Orientation independent meter

An analyte meter with a test strip port that detects an orientation of a test strip inserted therein. A control circuit of the test meter is configured to apply a first predetermined analyte measurement signal to a test strip electrode in response to detecting a first orientation of the test strip, and a second predetermined analyte measurement signal to the same, or a different, electrode in response to detecting a second orientation of the test strip.

TECHNICAL FIELD

This application generally relates to the field of blood analyte measurement systems and more specifically to portable analyte meters that are configured to detect an orientation of a test strip inserted therein and to correctly adjust a test signal applied thereto in response to the detected orientation.

BACKGROUND

Blood glucose measurement systems typically comprise an analyte meter that is configured to receive a biosensor, usually in the form of a test strip. Because many of these systems are portable, and testing can be completed in a short amount of time, patients are able to use such devices in the normal course of their daily lives without significant interruption to their personal routines. A person with diabetes may measure their blood glucose levels several times a day as a part of a self management process to ensure glycemic control of their blood glucose within a target range. A failure to maintain target glycemic control can result in serious diabetes-related complications including cardiovascular disease, kidney disease, nerve damage and blindness.

There currently exist a number of available portable electronic analyte measurement devices that are designed to automatically activate upon insertion of a test strip. Electrical contacts, or prongs, in the meter establish connections with contact pads on the test strip while a microcontroller in the meter determines, based on electrical signals from the test strip, whether the test strip is properly inserted. Unless the test strip is properly inserted in a proper orientation, however, the device will not activate or, in addition, it may display an error message until the test strip is properly reinserted. This effort may present difficulty for some users who might struggle to correctly orient the test strip prior to insertion, particularly if the test strip is small.

MODES OF CARRYING OUT THE INVENTION

As used herein, the terms “patient” or “user” refer to any human or animal subject and are not intended to limit the systems or methods to human use, although use of the subject invention in a human patient represents a preferred embodiment.

The term “sample” means a volume of a liquid, solution or suspension, intended to be subjected to qualitative or quantitative determination of any of its properties, such as the presence or absence of a component, the concentration of a component, e.g., an analyte, etc. The embodiments of the present invention are applicable to human and animal samples of whole blood. Typical samples in the context of the present invention as described herein include blood, plasma, red blood cells, serum and suspensions thereof.

The term “about” as used in connection with a numerical value throughout the description and claims denotes an interval of accuracy, familiar and acceptable to a person skilled in the art. The interval governing this term is preferably ±10%. Unless specified, the terms described above are not intended to narrow the scope of the invention as described herein and according to the claims.

FIG. 1Aillustrates an analyte measurement system100that includes an analyte meter10. The analyte meter10is defined by a housing11that retains a data management unit (“DMU”)140and further includes a port22sized for receiving a biosensor. According to one embodiment, the analyte meter10may be a hand held blood glucose meter and the biosensor is provided in the form of a test strip24inserted into test strip port22for performing blood glucose measurements. The analyte meter10further includes a plurality of user interface buttons16, and a display14as illustrated inFIG. 1A. A predetermined number of glucose test strips may be stored in the housing11and made accessible for use in blood glucose testing. The plurality of user interface buttons16are associated with the DMU140and can be configured to allow the entry of data, to prompt an output of data, to navigate menus presented on the display14, and to execute commands. Output data can include values representative of analyte concentration presented on the display14. Input information may include information related to the everyday lifestyle of an individual, such as food intake, medication use, occurrence of health check-ups, and general health condition and exercise levels of an individual. These inputs can be requested via prompts presented on the display14and can be stored in a memory module of the analyte meter10. Specifically and according to this exemplary embodiment, the user interface buttons16include markings, e.g., up-down arrows, text characters “OK”, etc, which allow a user to navigate through the user interface presented on the display14. Although the buttons16are shown herein as separate switches, a touch screen interface on display14with virtual buttons may also be utilized.

The electronic components of the analyte measurement system100can be disposed on, for example, a printed circuit board situated within the housing11and forming the DMU140of the herein described system.FIG. 1Billustrates, in simplified schematic form, several of the electronic subsystems disposed within the housing11for purposes of this embodiment. The DMU140includes a processing unit122in the form of a microprocessor, a microcontroller, an application specific integrated circuit (“ASIC”), a mixed signal processor (“MSP”), a field programmable gate array (“FPGA”), or a combination thereof, and is electrically connected to various electronic modules included on, or connected to, the printed circuit board, as will be described below. The processing unit122is electrically connected to, for example, a test strip port connector104(“SPC”) via an analog front end (AFE) subsystem125. The AFE125is electrically connected to the strip port connector104during blood glucose testing. To measure a selected analyte concentration, the AFE125detects a resistance magnitude change across electrodes of analyte test strip24which indicates that a blood sample has been applied thereto, using a potentiostat. At a predetermined time after the blood sample has been applied to the test strip24, a preset voltage waveform is applied across the sample via the electrodes which generates a an electric current therethrough. The AFE125converts the electric current measurement into digital form for presentation on the display14. The processing unit122can be configured to receive input from the strip port connector104, analog front end subsystem125, and may also perform a portion of the potentiostat function and the current measurement function.

