Abstract:
A sensor dispensing instrument adapted to handle a sensor pack containing a plurality of sensors and to perform a test using one of the sensors, wherein the sensor dispensing instrument includes an electronics assembly for performing the test and displaying test results. The electronics assembly includes a printed circuit board having electrical components, at least one button, and a liquid crystal display mounted thereon. The electronics assembly is formed and tested prior to assembling the electronics assembly into the outer housing of the sensor dispensing instrument.

Description:
CROSS-REFERENCE TO RELATED APPLICATION  
       [0001]     This application is a divisional application of prior application Ser. No. 10/207,596, entitled “Blood Glucose Sensor Dispensing Instrument Having A Modular Electronics Assembly,” filed Jul. 25, 2002, which claims benefit of priority to Provisional Application Ser. No. 60/311,768, filed on Aug. 13, 2001, each of which is incorporated herein by reference in their entireties. 
     
    
     BACKGROUND OF THE INVENTION  
       [0002]     1. Field of the Invention  
         [0003]     The present invention generally relates to a fluid monitoring system, and, more particularly, to a new and improved instrument for handling multiple sensors that are used in analyzing blood glucose or other analytes contained therein.  
         [0004]     2. Description of the Prior Art  
         [0005]     People suffering from various forms of diabetes routinely need to test their blood to determine the level of blood glucose. The results of such tests can be used to determine what, if any, insulin or other medication needs to be administered. In one type of blood glucose testing system, sensors are used to test a sample of blood.  
         [0006]     Such a sensor may have a generally flat, rectangular shape with a front or testing end and a rear or contact end. The sensor contains biosensing or reagent material that will react with blood glucose. The testing end of the sensor is adapted to be placed into the fluid being tested, for example, blood that has accumulated on a person&#39;s finger after the finger has been pricked. The fluid is drawn into a capillary channel that extends in the sensor from the testing end to the reagent material by capillary action so that a sufficient amount of fluid to be tested is drawn into the sensor. The fluid then chemically reacts with the reagent material in the sensor with the result that an electrical signal indicative of the blood glucose level in the blood being tested is supplied to contact areas located near the rear or contact end of the sensor.  
         [0007]     In order to couple the electrical signals produced at the sensor contacts to monitoring equipment, the sensors need to be inserted into sensor holders prior to the sensor end being placed into the fluid being tested. The holders have corresponding mating contact areas that become coupled to the contacts on the sensor when the sensor is inserted into the holder. Consequently, the holders act as an interface between the sensor and monitoring equipment that accumulates and/or analyzes the test results.  
         [0008]     Prior to being used, the sensors need to be maintained at an appropriate humidity level so as to insure the integrity of the reagent materials in the sensor. Sensors can be packaged individually in tear away packages so that they can be maintained at the proper humidity level. For instance, blister type packaging methods could be used. In this connection, the packages can include desiccant material to maintain the proper humidity in the package. In order for a person to use an individual sensor for testing blood glucose, the package must be opened by tearing the seal. Alternatively, some packages require the user to exert force against one side of the package resulting in the sensor bursting or rupturing the foil on the other side. As can be appreciated, the opening of these packages can be difficult. Moreover, once the package is opened, the user needs to be sure that the sensor is not damaged or contaminated as it is being placed into the sensor holder and used to test the blood sample.  
         [0009]     U.S. Pat. No. 5,630,986, issued on May 20, 1997, and entitled Dispensing Instrument For Fluid Monitoring Sensors (referred to hereinafter as “the &#39; 986  patent”), discloses a type of sensor pack with multiple sensors and a testing blood glucose and dispensing instrument for handling the sensors contained in such a sensor pack. In particular, the sensor dispensing instrument disclosed in the &#39;986 patent is adapted to receive a sensor pack containing a plurality of blood glucose sensors. The sensor pack includes a circular base having a plurality of sensor retaining cavities, each of which hold an individual sensor. Each of the sensors has a generally flat, rectangular shape with a front testing end through which fluid is drawn so as to react with a reagent material in the sensor and an opposite rear, contact end.  
         [0010]     The sensor instrument disclosed in the &#39;986 patent includes an outer housing having an upper and a lower case that are pivotable with respect to each other so that the sensor pack can be positioned in the housing on an indexing disk disposed in the housing. With the sensor pack loaded in the housing, a slide latch on a slide actuator disposed on the upper case of the housing controls whether the movement of the slide actuator places the instrument in a display mode or in a testing mode. The instrument is placed into its display mode when the slide latch is moved laterally and the slide actuator is pushed away from its standby position. When in the display mode, a person using the instrument can view data displayed on a display unit in the upper case and/or input data into the instrument.  
         [0011]     The instrument is in its testing mode when the slide latch is in its normal position and the slide actuator is pushed towards its testing position. As the slide actuator is moved towards its actuated position, the driver with the knife blade thereon moves toward the testing position of the feed mechanism and the disk drive arm travels in a straight, radially extending groove in the indexing disk such that the disk is not rotated as the feeding mechanism is moving towards its testing position. The knife blade is moved towards one of the sensor cavities in the sensor pack and pierces the foil covering the sensor cavity so as to engage the sensor disposed in the cavity. As the slide actuator and the driver are pushed toward the actuated position of the actuator, the knife blade ejects the sensor out from the sensor cavity and into a testing position near the testing end of the sensor housing.  
         [0012]     Once the blood analyzing test is completed, the slide actuator is moved in the opposite direction towards its standby position so that the sensor can be removed from the dispensing instrument. The continued retraction of the driver causes the indexing disk drive arm to travel along a curvilinearly extending groove in the indexing disk, resulting in the rotation of the indexing disk. The rotation of the indexing disk results in the sensor pack being rotated so that the next sensor is positioned in alignment with the knife blade for the next blood glucose test that is to be performed.  
         [0013]     Although the sensor instrument disclosed in the &#39;986 patent overcomes many of the problems discussed above in connection with the use of individual sensors, the sensor instrument is difficult and/or costly to manufacture. In particular, the disclosed sensor instrument includes numerous electronics and electrical components that are individually manufactured and separately assembled to various parts of the sensor instrument. For example, the disclosed sensor instrument includes a liquid crystal display that is electrically connected to a printed circuit board. During the manufacture of the sensor instrument, the liquid crystal display is assembled to the upper case of the housing, and the printed circuit board is assembled to, and is part of, the mechanical mechanism used to rotate the indexing disk. The liquid crystal display is not electrically connected to the printed circuit board until the mechanical mechanism is assembled into the housing, and the manufacture of the sensor instrument is complete. Similarly, the buttons that are used to activate and control the sensor instrument, and which are electrically connected to the printed circuit board, are assembled to the housing prior to the installation of the printed circuit board. In short, the various electronics and electrical components of the sensor instrument are not connected together until the final assembly of the sensor instrument is complete. Consequently, these components and their electrical connections cannot be tested until the sensor instrument has been assembled. If at this time, it is determined that one or more of the electrical components is malfunctioning, then the sensor instrument must either be disassembled to replace or repair the malfunctioning component, or the sensor instrument must be discarded. In either case, the cost of manufacturing the sensor instrument is greatly increased.  
