Abstract:
A coding module, a sensing meter and a sensing system are provided in the present application. The coding module is used to define a code for ciphering a parameter value employed in controlling an operation of the sensing meter. The code is exhibited by an electrical component having a determined characteristic, preferably, a resistance value.

Description:
FIELD OF THE INVENTION  
       [0001]     The invention mainly relates to a sensing meter for determining a presence of an analyte in a biological sample, and, more particularly, to a sensing meter whose operation is controlled by a code provided by a removable and pluggable coding module. The invention further relates to a removable coding module for the sensing meter and used for receiving a sample strip. The coding module defines at least one code, and the code ciphers at least one parameter value that is employed in controlling the operation of the sensing meter.  
       BACKGROUND OF THE INVENTION  
       [0002]     Sensing meters for detecting substances contained in the blood to be analyzed, such as glucose or cholesterol, normally include a disposable sample strip. The disposable sample strip has a reaction zone to allow blood placed thereon. The relevant operations of the sensing meter are controlled by a microprocessor. By execution of various procedures, analysis results of the measurement could be obtained.  
         [0003]     Nevertheless, it is normally necessary to calibrate the instrumentation used in connection with test device (such as the bio sensing meter) in order to compensate the variations on the sample strips manufactured in different batches. Various techniques have been suggested for encoding information into the sample strip, such as U.S. 5,053,199 and references cited therein. In the prior arts, the technique for encoding information includes a usage of the electronically encoded information on a carrier having an optical bar code, a magnetizable film, a perforated strip, a fluorogens or an electrically conductive medium on a foil. The conventional sample strips are always furnished with an information code, which costs an additional and expensive effort for a disposable device.  
         [0004]     In addition, the conventional sensing meter uses an additional coding module or a code key designed and inserted into a receptacle similar to the slot for the sample strip. While performing a measurement, a code key has to be inserted in the sensing meter all the time for the same batch of sample strips. According to the data and the code provided by the coding module, i.e. the code key, the operation procedure and parameter are selected and a correct measurement result could be obtained.  
         [0005]     U.S. Pat. No. 5,366,609 and documents cited therein disclosed the bio sensing meters having pluggable coding modules that enable reconfiguration of the test procedures and parameters employed by the sensing meters. Threshold potentials, test times, delay periods and other pertinent test procedures and constants may be entered and/or altered.  
         [0006]     The main purpose of the coding module is to provide information about the type of sample strip. Therefore, for each new batch of sensor strips, new related information is needed. In order to perform the sample measurement and the analysing routines, the sensing meter needs certain parameter values which determine thresholds, time intervals, control numbers and calibration curve attributes. The controlling process could be named as measurement method, and when a parameter of the controlling process is changed, it could be considered as a different measurement method. As sample strips are disposable, preferably coding modules are disposable too. Nevertheless, costs for the coding modules are always the effecting factors.  
         [0007]     As above, a new invention capable of overcoming the drawbacks of the prior arts, especially avoiding the usage of memory IC chip technology for storing codes on coding modules, providing a coding module and a bio sensing meter with pluggable coding module, which has a simple design, and being produced with lower costs is expected at present.  
       SUMMARY OF THE INVENTION  
       [0008]     In accordance with the present invention a coding module is presented, which includes at least one code, wherein the at least one code is exhibited by a parameter value of at least one electrical component having a determined characteristic, preferably a resistor, a switch or a capacitor.  
         [0009]     Electrical components can have various measurable characteristics, such as electrical characteristics, e.g. resistance, capacitance or impedance. The advantage of using electrical characteristics of a component for encoding information is that no additional measurement device, for example an optical or magnetic detector, is necessary in the relevant sensing meter. Usually the sensing meter provides means for performing a voltage and/or current measurement for analyzing the analyte concentration, the same measurement tools can be used for reading the code. Electrical components such as resistances are not expensive.  
         [0010]     It is a simple technique suitable for coding information to measure a resistance, like in the present case, where e.g. only one code number or a few parameter values have to be identified. Contrary to the state of the art IC chip technology, no integrated circuits are needed. Macroscopic electrical components can be used.  
