward scatter ( fals ) light , and annular detector 230 detects the small angle scatter ( sals ) light . fig1 shows another illustrative example of the present invention that includes three separate arrays of light sources and light detectors . each array of light sources and light detectors are positioned along a different light source axis that is slightly rotated relative to the central flow axis of the flow stream . by using three arrays , the optics associated with each array may be optimized for a particular application or function . for detecting small angle scattering ( sals ), laser light that is well - focussed on the plane of the core flow is desirable . for detecting forward scattering ( fals ), collimated light is desirable . referring specifically to fig1 , a first array of light sources and light detectors is shown at 300 . the light sources and light detectors are arranged in a linear array along a first light source axis . the first light source axis is rotated relative to the flow axis of the flow stream . the light sources and light detectors may be similar to that described above with respect to fig8 , and preferably are used to measure , for example , the lateral alignment of the cells in the flow stream , the particle size , and the velocity of the particles . fig1 is a schematic diagram showing an illustrative light source and detector pair of the first array 300 shown in fig1 . a vcsel 302 is shown providing light in an upward direction . the light is provided through a lens 304 , which focuses the light to a gaussian spot in the plane of the core flow . the light passes through the core flow , and is received by another lens 306 . lens 306 provides the light to in - line detector 308 . the in - line detector 308 detects the light that is not significantly scattered by the particles in the core stream . a second array of light sources and light detectors is shown at 310 . the light sources are arranged in a linear array along a second light source axis that is rotated relative to the flow axis of the flow stream . the light detectors include three linear arrays of light detectors . one array of light detectors is positioned in line with the linear array of light sources . the other two linear arrays of light detectors are placed on either side of the in - line array of light detectors , and are used for measuring the small angle scattering ( sals ) produced by selected particles in the flow stream . fig1 is a schematic diagram showing an illustrative light source and corresponding detectors of the second array shown in fig1 . a vcsel 320 is shown providing light in an upward direction . the light is provided through a lens 322 , which focuses the light to a gaussian spot in the plane of the core flow . the light passes through the core flow , and is received by another lens 324 , such as a diffractive optical element ( doe ) 324 . lens 324 provides the light to the in - line detector 326 and the two corresponding light detectors 328 and 330 placed on either side of the in - line light detector 326 . the in - line detector 326 may be used to detect the light that is not significantly scattered by the particles in the core stream . thus , the in - line linear array of light detectors of the second array 302 may be used to provide the same measurements as the in - line array of detectors of the first array 300 . the measurements of both in - line arrays of detectors may be compared or combined to provide a more accurate result . alternatively , or in addition , the in - line detectors of the second array 302 may be used as a redundant set of detectors to improve the reliability of the cytometer . it is contemplated that the in - line detectors of the second array 302 may also be used in conjunction with the in - line detectors of the first array 300 to more accurately determine the time - of - flight or velocity of the particles in the flow stream . the measurement may be more accurate because the distance between detectors may be greater . as indicated above , by knowing the velocity of the particles , small variations in the flow rate caused by the fluid driver can be minimized or removed by the controller . light detectors 328 and 330 of fig1 are used to measure the small angle scattering ( sals ) produced by selected particles in the flow stream . the light detectors 328 and 330 are therefore preferably spaced sufficiently from the in - line detector 326 to intercept the small angle scattering ( sals ) produced by selected particles in the flow stream . referring back to fig1 , a third array of light sources and light detectors 350 is preferably provided to measure the forward angle scattering ( fals ) produced by selected particles in the flow stream . the light sources are arranged in a linear array along a third light source axis that is rotated relative to the flow axis of the flow stream . each light source preferably has a corresponding light detector , and each light detector is preferably annular shaped with a non - sensitive region or a separate in - line detector in the middle . the annular shaped light detectors are preferably sized to intercept and detect the forward angle scattering ( fals ) produced by selected particles in the flow stream . fig1 is a schematic diagram showing an illustrative light source and detector pair of the third array of light sources and light detectors 350 shown in fig1 . a vcsel 360 is shown providing light in an upward direction . the light is provided through a lens 362 such as a collimating lens , which provides substantially collimated light to the core flow . as indicated above , collimated light is desirable for detecting forward scattering ( fals ) light . the light passes through the core flow , and is received by another lens 364 . lens 364 provides the received light to the annular shaped detector 