       BRIEF SUMMARY OF THE INVENTION  
       [0014]     Accordingly, an object of the present invention is to provide a new and improved sensor dispensing instrument for handling the sensors contained in a sensor pack of multiple sensors used in testing blood glucose. In particular, objects of the present invention are to provide a new and improved fluid sensor dispensing instrument handling device having a Modular electronics assembly that can be manufactured and tested prior to assembly in the sensor dispensing instrument, and which overcomes the problems or limitations discussed above.  
         [0015]     In accordance with these and many other objects of the present invention, the present invention is embodied in a sensor dispensing instrument that is adapted to handle a sensor pack containing a plurality of sensors, each of the plurality of sensors being disposed in a sensor cavity on the sensor pack and enclosed by a protective foil covering, the sensor dispensing instrument further adapted to perform a test using one of the sensors, wherein the sensor dispensing instrument includes an electronics assembly for performing the test and displaying test results. The electronics assembly comprises a printed circuit board, electrical components mounted on the printed circuit board for conducting electronic functions in response to electrical signals, at least one button mounted on the printed circuit board for supplying electrical signals to the electrical components, and a liquid crystal display mounted on the printed circuit board for displaying said test results. The electrical components, the at least one button, and the liquid crystal display are mounted on the printed circuit board to form an electronics subassembly prior to assembling the electronics sub assembly into the outer housing of the sensor dispensing instrument.  
         [0016]     In the preferred embodiment of the present invention, the sensor dispensing instrument also includes a sensor slot on the outer housing through which one of the sensors is disposed to conduct the test, and a mechanical mechanism generally disposed within the housing. The mechanical mechanism includes an indexing disk for supporting and rotating the sensor pack, an indexing disk drive arm for rotating the indexing disk, a knife blade assembly for puncturing the foil covering and ejecting one of the sensors from the sensor cavity and through the sensor slot, and a puller handle for moving the indexing disk drive arm and the knife blade assembly.  
         [0017]     In accordance with another aspect of the present invention, the present invention is embodied in a method of manufacturing a sensor dispensing instrument that is adapted to handle a sensor pack containing a plurality of sensors and to perform a test using one of the sensors, wherein the sensor dispensing instrument includes an electronics assembly for performing the test and displaying test results. The method comprises the step of manufacturing the electronics assembly by first mounting the electrical components, at least one button, and a liquid crystal display on to a printed circuit board before assembling the electronics assembly into the outer housing of the sensor dispensing instrument. 
     
    
     BRIEF DESCRIPTION OF SEVERAL VIEWS OF THE DRAWINGS  
       [0018]     The present invention, together with the above and other objects and advantages, can best be understood from the following detailed description of the embodiment of the invention illustrated in the drawing, wherein:  
         [0019]      FIG. 1  is a top perspective view of a blood glucose sensor dispensing instrument embodying the present invention;  
         [0020]      FIG. 2  is a bottom perspective view of the blood glucose sensor dispensing instrument of  FIG. 1 ;  
         [0021]      FIG. 3  is a perspective view of the blood glucose sensor dispensing instrument of  FIG. 1  in the opened position showing the insertion of a sensor pack;  
         [0022]      FIG. 4  is a perspective view of the blood glucose sensor dispensing instrument of  FIG. 1  in the opened position showing a sensor pack loaded onto the indexing disk;  
         [0023]      FIG. 5  is a top perspective view of the blood glucose sensor dispensing instrument of  FIG. 1  shown with the button door in the open position;  
         [0024]      FIG. 6  is a top perspective view of the blood glucose sensor dispensing instrument of  FIG. 1  with the disk drive pusher in the extended position;  
         [0025]      FIG. 7  is a top perspective view of the blood glucose sensor dispensing instrument of  FIG. 1  with the disk drive pusher in the testing position with a sensor projecting from the sensor opening;  
         [0026]      FIG. 8  is a top perspective view of a sensor for use with blood glucose sensor dispensing instrument of  FIG. 1 ;  
         [0027]      FIG. 9  is an exploded perspective view of a sensor pack for use with blood glucose sensor dispensing instrument of  FIG. 1  showing the protective foil separated from the base portion of the sensor pack;  
         [0028]      FIG. 10  is an exploded perspective view of the component subassemblies of blood glucose sensor dispensing instrument of  FIG. 1 ;  
         [0029]      FIG. 11  is an exploded perspective view of the component parts of the upper case sub assembly of the blood glucose sensor dispensing instrument of  FIG. 1 ;  
         [0030]      FIG. 12  is an exploded perspective view of the component parts of the lower case sub-assembly of the blood glucose sensor dispensing instrument of  FIG. 1 ;  
         [0031]      FIG. 13  is an exploded top perspective view of the component parts of the disk drive mechanism and indexing disk sub assembly of the blood glucose sensor dispensing instrument of  FIG. 1 ;  
         [0032]      FIG. 14  is an exploded bottom perspective view of the component parts of the disk drive mechanism and indexing disk sub assembly of the blood glucose sensor dispensing instrument of  FIG. 1 ;  
         [0033]      FIG. 15  is an exploded perspective view of the component parts of the battery tray sub assembly of the blood glucose sensor dispensing instrument of  FIG. 1 ;  
         [0034]      FIG. 16  is an exploded perspective view of the component parts of the electronics assembly of the blood glucose sensor dispensing instrument of  FIG. 1 ;  
         [0035]      FIG. 17  is a top perspective view of the electronics sub-assembly of the blood glucose sensor dispensing instrument of  FIG. 1 ; and  
         [0036]      FIG. 18  is a bottom perspective view of the electronics sub assembly of the blood glucose sensor dispensing instrument of  FIG. 1 . 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0037]     Referring now more specifically to the drawings, therein is disclosed a blood glucose sensor dispensing instrument generally designated by the reference numeral  10  and embodying the present invention. The sensor dispensing instrument  10  includes an outer housing  12  having an upper case  18  and a lower case  24 , the lower case  24  pivoting on the upper case  18 . The upper case  18  is pivotable with respect to the lower case  24  in a clamshell fashion so that a sensor pack  300  (see  FIGS. 3 and 4 ) can be positioned on an indexing disk  30  within the housing  12 . With the sensor pack  300  so loaded in the housing  12 , a puller handle  32  extending from a rear end  22  of the upper case  18  of the housing  12  can be moved to activate a disk drive mechanism, generally designated by the numeral  34  (see FIG,  10 ), to load a sensor  302  into a testing position on the front end  14  of the housing  12  (see  FIG. 3 ).  
