Patent Application
20150097549
The determination (e.g., detection, evaluation or calculation of the value or concentration measurement) of an analyte in a fluid sample is of particular interest in the medical field. For example, it may be desirable to determine glucose, cholesterol, acetaminophen and/or HbA1c concentrations in a sample of a bodily fluid such as urine, blood or interstitial fluid. Such determinations may be achieved using analyte test strips, based on, for example, photometric or electrochemical techniques, along with an associated test meter.
Typical electrochemical-based analyte test strips employ a plurality of electrodes (e.g., a working electrode and a reference electrode) and an enzymatic reagent to facilitate an electrochemical reaction with an analyte of interest and, thereby, determine the concentration of the analyte. For example, an electrochemical-based analyte test strip for the determination of glucose concentration in a blood sample can employ an enzymatic reagent that includes the enzyme glucose oxidase and the mediator ferricyanide. Such conventional analyte test strips are described in, for example, U.S. Pat. Nos. 5,708,247; 5,951,836; 6,241,862; and 6,284,125; each of which is hereby incorporated in full. Measuring instruments that use an electrochemical cell as are typically provided by a disposable test strip or the like are well known and popular with consumers. These instruments are used for the detection of various analyte levels in physiological fluid samples. For example, the concentration of an analyte in a variety of different physiological samples, such as urine, tears, saliva, and the like may be determined with these instruments. One popular application is for determining the concentration of an analyte in interstitial fluid, blood or blood fractions, and more particularly in whole blood.
In one embodiment, a method of determining a type of a test strip in a glucose meter is provided. The method can be achieved by: inserting a test strip into a strip port connector of the glucose meter, the strip port connector having first, second and third discrete contacts; determining whether there is a continuity between a first contact and a second contact that are in electrical connection with at least one contact pad of the test strip; evaluating whether there is a continuity between a third contact and the first contact or between the third contact and the second contact that are in electrical connection with one or more contact pads of the test strip; initiating a glucose test upon detection of continuity in the determining and evaluating.
In yet a further embodiment, a glucose meter is provided that includes a connector, a switch and a microcontroller. The connector includes first, second and third contact where the third contact is connected to a ground. The switch has a source input, a drain input, and a gate input, the source input connected to the ground, the drain input connected to the first contact of the connector. The microcontroller has a first interrupt connected to the gate input of the switch and a second interrupt connected to the second contact of the connector. The microcontroller is also in electrical communication with the first contact and the third contact upon insertion of a test strip.
In yet another embodiment, a glucose measurement system is provided that includes a glucose test strip and a glucose meter. The glucose test strip has a plurality of conductive tracks. The glucose meter includes a power supply, a ground, a strip port connector, a transistorized switch, and a microcontroller. The strip port connector has a first, a second and a third contact with the plurality of conductive tracks with the third contact connected to the ground. The transistorized switch has a source input connected the ground, a drain input connected to the first contact of the strip port connector and a gate input. The microcontroller has a first interrupt connected to the gate input of the switch and a second interrupt connected to the second contact. The microcontroller is also in electrical communication with the first contact and the third contact upon insertion of the test strip.
In yet a further embodiment, a method of differentiating between a first type of analyte test strip and other analyte test strip with a transistor switch and a microcontroller is provided. The transistor switch has its gate input connected to a first interrupt of the microcontroller and a drain input of the switch connected to a first contact and a source input of the switch connected to a ground. The method can be achieved by: inserting a test strip into a strip port connector so that contact pads of the strip are in electrical connection with the first contact, the second contact and the third contact; detecting via a second interrupt of the microcontroller whether the first contact is connected to the second contact and the third contact formed by a configuration of the one or more contact pads of the analyte test strip; upon detection of the connection of the first, second and third contacts in common, turning the switch on and off for a predetermined number of times via the first interrupt; detecting changes in logic states at the second interrupt; and identifying the glucose test strip as one of the first type or another type based on a number of high and low logic states of the second interrupt.
These and other embodiments, features and advantages will become apparent to those skilled in the art when taken with reference to the following more detailed description of the embodiments of the invention in conjunction with the accompanying drawings that are first briefly described here below.
The accompanying drawings, which are incorporated herein and constitute part of this specification, illustrate presently preferred embodiments of the invention, and, together with the general description given above and the detailed description given below, serve to explain features of the invention.