368 . the annular shaped detector 368 is preferably sized to intercept and detect the forward angle scattering ( fals ) produced by selected particles in the flow stream . a non - sensitive region or a separate in - line detector 370 may be provided in the middle of the annular shaped detector 368 . if a separate in - line detector 370 is provided , it can be used to provide the same measurement as the in - line detectors of the first array 300 and / or second array 302 . when so provided , the measurements from all three in - line arrays of detectors of first array 300 , second array 302 and third array 350 may be compared or combined to provide an even more accurate result . the in - line detectors of the third array 302 may also be used as another level or redundancy to improve the reliability of the cytometer . it is contemplated that the in - line detectors of the third array 350 may also be used in conjunction with the in - line detectors if the first array 300 and / or second array 302 to more accurately determine the time - of - flight or velocity of the particles in the flow stream . the measurement may be more accurate because the distance between detectors may be greater . as indicated above , by knowing the velocity of the particles , small variations in the flow rate caused by the fluid driver can be minimized or removed by the controller . by using three separate arrays of light sources and detectors , the optics associated with each array can be optimized for the desired application . as can be seen , the optics associated with the first array 300 are designed to provide well - focussed laser light on the plane of the core flow . this helps provide resolution to the alignment , size and particle velocity measurements performed by the first array 300 . likewise , the optics associated with the second array 302 are designed to provide well - focussed laser light on the plane of the core flow . well focussed light is desirable when measuring the small angle scattering ( sals ) produced by selected particles in the flow stream . finally , the optics associated with the third array 350 are designed to provide collimated light to the core flow . as indicated above , collimated light is desirable when measuring forward angle scattering ( fals ) produced by selected particles in the flow stream . fig1 is a perspective view of an illustrative example of the miniaturized portable cytometer of the present invention adapted to be worn around the wrist . this cytometer 400 may be similar to that shown in fig1 . a band 402 secures cytometer 400 to the wrist of a user . as indicated above , the user may obtain a removable cartridge and provide a blood sample to the sample collector port 32 ( see fig1 ) of the removable cartridge . the blood sample may be collected by , for example , a finger prick . the user may then insert the removable cartridge into the housing , and manually pressurize the system . the miniaturized portable cytometer may then provide a reading that indicates if the user should seek medical treatment . the reading may be a visual reading , an audible sound or any other suitable indicator . rather than obtaining the blood sample by a finger prick or the like , it is contemplated that a catheter 404 or the like may be inserted into a vein of the user and attached to the sample collector port 32 . this may allow the system to automatically collect a blood sample from the user whenever a reading is desired . alternatively , it is contemplated that the miniaturized portable cytometer may be implanted in the user , with the sample collector port 32 connected to a suitable blood supply . fig1 shows a cytometer cartridge 500 showing a scattering optical subsystem 501 and fluorescent optical subsystem 502 . optical subsystem 501 includes windows or openings 30 a on each side of flow channel 530 and optical subsystem 502 includes windows or openings 30 b . in each subsystem , there is a window or opening on each side of flow channel 530 . the openings may have optical inserts or lenses . this cytometer may be implemented for wearing , attachment on , or insertion in a person &# 39 ; s body fig1 shows systems 503 and 504 which incorporate optical subsystems 501 and 502 , respectively . system 503 also includes vcsel array 22 a and detector array 24 a for scattering measurements of particles , such as white blood cells , in core stream 160 . this system is may be used for the counting and classification of lymphocytes and neutrophils . self - alignment is may be enabled by a red vcsel - array based optical subsystem . illustrative examples of scattering system 503 are described above . system 504 is a fluorescent exciting and detection mechanism which may be used for identifying and counting specific subclasses of white blood cells and blood - based proteins . the detection of subclasses of white blood cells is enabled by the availability of suitable antibodies , many of which are commercially available in a fluorescently conjugated form . fig1 shows an outline sketch of blood composition and the cells that may be subject to counting and identification by fluorescent system 504 . the red blood cells are removed form the sample to be looked with the cytometer by lysing as noted above . the platelets are kept as the small size does not affect the results of the cytometer when checking the white blood cells . for an illustrative example , the cd4 - positive t - cells 505 , shown in the structure of fig1 have proportions and counts in blood that may be very important in following a clinical course of an hiv infection . an antibody with a marker added that associates with cd4 may be mixed in the sample of blood to get a resultant “ y ”- looking structure of the antibody ( ab ) 506 and its marker ( m ) 507 , attached to cd4 cell 505 , as shown in fig1 a . light