         [0038]     It should be noted that the sensor dispensing instrument  10  of the present invention incorporates components that are similar in design and/or function as those described in U.S. Pat. No. 5,630,986, issued May 20, 1997, and entitled Dispensing Instrument For Fluid Monitoring Sensors. The contents of this patent are hereby incorporated by reference to avoid the unnecessary duplication of the description of these similar components.  
         [0039]     The sensor pack  300  utilized by the sensor dispensing instrument  10  is of the type described in U.S. Pat. No. 5,575,403, issued Nov. 19, 1996, and entitled Dispensing Instrument For Fluid Monitoring Sensors, the contents of which are hereby incorporated by reference. In general, and as shown in  FIGS. 8 and 9 , the sensor pack  300  is adapted to house ten sensors  302 , with one of the ten sensors  302  in each of ten separate sensor cavities  304 . Each of the sensors  302  has a generally flat, rectangular shape extending from a front or testing end  306  to a back end  308 . The front end  306  is angled so that it will puncture an unsevered portion of the protective foil  310  overlying the sensor cavity  304  as the sensor  302  is being forced out of the sensor cavity  304  by a knife blade  36  (to be described below). The front end  306  is also adapted to be placed into blood that is being analyzed. The back end  308  of the sensor  302  includes a small notch  312  that is engaged by the knife blade  36  as the knife blade  36  ejects the sensor  302  from the sensor cavity  304 . Contacts  314  near the back end  308  of the sensor  302  are adapted to mate with metal contacts  38  on a sensor actuator  40  (to be described below) when the sensor  302  is in the testing position illustrated in  FIG. 7 . As a result, the sensor  302  is coupled to the electronic circuitry on the circuit board assembly  42  so that information generated in the sensor  302  during testing can be stored, analyzed and/or displayed.  
         [0040]     As best seen in  FIG. 8 , each sensor  302  is provided with a capillary channel  316  that extends from the front or testing end  306  of the sensor  302  to biosensing or reagent material disposed in the sensor  302 . When the testing end  306  of the sensor  302  is placed into fluid (for example, blood that is accumulated on a person&#39;s finger after the finger has been pricked), a portion of the fluid is drawn into the capillary channel  316  by capillary action. The fluid then chemically reacts with the reagent material in the sensor  302  so that an electrical signal indicative of the blood glucose level in the blood being tested is supplied to the contacts  314 , and subsequently transmitted through the sensor actuator  40  to the circuit board assembly  42 .  
         [0041]     As best seen in  FIG. 9 , the sensor pack  300  comprises a circularly shaped base portion  318  covered by a sheet of protective foil  310 . The sensor cavities  304  are formed as depressions in the base portion  318 , with each of the sensor cavities  304  adapted to house an individual sensor  302 . Each of the sensor cavities  304  has an inclined or sloped support wall  320  to guide the sensor  302  as the sensor  302  is ejected through the foil  310  and out of the sensor cavity  304 .  
         [0042]     Each of the sensor cavities  304  is in fluid communication with a desiccant cavity  322  formed by a small depression in the base portion  318 . Desiccant material is disposed in each of the desiccant cavities  322  in order to insure that the sensor cavities  304  are maintained at an appropriate humidity level to preserve the reagent material in the sensor  302 .  
         [0043]     Notches  324  are formed along the outer peripheral edge of the base portion  318 . The notches  324  are configured to engage pins  44  on the indexing disk  30  so that the sensor cavities  304  are in proper alignment with the indexing disk  30  when the sensor pack  300  is loaded into the sensor dispensing instrument  10 . As will be explained in greater detail below, the sensor cavities  304  must be aligned with the knife slots  46  in the indexing disk  30  to permit the knife blade  36  to engage, eject and push one of the sensors  302  into a testing position on the front end  14  of the housing  12 .  
         [0044]     The sensor pack  300  further comprises a conductive label  326  on the central portion of the base portion  318 . As will be explained below, the conductive label  326  provides calibration and production information about the sensor pack  300  that can be sensed by calibration circuitry in the sensor dispensing instrument  10 .  
         [0045]     To operate the sensor dispensing instrument  10 , the puller handle  32  is first manually pulled from a standby position ( FIG. 1 ) adjacent the rear end  16  of the housing  12  to an extended position ( FIG. 6 ) away from the rear end  16  of the housing  12 . The outward movement of the puller handle  32  causes the disk drive mechanism  34  to rotate the sensor pack  300  and place the next sensor  302  in a standby position prior to being loaded into a testing position. The outward movement of the puller handle  32  also causes the sensor dispensing instrument  10  to turn ON (i.e., the electronic circuitry on the circuit board assembly  42  is activated).  
         [0046]     As will be described in greater detail below, the disk drive mechanism  34  includes a disk drive pusher  48  on which an indexing disk drive arm  50  is mounted (see  FIGS. 13 and 14 ). The indexing disk drive arm  50  comprises a cam button  52  disposed at the end of a plate spring  54 . The cam button  52  is configured to travel in one of a plurality of curvilinearly extending grooves  56  on the upper surface of the indexing disk  30 . As the puller handle  32  is manually pulled from a standby position adjacent the rear end  16  of the housing  12  to an extended position away from the rear end  16  of the housing  12 , the disk drive pusher  48  is pulled laterally towards the rear end  22  of the upper case  18 . This causes the cam button  52  on the indexing disk drive arm  50  to travel along one of the curvilinearly extending grooves  56  so as to rotate the indexing disk  30 . The rotation of the indexing disk  30  causes the sensor pack  300  to be rotated so that the next one of the sensor cavities  304  is placed in a standby position.  
         [0047]     The puller handle  32  is then manually pushed inwardly from the extended position ( FIG. 6 ) back past the standby position ( FIG. 1 ) and into a testing position ( FIG. 7 ). The inward movement of the puller handle  32  causes the disk drive mechanism  34  to remove a sensor  302  from the sensor pack  300  and place the sensor  302  into a testing position on the front end  14  of the housing  12 .  
         [0048]     As will be described in greater detail below, the disk drive mechanism  34  includes a knife blade assembly  58  that is pivotally mounted to the disk drive pusher  48  (see  FIGS. 13 and 14 ). As the puller handle  32  is manually pushed from the extended position to the testing position, the disk drive pusher  48  is pushed laterally towards the testing or front end  20  of the upper case  18 . This causes the knife blade assembly  58  to pivot downwardly so that a knife blade  36  on the end of the knife blade assembly  58  pierces a portion of the protective foil  310  covering one of the sensor cavities  304  and engages the sensor  302  in the sensor cavity  304 . As the disk drive pusher  48  continues to move towards the front end  20  of the upper case  18 , the knife blade assembly  58  forces the sensor  302  out of the sensor cavity  304  and into a testing position at the front end  14  of the housing  12 .  