         [0011]     Preferably, the coding module of the present application includes at least a resistor, which is inexpensive and can be measured easily. A resistor is a simple implementation of non-volatile information carrier. Since a broad variety of standard resistor is available, a big number of codes can be exhibited only by the value of the relevant resistances. A greater number of possibilities for encoding could be achieved, when the at least one code is exhibited by a plurality of resistances, e.g. one to six, preferably four resistances.  
         [0012]     It is turned out that 2 different resistance values on four to seven places, resulting in 16 to 24 different codes, provide enough information to control the analysing process.  
         [0013]     Preferably, the code contains information regarding the sample strip batch. Sample strips should always be used with a relevant coding module. In order to reduce the error rate and to protect the slot of the sensing meter from a contamination resulting from the analyte or a biologic sample, in a preferred embodiment, the coding module has a receptacle serving as a sample strip.  
         [0014]     Usually, the sample strip includes a plurality of electrodes, for applying and/or measuring a voltage and/or a current.  
         [0015]     In a preferred embodiment of the present application, the coding module includes means for establishing an electrical contact between the sensing meter and the sample strip.  
         [0016]     The coding module allows for a direct connection of the sample strip electrodes and the contacts of the sensing meter, for example by providing a recess or a hole in the area of the connection zone.  
         [0017]     Alternatively, the coding module may have contacts connecting the sample strip electrodes with the sensing meter contacts. According to another aspect of the present invention, a sensing meter is provided in connection with a pluggable coding module with at least one code. The sensing meter has an electrical receptacle serving as a pluggable coding module and includes means for receiving information from the coding module defining at least one code. The code is exhibited by at least one electrical component having a determined characteristic, preferably a resistance.  
         [0018]     The coding module is preferably of the above described type, wherein the code is exhibited by at least one, typically one to six, in particular four resistances and/or selected from a variety of different resistances. The at least one resistance can also be formed by at least one resistor. The sensing meter is provided with information about the sample batch by the code on the coding module.  
         [0019]     The code can be a simple binary code, exhibited by one or more resistances interpreted as one of two sets of parameter values stored in the sensing meter or defining a binary code. Each resistance forms a bit. The encoding can be made more complex by using a wider range of resistance values or a bigger number of resistances.  
         [0020]     In a preferred embodiment, the parameter value is correlated to the value of the at least one resistance. The parameter may also be encoded by the value and the order of at least two resistances, in particular by the order of four resistance values. In a preferred embodiment, the coding module only hosts the code exhibited by the resistances. The value of the at least one resistance and/or the order of at least two resistances could be detected by a microprocessor routine performed by the sensing meter.  
         [0021]     The generation of the code based on the resistance measurements and the translation of the code into parameter values are performed by the sensing meter. The coding module is only a carrier of the code. The sensing meter has the capability of reading the code, decoding and using the information.  
         [0022]     The code can be derived from the resistance measurement by correlating the measured values, such as the resistances, currents or voltages, with code numbers. The code can also be formed by the resistance values. The parameter values can be derived from the code by a microprocessor routine.  
         [0023]     In a preferred embodiment the at least one code is decoded by extracting parameter values via using a look-up table stored in a memory of the sensing meter.  
         [0024]     This memory can be a read only memory. It can also be exchangeable or it can be rewritable, so that the look-up table can be exchanged or updated accordingly.  
         [0025]     The sensing meter may have different receptacles for the sample strips, the coding module and a calibration module.  
         [0026]     In a preferred embodiment of the present application, the electrical receptacle is able to accept the coding module and is also able to accept the calibration module.  
         [0027]     A single electrical receptacle is user friendly because of the less error possibility, and electrical circuits can be framed more effectively.  
         [0028]     A further concept is achieved by providing a coding module having a receptacle able to accept sample strip.  
         [0029]     Accordingly, the receptacle able to accept the coding module is also a receptacle for the sample strip, without the direct contact with the sample strip.  
         [0030]     For sample strips including electrodes, the coding module enables the electrical coupling between the sensing meter and sample strips.  
         [0031]     According to a further aspect of the present application, a sensing system for analysing an analyte is provided. The sensing system includes a coding module with at least one code, preferably of the above described type and a sensing meter, preferably of the above described type, with means for receiving the at least one code from the coding module. The code ciphers at least one parameter value used in controlling the operation of the sensing meter, for example in controlling the execution of an algorithm performed by the sensing meter that enables a determination of an analyte concentration value. The at least one code is exhibited by at least one electrical component having a determined characteristic, e.g. a resistance.  
