KR20070026606A - System and method for quality assurance of a biosensor test strip - Google Patents

Abstract

The present invention provides a test strip (200) for measuring a signal of interest in a biological fluid when the test strip (200) is mated to an appropriate test meter (not shown), wherein the test strip and the test meter include structures to verify the integrity of the test strip traces (214C, 216C, 224C), to measure the parasitic resistance of the test strip traces, and to provide compensation in the voltage applied to the test strip to account for parasitic resistive losses in the test strip traces. ® KIPO & WIPO 2007

Description

SYSTEM AND METHOD FOR QUALITY ASSURANCE OF A BIOSENSOR TEST STRIP}

This application claims the benefit of US Provisional Application No. 60 / 581,002, filed June 18, 2004. This application also relates to application number 10 / 871,937, filed June 18, 2004, the entirety of which is incorporated herein by reference.

The present invention is an apparatus for use in measuring signals relating to the concentration of analyte (blood sugar, etc.) in an organism's body fluid, as well as signals relating to the interferant (hematocrit and temperature for blood sugar, etc.) to analyte concentration signal. It is about. More specifically, the present invention relates to systems and methods for quality assurance of biosensor test strips.

Measurement of the concentration of a substance in the body fluids of an organism is an important means for the diagnosis and treatment of many medical conditions. For example, glucose measurement in body fluids such as blood is important for effective treatment of diabetes.

Diabetes treatment typically involves two forms of insulin treatment, basal and meal-time. Basal insulin, for example time-released insulin, often appears continuously before bedtime. Mealtime insulin provides an additional dose of insulin that acts more quickly to adjust for fluctuations in blood glucose caused by various factors, including metabolism of sugars and carbohydrates. Proper adjustment of blood glucose fluctuations requires accurate measurement of the concentration of sugar in the blood. Failure to make accurate measurements can lead to serious complications, including blindness and distal circulatory disorders, and extremes can lead to the failure of fingers, hands, feet, and the like.

Many methods are known for determining the concentration of analyte in a blood sample, such as, for example, glucose. Such methods typically result in one of two categories: optical and electrochemical methods. Optical methods typically include spectrometers and, in combination with reactants that produce a known color when combined with the analyte, observe the shift of the spectrum in the body fluid generated by the concentration of the analyte. Electrochemical methods, typically in combination with reactants that produce charge-carriers when combined with the analyte, are the current (ammeter), potential (potentiometric method) or accumulated charge (electrometer) of the analyte. Depends on the correlation between and concentration. For example, US Pat. No. 4,233,029 to Columbus, 4,225,410 to Pace, 4,323,536 to Columbus, 4,008,448 to Mugly, 4,654,197 to Liza et al., Zuminsky 5,108,564 to Back, 5,120,420 to Nankai, 5,128,015 to Zminski, 5,243,516 to White, 5,437,999 to Divald, and Paulman, etc. 5,288,636 5,628,890 to Cartel et al., 5,682,884 to Hill et al., 5,727,548 to Hill et al., 5,997,817 to Chris Moore et al., 6,004,441 to Fujiwara et al., Friedel. See 4,919,770 to Back, and 6,054,039 to Shear. Biosensors for performing tests are typically disposable test strips with reactants that chemically react with the analyte associated with the body fluids of the organism. The test strip is suitable for a non-disposable test meter so that the test meter can measure the reaction between the analyte and the reactant to determine and display the concentration of the analyte to the user.

1 shows a conventional prior art disposable biosensor test strip, typically designated as 10 (see, for example, US Pat. Nos. 4,999,582 and 5,438,271, assigned to the same assignee as the present application and referenced herein). Shown schematically. The test strip 10 is formed on the nonconductive substrate 12, and the conductive regions 14 and 16 are formed thereon. The chemical reactant 18 is applied to the conductive regions 14, 16 at one end of the test strip 10. Reactant 18 reacts with the analyte associated with the sample of the organism in a manner that can be detected when an electrical potential acts between the measurement electrodes 14a and 16a.

The test strip 10 has a reaction zone 20 comprising measuring electrodes 14a, 16a in direct contact with the sample comprising the analyte for which the concentration in the sample is to be determined. In an amperometric or electrochemical electrochemical measurement system, the measuring electrodes 14a, 16a of the reaction zone 20 supply an electrical potential to the measuring electrode, and these potentials (eg, current, impedance, charge, etc.) It is connected to an electrical circuit (usually known in the art, a test meter with an inserted test strip 10 (not shown)) measuring the response of the electrochemical sensor to. This reaction is proportional to the reactant concentration.