         [0049]     While the disk drive pusher  48  is being pushed from the extended position to the testing position, the cam button  52  on the indexing disk drive arm  50  travels along one of the radially extending grooves  60  to prevent the indexing disk  30  from rotating. Similarly, while the disk drive pusher  48  is being pulled from the standby position to the extended position, the knife blade assembly  58  is in a retracted position so as to not interfere with the rotation of the indexing disk  30 .  
         [0050]     After the sensor  302  has been completely ejected from the sensor cavity  304  and pushed into a testing position projecting out from the front end  14  of the housing  12 , the disk drive pusher  48  engages and forces a sensor actuator  40  against the sensor  302  to thereby maintain the sensor  302  in the testing position. The sensor actuator  40  engages the sensor  302  when the puller handle  32  is pushed past the standby position and into the testing position. The sensor actuator  40  couples the sensor  302  to an electronics assembly  62  disposed in the upper case  18 . The electronics assembly  62  includes a microprocessor or the like for processing and/or storing data generated during the blood glucose test procedure, and displaying the data on a liquid crystal display  64  in the sensor dispensing instrument  10 .  
         [0051]     Once the blood analyzing test is completed, a button release  66  on the upper case  18  is depressed so as to disengage the sensor actuator  40  and release the sensor  302 . Depressing the button release  66  causes the disk drive pusher  48  and the puller handle  32  to move from the testing position back to the standby position. At this point, the user can turn the sensor dispensing instrument  10  OFF by depressing the button  96  on the upper case  18 , or by allowing the sensor dispensing instrument  10  automatically turn OFF pursuant a timer on the electronics assembly  62 .  
         [0052]     As seen in  FIGS. 1-7  and  10 - 12 , the upper case  18  and the lower case  24  of the sensor dispensing housing  12  are complementary, generally oval shaped hollow containers that are adapted to be pivoted with respect to each other about pivot pins  68  extending outwardly in the rear end  22  of the upper case  18  into pivot holes  70  in a rear section  28  of the lower case  24 . The upper case  18  and the lower case  24  are maintained in their closed configuration by a latch  72  that is pivotally mounted in a front section  26  of the lower case  24  by pins  74  that extend inwardly into pivot holes  76  in the latch  72  (see  FIG. 12 ). The latch  72  has recesses  78  that are configured to mate with hooks  80  on the upper case  18  to secure the upper case  18  and the lower case  24  in their closed configuration. The latch  72  is biased in a vertical or closed position by a latch spring  82 . The ends  84  of the latch spring  82  are secured in slots  86  on the inside of the lower case  24 . When the latch  72  is pivoted against the biasing force of the latch spring  82 , the hooks  80  on the upper case  18  disengage from the recesses  78  to permit the upper case  18  and the lower case  24  to open.  
         [0053]     As seen in FIGS.  1 ,  5 - 7  and  10 - 11 , the upper case  18  includes a rectangular opening  30  through which a liquid crystal display  64  is visible below. The liquid crystal display  64  is visible through a display lens  88  that is affixed to upper surface of the upper case  18 . In the preferred embodiment shown, the display lens  88  has an opaque portion  90  and a transparent portion  92 , the transparent portion  92  being coincident with the display area of liquid crystal display  64 . The liquid crystal display  64  is a component of the electronics assembly  62 , and is coupled to the circuit board assembly  42  via elastomeric connectors  94  (see  FIG. 16 ). The liquid crystal display  64  displays information from the testing procedure and/or in response to signals input by the buttons  96  on the upper case  18 . For example, the buttons  96  can be depressed to recall and view the results of prior testing procedures on the liquid crystal display  64 . As best seen in  FIG. 11 , the buttons  96  are part of a button set  98  that is attached to the upper case  18  from below so that the individual buttons  96  project upwardly through button openings  100  in the upper case  18 . When pressed, the buttons  96  are electrically connected to the circuit board assembly  42 .  
         [0054]     As best seen in  FIGS. 1, 5  and  11 , a button door  102  is pivotally connected to the upper case  18  by a pair of pins  104  projecting outwardly from either side of the button door  102  that engage holes  106  on the side walls of the upper case  18 . The button door  102  also comprises a pair of ears  108  that fit into recesses  110  in the side walls of the upper case  18  when the button door  102  is closed. The ears  108  extend slightly beyond the side walls of the upper case  18  so that they can be grasped by the user to open the button door  102 . A pivot edge  112  of the button door  102  engages a tab  114  on the upper surface of the upper case  18 . The tab  114  rubs against the pivot edge  112  in such a manner so as to bias the button door  102  in either a closed or fully open position. In the preferred embodiment shown, the button door  102  has an opening  116  that permits one of the buttons  96  (e.g., an On/Off button) to be accessed when the button door  102  is closed (see  FIG. 1 ). This permits dedicated, but seldom or lesser used buttons  96  to be concealed underneath the button door  102 , thereby simplifying the learning curve and daily operation of the sensor dispensing instrument  10  for the user.  
         [0055]     The upper case  18  also contains an opening  118  for the button release  66 , which projects upwardly through the upper case  18 . As will be described in more detail below, the button release  66  is depressed to disengage the sensor actuator  40  and release a sensor  302  from the testing position.  
         [0056]     The upper case  18  also contains an opening  120  for a battery tray assembly  122 . The battery tray assembly  122  includes a battery tray  124  in which a battery  126  is disposed. The batter tray assembly  122  is inserted into the opening  120  in the side of the upper case  18 . When so inserted, the battery  126  engages battery contacts  128  and  130  on the circuit board assembly  42  so as to provide power for the electronics within the instrument  10 , including the circuitry on the circuit board assembly  42  and the liquid crystal display  64 . A tab  132  on the lower case  24  is configured to engage a slot  134  in the battery tray assembly  122  so as to prevent the battery tray assembly  122  from being removed from the sensor dispensing instrument  10  when the upper case  18  and the lower case  24  are in the closed configuration.  
         [0057]     An electronics assembly  62  is affixed to the upper inside surface of the upper case  18 . As best seen in FIGS.  16   18 , the electronics assembly  62  comprises a circuit board assembly  42  on which various electronics and electrical components are attached. A positive battery contact  128  and a negative battery contact  130  are disposed on the bottom surface  136  (which is the upwardly facing surface as viewed in  FIGS. 16 and 18 ) of the circuit board assembly  42 . The battery contacts  128  and  130  are configure to electrically connect with the battery  126  when the battery tray assembly  122  is inserted into the side of the upper case  18 . The bottom surface  136  of the circuit board assembly  42  also includes a communication interface  138 . The communication interface  138  permits the transfer of testing or calibration information between the sensor dispensing instrument  10  and another device, such as a personal computer, through standard cable connectors (not shown). In the preferred embodiment shown, the communication interface  138  is a standard serial connector. However, the communication interface  138  could alternatively be an infra red emitter/detector port, a telephone jack, or radio frequency transmitter/receiver port. Other electronics and electrical devices, such as memory chips for storing glucose test results or ROM chips for carrying out programs are likewise included on the bottom surface  136  and the upper surface  140  of the circuit board assembly  42 .  