The following detailed description should be read with reference to the drawings, in which like elements in different drawings are identically numbered. The drawings, which are not necessarily to scale, depict selected exemplary embodiments and are not intended to limit the scope of the invention. The detailed description illustrates by way of example, not by way of limitation, the principles of the invention. This description will clearly enable one skilled in the art to make and use the invention, and describes several embodiments, adaptations, variations, alternatives and uses of the invention, including what is presently believed to be the best mode of carrying out the invention.
As used herein, the terms “about” or “approximately” for any numerical values or ranges indicate a suitable dimensional tolerance that allows the part or collection of components to function for its intended purpose as described herein. In addition, as used herein, the terms “patient,” “host,” “user,” and “subject” 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.
Referring back to
Operational amplifier circuit 208 may be two or more operational amplifiers configured to provide a portion of the potentiostat function and the current measurement function. The potentiostat function can refer to the application of a test voltage between at least two electrodes of a test strip. The current function can refer to the measurement of a test current resulting from the applied test voltage to the test strip 120. The current measurement may be performed with a current-to-voltage converter. Microcontroller 202 may be in the form of a mixed signal microprocessor (MSP) such as, for example, the Texas Instrument MSP430F2419. The TI-MSP430F2419 may be configured to also perform a portion of the potentiostat function and the current measurement function. In addition, the MSP430F2419 can also include volatile and non-volatile memory. In another embodiment, many of the electronic components may be integrated with the microcontroller in the form of an application specific integrated circuit (ASIC).
Referring back to
Referring back to
For use with the meter 100 is an exemplary test strip 120, as illustrated in
Referring back to
Electrochemical-based analytical test strip 120 may be manufactured, for example, by the sequential aligned formation of patterned conductor layer 14, patterned insulation layer 16 (with electrode exposure window 17 extending therethrough), enzymatic reagent layer 18, patterned adhesive layer 20, hydrophilic layer 22 and top film 24 onto electrically-insulating substrate 12. Any suitable techniques may be used to accomplish such sequential aligned formation, including, for example, screen printing, photolithography, photogravure, and chemical vapor deposition and tape lamination techniques.
During use of electrochemical-based analytical test strip 120 to determine an analyte concentration in a fluid sample (e.g., blood glucose concentration in a whole blood sample), electrodes 14a, 14b and 14c of patterned conductor layer 14 are employed to monitor an electrochemical reaction induced current of interest. The magnitude of such a current may then be correlated with the amount of analyte present in the fluid sample under investigation. During such use, a bodily fluid sample is introduced into sample-receiving chamber 26 of electrochemical-based analytical test strip 10.
Referring back to
Electrically-insulating substrate 12, which is common to both the first type of strip 120 and the second type of strip 124, may be a nylon substrate, polycarbonate substrate, a polyimide substrate, a polyvinyl chloride substrate, a polyethylene substrate, a polypropylene substrate, a glycolated polyester (PETG) substrate, or a polyester substrate. The electrically-insulating substrate may have any suitable dimensions including, for example, a width dimension of about 5 mm, a length dimension of about 27 mm and a thickness dimension of about 0.5 mm.
Electrically-insulating substrate 12 provide structure to the strip for ease of handling and also serves as a base for the application (e.g., printing) of subsequent layers (e.g., a carbon-based patterned conductive layer). It should be noted that patterned conductor layers employed in analytical test strips may take any suitable shape and be formed of any suitable materials including, for example, metal materials and conductive carbon materials.
Patterned conductive layer 14 includes a counter electrode 14a (also referred to as a reference electrode), a first working electrode 14b, and a second working electrode 14c (see
Counter electrode 14a, first working electrode 14b and second working electrode 14c may be formed of any suitable material including, for example, gold, palladium, platinum, indium, titanium-palladium alloys and electrically conducting carbon-based materials. Details regarding the use of electrodes and enzymatic reagent layers for the determination of the concentrations of analytes in a fluid sample are in U.S. Pat. No. 6,733,655, which is hereby fully incorporated by reference.
Patterned insulation layer 16 may be formed, for example, from a screen printable insulating ink. Such a screen printable insulating ink is commercially available from Ercon of Wareham, Mass. U.S.A. under the name “Insulayer.”
Patterned adhesive layer 20, which may be common for both strip 120 and strip 124, may be formed, for example, from a screen-printable pressure sensitive adhesive commercially available from Apollo Adhesives, Tamworth, Staffordshire, UK. In the embodiment of
Hydrophilic layer 22, which may be common for both strip 120 and strip 124, may be, for example, a clear film with hydrophilic properties that promote wetting and filling of electrochemical-based analytical test strip 120 by a fluid sample (e.g., a whole blood sample). Such clear films are commercially available from, for example, 3M of Minneapolis, Minn. U.S.A.