         [0032]     According to a further aspect of the present application, a sensing test set is provided. The sensing test set includes at least one test strip and a coding module with at least one code, preferably of the above described type, pluggable into a sensing meter.  
         [0033]     The at lease one code ciphers at least one parameter value used in controlling the operation of the sensing meter, for example in controlling the execution of an algorithm performed by the sensing meter that enables a determination of an analyte concentration value. The at least one code is exhibited by at least one electrical component having a determined characteristic, e.g. a resistance.  
         [0034]     Usually, a sensing test set having one coding module and a plurality of sample strips form a commercial unit which is sold together in one package.  
         [0035]     According to a further aspect of the present application, a method for operating a sensing meter, preferably of the above described type, is provided. The method including the steps of (i) inserting a coding module with at least one code into the sensing meter, (ii) detecting the at least one code, (iii) determining at least one parameter value used for controlling an operation of the sensing meter, (iv) inserting a sample strip and adding a sample thereon, (v) analysing the sample on the basis of the at least one parameter value, whereby the at least one code is exhibited by at least one electrical component having a determined characteristic, e.g. a resistance.  
         [0036]     The above contents and the advantages of the present invention will become more readily apparent to those ordinarily skilled in the art after reviewing the following detailed descriptions and accompanying drawings, in which: 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0037]      FIG. 1  is a perspective view of an example of a bio sensing meter according to a preferred embodiment of the present application;  
         [0038]      FIG. 2   a  is a perspective bottom view of a coding module according to a preferred embodiment of the present application;  
         [0039]      FIG. 2   b  is a perspective top view of a coding module according to a preferred embodiment of the present application;  
         [0040]      FIG. 3   a  is an exploded top view of a coding module according to a preferred embodiment of the present application;  
         [0041]      FIG. 3   b  is exploded bottom view of a coding module according to a preferred embodiment of the present application;  
         [0042]      FIG. 4  shows the relation between analyte concentration and a measuring current according to a preferred embodiment of the present application;  
         [0043]      FIG. 5   a  is a schematic representation of a first embodiment of the present invention;  
         [0044]      FIGS. 5   b  and  5   c  are different tables showing coding information according to the first preferred embodiment of the present application;  
         [0045]      FIG. 6   a  is a schematic representation of a second embodiment of the present invention;  
         [0046]      FIGS. 6   b  and  6   c  show tables with coding information according to the second preferred embodiment of the present application; and  
         [0047]      FIG. 7  is a schematic representation of a third embodiment of the present invention. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0048]     The present invention will now be described more specifically with reference to the following embodiments. It is to be noted that the following descriptions of preferred embodiments of this invention are presented herein for purpose of illustration and description only; it is not intended to be exhaustive or to be limited to the precise form disclosed.  
         [0049]     Please refer to  FIG. 1 , which is a bio sensing meter according to a preferred embodiment of the present application. The bio sensing meter  10  has a display  12 , and is able to get in contact with a disposable sample strip  18 . The sample strip  18  has conductive electrodes (not shown). An enzymatic reactant layer (not shown) is formed in the reaction zone to cover the electrodes. An analyte-containing fluid, for example, a drop of blood, can be dripped on the substance entrance  20 .  
         [0050]     The bio sensing meter  10  further has a plug-in coding module  30 , which is inserted into a slot  14  of the bio sensing meter  10  to be electrically connected thereto and to establish a mutual communication therebetween.  
         [0051]     The coding module  30  has a receptacle  46  able to accept the sample strip  18 .  
         [0052]     The coding module  30  is electrically connected between the bio sensing meter  10  and the sample strip  18 . When the coding module  30  is plugged into the slot  14  of the bio sensing meter  10 , contacts  52  of the bio sensing meter  10  would be electrically contacted with the electrodes of the sample strip  18  inserted in the coding module  30 .  
         [0053]     The coding module  30  contains electrical components not explicitly shown in  FIG. 1 , which are connectable to the contacts  56  of the bio sensing meter  10 .  
         [0054]     Alternatively, the bio sensing meter  10  may have two slots, one for accepting the sample strip  18  and a further one for accepting the coding module  30 .  
         [0055]     Please refer to  FIGS. 2   a  and  2   b , where the coding module  30  is shown therein.  