         [0058]     A liquid crystal display  64  is affixed to the upper surface  140  (upwardly facing surface in  FIG. 17 ) of the circuit board assembly  42 . The liquid crystal display  64  is held by a snap in display frame  142 . The snap in display frame  142  includes side walls  144  that surround and position the liquid crystal display  64 . An overhang  146  on two of the side walls  144  holds the liquid crystal display  64  in the snap in display frame  142 . The snap in display frame  142  includes a plurality of snap fasteners  148  that are configured to engage mating holes  150  on the circuit board assembly  42 . The liquid crystal display  64  is electrically connected to the electronics on the circuit board assembly  42  by a pair of elastomeric connectors  94  disposed in slots  152  in the snap in display holder  142 . The elastomeric connectors  94  generally comprise alternating layers of flexible conductive and insulating materials so as to create a somewhat flexible electrical connector. In the preferred embodiment shown, the slots  152  contain a plurality of slot bumps  154  that engage the sides of the elastomeric connectors  94  to prevent them from failing out of the slots  152  during assembly.  
         [0059]     As set forth in detail in the U.S. Patent Application entitle Snap in Display Frame, which is being filed together with the present application, the snap in display frame  142  eliminates the screw type fasteners and metal compression frames that are typically used to assemble and attach a liquid crystal display  64  to an electronic device. In addition, the snap in display frame  142  also permits the liquid crystal display  64  to be tested prior to assembling the liquid crystal display  64  to the circuit board assembly  42 .  
         [0060]     The button set  98  also mates to the upper surface  140  of the circuit board assembly  42 . As mentioned above, the button set  98  comprises several individual buttons  96  that are depressed to operate the electronics of the sensor dispensing instrument  10 . For example, the buttons  96  can be depressed to activate the testing procedure of the sensor dispensing instrument  10 . The buttons  96  can also be depressed to recall and have displayed on the liquid crystal display  64  the results of prior testing procedures. The buttons  96  can also be used to set and display date and time information, and to activate reminder alarms which remind the user to: conduct a blood glucose test according to a predetermined schedule. The buttons  96  can also be used to activate certain calibration procedures for the sensor dispensing instrument  10 .  
         [0061]     The electronics assembly  62  further comprises a pair of surface contacts  139  on the bottom surface  136  of the circuit board assembly  42  (see  FIGS. 16 and 18 ). The surface contacts  139  are configured so as to be contacted by one or more fingers  143  on the cover mechanism  188 , which in turn are configured to be engaged by a pair of ramp contacts  141  on the disk drive pusher  48  (see  FIGS. 6 and 13 ). Movement of the puller handle  32  causes the ramp contacts  141  to push the fingers  143  into contact with one or both of the surface contacts  139  so as to communicate the position of the puller handle  32  to the electronics assembly  62 . In particular, movement of the puller handle  32  from the stand by or testing positions to the extended position will turn the sensor dispensing instrument ON. In addition, if the housing  12  is opened while the puller handle  32  is in the extended position, an alarm will be activated to warn the user that the knife blade  36  may be in the extended position.  
         [0062]     It should be noted that the design and configuration of the electronics assembly  62  permits the assembly and testing of the electronics and electrical components prior to assembly of the electronics assembly  62  to the upper case  18  of the sensor dispensing instrument  10 . In particular, the liquid crystal display  64 , the button set  98 , the battery contacts  128  and  130 , and the other electronics and electrical components can each be assembled to the circuit board assembly  42  and tested to verify that these components, and the electrical connections to these components, are working properly. Any problem or malfunction identified by the testing can then be corrected, or the malfunctioning component can be discarded, prior to assembling the electronics assembly  62  to the upper case  18  of the sensor dispensing instrument  10 .  
         [0063]     As mentioned above, the sensor dispensing instrument  10  includes calibration circuitry for determining calibration and production information about the sensor pack  300 . As best seen in  FIG. 12 , the calibration circuitry comprises a flex circuit  156  located in the lower case  24 . The flex circuit  156  is held in position in the lower case  24  by an autocal disk  158  that is connected to the rear section  28  of the lower case  24  by a pair of pins  160 . The autocal disk  158  has a raised central portion  162  configured to engage the sensor cavities  304  on the sensor pack  300  so as to hold the sensor pack  300  against the indexing disk  30 . The autocal disk  158  also has an open area  164  located between the pins  160  to expose contacts  166  on the flex circuit  156 .  
         [0064]     The flex circuit  156  comprises a plurality of probes  166  that extend upwardly from the flex circuit  156  through holes  170  in the inner region of the autocal disk  158 . These probes  168  are connected to the contacts  166  on the end of the flex circuit  156 . When the sensor dispensing instrument  10  is closed with the lower case  24  latched to the upper case  18 , the probes  168  make contact with a conductive label  326  on the sensor pack  300  being used in the sensor dispensing instrument  10 . A foam pad  172  is positioned below the flex circuit  156  to provide a biasing force to assure that the probes  168  press against the conductive label  326  with a force sufficient to make an electrical connection. The foam pad  172  also provides a cushioning force so that the probes  168  can move independently with respect to each other as the sensor pack  300  is being rotated by the indexing disk  30 . As a result, information, such as calibration and production data, contained on the conductive label  326  can be transmitted via the probes  168  to the flex circuit  156 , which in turn couples the data to the electronic circuitry on the circuit board assembly  42  via an elastomeric connector  174 . This information can then be used by the electronics assembly  62  to calibrate the sensor dispensing instrument  10 , or can be displayed on the liquid crystal display  64 . As best seen in  FIG. 10 , the elastomeric connector  174  is made of layers of silicon rubber extending from a top edge  176  to a bottom edge  178  with alternate layers having conductive materials dispersed therein to connect contacts on the top edge  176  to contacts on the bottom edge  178 . When the upper case  18  and the lower case  24  are closed, the elastomeric connector  174  is compressed in the direction between the edges  176  and  178  such that the contacts along the top edge  176  engage electronic circuitry on the circuit board assembly  42  in the upper case  18 , and the contacts along the bottom edge  178  engage the contacts  166  on the flex circuit  156  in the lower case  24 . With the elastomeric connector  174  so compressed, low voltage signals can be readily transmitted between the circuit board assembly  42  and the flex circuit  156  through the elastomeric connector  174 .  
         [0065]     The elastomeric connector  174  is held in position by a slotted housing  180  on the guide block  182 . In the preferred embodiment shown, the slotted housing  180  has a serpentine cross section configured to allow the connector  174  to compress when the upper case  18  and the lower case  24  are closed, while still holding the elastomeric connector  174  when the upper case  18  and the lower case  24  are open. Alternatively, the slotted housing  180  may include inwardly projecting ridges that engage the sides of the connector  174 .  