The test meter is in contact with the test strip 10 at the contact pads 14b, 16b of the contact zone 22 of the test strip 10. The contact zone 22 is located somewhat further away from the measurement zone 20 and is usually (but not always) at the opposite end of the test strip 10. The conductive traces 14c and 16c connect the contact pads 14b and 16b of the contact zone 22 to the respective measuring electrodes 14a and 16a of the reaction zone 20.

In particular, the electrodes, traces and contact pads for the biosensor 10 consist of an electrically conductive thin film (eg, pure metal, carbon ink, and silver plating, but not limited to), and the contact zone 22 is a reaction zone. The resistivity of the conductive traces 14c and 16c connecting to (20) is more than a few hundred ohms. This eddy current causes a drop in the potential along the length of the traces 14c and 16c, so that the potential present in the measuring electrodes 14a and 16a of the reaction zone 20 is measured by the test meter in the contact zone 22. It is considerably smaller than the potential applied to the contact pads 14b and 16b of the test strip 10. Since the impedance of the reaction introduced into the reaction zone 20 can be within the order of the magnitude of the vortex resistance of the traces 14c and 16c, the signal to be measured is the IR (current x resistance) drop induced by the trace. Can have a significant offset. If the offset is different for each test strip, noise is added to the measurement results. In addition, physical damage to the test strip 10, such as wear, cracks, scratches, chemical degradation, and the like, may occur during manufacture, shipping, storage and / or user malfunction. Such defects can damage the conductive region in that there is an extremely high resistance or open circuit in the conductive region 14, 16. Such an increase in trace resistance can hinder the test meter from performing the correct test.

Accordingly, what is needed is a system and method for verifying the integrity of a test strip trace, measuring the eddy current resistance of the test strip trace, and controlling the potential level actually applied to the test strip measurement electrode in the reaction zone.

The present invention measures the signal associated with the body fluids of the organism when the test strip is matched to an appropriate test meter, the test strip and the test meter confirm the integrity of the test strip trace, measure the eddy current resistance of the test strip trace, It also provides a test strip that compensates for the voltage applied to the test strip to calculate the loss of eddy currents in the test strip trace.

The invention is further illustrated by way of example with reference to the accompanying drawings.

1 is a schematic plan view of a conventional prior art test strip used to measure the concentration of an analyte associated with a body fluid of an organism.

2 is a schematic plan view of a test strip of a first embodiment according to the present invention.

FIG. 3 is a schematic diagram of the electrical test circuit of the first embodiment used with the first embodiment test strip of FIG. 2.

4 is an exploded view of a second conventional prior art test strip used to measure the concentration of analyte associated with biological fluids.

5 shows a view of a removal device suitable for use with the present invention.

FIG. 6 is a view of the laser ablation apparatus of FIG. 5 showing a second mask. FIG.

7 is a diagram of a removal device suitable for use with the present invention.

8 is a schematic plan view of a test strip of a second embodiment according to the present invention.

FIG. 9 is a schematic diagram of an electrical test circuit of the second embodiment used with the test strip of the second embodiment of FIG. 8.

FIG. 10 is a schematic diagram of an electrical test circuit of a third embodiment used with the test strip of the second embodiment of FIG. 8.

For the purpose of facilitating the understanding of the principles of the invention, reference has been made to the embodiments shown in the drawings, and special language has been used to describe the embodiments. Nevertheless, it will be understood that the scope of the present invention is not limited. It is desirable that modifications and variations in the devices shown, as well as other applications of the scope of the inventions shown, be protected as those related inventions would normally arise to those skilled in the art to be expected. In particular, although the present invention is discussed in terms of blood glucose meters, it is contemplated that the present invention can be used as an apparatus for measuring other analytes and other sample types. Such alternative embodiments require certain adaptations to the embodiments which are obviously discussed in the art.

