Abstract:
A system, method and biosensor apparatus are provided for data communications with a personal data assistant. The biosensor apparatus includes a sensor for receiving a user sample to be measured and a microcontroller for performing a predefined test sequence for measuring a predefined parameter value. An interface logic block is coupled to the microcontroller for communicating the predefined parameter data value to the personal data assistant. The personal data assistant provides an operator interface, data management and analysis of biosensor results.

Description:
This application claims the benefit of Provisional Application No. 60/211,964, filed Jun. 16, 2000. 
    
    
     FIELD OF THE INVENTION 
     The present invention generally relates to a biosensor, and, more particularly, to a new and improved system, method and biosensor apparatus for data communications with a personal data assistant. 
     DESCRIPTION OF THE PRIOR ART 
     The quantitative determination of analytes in body fluids is of great importance in the diagnoses and maintenance of certain physiological abnormalities. For example lactate, cholesterol and bilirubin should be monitored in certain individuals. In particular, the determination of glucose in body fluids is of great importance to diabetic individuals who must frequently check the level of glucose in their body fluids as a means of regulating the glucose intake in their diets, insulin intake and events. While the remainder of the disclosure herein will be directed towards the determination of glucose, it is to be understood that the procedure and apparatus of this invention can be used with other diagnostic systems. 
     Diagnostic systems, such as, blood glucose systems include a biosensor apparatus used to calculate the actual glucose value based on a measured output, such as, current or color, and the known reactivity of the reagent sensing element used to perform the test. The test results typically are displayed to the user and stored in a memory in the biosensor apparatus. 
     One known personal data assistant is a Palm™ handheld personal data assistant. It is desirable to provide a mechanism to enable the use a personal data assistant with a biosensor apparatus to eliminate the need for a user to manually enter data or go through a hook-up process to download measurements from a separate blood glucose monitor. A need exists for an efficient and effective mechanism to enable a biosensor to communicate with a personal data assistant. It is desirable to provide an improved method for storing and displaying information for use by a diabetic patient and also allows the user to augment stored glucose results by entering and storing insulin amounts and time as well as other relevant markers, for example, logbook capability. 
     SUMMARY OF THE INVENTION 
     An important object of the present invention is to provide a new and improved system, method and biosensor apparatus for data communications with a personal data assistant. Other important objects of the present invention are to provide such system, method and apparatus that eliminates or minimizes the need for user interaction; and to provide such method and apparatus substantially without negative effect; and that overcome some disadvantages of prior art arrangements. 
     In brief, a system, method and biosensor apparatus are provided for communications with a personal data assistant. The biosensor apparatus includes a sensor for receiving a user sample to be measured and a microcontroller for performing a predefined test sequence for measuring a predefined parameter value. An interface logic block is coupled to the microcontroller for communicating with the personal data assistant. The personal data assistant includes an interface logic block for communicating with the biosensor apparatus. The personal data assistant provides an operator interface, data management and analysis of biosensor results. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The present invention together with the above and other objects and advantages may best be understood from the following detailed description of the preferred embodiments of the invention illustrated in the drawings, wherein: 
     FIG. 1 is a block diagram representation of a system including a biosensor apparatus and a personal data assistant in accordance with the present invention; 
     FIG. 2 is a block diagram representation of a biosensor apparatus in accordance with the present invention of the system of FIG. 1; 
     FIG. 3 is a block diagram representation of a personal data assistant used with the biosensor apparatus of FIGS. 1 and 2 in accordance with the present invention; 
     FIG. 4 is a flow chart illustrating exemplary user interface operations of the personal data assistant of FIG. 3 in the system of FIG. 1 in accordance with the present invention; 
     FIG. 5 is a flow chart illustrating exemplary sequential timing steps performed by the biosensor apparatus of FIGS. 1 and 2 in accordance with the present invention; 
     FIGS. 6-13 are flow charts illustrating exemplary sequential steps performed by the personal data assistant of FIGS. 1 and 3 in accordance with the present invention; and 
     FIGS. 14-16 are flow charts illustrating exemplary sequential steps performed by the biosensor apparatus of FIGS. 1 and 2 in accordance with the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Having reference now to the drawings, in FIG. 1 there is illustrated a system designated as a whole by the reference character  10  and arranged in accordance with principles of the present invention. System  10  includes a biosensor apparatus  100  used together with a personal data assistant  200 . Personal data assistant  200  also is adapted for bi-directional communications with a host computer  300 . 