         [0066]     The disk drive mechanism  34  is affixed to the upper inside surface of the upper case  18 . As best seen in  FIG. 10 , the disk drive mechanism  34  is attached to the upper case by a plurality of mounting screws  184  that engage posts (not shown) on the upper inside surface of the upper case  18 . The mounting screws  184  also pass through and secure the electronics assembly  62 , which is disposed between the disk drive mechanism  34  and the upper case  18 .  
         [0067]     Although the disk drive mechanism  34  will be described in greater detail below, it should be noted that the disk drive mechanism  34  is configured so as to permit the assembly and testing of its operation prior to mounting the disk drive mechanism  34  to the upper inside surface of the upper case  18 . In other words, the disk drive mechanism  34  has a modular design that can be tested prior to final assembly of the sensor dispensing instrument  10 .  
         [0068]     As best seen in  FIGS. 13 and 14 , the disk drive mechanism  34  comprises a guide block  182 , a sensor actuator  40 , a housing guide  186 , a disk drive pusher  48 , an indexing disk drive arm  50 , a knife blade assembly  58 , a puller handle  32 , a cover mechanism  188 , and a button release  66 . The housing guide  186  is fixed to the upper surface  190  (as viewed in  FIG. 13 ) of the guide block  182  by one or more pins  192 . The disk drive pusher  48  is supported on the housing guide  186  and the guide block  182  in such a manner as to permit the disk drive pusher  48  to slide laterally relative to the housing guide  186  and the guide block  182 . The knife blade assembly  58  is pivotally connected to the underside of the disk drive pusher  48 , and is guided by the housing guide  186  and the guide block  182 . The indexing disk drive arm  50  is also connected to the disk drive pusher  48 , and is partially guided by the guide block  182 . The puller handle  32  comprises an upper puller handle  194  and a lower puller handle  196  connected to each other by snap-press fittings  198  that pass through holes  200  in the rear end  202  of the disk drive pusher  48 . In the preferred embodiment shown, the upper puller handle  194  and the lower puller handle  196  each have a concaved, textured outer surface (i.e., the top and bottom surfaces of the puller handle  32 ) to facilitate gripping of the puller handle  32  between the thumb and finger of the user&#39;s hand. The cover mechanism  188  is affixed to the guide block  182  with the disk drive pusher  48  and the housing guide  186  disposed therebetween. The sensor actuator  40  is attached to the guide block  182  and is engaged by the front end  204  of the disk drive pusher  48  when the disk drive pusher  48  is in the testing position. The button release  66  is slidably connected to the cover mechanism  188  so as to engage the front end  204  of the disk drive pusher  48  when the disk drive pusher  48  is in the testing position.  
         [0069]     In addition, an indexing disk  30  is rotatably secured to the disk drive mechanism  34  by a retainer disk  206  connected through the indexing disk  30  and into guide block  182 . As best seen in  FIG. 14 , the retainer disk  206  has a pair of latch arms  208  that extend through a central hole  210  in the indexing disk  30  and latch into an opening  212  in the guide block  182 . As mentioned above, the indexing disk  30  includes a plurality of pins  44  protruding from the lower surface  214  thereof. These pins  44  are configured to engage notches  324  on the sensor pack  300  (see  FIG. 4 ) so as to align and rotate the sensor pack  300  in accordance with the position of the indexing disk  30 . Hence, the pins  44  and the notches  324  have the dual purpose of retaining the sensor pack  300  on the indexing disk  30  so that the sensor pack  300  will rotate with the indexing disk  30  and of positioning the sensor pack  300  in proper circumferential alignment relative to the indexing disk  30 .  
         [0070]     As previously indicated, the disk drive pusher  48  is pulled away from the rear end  16  of the housing  12  (away from the testing end  14 ) by the user manually exerting a pulling force on the puller handle  32  to move the handle  32  from the standby position to the extended position. As the puller handle  32  is pulled away from the rear end  22  of the upper case  18 , the disk drive pusher  48  is guided in a lateral direction by the guide block  182 , the housing guide  186 , and the cover mechanism  188 . As the disk drive pusher  48  slides towards the rear end  22  on the upper case  18 , the indexing disk drive arm  50  causes the indexing disk  30  to rotate.  
         [0071]     The indexing disk drive arm  50  extends rearwardly from the disk drive pusher  48 . The indexing disk drive arm  50  includes a plate spring  54  made of spring type material such as stainless steel so as to bias the arm  50  outwardly from the disk drive pusher  48 . A cam button  52  is affixed to the distal end of the arm  50 , and is configured to engage the upper surface  216  (as viewed in  FIG. 13 ) of the indexing disk  30 . In particular, the indexing disk drive arm  50  is bent so as to protrude downwardly through a slot  218  in the guide block  182  such that the cam button  52  projects outwardly from the surface thereof. The slot  218  is designed such that the indexing disk drive arm  50  and the cam button  52  can move along the slot  218  as the disk drive pusher  48  is moved back and forth during the testing procedure. The slot  218  also prevents the indexing disk drive arm  50  from moving sideways with respect to the disk drive pusher  48  (i.e., it provides lateral support to the indexing disk drive arm  50 ).  
         [0072]     As best seen in  FIG. 13 , the upper surface  216  of the indexing disk  30  comprises a series of radially extending grooves  60  and a plurality of curvilinearly extending grooves  56 . The cam button  52  is configured to ride along these grooves  56  and  60  during the movement of the disk drive pusher  48 . As the disk drive pusher  48  slides towards the rear end  22  of the upper case  18 , the cam button  52  moves along one of the curvilinearly extending grooves  56 . This causes the indexing disk  30  to rotate. In the preferred embodiment shown, there are ten radially extending grooves  60  and ten curvilinearly extending grooves  56  equally spaced about the circumference of the indexing disk  30 , with each radially extending groove  60  being disposed between a pair of curvilinearly extending grooves  56 . Accordingly, the movement of the disk drive pusher  48  towards the rear end  22  on the upper case  18  results in a 1/10th rotation of the indexing disk  30 .  
         [0073]     As the puller handle  32  is pulled away from the rear end  16  of the housing  12  to a fully extended position, the cam button  52  passes over an outer step  220  that separates the outer end  222  of the curvilinearly extending groove  56  from the adjacent radially extending groove  60 . The outer step  220  is formed by the difference in depth between the outer end  222  of the curvilinearly extending groove  56  and the outer end  224  of the adjacent radially extending groove  60 . In particular, the outer end  224  of the radially extending groove  60  is deeper than the outer end  222  of the curvilinearly extending groove  56 . Thus, when the cam button  52  moves from the curvilinearly extending groove  56  into the adjacent radially extending groove  60 , the biasing force of the plate spring  54  of the indexing disk drive arm  50  causes the cam button  52  to travel downwardly past the outer step  220 . The outer step  220  prevents the cam button  52  from re entering the outer end  222  of the curvilinearly extending groove  56  when the direction of travel of the disk drive pusher  48  is reversed (as will be explained below).  