The analyte test strip24can be in the form of an electrochemical glucose test strip, of which various embodiments are described below. The test strip24is defined by a nonporous substrate that can include one or more working electrodes. Test strip24can also include a plurality of electrical contact pads, where each electrode can be in electrical communication with at least one electrical contact pad, as described below in relation toFIGS. 2A-9C. Strip port connector104can be configured to electrically interface to the electrical contact pads, using electrical contacts in the form of prongs, and form electrical communication with the electrodes. Test strip24can include a reagent layer that is disposed over one or more electrodes within the test strip24, such as a working electrode. The reagent layer can include an enzyme and a mediator. Exemplary enzymes suitable for use in the reagent layer include glucose oxidase, glucose dehydrogenase (with pyrroloquinoline quinone co-factor, “PQQ”), and glucose dehydrogenase (with flavin adenine dinucleotide co-factor, “FAD”). An exemplary mediator suitable for use in the reagent layer includes ferricyanide, which in this case is in the oxidized form. The reagent layer can be configured to physically transform glucose in the applied sample into an enzymatic by-product and in the process generate an amount of reduced mediator (e.g., ferrocyanide) that is proportional to the glucose concentration of the sample. The working electrode can then be used to apply the preset voltage waveform to the sample and to measure a concentration of the reduced mediator in the form of an electric current. In turn, microcontroller122can convert the current magnitude into a glucose concentration for presentation on the display14. An exemplary analyte meter performing such current measurements is described in U.S. Patent Application Publication No. US 2009/0301899 A1 entitled “System and Method for Measuring an Analyte in a Sample”, which is incorporated by reference herein as if fully set forth in this application.

A display module119, which may include a display processor and display buffer, is electrically connected to the processing unit122over the electrical interface123for receiving and displaying output data, and for displaying user interface input options under control of processing unit122. The structure of the user interface, such as menu options, is stored in user interface module103and is accessible by processing unit122for presenting menu options to a user of the blood glucose measurement system100. An audio module120includes a speaker121for outputting audio data received or stored by the DMU140. Audio outputs can include, for example, notifications, reminders, and alarms, or may include audio data to be replayed in conjunction with display data presented on the display14. Such stored audio data can be accessed by processing unit122and executed as playback data at appropriate times. A volume of the audio output is controlled by the processing unit122, and the volume setting can be stored in settings module105, as determined by the processor or as adjusted by the user. User input module102receives inputs via user interface buttons16which are processed and transmitted to the processing unit122over the electrical interface123. The processing unit122may have electrical access to a digital time-of-day clock connected to the printed circuit board for recording dates and times of blood glucose measurements, which may then be accessed, uploaded, or displayed at a later time as necessary.

The display14can alternatively include a backlight whose brightness may be controlled by the processing unit122via a light source control module115. Similarly, the user interface buttons16may also be illuminated using LED light sources electrically connected to processing unit122for controlling a light output of the buttons. The light source module115is electrically connected to the display backlight and processing unit122. Default brightness settings of all light sources, as well as settings adjusted by the user, are stored in a settings module105, which is accessible and adjustable by the processing unit122.

A memory module101, that includes but are not limited to volatile random access memory (“RAM”)112, a non-volatile memory113, which may comprise read only memory (“ROM”) or flash memory, and a circuit114for connecting to an external portable memory device, for example, via a USB data port, is electrically connected to the processing unit122over a electrical interface123. External memory devices may include flash memory devices housed in thumb drives, portable hard disk drives, data cards, or any other form of electronic storage devices. The on-board memory can include various embedded applications and stored algorithms in the form of programs executed by the processing unit122for operation of the analyte meter10, as will be explained below. On board memory can also be used to store a history of a user's blood glucose measurements including dates and times associated therewith. Using the wireless transmission capability of the analyte meter10or the data port13, as described below, such measurement data can be transferred via wired or wireless transmission to connected computers or other processing devices.