         [0056]     Please refer to  FIGS. 1, 2   a - 2   b ,  3   a  and  3   b , after the coding module  30  is inserted into the bio sensing meter  10 , the contacts  56  of the bio sensing meter  10  are in connection with contacts  36 , such that the resistance values of the resistors  32   a ,  32   b ,  32   c  and  32   d  (see  FIG. 3   a ) can be detected. The coding module  30  has to be inserted in the bio sensing meter  10  at least once before the relevant measurement or permanently.  
         [0057]     The contacts  34  of the coding module  30  get in contact with the contacts  52  of the bio sensing meter  10  so that characteristics of the sample on the sample strip  18  can be measured.  
         [0058]     The chemistries used for the sample strips and analyte determination algorithms are known in the art. They will not be described in detail hereinafter.  
         [0059]     As an example, the analyte-containing sample may be a drop of blood that is subjected to a glucose determination. A disposable sample strip for a glucose determination will include, in a reaction zone, chemical reagents, basically an enzyme, such as a glucose oxidase and a redox mediator, such as a potassium ferricyanide.  
         [0060]     As shown in  FIG. 2   b , within the receptacle  46 , there are contacts  44  which are electrically connected to the contacts  34 . Upon an insertion of the sample strip  18  in the receptacle  46 , the electrodes (not shown) of the sample strip  18  get in contact with the contracts  44 .  
         [0061]      FIGS. 3   a  and  3   b  show an upper and lower exploded view of the coding module  30 . The coding module  30  is formed by a upper part  30   a  and a lower part  30   b . A printed circuit board  31  is arranged between the upper part  30   a  and the lower part  30   b . Resistors  32   a ,  32   b ,  32   c  and  32   d  are arranged on the printed circuit board  31  and are able to cipher a code as will be described hereinafter. Contacts  44  are arranged between the printed circuit board  31  and the upper part  30   a . Springs  45  are arranged on spring contact pads  43 . The springs  45  are used to hold the contacts  44  in good contacts against the electrodes of the sample strip  18 .  
         [0062]     Please refer to  FIG. 3   b  showing an exploded bottom view of the coding module  30 . The bottom part  30   b  is provided with a lock  33  for positioning and holding the coding module  30  in the bio sensing meter  10 . The bottom part  30   b  includes holes  35  through which the contacts  34  and  36  of the printed circuit board  31  may be in contact the contacts  52 ,  56  of the bio sensing meter  10  (referring to  FIG. 1 ). The upper part  30   a  and the lower part  30   b  are formed of a plastic material, typically in an injection moulding.  
         [0063]      FIG. 4  shows a diagram of a curve of the concentration of the analyte in the sample, in particular the glucose in the blood, in relation to the measuring currents determined by the bio sensing meter. The concentration linearly depends on the measuring current. The concentration may be given by the formula Y=AX−B. The parameters A and B, however, depend on several conditions, in particular on the reactant composition which is used. Depending on the manufacturing process and depending on specific reactant compositions of the different batches of sample strips, different slopes (factor A) and different off-sets (factor B) may be applicable. The different relations are characterised by several codes C 1 , C 2 , . . . Cn which are associated to specific manufacturing batches. The coding module according to the present application in particular may be used for coding the codes C 1  to Cn. It may, however, also be used for coding different analyte types or different measurement methods.  
         [0064]      FIG. 5   a  shows a schematic view of a bio sensing meter  10  with a coding module  30  according to the present invention and with a test sample strip  18 . The bio sensing meter  10  includes the standard components, such as a microprocessor with a central processing unit, a read-only memory (ROM) and a random accessible memory (RAM), a display, a current measuring unit, an electrode working voltage supply unit (not shown) and a temperature measuring unit. These components are standard in state of the relevant art devices. In addition, the bio sensing meter  10  further includes a resistance measuring unit  60  which on the one hand is in operative connection with the coding module  30 . The resistors  32   a  to  32   n  have specific resistance values R 1 , R 2 , . . . Rn and cipher certain codes as will be shown hereinafter. The determination of the resistance value is made in a manner known to one skilled in the art, in particular by measuring a current flowing through the relevant resistor if a pre-defined potential is applied to the resistor. Analog/digital converters are used to transmit the resistance values to the microprocessor.  