         [0074]     Rotation of the indexing disk  30  causes the sensor pack  300  to likewise rotate so that the next available sensor cavity  304  is placed in a standby position adjacent to the testing end  14  of the housing  12 . The sensor pack  300  rotates with the indexing disk  30  because of the engagement of the notches  324  on the sensor pack  300  by the pins  44  on the indexing disk  30 . As explained above, each sensor cavity  304  contains a disposable sensor  302  that is used during the glucose testing procedure.  
         [0075]     Further rearward movement of the disk drive pusher  48  is prevented by a rear wall  226  on the guide block  182 . In the preferred embodiment shown, the rear wall  226  includes a slotted housing  180  for holding the elastomeric connector  174  that connects the electronics assembly  62  to the flex circuit  156  disposed in the lower case  24 . An interior edge  228  of the disk drive pusher  48  engages the rear wall  226  on the guide block  182  when the disk drive pusher  48  is in the fully extended position (see  FIG. 6 ).  
         [0076]     From the fully extended position, the puller handle  32  is then manually pushed inwardly back past the standby position ( FIG. 1 ) and into a testing position ( FIG. 7 ). As previously indicated, the inward movement of the puller handle  32  causes the disk drive mechanism  34  to remove a sensor  302  from the sensor pack  300  and place the sensor  302  into a testing position.  
         [0077]     As best seen in  FIGS. 13 and 14 , the disk drive mechanism  34  includes a knife blade assembly  58  that is pivotally mounted to the disk drive pusher  48 . The knife blade assembly  58  comprises a swing arm  230  having a first end  232  that is pivotally connected to the disk drive pusher  48  by a pair of pivot pins  234 . A knife blade  36  is connected to the second end  236  of the swing arm  230 . The second end  236  of the swing arm  230  also includes a first cam follower  238  and a second cam follower  240 , each in the shape of a transversely extending post. The first cam follower  238  is configured to follow a pathway formed on one side of the knife blade assembly  58  by the guide block  182 , the housing guide  186 , and the cover mechanism  188 . In particular, this pathway is formed by a cam projection  242  on the housing guide  186  that forms an upper pathway  244  between the cam projection  242  and the cover mechanism  188  and a lower pathway  246  between the cam projection  242  and the guide block  182 . When the first cam follower  238  is disposed in the upper pathway  244 , the knife blade  36  is in the retracted position. On the other hand, when the first cam follower  238  is disposed in the lower pathway  246 , then the knife blade  36  is in the extended position. The upper pathway  244  and the lower pathway  246  are connected together at both ends of the cam projection  242  so as to form a continuous loop about which the first cam follower  238  can travel.  
         [0078]     The second cam follower  240  engages a cam spring  248  attached to the housing guide  186 . As will be explained below, the cam spring  248  guides the knife blade assembly  58  from the lower pathway  246  to the upper pathway  244  when the disk drive pusher  48  is initially pulled rearward from standby position towards the extended position. The disk drive pusher  48  also comprises a spring  250  for biasing the knife blade  36  towards the extended position when the disk drive pusher  48  is initially pushed forward from the extended position towards the testing position. In the preferred embodiment shown, the spring  250  comprises a plate spring that presses against the upper side of the swing arm  230 .  
         [0079]     As the puller handle  32  is manually pushed from the extended position to the testing position, the disk drive pusher  48  is pushed laterally towards the testing or front end  14  of the housing  12 . As the disk drive pusher  48  begins to move forward, the spring  250  biases the swing arm  230  downwardly towards the indexing disk  30  so that the first cam follower  238  engages a sloped surface  252  on the interior end  268  of the cam projection  242  and is forced into the lower pathway  246 . This causes the knife blade  36  to assume an extended position whereby the knife blade  36  projects outwardly through a knife slot  46  in the indexing disk  30  to pierce the protective foil  310  covering one of the sensor cavities  304  and engage the notch  312  on the back end  308  of the sensor  302  contained therein. As the disk drive pusher  48  continues to move towards the front end  20  of the upper case  18 , the first cam follower  238  continues along the lower pathway  246 , thereby causing the knife blade  36  to remain in the extended position projecting through the knife slot  46  so that it will travel along the knife slot  46  and push the sensor  302  forward out of the sensor cavity  304  and into a testing position at the front end  14  of the housing  12 . The sensor  302  is in the testing position when the front end  306  of the sensor  302  projects out of the sensor opening  254  formed on the front end of the guide block  182 . While in the testing position, the sensor  302  is prevented from being pushed back through the sensor opening  254  by the engagement of the knife blade  36  against the notch  312  on the back end  308  of the sensor  302 .  
         [0080]     As the disk drive pusher  48  reaches the testing position, the front end  204  of the disk drive pusher  48  simultaneously engages the sensor actuator  40  and the button release  66 . In particular, the front end  204  of the disk drive pusher  48  engages and pushes the button release  66  outwardly so as to project upwardly from the upper surface of the upper case  18 . At the same time, the front end  204  of the disk drive pusher  48  engages a contact pad  256  on the sensor actuator  40  so as to force the sensor actuator  40  downward. This downward motion causes a pair of metal contacts  38  on the sensor actuator  40  to project into the sensor opening  254  on the guide block  182  and engage the contacts  314  on the sensor  302  for the glucose testing procedure. The metal contacts  38  also apply a frictional force to the sensor  302  so that the sensor  302  does not prematurely fall out of the sensor opening  254  prior to completion of the glucose testing procedure. In the preferred embodiment shown, the metal contacts  38  are somewhat flexible and are made of stainless steel The housing guide  186  includes support ribs  187  disposed adjacent to the metal contacts  38  so as to prevent the metal contacts  38  from bending. As explained above, the metal contacts  38  permit the transmission of electrical signals between the sensor  302  and the electronics assembly  62  during the glucose testing procedure.  
         [0081]     When the glucose testing procedure is complete, the button release  66  is depressed to release the sensor  302  from the testing position. The button release  66  has a sloped contact surface  258  that engages the front end  204  of the disk drive pusher  48  at an angle. As the button release  66  is depressed, the sloped contact surface  258  slides along the front end  204  of the disk drive pusher  48 , thereby causing the disk drive pusher  48  to move rearward from the testing position and into the standby position. In the preferred embodiment shown, the disk drive pusher  48  is moved laterally a distance of 0.080 inches. The movement of the disk drive pusher  48  to the standby position also causes the front end  204  of the disk drive pusher  48  to disengage from the contact pad  256  on the sensor actuator  40 , thereby allowing the sensor actuator  40  to move away from and disengage the sensor  302 . The sensor  302  can then be removed by tipping the front end  14  of the sensor dispensing instrument  10  downwardly.  