A wireless module106may include transceiver circuits for wireless digital data transmission and reception via one or more internal digital antennas107, and is electrically connected to the processing unit122over electrical interface123. The wireless transceiver circuits may be in the form of integrated circuit chips, chipsets, programmable functions operable via processing unit122, or a combination thereof. Each of the wireless transceiver circuits is compatible with a different wireless transmission standard. For example, a wireless transceiver circuit108may be compatible with the Wireless Local Area Network IEEE 802.11 standard known as WiFi. Transceiver circuit108may be configured to detect a WiFi access point in proximity to the analyte meter10and to transmit and receive data from such a detected WiFi access point. A wireless transceiver circuit109may be compatible with the Bluetooth protocol and is configured to detect and process data transmitted from a Bluetooth beacon in proximity to the analyte meter10. A wireless transceiver circuit110may be compatible with the near field communication (“NFC”) standard and is configured to establish radio communication with, for example, another NFC compliant device in proximity to the analyte meter10. A wireless transceiver circuit111may comprise a circuit for cellular communication with cellular networks and is configured to detect and link to available cellular communication towers.

A power supply module116is electrically connected to all modules in the housing11and to the processing unit122to supply electric power thereto. The power supply module116may comprise standard or rechargeable batteries118or an AC power supply117may be activated when the analyte meter10is connected to a source of AC power. The power supply module116is also electrically connected to processing unit122over the electrical interface123for supplying power thereto and so that processing unit122can monitor a power level remaining in a battery power mode of the power supply module116.

FIGS. 2A-9Cillustrate embodiments of a substantially flat (planar), elongated test strip200and strip port connector104that may be used for analyte measurement when the test strip200is inserted into a test strip port22of the analyte meter100in either of at least two orientations. With reference toFIGS. 2A-B, a test strip200is defined by opposing sides herein referred to as a top side202and a bottom side204of the test strip200. Referring specifically toFIG. 2C, the test strip200having conductive contact pads206,208disposed at opposite ends of the test strip200, and in which contact pad206is provided on the top side202and contact pad208is provided on the bottom side204of the test strip200. An arrow210indicates the direction of insertion of the test strip200into the test strip port22, which may be inserted with either side202,204of the test strip200facing upwardly. The test strip200includes a sample chamber212for receiving a sample therein provided by a user at one end213of the sample chamber212. Electrodes207,209extend from each contact pad206,208, respectively, to the sample chamber212wherein the sample provided therein makes physical contact with the electrodes207,209and thereby establishes an electrical communication path between the contact pads206,208on opposite ends and opposite sides202,204, of the test strip200.

The analyte meter100that receives the test strip200in its test strip port22uses strip port connector104to make an electrical connection with the pair of the contact pads206,208using contacts, such as prongs,220,222, respectively, that engage the contact pads206,208, of the test strip200. One of the prongs222is disposed to contact the bottom side contact pad208while another prong220is configured to electrically connect with the top side contact pad206when the test strip200is inserted into the test strip port22in the first orientation. When the test strip200is inserted into the test strip port22in the second orientation, the prong222electrically connects with the top side contact pad206and the prong220electrically connects with the bottom side contact pad208.

The illustrations ofFIGS. 2A-Cdepict a test strip200whose orientation (i.e., first orientation or second orientation) is detected upon insertion into the test strip port22of the analyte meter100. According to this embodiment, a projection, or lug,214disposed along a longitudinal edge of the test strip200may be sensed by the analyte meter100to determine the orientation of the test strip, for example, determining whether the top contact pad206faces upward or the bottom contact pad208faces upward, indicative of the first orientation and the second orientation, respectively. The first orientation, i.e., the top contact pad206facing upward, may be referred to herein as the default orientation. In one embodiment, the projection214may work in conjunction with a deflectable conductive element in the analyte meter, such as a conductive switch, that transmits a signal upon being deflected by the projection214when the test strip200is inserted in the test strip port22in one orientation, e.g., “top side up”, and is not deflected if the test strip200is inserted into the test strip port22in a second orientation, e.g., “bottom side up”. Alternatively, a sensing device, such as a mechanical microswitch, photodiode, capacitance sensor, or any other kind of detector may be used to detect the presence or absence of the projection214.FIGS. 3A-Billustrate a test strip300that is similar in all respects to the test strip200just described with reference toFIGS. 2A-C, except that the projection214of the test strip200is replaced with an indentation216in the test strip300. The indentation216may be used to detect an orientation of the test strip300at the time of its insertion into the analyte meter100, in the direction indicated by arrow210, such as by using any of the sensing devices identified above that detects the presence or absence of the indentation216of the test strip300at the time of insertion of the test strip300or, as described above with respect to the projection214, a conductive deflectable element in the test strip port22of the analyte meter100, such as a conductive switch, may be used to detect the indentation216wherein the indentation216positioned over the deflectable element fails to deflect it.