     In FIG. 2 there is illustrated the biosensor apparatus designated as a whole by the reference character  100  and arranged in accordance with principles of the present invention. Biosensor apparatus  100  includes a data acquisition circuit generally designated by the reference character  102  and a microcontroller section generally designated by the reference character  104 . Data acquisition circuit  102  includes a sensor  106  for receiving a blood sample from a user for performing a blood glucose test. A sensor drive input and a current input are applied to the sensor  106 . One of a pair of electrostatic discharge suppressors  108  and  109  is coupled respectively to the sensor drive input and the current input. A programmable voltage source  110  is coupled to an analog switching device  112 . A voltage reference VREF and an analog ground or common ACOM are applied to the programmable voltage source  110 . Analog switching device  112  is also coupled to a reference resistor  114  and a thermistor  116 . Both the reference resistor  114  and the thermistor  116  are also connected to a transimpedance amplifier  118 . Analog switching device  112  couples a drive voltage or open to the sensor  106  at the sensor drive input. The transimpedance amplifier  118  coupled to the sensor current input applies an input to an analog-to-digital converter (ADC) with threshold detection  120 . A voltage reference VREF and an analog ground or common ACOM are applied to the ADC with threshold detection  120 . A gain resistor  122  and a parallel, series connected shunt  124  and current shunt  126  are connected across the transimpedance amplifier  118 . Data acquisition circuit  102  includes a voltage reference and distribution block  128  to supply reference voltages to the rest of the system. The sensor detect input connects to the microcontroller  130 . 
     Microcontroller section  104  includes a microcontroller  130  receiving a voltage supply VCC input from the voltage reference and distribution block  128 . A meter and communications program  131  is used with the microcontroller  130  in accordance with features of the preferred embodiment. Microcontroller is coupled to the programmable voltage source  110  and the ADC with threshold detection  120 . Microcontroller section  104  includes an interface logic block  132  coupled between the microcontroller  130  and a module interface connector  134  enabling communications with the personal data assistant  200  of FIG.  2 . Microcontroller  130  contains suitable programming to perform the methods of the invention as illustrated in FIGS.  5  and  14 - 16 . 
     Referring to FIG. 3, the personal data assistant (PDA)  200  includes a processor section  202  and a user interface  204 . The processor section  202  includes a processor  206  together with a biosensor program  207  in accordance with features of the preferred embodiment. Processor section  202  contains suitable programming to perform the methods of the invention as illustrated in FIGS.  4  and  6 - 13 . The processor section  202  includes a PDA interface connector  208  enabling communications with the biosensor apparatus  100 . An interface logic block  210  is coupled between the PDA interface connector  208  and the processor  206 . An IR interface  212  and a RF interface  214  are coupled to the processor  206  for communications with a host computer  300 . It should be understood that the principles of the present invention are not limited to the use of connectors  134  and  208  of FIGS. 2 and 3. For example, the IR interface  212  could be used with an IR port (not shown) on the biosensor apparatus  100  for communications between the biosensor apparatus  100  and the PDA  200 . 
     PDA user interface  204  includes a touch sensitive display  220  coupled to the processor  206 . PDA user interface  204  includes a stylus  222  for providing user selections. PDA user interface  204  includes a plurality of switches or buttons  224  for providing user selections. 
     In accordance with the invention, the desired system behavior includes that the user attaches the biosensor apparatus  100  to the PDA  200 ; the users inserts a strip into the biosensor apparatus  100 ; the PDA  200  turns on if it is off; or if it is on immediately runs the biosensor program. Then the biosensor apparatus  100  and meter and communications program  131 , and PDA  200  and biosensor program  207 , run in test mode. 
     To enable the biosensor apparatus  100  to wake up the PDA  200  when a strip is inserted, an interrupt line of PDA  200  is used. The PDA Modem Hotsync program also uses this interrupt line. Therefore the PDA Modem Hotsync button is re-mapped to run the biosensor program  207  and not the Modem Hotsync program. This re-mapping is done by setting the modem hotsync button in the Preferences program, a PDA supplied application. This re-mapping is performed at installation time. The default mapping of the hotsync modem button is to run the Modem Hotsync program. 