Enzymatic reagent layer 18, which may be common for both strip 120 and strip 124, may include any suitable enzymatic reagents, with the selection of enzymatic reagents being dependent on the analyte to be determined. In an embodiment, two overlapping enzymatic reagent layers 18 may be printed over the conductive layer, which is illustrated in
Enzymatic reagent layer 18 may include, for example, glucose oxidase, tri-sodium citrate, citric acid, polyvinyl alcohol, hydroxyl ethyl cellulose, potassium ferricyanide, antifoam, cabosil, PVPVA, and water.
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 may be configured to physically transform glucose 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 value. Further details regarding enzymatic reagent layers, and electrochemical-based analytical test strips in general, are in U.S. Pat. No. 6,241,862, the contents of which are hereby fully incorporated by reference.
Top layer 24, which may be common for both strip 120 and strip 124, includes a first portion 24a (e.g. a transparent or translucent first portion) and an opaque second portion 24b. First portion 24a and the opaque second portion 24b of the top layer are configured and aligned with the remainder of the analytical test strip such that a user can view the working portion of the sample-receiving chamber through the first portion of the top layer and is precluded from viewing the non-working portion of the sample-receiving chamber by the opaque second portion of the top layer. This configuration prevents a user from erroneously determining that a sample fill error has occurred when the working portion of the sample-receiving chamber has been filled but the non-working portion has not been filled.
Top layer 24 may be, for example, a clear film, with opaque second portion 24b being created, for example, by overprinting of the clear film with an opaque ink and first portion 24a being simply clear film without overprinting. A suitable clear film is commercially available from Tape Specialties UK.
Applicants recognized that there is a need for a blood glucose meter that can differentiate between different types of test strips. A blood glucose meter may be configured to perform a glucose test with a particular type of test strip, and if a different type of test strip is inserted, then the meter can output an error message. A method for determining a type of test strip should be robust so that an inadvertent withdrawal of the test strip or introduction of noise would not cause a misidentification.
In an embodiment, electronic circuitry may be employed to differentiate between different types of test strips.
Switch 304 may be in the form of metal oxide semiconductor field effect transistor (e.g., MOSFET or FET). Microcontroller 306 may control the switch 304 for applying a voltage waveform and to measure the resulting signal. More specifically, microcontroller 306 may be configured to open and close the transistor switch 304 with a first interrupt and also to measure transitions in a logic state at a second interrupt so that the glucose meter 100 may identify a first or second type of test strip 120 or 124, respectively. A transistor switch may have a source input 310 connected to a ground, a drain input 312 connected to connector point p4, and a gate input 314 connected to the first interrupt of a microcontroller along a strip discriminate line (S_DISC).
Electronic circuitry 300 may be electrically connected to the contacts (212d, 212a, 212b, 212c, and 212e) of the strip port connector 212, which in turn, respectively connect to the connector points (p4, ref, w2, w1, and p5). A strip detect line (S_DET) may be a second interrupt to connector point p5 and from microcontroller 306. A strip discriminate line (S_DISC) may be a first interrupt to switch 304. Switch 304 may be connected to reference connector point p4, microcontroller 306, and ground. The reference connector point ref may be connected to ground.
Referring back to
When a first type of test strip 120 is inserted into the strip port connector 212 causing connector points ref, p4, and p5 to short together, as illustrated in
For a situation in which a first type of test strip 120 has been inserted, point D will always be held at a logic low (i.e., GND) while switch is opened and closed four times because of the connection through p4 to ref, where ref is connected to GND. After the application of the pulses, microcontroller 306 will look to determine if there is a continual low level logic to ensure that the test strip has not been removed during the strip identification process. Where microcontroller 306 detects continual low level logic during the pulses and for a period of time thereafter, the software recognizes the presence of the first type of test strip 120 and initiates a blood glucose test by prompting a user to apply blood.
The frequency of pulses has to be sufficiently high so that it cannot be replicated by a manual removal and insertion process by a user. The user may insert and remove a strip about 10 times per second (i.e., 100 milliseconds per cycle). Thus, in an embodiment, a pulse length may be less than 50 milliseconds so that the pulse length will be shorter than the manual process by about a factor of two. In an alternative embodiment, the pulse waveform may be asymmetric where the low pulse may be about 20 milliseconds and the high pulse may be about 5 milliseconds.