FIGS. 4A-Eillustrate another embodiment of a substantially flat (planar), elongated test strip400and strip port connector104that may be used for analyte measurement when the test strip400is inserted into a test strip port22of the analyte meter100in either of at least two orientations. With reference toFIGS. 4A-B, a test strip400is defined by opposing sides herein referred to as a top side402and a bottom side404of the test strip400. Referring specifically toFIG. 4C, the test strip400having conductive contact pads406and428at one end of the test strip400, and contact pads408and426at an opposite end of the test strip400, and in which contact pads406and426are provided on the top side402, and contact pads408and428are provided on the bottom side404of the test strip400. An arrow210indicates the direction of insertion of the test strip400into the test strip port22, which may be inserted with either side402,404of the test strip400facing upwardly. The test strip400includes a sample chamber412for receiving a sample therein provided by a user at one end413of the sample chamber412. Electrodes407,427,409,429extend from each contact pad406,426,408,428, respectively, to the sample chamber412wherein the sample provided therein makes physical contact with the electrodes407,427,409,429and thereby establishes an electrical communication path between the contact pads406,408,426,428on opposite ends and opposite sides402,404, of the test strip400.

In one embodiment, illustrated inFIGS. 4A-C, the analyte meter100that receives the test strip400in its test strip port22may use strip port connector104to make an electrical connection with a pair of the contact pads,406and426, or408and428, using a strip port connector having at least one pair of electrical contacts, herein referred to as prongs,420,424(FIG. 4C), that engage the corresponding pair of contact pads406-426or408-428on the same side402,404, respectively, of the test strip400, depending on the orientation of the test strip400in the test strip port22. The prongs420,424are shown facing downward, but may also face upward to connect with the same pairs of contact pads406-426or408-428in the manner described herein.

In another embodiment, illustrated inFIGS. 4A-Band4D-E, the analyte meter100that receives the test strip400in its test strip port22may use strip port connector104to make an electrical connection with the contact pads,406,426,408, and428, using a strip port connector having at least two sets of electrical contacts, herein referred to as prongs,420,424, and421,425, (FIG. 4D), that engage the corresponding pairs of contact pads406-426and408-428on the sides402,404, respectively, of the test strip400, when the test strip400is inserted in a first (default) orientation in the test strip port22. The test strip400may be inserted in a second orientation, in the manner described herein, wherein prongs,420,424, and421,425, engage the corresponding pairs of contact pads408-428and426-406on the sides404,402, respectively, of the test strip400.FIG. 4Eillustrates an end view of an embodiment of the two sets of prongs,420,424, and421,425, wherein upper prong424and lower prong425are visible in the perspective ofFIG. 4Ewhile upper prong420and lower prong421are similarly structured and positioned behind prongs424,425, respectively, in the view ofFIG. 4E. The prongs,420,424,421, and425, comprise flexible spring arms, of which spring arms410,411corresponding to prongs424,425, respectively, are visible in the perspective ofFIG. 4. Such prongs may be fabricated from a conductive metallic material which flex in a direction away from the test strip400when the test strip is inserted therebetween by a user in the direction indicated by arrow210. The prongs424,425may be electrically shorted together by an optional electrical connector423, as well as prongs420,421, by a corresponding electrical connector, thereby forming a single circuit node therewith of common voltage. The flexible spring arms410,411provide enough compressive force to make electrical contact with contact pads426,408, respectively, (as well as spring arms corresponding to prongs420,421making electrical contact with contact pads406,428, respectively) and to secure the test strip400therebetween when the test strip is inserted and when an analyte measurement process is undertaken by the meter100, as described herein.

The illustrations ofFIGS. 4A-Edepict a system wherein an orientation of test strip400(i.e., first orientation or second orientation) is detected upon insertion into the test strip port22of the analyte meter100. According to this embodiment, a projection, or lug,414disposed along a longitudinal edge of the test strip400may be sensed by the analyte meter100to determine the orientation of the test strip, for example, determining whether the top contact pads406,426face upward or the bottom contact pads408,428face upward, indicative of the first and second orientations, respectively. The first orientation, i.e., the top contact pads406,426facing upward, may be referred to herein as the default orientation. In one embodiment, the projection414may work in conjunction with a sensing element415in the analyte meter, such as a conductive switch, that transmits a signal upon being deflected by the projection414when the test strip400is inserted in the test strip port22in one orientation, e.g., “top side up” and is not deflected if the test strip400is inserted into the test strip port22in a second orientation, e.g., “bottom side up”. The sensing device415may be embodied as a mechanical microswitch, a deflectable conductive element, a photodiode, a capacitance sensor, or any other suitable detector to detect the presence or absence of the projection414.