     In order to allow a user to hotsync their PDA  200  with a modem and then to use the biosensor program  207  a check in the biosensor communciations program is performed to see if the test module biosensor apparatus  100  is attached to the PDA  200  or a modem is attached to the PDA  200 . When the biosensor program  207  starts up by the insertion of a test sensor strip, a check is done to see if the biosensor apparatus  100  is attached. If the biosensor apparatus  100  is attached then the biosensor communications program continues in Test mode. If the biosensor apparatus  100  is not attached then the biosensor program  207  terminates and the Modem Hotsync program is initiated. 
     After installation of the biosensor program  207 , if the user modifies the mapping of the modem hotsync button (by the Preferences program) or a hard reset is done on the PDA  200  (which puts the modem hotsync button back to its default) the biosensor program  207  will not run when a user inserts a strip into the test module attached to the PDA  200 . The logbook portion of the biosensor program  207  will still run because this program is started when the user taps on a predefined icon. The logbook portion is not started via the interrupt line. 
     If the user repeatedly inserts and removes a sensor without applying sample, the system will handle these multiple inserts thereby preventing the program from running multiple times. 
     FIG. 4 illustrate exemplary user interface operations of system  10  including the biosensor apparatus  100  of FIG.  1  and the personal data assistant  200  of FIG. 2 in accordance with the present invention. A logbook block  400  is provided for displaying historical data and a graphs block  402  enables analysis of results data and graphical display of the historical data. A download external meter data block  404  enables downloading of data stored in the biosensor apparatus  100 . A delete records block  406  enables the user to delete data records. A change user preferences block  408  enables the user to enter and update user preferences. An about block  410  is provided for displaying system information to the user. An edit/enter user-entered records block  412  is provided for the user to enter and edit records, such as insulin, event, blood, and the like. An edit meter records block  414  is provided for the user to edit records, meter and module records, such as markers, and the like. A waiting for application of sample block  416  enables the user to process a change in a code F# for a test strip and start a test. A test countdown block  418  displays a countdown for the user after a sample is applied to the test strip in the biosensor apparatus  100 . 
     FIG. 5 illustrates exemplary sequential timing steps performed by the biosensor apparatus  100  in accordance with the present invention. In accordance with features of the invention, steps are taken to keep power usage to a minimum. When the serial port is enabled a charge pump in the PDA  200 &#39;s RS232 interface chip uses a lot of power. To reduce power consumption the biosensor program  207  will briefly enable the serial port to monitor the clear to send (CTS) line. The CTS line is used to detect if the test module has been disconnected; to indicate when an error has occurred in the test module; to indicate when a sample has been applied to the test sensor; and to indicate a test complete. 
     In FIG. 5, a strip is inserted as indicated in a block  500 . Initial offset, reference and temperature readings are taken as indicated in a block  502 . Then waiting for a sample to be applied or threshold is performed as indicated in a block  504 . Then the CTS line is toggled from low to high as indicated in a block  506 . At a first set time, such as 16 seconds, an offset reading is taken as indicated in a block  508 . At a second set time, such as 14 seconds, a reference reading is taken as indicated in a block  510 . At a third set time, such as 12 seconds, a temperature reading is taken as indicated in a block  512 . At a fourth set time, such as 5 seconds, the voltage shunt  124  in the biosensor apparatus  100  is turned on as indicated in a block  514 . At a fifth set time, such as 1 second, the voltage shunt  124  in the biosensor apparatus  100  is turned off as indicated in a block  516 . Finally, at 0 seconds, the sensor reading is takes and a glucose reading is computed as indicated in a block  518 . The data is sent to the PDA  200  as indicated in a block  520 . Then the biosensor apparatus  100  is shutdown as indicated in a block  522 . 
     In accordance with features of the invention, steps are taken to maintain critical test timing. It is important to keep the user from wasting a strip. Because of the critical timing of the test countdown and the desire not to waste a strip, it is important to remain in the meter and communications program  131  while waiting for sample and during test countdown. Therefore external PDA  200  system interrupts are either ignored or delayed, for example, system timers, button presses, menu choices, or the power off button. Because the test timing is critical therefore the biosensor apparatus  100  handles all of the test timing and does not rely on the PDA  200 . To conserve power the biosensor apparatus  100  is only turned on when a strip is inserted. The biosensor apparatus  100  generates an interrupt to wake up the PDA  200  so that the PDA  200  does not need to be running prior to the insertion of a strip. When a test has completed or when an error has occurred the biosensor apparatus  100  is shutdown immediately after reporting its status to the PDA  200 . However, the PDA  200  will remain on. The system  10  has the capability of allowing the PDA  200  to wake up the biosensor apparatus  100  by asserting the data terminal ready (DTR) line. The communication protocol, as illustrated and described with respect to FIGS. 6-16, was designed to keep the power usage by both the PDA  200  and the biosensor apparatus  100  to a minimum. 