         [0065]     The contacts  36  on the coding module  30  get in electrical contact with the contacts  56  on the bio sensing meter  10 . In a similar manner, contacts  52  of the bio sensing meter  10  are brought into electrical contact with the contacts  34  of the coding module  30  and consequently with the pins  40  and the electrodes of the sample strip  18 .  
         [0066]      FIG. 5   b  shows a resistor table. If only one single resistor is used, different resistance values may be used for defining several codes, in particular codes for different linear relationships as shown in  FIG. 4 . Typically, one hundred different code values may be encoded with resistance values in the range between 0 KΩ (short circuit) and 910 KΩ. In addition, one further code may be defined by an open circuit.  
         [0067]     Instead of directly coding certain codes, it is also possible to code the parameter values A, B of the linear relationship as shown in  FIG. 4 .  FIG. 5   c  shows a table where four different resistors are used for defining four codes. A quadruplet of resistance values is used to define specific values for the parameters A, B. For example, the resistance value sequence 150 KΩ/68 K Ω/51 KΩ/68 KΩ is used to define a slope A of 0.75 and a off ser B of −45.  
         [0068]     Furthermore, it is also possible to code different calculations or measurement methods. Typically, incubation times or other process parameters may depend on a batch of the sample strips. Therefore, several, such as ten, standard measurement methods may be used.  FIG. 5   d  shows a table where different resistance values between 10 KΩ and 390 KΩ are used to code for one of the ten several standard measurement methods.  
         [0069]     Please refer to  FIGS. 5   a  to  5   e . The first resistor  32   a  shown in  FIG. 5   a  could be used for coding the code values shown in  FIG. 5   b  and the second resistor  32   b  could be used for coding the method shown in  FIG. 5   d.    
         [0070]     In an alternative embodiment, it is also possible to code different analyte types with a coding module  30 . In the table shown in  FIG. 5   e , three different analyte types are coded in context with a plurality of measurement methods by the use of eight different resistance values.  
         [0071]      FIG. 6   a  shows an alternative embodiment for a coding module  30 . The sample strip  18  and the sensing meter  10  are built identically to the one shown in  FIG. 5   a . For coding, instead of resistances having different values, a plurality of open or short circuits are used. These open or short circuit connections L 1 , L 2 , . . . Ln or switch code values such as “1” or “0” form a binary code. Such open or short circuit connections may be easily arranged on the PCB layout. The determination of the resistance value is made in a similar way as explained with reference to  FIG. 5   a.    
         [0072]      FIG. 6   b  shows a table where different calibration formulas according to 16 different codes are coded with a 4-bit arrangement of open or short circuit connections defining code  1 , code  2 , code  3  and code  4 . Four binary codes allow the definition of 16 different calibration formulas.  
         [0073]     In  FIG. 6   c , a method code of 3 bit coding for coding different analyte types or methods is shown. Three additional open or short circuit connections L 5 , L 6  and L 7  define six further codes which may describe eight combinations of the analyte and measurement methods.  
         [0074]      FIG. 7  shows a coding module according to another preferred embodiment of the present application. Instead of resistors as shown in  FIG. 5   a , capacitors  62   a ,  62   b  . . .  62   n  having different capacitances C 1 , C 2 , . . . C n  are used for defining a code. Instead of a resistance measurement unit as shown in  FIG. 5   a , a capacitance measuring unit  64  is used in the embodiment as shown in  FIG. 7 . Capacitance to frequency converters are used for providing a coding signal to the microprocessor.  
         [0075]     Coding module  30  thus may include a variety of data that are used in operation of bio sensing meter  10 . Those data encompass, such as measurement delay times, the incubation time, the number of measurements to be taken during a measurement period, thresholds against which voltage levels are to be compared, values of excitation voltage levels to be applied to sample strip  18  during a test procedure, and the glucose value conversion factors. In addition, although the above preferred embodiments relate to the bio sensing meter, it should be noted that the present application could also relate to other sensing meter and system.  
         [0076]     While the invention has been described in terms of what is presently considered to be the most practical and preferred embodiments, it is to be understood that the invention needs not be limited to the disclosed embodiment. On the contrary, it is intended to cover various modifications and similar arrangements included within the spirit and scope of the appended claims which are to be accorded with the broadest interpretation so as to encompass all such modifications and similar structures.