FIGS. 5A-Billustrate a test strip500that is similar in all respects to the test strip400just described with reference toFIGS. 4A-E, except that the projection414of the test strip400is replaced with an indentation416in the test strip500. The indentation416may be used to detect an orientation of the test strip500at the time of its insertion into the analyte meter100, in the direction indicated by arrow210, for example, using a sensing device415, such as a mechanical microswitch, photodiode, capacitance sensor, or any other kind of detector that senses the presence or absence of the indentation416of the test strip500or, as described above with respect to the projection414, a deflectable element in the test strip port22of the analyte meter100may be used to detect the indentation416wherein the indentation416positioned over the deflectable element fails to deflect it. Although a projection414and an indentation416have been described as exemplary physical features that may be used to detect an orientation of a test strip24, such examples should not be interpreted as limiting the embodiments described herein. Other detectable physical features may be formed or fabricated in the test strip24without departing from the spirit of the embodiments described herein. For example, a magnetic strip or indicator in the test strip24may be detected by a magnetic relay in the test strip port22. Likewise, rotationally variant or invariant optical features may be printed or embedded in the test strip24which may be detected by optical readers, such as 1D or 2D barcode scanners, or an optical pattern matching system in the analyte meter100, as a further example. In addition, the various mechanisms and methods described herein to determine test strip24orientation may be used in combination, which may serve as a verification of a determined test strip24orientation.

FIGS. 6A-Cillustrate another embodiment of a substantially flat (planar), elongated test strip600and strip port connector104that may be used for analyte measurement when the test strip600is inserted into a test strip port22of the analyte meter100in either of at least two orientations. With reference toFIGS. 6A-B, the test strip600is defined by opposing sides herein referred to as a top side602and a bottom side604of the test strip600. Referring specifically toFIG. 6C, the test strip600having conductive contact pads606,608disposed at opposite ends of the test strip600, and in which contact pad606is provided on the top side602and contact pad208is provided on the bottom side604of the test strip600. An arrow210indicates the direction of insertion of the test strip600into the test strip port22, which may be inserted with either side602,604of the test strip600facing upwardly. The test strip600includes a sample chamber612for receiving a sample therein provided by a user at one end613of the sample chamber612. Electrodes607,609extend from each contact pad606,608, respectively, to the sample chamber612wherein the sample provided therein makes physical contact with the electrodes607,609and thereby establishes an electrical communication path between the contact pads606,608on opposite ends and opposite sides602,604, of the test strip600.

One of the contact pads606comprises a border605that is non-conductive. This border605may be formed by ablation of the conductive material of the contact pad606, such as using laser ablation, or, in another embodiment, the region surrounded by the non-conducive border605could be entirely formed as a non-conductive patch. The analyte meter100into which the test strip is inserted comprises two prongs620,621, proximate one end of the test strip600, wherein one prong620is used for electrically contacting the region of the contact pad606within the border605and the other prong621for contacting the region of the contact pad606outside the border605, when the top side602of the test strip is facing upward, as indicated by the contact points614. A resistance between these two prongs620,621of the analyte meter100can be measured while the prongs620,621are physically simultaneously touching the region within the border605and the region outside the border605of contact pad606, respectively. A high resistance will be measured because there is no conductive path between the prongs620,621when they are touching contact points614, thereby indicating the orientation of the test strip600as being “top side up”. Thus, a first orientation of the test strip600may be determined based on the high resistance, and may be referred to herein as the default orientation.

The two prongs620,621, proximate one end of the test strip600may electrically connect to the contact pad608when the test strip600is inserted into the test strip port with the bottom side604facing upward (FIG. 6B) as indicated by the contact points615. A resistance between the prongs620,621of the analyte meter100can be measured while the prongs620,621are physically simultaneously touching contact pad608. A low resistance will be measured because contact pad608is entirely conductive, thereby indicating the orientation of the test strip600as being “bottom side up”. Thus, a second orientation of the test strip600may be determined based on the low measured resistance. Based on these measured resistances using two prongs620,621proximate one end of the test strip600, analyte meter100may determine in which orientation the test strip600has been inserted.

The analyte meter100that receives the test strip600in its test strip port22uses strip port connector104to make an electrical connection with the contact pads606,608using a strip port connector having at least one pair of electrical contacts, herein referred to as prongs,621,622, respectively, that engage the contact pads606,608, of the test strip600. One of the prongs622is disposed to contact the bottom side contact pad608while another prong621is configured to electrically connect with the top side contact pad606when the test strip is inserted into the test strip port22in the first orientation. When the test strip600is inserted into the test strip port22in the second orientation, the prong622electrically connects with the top side contact pad606and the prong621electrically connects with the bottom side contact pad608.