source 22 b may emit light which may be absorbed by marker 507 . in response , marker 507 fluoresces and emits light of a particular wavelength which may be detected to identify cd4 cell 505 . checking blood for anthrax may be another application of the present cytometer . antibodies 508 for the anthrax - causing bacteria 509 may be mixed with the blood sample . the antibodies may associate with bacteria 509 . the antibodies may have markers 510 that fluoresce upon impingement of light . the “ y ” structure of antibody 508 is shown in fig1 b . markers 510 emit a light of a particular bandwidth which may be different from the bandwidth of marker 507 of antibody 506 for cd4 cell 505 . so the anthrax problem may be identified separately from the hiv problem in the same blood sample test by the fluorescent emissions having different wavelengths , colors or signatures . the number of different problems being detected at the same time in the same blood sample may be many more than two . for another illustrative example , neupogen r ( a type of protein ) has been regarded as used to provide neutrophil counts in cancer patients undergoing myelosuppressive chemotherapy . while doing this therapy , there may a need to accurately monitor the white blood cell counts ( specifically neutrophils , monocytes and platelet counts during the neupogen r therapy period ). the present cytometer may be used by untrained personnel to monitor such chemotherapy patients in their homes . the present miniaturized portable cytometer may be use in biowarfare . it may be used for quantitative detection and identification of biowarfare agents . this detection and identification may be based antibody - antigen type immunoassay that may be implemented with fluorescent measurements . the environment , water and food may be monitored for any possible presence of biological agents . it would involve sample collection and preparation appropriated for the present cytometer . other applications of the cytometer may include high throughput analysis ( using the fluorescent detection features ) and sequencing of dna and rna , studying the response of cell to potential drugs , immunophenotyping of leukemia and lymphomas and monitoring residual disease in cancer patients , and cell sorting and cell isolation , including high - speed separation of rare event populations . note that the above - mentioned applications , and other applications and uses may be accomplished with the single , portable , miniaturized , integrated scattering and multi - color fluorescent , low - power , low - cost cytometry instrument having a compact precision fluid driving system , not requiring operator intervention or adjustment during the analytical phase , not requiring trained personnel to operate the instrument , and using sanitary , disposable plastic - or other material - based microfluidic cartridges 14 having integrated optics and internal blood sample processing , among other features . system 504 of fig1 has a laser light source 22 b positioned to direct light 511 at particles 512 flowing single file through flow channel 530 . for illustrative purposes , particles 512 may include structures 513 and 514 of fig1 a and 19 b , respectively . light 511 may be from a red or a blue laser source , such as a light emitting diode ( led ), which may have a bandwidth of , for example , 650 to 700 nanometers or 380 to 420 nanometers , respectively . other types of sources having appropriate wavelengths may be used for light 511 . as light 511 impinges fluorescent markers 507 and 510 , these markers fluoresce and emit light 515 and 516 , respectively . since the markers are different from each other , light 515 and light 516 have different wavelengths . thus , structures 513 and 514 not only may be identifiable by the wavelengths of their emitted light but can be differentiated form each other in the same sample , blood or otherwise . light 515 and 516 may go to a dichroic beam splitter 517 which separates the two beams by directing each of them in different directions . beam 516 may go to a fluorescence photo detector 518 for detection and conversion of light 516 into an electrical signal 520 to processor 40 . beam 515 may go to a fluorescence photo detector 521 for detection and conversion of light 515 into an electrical signal 522 to processor 40 . band pass filter 519 , which is in the path of beam 516 , may filter out light 511 from light source 22 b that managed to be present in beam 516 . band pass filter 523 may serve the same purpose for beam 515 as filter 519 for beam 515 . a mirror 524 may be used to redirect beam 515 for purposes of detector 521 location for the possibility of more compact packaging of detection system 504 or for other reasons . mirror 524 may on the other hand be another dichroic beam splitter for splitting out light 525 of a wavelength different from that of beams 515 and 516 . more splitters might be used in a cascade - like or other structure to split out light of still other frequencies . also going to processor 40 is a signal from detector array 24 a of scattering detection system 503 . splitter 517 may be replaced with other mechanisms for separating out the light of various wavelengths or selecting certain wavelengths . they may include notch and step function filters of various kinds , tunable diffraction gratings , thin film dielectric stacks , mirror beam splitters , photonic bandgap filters , photonic crystals , tunable band pass filters , etalon comb and other structures , wafers having light guides with structural or other filtering , silicon or glass wafers having a waveguide and perforations of a specific size and pitch for absorbing / filtering , and so on . fig2 shows the structure of the fluorescence optical subsystem 502 . a beam 511 may be emitted by light source 22 b and focused onto a particle 