     FIGS. 6-13 are flow charts illustrating exemplary sequential steps performed by the personal data assistant  200  in accordance with the present invention. Referring to FIG. 6, PDA  200  waits for a message B from the biosensor apparatus  100  or timeout as indicated in a block  600 . The message B provides a software version number and reference method for the biosensor apparatus  100 . Checking whether message B has arrived is performed as indicated in a decision block  602 . If message B has not arrived, then the biosensor application is terminated as indicated in a block  604 . Then the modem hotsync application is run as indicated in a block  606 . When the message B has arrived, then a message C is sent to the biosensor apparatus  100  as indicated in a block  608 . The message C is a query for a type of test strip. Next waiting for a message D from the biosensor apparatus  100  or a timeout is performed as indicated in a block  610 . Checking whether message D has arrived is performed as indicated in a decision block  612 . If message D has not arrived, then an error message is displayed as indicated in a block  614 . Next waiting for the user to tap an OK button is performed as indicated in a block  616 . Then the logbook screen is displayed as indicated in a block  618 . If message D has arrived, then checking for a type of message D is performed as indicated in a block  620 . With an error message, sequential operations continue following entry point A in FIG.  7 . With a test strip message, sequential operations continue following entry point B in FIG.  7 . With a code strip message, sequential operations continue following entry point C in FIG.  12 . 
     Referring to FIG. 7 following entry point A, an error from the module biosensor apparatus  100  is processed as indicated in a block  702 . An error message is displayed as indicated in a block  704 . Waiting for user to tap an OK button is performed as indicated in a block  706 . Then the logbook screen is displayed as indicated in a block  708 . Otherwise for a test strip message following entry point B, the test strip message is processed as indicated in a block  710 . Checking whether the battery in the biosensor apparatus is dead is performed as indicated in a decision block  712 . If the battery is dead, then an error message is displayed as indicated in a block  714 . Waiting for user to tap an OK button is performed as indicated in a block  716 . Then the logbook screen is displayed as indicated in a block  718 . If the battery is not dead, then checking whether the temperature is out of range as indicated in a decision block  720 . If the temperature is out of range, then an error message is displayed as indicated in a block  722 . Waiting for user to tap an OK button is performed as indicated in a block  724 . Then the logbook screen is displayed as indicated in a block  726 . If the temperature is in range, then a test screen is displayed with a blinking blood drop and enabling the user to change the test strip code F# as indicated in a block  728 . Then the sequential operations continue following entry point D in FIG.  8 . 
     Referring to FIG. 8, following entry point D checking for a low battery status is performed as indicated in a decision block  802 . If a low battery is identified, then a low battery indicator is displayed as indicated in a block  804 . Next checking for a marginal temperature status is performed as indicated in a decision block  806 . If a marginal temperature is identified, then a marginal temperature indicator is displayed as indicated in a block  808 . Then the CTS line is monitored on a set time interval, such as every ¼ second as indicated in a block  810 . Waiting for a timeout, such as 3 minutes or the CTS line to go low; with a user applied sample or an error for the module disconnected from the PDA as indicated in a block  812 . Checking whether the CTS line is low is performed as indicated in a decision block  814 . If the CTS line is not low, then an error message is displayed as indicated in a block  816 . Waiting for user to tap an OK button is performed as indicated in a block  818 . Then the logbook screen is displayed as indicated in a block  820 . If the CTS line is low, then a message E is sent to query the biosensor apparatus whether the test has started as indicated in a block  822 . Then waiting for a message F from the biosensor apparatus or a timeout is performed as indicated in a block  824 . Checking whether message F has arrived is performed as indicated in a decision block  826 . When the message F is not identified, then an error message is displayed as indicated in a block  828 . Waiting for the user to tap OK button is performed as indicated in a block  830 . Then the logbook screen is displayed as indicated in a block  832 . When the message F is identified, then the sequential operations continue following entry point E in FIG.  9 . 