FIGS. 7A-Cillustrate another embodiment of a substantially flat (planar), elongated test strip700and strip port connector104that may be used for analyte measurement when the test strip700is inserted into a test strip port22of the analyte meter100in either of at least two orientations. With reference toFIGS. 7A-B, a test strip700is defined by opposing sides herein referred to as a top side702and a bottom side704of the test strip700. Referring specifically toFIG. 7C, the test strip700having conductive contact pads706and728at one end of the test strip700, and contact pads708and726at an opposite end of the test strip700, and in which contact pads706and726are provided on the top side702, and contact pads708and728are provided on the bottom side704of the test strip700. The arrow210indicates the direction of insertion of the test strip700into the test strip port22, which may be inserted with either side702,704of the test strip700facing upwardly. The test strip700includes a sample chamber712for receiving a sample therein provided by a user at one end713of the sample chamber712. Electrodes707,709,727,729extend from each contact pad706,708,726,728respectively, to the sample chamber712wherein the sample provided therein makes physical contact with the electrodes707,727,709,729and thereby establishes an electrical communication path between the contact pads706,708,726,728on opposite ends and opposite sides702,704, of the test strip700.

Two of the contact pads706,728comprise a border705,727, respectively, that is non-conductive. These borders705,727, may be formed by ablation of the conductive material of the contact pads706,728, such as using laser ablation, or, in another embodiment, the region surrounded by the non-conducive borders705,727, could be entirely formed as a non-conductive patch. The analyte meter100into which the test strip700is inserted comprises two prongs720,721, proximate one end of the test strip700. One of the prongs720is used for electrically contacting the region of the contact pad706within the border705and the other prong721for contacting the region of the contact pad706outside the border705, when the top side702of the test strip is facing upward, as indicated by the contact points714. A resistance between these two prongs720,721of the analyte meter100can be measured while the prongs720,721are physically simultaneously touching the region within the border705and the region outside the border705of contact pad706, respectively. A high resistance will be measured because there is no conductive path between the prongs720,721when they are touching contact points714, thereby indicating the orientation of the test strip700as being “top side up”. Thus, a first orientation of the test strip700may be determined based on the high resistance, and may be referred to herein as the default orientation.

The two prongs720,721, proximate one end of the test strip700may electrically connect to the contact pad708when the test strip700is inserted into the test strip port with the bottom side704facing upward (FIG. 7B) as indicated by the contact points715. A resistance between the prongs720,721of the analyte meter100can be measured while the prongs720,721are physically simultaneously touching contact pad708. A low resistance will be measured because contact pad708is entirely conductive, thereby indicating the orientation of the test strip700as being “bottom side up”. Thus, a second orientation of the test strip700may be determined based on the low measured resistance. Based on these measured resistances using two prongs720,721proximate one end of the test strip700, analyte meter100may determine in which orientation the test strip700has been inserted.

The analyte meter100that receives the test strip700in its test strip port22uses strip port connector104to make an electrical connection with a pair of the contact pads,706and726, or708and728, using a strip port connector having at least one pair of electrical contacts, herein referred to as prongs,721,724, that engage the corresponding pair of the contact pads706-726, or708-728, on the same side702,704, respectively, of the test strip700depending on the orientation of the test strip700in the test strip port22. The prongs720,721,724are shown facing downward, but may also face upward to electrically connect with the same pairs of contact pads706-726, or708-728in the manner described herein.

FIGS. 8A-Cillustrate embodiments of a substantially flat (planar), elongated test strip800and strip port connector104that may be used for analyte measurement when the test strip800is inserted into a test strip port22of the analyte meter100in either of at least two orientations. With reference toFIGS. 8A-B, a test strip800is defined by opposing sides herein referred to as a top side802and a bottom side804of the test strip800. Referring specifically toFIG. 8C, the test strip800having conductive contact pads806,808disposed at opposite ends of the test strip800, and in which contact pad806is provided on the top side802and contact pad808is provided on the bottom side804of the test strip800. An arrow210indicates the direction of insertion of the test strip800into the test strip port22, which may be inserted with either side802,804of the test strip800facing upwardly. The test strip800includes a sample chamber812for receiving a sample therein provided by a user at one end813of the sample chamber812. Electrodes807,809extend from each contact pad806,808, respectively, to the sample chamber812wherein the sample provided therein makes physical contact with the electrodes807,809and thereby establishes an electrical communication path between the contact pads806,808on opposite ends and opposite sides802,804, of the test strip800.