When a second type of test strip 124 is inserted into the strip port connector configured specifically for the first type of strip 120, this causes connector points p4, and p5 to short together, as illustrated in
For the situation in which a second type of test strip 124 (instead of the first type of strip 120) has been inserted, the S_DET pin will read back the four pulses. The logic level will transition to high when switch 304 is open and transition to low when switch 304 is closed. Note, that in contrast to the insertion of the first type of test strip 120, point D will not always be held at a logic low (i.e. GND) because there is a discontinuous connection between p4 to ref. Microcontroller will determine whether the S_DET pin measures the same number of pulses (e.g., four pulses) that were sent out by the S_DISC pin. If this condition is true, then microcontroller 306 may determine that a second type of test strip 124 has been inserted and output an error message, which may be by audio, visual or both audiovisual annunciation by the meter 100. However, if the S_DET pin measures a different number of pulses that were sent out by the S_DISC pin, then the process of sending four pulses is repeated two more times to detect the presence of the second type of test strip 124.
Under certain circumstances, removal and re-insertion of the test strip or environmental noise may cause the S_DET pin to measure a different number of pulses than that sent out by the S_DISC pin.
After step 1502, a sub-routine 1600 is performed, as illustrated in
Note that in both the scenarios where the strip is not identified, but is determined to be present, and where the strip is determined not to be present, the strip removal debounce timer is started and a ‘bad strip’ timer is set to fire just after the debounce time expires. If this ‘bad strip’ timer event is received, an error message is displayed, as illustrated in a step 1520. If the debounce timer expires (which will happen before the ‘bad strip’ timer event if the strip has not been reinserted) and detects strip removal, then the normal strip removal event will be raised and handled before an error message is displayed, as illustrated in a step 1522. If, when the debounce timer expires, the strip is determined to be present, then the strip removal event will not be raised, and an error message will be displayed when the ‘bad strip’ timer event is received. This prevents the transient display of an error message when a strip is removed during the strip type detect operation.
Next, there is a wait time for a strip_type_detect_transient_delay (in milliseconds), as illustrated in a step 1720. After step 1720, the strip detect line is read by the microcontroller, as illustrated in a step 1722. A determination is made as to whether the strip detect line is high or low, as illustrated in a step 1724. If the strip detect is low, then the low_count is incremented by one, as illustrated in a step 1726. However, if the strip detect is high, then the pulse_count is incremented by one, as illustrated in a step 1728
After step 1728, a determination is made as to whether the pulse_count is equal to four, as illustrated in a step 1730. If the pulse_count is less than a predetermined number (e.g., preferably 4), then the process goes back to step 1708. However, if the pulse_count is equal to the predetermined number (e.g., preferably 4), then a determination is made as to the number of high_count increments and low_count increments, as illustrated in a step 1732. If the high_count equals four and the low_count equals zero, then the strip has been removed, as illustrated in a step 1740. If the high_count equals zero and the low_count equals four, then the strip is a first type, as illustrated in a step 1738. If the high_count equals four and the low_count equals four, then the strip is a second type, as illustrated in a step 1734. If the high_count and the low_count equal any other combination not listed in steps 1734, 1738, and 1740, then the strip type is not determined, as illustrated in a step 1736.
Any implementation of the processes of
While preferred embodiments of the present invention have been shown and described herein, it will be obvious to those skilled in the art that such embodiments are provided by way of example only. For example, the invention may be applied not only to docking stations and glucose meters, but can also be applied to any electronic device that needs a power supply and that may be re-set such as insulin infusion pump, continuous glucose monitoring system and the like. Moreover, while the various embodiments have been described in relation to blood glucose as an analyte, other analytes can be utilized such as, for example, ketones, cholesterols and the like. Numerous variations, changes, and substitutions will now occur to those skilled in the art without departing from the invention. Various alternatives to the embodiments of the invention described herein may be employed in practicing the invention. It is intended that the following claims define the scope of the invention and that methods and structures within the scope of these claims and their equivalents be covered thereby.
This DIVISIONAL application claims the benefits of priority under 35 USC §§120 and 121 from prior filed U.S. application Ser. No. 12/875,924 filed on Sep. 3, 2010, pending, which prior filed application (Ser. No. 12/875,924) claims the benefits of priority under 35 USC §119 and/or §120 from prior filed U.S. Provisional Application Ser. No. 61/240,133 filed on Sep. 4, 2009, in which all prior filed applications are incorporated by reference in their entirety into this application.
| Number | Date | Country | |
|---|---|---|---|
| 61240133 | Sep 2009 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 12875924 | Sep 2010 | US |
| Child | 14483472 | US |