     In FIG. 9, a type of message F is identified as indicated in a block  902 . An error from the module is processed as indicated in a block  904 . An error message is displayed as indicated in a block  906 . Waiting for user to tap an OK button is performed as indicated in a block  908 . Then the logbook screen is displayed as indicated in a block  910 . Otherwise for a test started message is processed as indicated in a block  912 . A test countdown screen is displayed as indicated in a block  914 . The CTS line is monitored, for example every quarter second as indicated in a block  916 . Then waiting for a timeout, such as 35 seconds or the CTS line to go low for a completed test, an error in the module, or module disconnected from the PDA is performed as indicated in a block  918 . Then checking whether the CTS line is low is performed as indicated in a decision block  920 . If the CTS line is not low, then an error message is displayed as indicated in a block  922 . Waiting for user to tap an OK button is performed as indicated in a block  924 . Then the logbook screen is displayed as indicated in a block  926 . If the CTS line is low, then a message G is sent as indicated in a block  928 . Message G is a command and data message type for storing the F# (program #) in the biosensor apparatus. Sequential operations continue following entry point F in FIG.  10 . 
     Referring to FIG. 10, next a message H is sent to query the module for the test value as indicated in a block  1000 . Waiting for a message I response and the test value data is performed as indicated in a block  1002 . Checking whether the message I has arrived is performed as indicated in a decision block  1004 . When the message I has not arrived, then an error message is displayed as indicated in a block  1006 . Waiting for user to tap an OK button is performed as indicated in a block  1008 . Then the logbook screen is displayed as indicated in a block  1010 . When the message I has arrived, then the type of message I is identified as indicated in a block  1012 . An error from the module is processed as indicated in a block  1014 . Then an error message is displayed as indicated in a block  1016 . Waiting for user to tap an OK button is performed as indicated in a block  1018 . Then the logbook screen is displayed as indicated in a block  1020 . Otherwise, a glucose value is processed as indicated in a block  1022 . Next checking whether the module battery is dead is performed as indicated in a block  1024 . If the module battery is dead, then an error message is displayed as indicated in a block  1026 . Waiting for user to tap an OK button is performed as indicated in a block  1028 . Then the logbook screen is displayed as indicated in a block  1030 . If the module battery is not dead, then checking whether the module temperature is out of range as indicated in a decision block  1032 . If the module temperature is out of range, then sequential operations continue following entry point G in FIG.  11 . If the module temperature is not out of range, then sequential operations continue following entry point H in FIG.  11 . 
     Referring to FIG. 11, following entry point G an error message is displayed as indicated in a block  1102 . Waiting for user to tap an OK button is performed as indicated in a block  1104 . Then the logbook screen is displayed as indicated in a block  1106 . Following entry point H the glucose value is displayed as indicated in a block  1108 . Checking for a low battery is performed as indicated in a decision block  1110 . If a low battery is identified, then a low battery indicator is displayed as indicated in a block  1112 . Checking for a marginal temperature is performed as indicated in a decision block  1114 . If a marginal temperature is identified, then a marginal temperature indicator is displayed as indicated in a block  1116 . Next waiting for the user to tap a DONE button is performed as indicated in a block  1118 . The glucose record is stored as indicated in a block  1120 . Then the logbook screen is displayed as indicated in a block  1122 . 
     Referring to FIG. 12, following entry point C after a code strip message type is identified at block  620  in FIG. 6, the code strip message is processed as indicated in a block  1202 . Checking whether the battery in the biosensor apparatus is dead is performed as indicated in a decision block  1204 . If the battery is dead, then an error message is displayed as indicated in a block  1206 . Waiting for user to tap an OK button is performed as indicated in a block  1208 . Then the logbook screen is displayed as indicated in a block  1210 . If the battery is not dead, then checking whether the temperature is out of range as indicated in a decision block  1212 . If the temperature is out of range, then an error message is displayed as indicated in a block  1214 . Waiting for user to tap an OK button is performed as indicated in a block  1216 . Then the logbook screen is displayed as indicated in a block  1218 . If the temperature is not out of range, then a test screen is displayed without the blinking blood drop and without enabling the user to change the test strip code F# as indicated in a block  1220 . Then the sequential operations continue following entry point I in FIG.  13 . 