The analyte meter100that receives the test strip800in its test strip port22uses strip port connector104to make an electrical connection with the pair of the contact pads806,808using a strip port connector having at least one pair of electrical contacts, herein referred to as prongs,820,822, respectively, that engage the contact pads806,808, of the test strip800. One of the prongs822is disposed to contact the bottom side contact pad808while another prong820is configured to connect with the top side contact pad806when the test strip800is inserted into the test strip port22in the first orientation, i.e., the “default” orientation. When the test strip800is inserted into the test strip port22in the second orientation, the prong822electrically connects with the top side contact pad806and the prong820electrically connects with the bottom side contact pad808.

FIGS. 9A-Cillustrate another embodiment of a substantially flat (planar), elongated test strip900and strip port connector104that may be used for analyte measurement when the test strip900is inserted into a test strip port22of the analyte meter100in either of at least two orientations. With reference toFIGS. 9A-B, a test strip900is defined by opposing sides herein referred to as a top side902and a bottom side904of the test strip900. Referring specifically toFIG. 9C, the test strip900having conductive contact pads906and928at one end of the test strip900, and contact pads908and926at an opposite end of the test strip900, and in which contact pads906and926are provided on the top side902, and contact pads908and928are provided on the bottom side904of the test strip900. An arrow210indicates the direction of insertion of the test strip900into the test strip port22, which may be inserted with either side902,904of the test strip900facing upwardly. A default orientation of the test strip900may be referenced herein as the side902facing upwardly. The test strip900includes a sample chamber912for receiving a sample therein provided by a user at one end913of the sample chamber912. Electrodes907,927,909,929extend from each contact pad906,926,908,928, respectively, to the sample chamber912wherein the sample provided therein makes physical contact with the electrodes907,927,909,929and thereby establishes an electrical communication path between the contact pads906,908,926,928on opposite ends and opposite sides902,904, of the test strip900.

The analyte meter100that receives the test strip900in its test strip port22uses strip port connector104to make an electrical connection with a pair of the contact pads906and926, or908and928, using a strip port connector having at least one pair of electrical contacts, herein referred to as prongs,920,924, that engage the corresponding pair of the contact pads906-926, or908-928, on the same side902,904, respectively, of the test strip900depending on the orientation of the test strip900in the test strip port22. The prongs920,924are shown facing downward, but may also face upward to connect with the same pairs of contact pads906-926or908-928in the manner described herein.

The illustrations inFIGS. 8A-Cand9A-C depict test strips800,900whose orientation (i.e., first orientation or second orientation) is detected after insertion into the test strip port22of the analyte meter100and upon providing a sample in the sample chamber812,912. As described above, a mediator, that may include, for example, ferricyanide, is deposited on one of the electrodes in the test strip, namely, the working electrode, which will be designated as the electrodes807and907,909in the exemplary test strips ofFIGS. 8A, 9A, and 9B, respectively, although opposing electrodes corresponding to these may, instead, be designated as working electrodes. The mediator may comprise one or more components that mix with the sample upon application in the sample chamber812,912, and are used in the generation of a glucose measurement current therethrough using the electrodes807,809, and907-927or909-929, via the analyte meter contacts820,822, and920,924, respectively, having been electrically connected to corresponding contact pads, as described herein. Such mixing of the mediator with the sample in the sample chamber takes a finite time until an equilibrated initial sample and mediator mixture is achieved in the sample chamber, during or after which time the glucose measurement input signal is applied to the mixture for the purpose of glucose testing. Immediately after the sample is applied to the sample chamber812,912it establishes a physical connection with the corresponding electrodes, thereby electrochemically connecting the electrodes on opposite sides of the sample chamber812,912. The electrochemical characteristics as between the electrodes807,809, and907-927or909-929, are asymmetric due to the mediator being present on only one of the electrodes, e.g. on electrode807of test strip800and on electrodes907,909of test strip900, for example. This results in a time duration during which the orientation of the test strip may be ascertained by detecting the asymmetric electrical or electrochemical property of these electrodes.

An example of the asymmetric electrical/electrochemical properties just described are illustrated inFIG. 10. In this example, time 0 on the horizontal axis, measured in milliseconds, indicates the time at which the sample is applied to the test strip800,900. Upon the provided sample making physical contact with electrodes807,809of test strip800or electrodes907,927, and909,929of test strip900, for example, the voltage potential as measured between these electrodes is indicated by the voltage swings1002,1004which occurs prior to the mediator mixing thoroughly with the provided sample. In this example embodiment, open circuit galvanostatic potentiometry is used to measure the voltage potential. The voltage swings1002and1004depicted inFIG. 10illustrate six test cases, three in each of a positive and a negative going direction, that clearly demonstrate a detectable voltage potential generated by application of a sample in the test strip800,900. The voltage potential will swing toward the working electrode807, or907,909, having the mediator deposited thereon. Thus, there exists a time duration of about two hundred (200) to three hundred (300) milliseconds1006after application of the sample to the test strip wherein the positive- or negative going voltage potential waveform reaches a positive or negative peak and may be easily and clearly detected by programmed operation of the microcontroller122to determine an orientation of the test strip800,900in the test strip port22of the analyte meter100. The positive or negative going voltage potential waveform may even be detected up to about 1000 milliseconds after application of the sample to the test strip. In the example graph illustrated inFIG. 10, the positive going voltage swings1002indicate a topside802,902of a test strip800,900, respectively, facing downwardly. The negative going voltage swings1004indicate a topside802,902of a test strip800,900, respectively, facing upwardly.