Although the systems and methods of the present invention can be used in a wide variety of test strips of construction and the configurations and processes can be manufactured in a wide variety, the electrochemical test strips of the first embodiment of the present invention are schematically illustrated in FIG. It is represented by 200. Portions of the test strip 200 that are substantially the same as the test strip 10 are denoted by the same reference numerals. Referring to FIG. 2, test strip 200 is a 350 μm thick poly coated on top surface that is a 50 nm conductive gold layer (eg, by way of non-limiting sputtering or vapor deposition). Bottom substrate 12 formed of an opaque body of an ester (Melinex 329 available from DuPont). Electrodes connecting the traces and contact pads are engraved on the conductive layer by a laser ablation process. Laser ablation treatment is performed by an excimer laser that penetrates a chrome-on-quartz mask. The mask pattern reflects a portion of the laser field, penetrates the other portion of the field, and creates a pattern on the gold plating that is contacted and evaporated by the laser light. The laser ablation treatment is described in more detail below. For example, the actuation 214a, opposing 216a, and opposing sense 224a electrodes may be formed as shown and each measuring contact pad 214b by a respective trace 214c, 216c and 224c. , 216b, 224b. As is known in the art, when test strip 200 is inserted into a test meter, such contact pads 214b, 216b and 224b provide a conductive area on test strip 200 by contacting the connector of the test meter. Contact.

2 and 3 show an embodiment of the present invention that improves the test strip of the prior art by compensating for the vortex I-R drop in the opposite electrode line of the test strip. The test strip 200 of FIG. 2 is substantially the same as the prior art test strip 10 of FIG. 1, except for the opposing sense electrode 224a, the contact pad 224b, and the trace 224c. The provision of the opposite sense line 224 allows the test meter (described below) to compensate for the eddy current resistance between the contact pads 216b, 224b. Using the circuit of FIG. 3, the embodiment of FIG. 2 only compensates for the I-R drop at the opposite electrode side of the test strip 200. Although it can be imitated at the working electrode side, the eddy current resistance at the working electrode side of the test strip 200 cannot be detected using this circuit, which will be apparent to those skilled in the art with reference to the present invention. Another way of compensating for eddy current resistance on the working and opposing sides of the test strip is represented below. Thus, the opposing line 216 of FIG. 2 allows the test meter to compensate for the desired vortex resistance potential drop and is described in more detail by FIG.

FIG. 3 shows a schematic electrical circuit diagram of the electrode compensation circuit (usually denoted 300) of the first embodiment mounted in a test meter. As shown, the circuitry connects to the contact pads 214b, 216b and 224b when the test strip 200 is inserted into the test meter. As will be appreciated by those skilled in the art, the potential is applied to the counter electrode contact pad 216b, and the ratio of the amount of analyte present in the sample of the organism applied to the reactant 18, the counter electrode 216a and the working electrode 214a Create a current in between. Current from the working electrode 214a is transmitted to the working electrode contact pad 214b by the working electrode trace 214c and is provided to the current-voltage amplifier 310. The analog output voltage of the amplifier 310 is converted into a digital signal by an analog-to-digital converter (A / D) 312. This digital signal is processed by the microprocessor 314 according to a pre-stored program to determine the concentration of the analyte in the sample of the organism applied to the test strip 200. This concentration is displayed to the user by an appropriate output device 316, such as a liquid crystal display (LCD) screen.

The microprocessor 314 also outputs a digital signal indicative of the potential applied to the counter electrode contact pad 216b. This digital signal is converted into an analog voltage signal by a digital-to-analog converter (D / A) 318. The analog output of the D / A 318 is applied to the first input of the OP amplifier 320. The second input of the OP amplifier 320 is connected to the opposing sense electrode contact pads 224b. OP amplifier 320 is connected to opposing electrode contact pad 216b.

OP amplifier 320 is connected to a voltage follower arrangement, and the amplifier adjusts the output (physical limit of operation) until the voltage appearing at the second input is equal to the voltage appearing at the first input. The second input of the OP amplifier 320 is a high impedance input, so substantially no current flows in the opposite sense line 224. Since there is no substantially flowing current, the predetermined eddy current resistance of the opposing sense line 224 does not cause a potential drop, and the voltage appearing at the second input of the OP amplifier 320 is substantially equal to the voltage at the opposing sense electrode 224a. Are substantially the same as the voltage present at the counter electrode 216a by its close physical proximity. Thus, the op amp 320 is provided with the opposing electrode contact pad (until the opposing electrode 216a (feed back to the opposing sense line 224) becomes equal to the potential named by the microprocessor 314. Serves to change the potential applied to 216b). Thus, the OP amplifier 320 automatically compensates for the predetermined potential drop caused by the eddy current resistance at the counter electrode trace 216c, and the potential at the counter electrode 216a is the desired potential. Since the voltage generating the current is exactly the same as the voltage commanded by the microprocessor 314, the calculation of the analyte concentration in the sample of the organism from the current generated by the working electrode becomes more accurate. Without compensating for the eddy resistance voltage drop provided by the circuit 300, the microprocessor 314 analyzes the current under false estimation that the commanded voltage is substantially applied to the counter electrode 216a.