     Referring to FIG. 13, following entry point I checking for a low battery status is performed as indicated in a decision block  1302 . If a low battery is identified, then a low battery indicator is displayed as indicated in a block  1304 . Next checking for a marginal temperature status is performed as indicated in a decision block  1306 . If a marginal temperature is identified, then a marginal temperature indicator is displayed as indicated in a block  1308 . Waiting for a timeout; the user to turn off the PDA; or the user to select another application is performed as indicated in a block  1312 . Then the display returns to the logbook screen as indicated in a block  1314 . Then the user turns off the PDA or runs another application as indicated in a block  1316 . 
     FIGS. 14-16 are flow charts illustrating exemplary sequential steps performed by the biosensor apparatus  100  in accordance with the present invention. Referring to FIG. 14, first the biosensor apparatus  100  sends a message B to the PDA as indicated in a block  1402 . Message B provides a software version number. The biosensor apparatus  100  waits for the message C, query for type of test strip, from the PDA or a timeout as indicated in a block  1404 . Checking whether message C has arrived is performed as indicated in a decision block  1406 . When message C has not arrived, then the biosensor apparatus  100  is shut down as indicated in a block  1408 . When message C has arrived, then the biosensor apparatus  100  sends message D as indicated in a block  1410 . When an error and error code is sent as indicated in a block  1412 , then the biosensor apparatus  100  is shut down as indicated in a block  1414 . When a code strip response is sent as indicated in a block  1416 , then the biosensor apparatus  100  is shut down as indicated in a block  1418 . When a test strip response is sent as indicated in a block  1420 , then the CTS line is set to high as indicated in a block  1422 . Then the biosensor apparatus  100  waits for a timeout, such as after three minutes or for the user to apply a sample as indicated in a block  1424 . Checking for a user applied sample is performed as indicated in a decision block  1426 . When a user applied sample is not identified, then the biosensor apparatus  100  is shut down as indicated in a block  1428 . When a user applied sample is identified, then the sequential operations continue following entry point J in FIG.  15 . 
     Referring to FIG. 15, after a user applied sample is identified, then the CTS line is set low as indicated in a block  1502 . Then the biosensor apparatus  100  waits for a message E or a timeout after a set number of seconds as indicated in a block  1504 . Checking whether message E has arrived is performed as indicated in a decision block  1506 . When message E has not arrived, then the biosensor apparatus  100  is shut down as indicated in a block  1508 . When message E has arrived, then the biosensor apparatus  100  sets the CTS line high as indicated in a block  1510 . The biosensor apparatus  100  sends a message F to the PDA as indicated in a block  1512 . Message F provides an error as indicated in a block  1514 . Then the biosensor apparatus  100  is shut down as indicated in a block  1516 . Message F indicates that the test has started as indicated in a block  1518 . Next the biosensor apparatus  100  waits for the test to complete, or the user to remove sensor or an error to occur as indicated in a block  1520 . Then the biosensor apparatus  100  sets the CTS line low as indicated in a block  1522 . Next the biosensor apparatus  100  waits for a message G or timeout as indicated in a block  1524 . Then the sequential operations continue following entry point K in FIG.  16 . 
     Referring to FIG. 16, checking whether message G has arrived is performed as indicated in a decision block  1602 . When message G has not arrived, then the biosensor apparatus  100  is shut down as indicated in a block  1604 . When message G has arrived, then the biosensor apparatus  100  stores the test strip code F# as indicated in a block  1606 . Next the biosensor apparatus  100  waits for a message H from the PDA or a timeout as indicated in a block  1608 . Message H is a query for the test value. Checking whether message H has arrived is performed as indicated in a decision block  1610 . When message H has not arrived, then the biosensor apparatus  100  is shutdown as indicated in a block  1612 . When message H has arrived, then the biosensor apparatus  100  sends a message I as indicated in a block  1614 . Message I provides an error as indicated in a block  1616 . Then the biosensor apparatus  100  is shut down as indicated in a block  1618 . Message I indicates a glucose value as indicated in a block  1620 . Then the biosensor apparatus  100  is shut down as indicated in a block  1622 . 
     While the present invention has been described with reference to the details of the embodiments of the invention shown in the drawings, these details are not intended to limit the scope of the invention as claimed in the appended claims.