One advantage of using a short duration, e.g. less than 1 s duration or less than 300 ms, open circuit (0 amps) galvanostatic potentiometry is that it enables the potentiometric insertion orientation signal to be detected with minimal interference or impact upon the subsequent amperometric glucose measurement current because neither an external potential is applied nor current drawn from within the electrochemical cell over the duration of this orientation detection measurement phase.

In all of the above examples illustrated inFIGS. 2A-9Cdescribing a determination of test strip24insertion orientation in the test strip port22of the analyte meter100, after the orientation of the test strip is determined the glucose measurement current may be applied to the sample through the analyte meter100contact220in the example ofFIG. 2C, the contact420in the example ofFIG. 4C, the contact621in the example ofFIG. 6C, the contact721in the example ofFIG. 7C, the contact820n the example ofFIG. 8C, and the contact920in the example ofFIG. 9C. The glucose measurement current is applied in an appropriate polarity so that the blood glucose level may be measured correctly. The application of the correct polarity of a glucose measurement input signal includes the microcontroller122programmably controlling a circuit capable of inverting or not inverting the polarity the signal applied to the analyte meter100contact and thereby to a contact pad of the test strip24depending on the aforementioned determination of the orientation of the test strip24.

FIG. 11Aillustrates the input signal voltage1102, i.e., the default analyte measurement input signal, controllably applied by the analyte meter100to the exemplary contacts identified above when the test strip24is inserted into the test strip port22top side up.FIG. 11Billustrates the analyte measurement input signal1104controllably applied by the analyte meter100to the exemplary contacts identified above when the test strip24is inserted into the test strip port22bottom side up. In one embodiment, the voltage applied to a top side up oriented test strip24includes a voltage of about +20 mV for about one second, followed by a voltage of about +300 mV for about three seconds, followed by a voltage level of about −300 mV for about one second. These applied voltages generate the glucose measurement current in the sample which is used to determine the glucose level of the sample, as described above. A test strip24determined to be oriented bottom side up in the analyte meter100would have the voltage waveform1104ofFIG. 11Bapplied thereto, i.e., the inverse analyte measurement input signal, which is the inverse, or reverse polarity, of the default input signal waveform ofFIG. 11A, through the analyte meter100contacts as identified above. An exemplary analyte meter applying such analyte measurement input signals for measuring glucose current is described in U.S. Patent Application Publication No. US 2009/0084687 A1 entitled “Systems and Methods of Discriminating Control Solution from a Physiological Sample”, which is incorporated by reference herein as if fully set forth in this application.

FIG. 12illustrates an exemplary flow chart demonstrating a method of operating an analyte meter100as described herein. At step1201the analyte meter100receives a test strip24inserted into its test strip port22. At step1202the analyte meter100determines the orientation of the test strip24as inserted using any of mechanical, optical, or electrical detection means as described herein, or a combination thereof. The determination step1202may be performed before or after a sample is applied to the test strip24depending upon whether the determination means requires the sample to be present so as to apply test signals thereto, as described above, or whether the test strip24includes physical features that are detected by the meter100upon insertion. If the test strip is determined to be in the default orientation at step1202then, upon receiving a sample in the sample chamber, the default analyte measurement input signal is applied to the sample at step1203. If the test strip is determined not to be in the default orientation at step1202then, upon receiving a sample in the sample chamber, the inverse analyte measurement input signal (inverse of the default) is applied to the sample at step1204. At step1205the analyte meter100receives an output signal from the test strip24corresponding to a current level flowing through the sample therein which is used by the analyte meter100to determine an analyte level of the sample.

Program code and/or executable instructions embodied on a computer readable medium may be transmitted using any appropriate medium, including but not limited to wireless, wireline, optical fiber cable, RF, etc., or any suitable combination of the foregoing.

Furthermore, the various methods described herein can be used to generate software codes using off-the-shelf software development tools. The methods, however, may be transformed into other software languages depending on the requirements and the availability of new software languages for coding the methods.

PARTS LIST FOR FIGS.1A-12