         [0082]     As mentioned above, when the disk drive pusher  48  is pushed from the extended position towards the testing position, the cam button  52  on the indexing disk drive arm  50  travels along one of the radially extending grooves  60  to prevent the indexing disk  30  and the sensor pack  300  from rotating. The radially extending groove  60  includes a sloped portion  260  that changes the depth of the groove  60 . In particular, the sloped portion  260  decreases the depth of the radially extending groove  60  so that the middle portion of the radially extending groove  60  is shallower than the curvilinearly extending grooves  56 . The radially extending groove  60  also comprises an inner step  262  near its inner end  264  (i.e., near the center of the indexing disk  30 ). The inner step  262  is formed along the juncture of the inner end  264  of the radially extending groove  60  and the inner end  266  of the curvilinearly extending groove  56 . As the disk drive pusher  48  is pushed from the extended position towards the testing position, the cam button  52  travels up the sloped portion  260  of the radially extending groove  60 , past the inner step  262 , and into the adjacent curvilinearly extending groove  56 . The biasing force of the plate spring  54  of the indexing disk drive arm  50  causes the cam button  52  to travel downwardly past the inner step  262 . The inner step  262  prevents the cam button  52  from re entering the radially extending groove  60  when the direction of travel of the disk drive pusher  48  is reversed (as explained above in connection with the outward movement of the disk drive pusher  48 ).  
         [0083]     As the disk drive pusher  48  reaches the testing position, the first cam follower  238  passes the exterior end  270  of the cam projection  242 . At the same time, the second cam follower  240  passes over the end of the cam spring  248 , which retracts upwardly and out of the way as the first cam follower  238  nears the exterior end  270  of the cam projection  242 . Once the first cam follower  238  has passed the end of the cam spring  248 , the cam spring  248  moves downwardly so as to engage and guide the second cam follower  240  upwardly when the direction of travel of the disk drive pusher  48  is reversed and pulled outward towards the extended position. In particular, when the disk drive pusher  48  is subsequently pulled outward towards the extended position, the cam spring  248  guides the second cam follower  240  upwardly so that the first cam follower  238  enters the upper pathway  244  and the knife blade  36  is retracted.  
         [0084]     As explained above, the disk drive pusher  48  is pulled outwardly to initiate the testing procedure. During the outward motion of the disk drive pusher  48 , the cam button  52  on the indexing disk drive arm  50  travels along one of the curvilinearly extending grooves  56  so as to rotate the indexing disk  30 . During this outward motion, the first cam follower  238  on the knife blade assembly  58  travels along the upper pathway  244 . As a result, the knife blade  36  is retracted from the knife slot  46  on the indexing disk  30  so that the indexing disk  30  is free to rotate in response to action of the cam button  52  in the curvilinearly extending groove  56 . As the disk drive pusher  48  reaches the fully extended position, the first cam follower  238  passes the interior end  268  of the cam projection  242  and is guided into the lower pathway  246  by the biasing force of the spring  250  on the swing arm  230  of the knife blade assembly  58 .  
         [0085]     Prior to operating the sensor dispensing instrument  10 , a sensor pack  300  must first be loaded into the sensor dispensing instrument  10  if one has not already been so loaded, or if all of the sensors  302  in the previously loaded sensor pack  300  have been used. To load a sensor pack  300 , the lower case  24  and the upper case  18  are opened by depressing the latch  72  on the lower case  24 . In the preferred embodiment shown, the opening of the lower case  24  and the upper case  18  causes the elastomeric connector  174  to separate from the contacts  166  on the autocal disk  158 , thereby breaking the electrical connection between the autocal disk  158  and the electronics assembly  62 . This causes an electronic counter (which is part of the electronics assembly  62 ) that keeps count of the number of unused sensors  302  in the sensor pack  300  to re set to zero (0).  
         [0086]     The opened housing  12  is then turned so that the lower surface  214  of the indexing disk  30  faces upwardly as shown in  FIG. 3 . A sensor pack  300  is then placed on the indexing disk  30  by aligning the notches  324  along the periphery of the sensor pack  300  with the pins  44  on the indexing disk  30 . The lower case  24  is then pivoted on to the upper case  18  so as to enclose the sensor pack  300  within the housing, Once the lower case  24  is secured to the upper case  18  by the latch  72 , the sensor dispensing instrument  10  is ready for operation.  
         [0087]     The following is a brief description of the operation of the sensor dispensing instrument  10 . First, the puller handle  32  is manually pulled from a standby position ( FIG. 1 ) adjacent the rear end  16  of the housing  12  to an extended position ( FIG. 6 ) away from the rear end  16  of the housing  12 . The outward movement of the puller handle  32  causes the sensor dispensing instrument  10  to turn ON. The outward movement of the puller handle  32  also causes the cam button  52  on the indexing disk drive arm  50  to travel along one of the curvilinearly extending grooves  56  on the upper surface  216  of the indexing disk  30  so as to rotate the indexing disk  30  1/10th of a complete rotation. The rotation of the indexing disk  30  causes the sensor pack  300  to be rotated so that the next one of the sensor cavities  304  is placed in a standby position aligned with the testing end  14  of the housing  12 . At the same time, the knife blade assembly  58  is retracted and moved towards the center of the indexing disk  30 .  
         [0088]     Next, the puller handle  32  is manually pushed inwardly from the extended position ( FIG. 6 ) back past the standby position ( FIG. 1 ) and into a testing position ( FIG. 7 ). The inward movement of the puller handle  32  causes the knife blade assembly  58  to pivot downwardly so that a knife blade  36  pierces a portion of the protective foil  310  covering the sensor cavity  304  in the standby position and engages the sensor  302  in the sensor cavity  304 . As the puller handle  32  continues to move back towards the housing  12 , the knife blade assembly  58  forces the sensor  302  out of the sensor cavity  304  and into a testing position at the front end  14  of the housing  12 . At the same time, the cam button  52  on the indexing disk drive arm  50  travels along one of the radially extending grooves  60  to prevent the indexing disk  30  from rotating.  
         [0089]     After the sensor  302  has been completely ejected from the sensor cavity  304  and pushed into a testing position projecting out from the front end  14  of the housing  12 , the sensor actuator  40  engages the sensor  302  to hold the sensor  302  in the testing position and to couple the sensor  302  to the electronics assembly  62 . The front end  306  of the sensor is then inserted into a drop of blood to be tested, whereby the blood is analyzed by the electronics assembly  62 . The results of the analysis are then displayed on the liquid crystal display  64  of the sensor dispensing instrument  10 .  
         [0090]     Once the analysis of the blood is complete, the button release  66  on the upper case  18  is depressed so as to disengage the sensor actuator  40  and release the sensor  302 , which can be disposed of by tipping the front end  14  of the housing  12  downwardly.  
         [0091]     While the invention has been described with reference to details of the illustrated embodiment, these details are not intended to limit the scope of the invention as defined in the appended claims. For example, the sensor dispensing instrument  10  can be used for testing fluids other than blood glucose. In fact, the sensor dispensing instrument  10  can be used in connection with the analysis of any type of chemistry fluid that can be analyzed by means of a reagent material.