512 by a microlens 526 through window 30 b . light beam 511 may or may not be collimated . particle 512 may have a marker that fluoresces and emits a light beam 515 , 516 through window 30 b , a thin film coating filter 527 and a microlens 528 , respectively . filter 527 may filter out light 511 from light source 22 b . filter 527 may be a dielectric stack situated under lens 528 and be a notch or step function filter to block source 22 b light 511 . lens 528 may focus fluorescent light emitted from the marker into a beam 515 / 516 which may go on to a beam splitter such as splitter 517 . beam 515 / 516 may or may not be collimated . an opaque or absorptive layer 529 is formed around or before and after window 30 b or lens 528 on a glass , quartz or plastic ( laminated or not ) substrate 531 of flow channel 530 . layer 529 may block any light 511 emanating from light source 22 b from exiting out with fluorescent light 515 / 516 . layer or blocking filter 529 may a thin film that is black or opaque to the wavebands desired to be blocked . filter 529 could be a notch or step function filter . the other glass , quartz or plastic ( laminated or not ) substrate 532 forms flow channel 530 for the core flow of particles 512 . the material of substrates 531 and 532 , windows 30 b and lens 526 and 528 should not contain ingredients that may fluoresce . in one illustrative example , the direction of light 511 from source 22 b may be about 90 degrees relative to the direction of fluorescent light 515 / 516 emitted from particle 512 . this angle between source light 511 and emitted fluorescent light 515 / 516 may effectively reduce or eliminate source light emanating out with fluorescent light 515 / 516 . the angle of the direction of light 511 from source 22 b in the example may be about 45 degrees relative to the direction of the longitudinal dimension flow channel 530 or the direction of the core flow of particles 512 . however , in some applications , the angle between the directions of light 511 and light 515 / 516 may be between 0 and 120 degrees . fig2 a shows an end view of flow channel 530 for scattering optical subsystem 501 and fig2 b shows an end view of flow channel 530 for fluorescence optical subsystem 502 . the thicknesses of substrates 531 and 532 are about 100 to 200 microns . the thicknesses of windows 30 a and 30 b are about 25 to 30 microns . microlenses 526 and 528 may be diffractive or refractive , plastic or glass and be aspheric lenses about 500 microns in diameter . channel 533 may be laser cut . fig2 c , 21 d and 21 e are variations of fig2 a and 21 b . fig2 c shows a flow channel having windows or openings 30 a and 30 b . openings or windows 30 a and 30 b may be one window on each side of the flow channel , respectively . the openings may have optical inserts or lenses in them . micro lenses 526 and 528 or other types of lenses may be formed on , attached to , inserted in , situated on or formed as an integral portion of openings or windows 30 b and 30 a which may be one piece on each side of the channel . fig2 d illustrates windows 30 a and 30 b without micro lenses attached or formed on them , but with lenses 541 and 542 situated at a certain and appropriate distance from them . fig2 e shows a window configuration with both micro lenses 526 and 528 along with detached lenses 541 and 542 , respectively . fig2 shows a diagram of cytometer configuration of fig1 , but with the placement of lenses 541 and 542 . as noted above , windows and openings 30 b may or may not have micro lenses in addition to lenses 541 and 542 . fig2 is a perspective view of an illustrative example of a miniaturized portable cytometer having both scattering and fluorescent detection and monitoring adapted to be worn around the wrist or palm . this cytometer 600 may be similar to that shown in fig1 and 16 . a band 602 secures the miniaturized portable cytometer 600 to the wrist of a user . as indicated above , the user may obtain a removable cartridge and provide a blood sample to the sample collector port 32 ( see fig1 , 17 and 22 ) of the removable cartridge . the blood sample may be collected by , for example , a finger prick . the user may then insert the removable cartridge into the housing , and manually pressurize the system . the miniaturized and portable cytometer may then provide a reading that indicates if the user should seek medical treatment . the reading may be a visual reading , an audible sound or any other suitable indicator . rather than obtaining the blood sample by a finger prick or the like , it is contemplated that a catheter 604 or the like may be inserted into a vein of the user and attached to sample collector port 32 . this may allow the system to automatically collect a blood sample from the user whenever a reading is desired . alternatively , it is contemplated that the miniaturized portable cytometer may be implanted in the user , with sample collector port 32 connected to a suitable blood supply . although the invention has been described with respect to at least one illustrative example , many variations and modifications will become apparent to those skilled in the art upon reading the present specification . it is therefore the intention that the appended claims be interpreted as broadly as possible in view of the prior art to include all such variations and modifications .
an apparatus having scattering and multi - color fluorescence detecting , analyzing and identification capabilities of blood or other fluids of interest . the sample to be tested may be entered in a disposable microfluidic cartridge which in turn is insertable in a hand - holdable or implantable miniaturized and portable cytometer instrument . this cytometer has significant application in biological warfare agent detection , hematology and other clinical and research fields .