Methods that are not limited to examples such as carbon ink printing, silver paste silk-screening, metallized plastic scribing, electroplating, chemical plating, and photochemical etching include testing with multiple electrodes. Useful for providing strips. One preferred method of providing test strips with additional electrode senses as described herein is the use of laser ablation techniques. An example of the use of this technique to provide an electrode for a biosensor is to have a laser ablation electrode with a continuous Coverer channel of US Patent Application No. 09 / 866,030, filed May 25, 2001. Biosensor ", US Patent Application No. 09 / 411,940, filed Oct. 4, 1999," Laser Formed with Patterned Laminates and Electrodes ", both publications are referenced. Laser conduction is particularly useful for providing test strips according to the present invention, since conductive regions with extremely small feature sizes are produced accurately in an iterative manner. Laser ablation provides a means to add an extra sense line of the present invention to the test strip without expanding the size of the test strip.

In the present invention, it is desirable to provide accurate placement of electrical components with respect to each other and throughout the biosensor. In a preferred embodiment, the relative placement of the components is at least partly made by the use of wide field laser ablation, which is carried out through a mask or other device having the correct pattern for the electrical component. This precisely positions the adjacent edges and improves the smoothness of the edges to close tolerances.

4 shows a simple biosensor 401 useful for explaining the laser ablation process of the present invention, wherein a first electrode set 404 and a second electrode set 405, and corresponding traces 406 and 407, respectively; A substrate 402 formed in a conductive material 403 forming an electrode system comprising contact pads 408 and 409. The biosensor 401 is used for the purpose of explaining the laser ablation process and is not embodied in the sense line of the present invention. Conductive material 403 may comprise a pure metal or alloy, or a metal or chain other material. Preferably, the conductive material absorbs the wavelength of the laser used to form the electrode and has a thickness following rapid and accurate processing. Non-limiting examples include aluminum, carbon, copper, chromium, gold, indium tin oxide (ITO), palladium, platinum, silver, tin oxide / gold, titanium, mixtures thereof, and alloys or metal compositions of these elements. Preferably, the conductive material comprises a pure metal or alloy or oxides thereof. Most preferably, the conductive material includes gold, palladium, aluminum, titanium, platinum, ITO and chromium. The conductive material has a thickness of about 10 to 80 nm, more preferably 30 to 70 nm, most preferably 50 nm. The thickness of the conductive material depends on the transmission properties of the material and other factors related to the use of the biosensor.

Although not shown, the patterned conductive material may be coated or plated with additional metal layers. For example, the conductive material may be copper, which is removed with a laser pattern through a laser, after which the copper may be plated with a titanium / tungsten layer, and a gold layer to form the desired electrode. Preferably, a single layer of conductive material is used and lies on the base 402. Although not normally required, as is known in the art, the use of a seed or auxiliary layer, such as chromium nickel or titanium, can improve the adhesion of the conductive material to the base. In a preferred embodiment, the biosensor 401 has a single layer of gold, palladium, platinum or ITO.

The biosensor 401 is exemplarily manufactured using the two devices 10, 10 ′ shown in FIGS. 5, 6 and 7, respectively. Although not described otherwise, the devices 410 and 410 'operate in a similar manner. Referring to FIG. 5, the biosensor 401 has a gold laminate of 80 nm and is manufactured with a custom-made wide field laser removal device 410 by supplying a ribbon roll 420 having a width of about 40 mm. Apparatus 410 includes a laser source 411, a chrome plated quartz mask 414, and a lens 416 that produce a beam of laser light 412. Although the illustrated lens 416 is a single lens, a plurality of lenses are preferred in which the lens 416 cooperates to make the light 412 into a predetermined shape.

Non-limiting examples of suitable removal devices 410 (FIGS. 5-6) are custom-made microline lasers 200-4 commercially available from LPKF Laser Electronic GmbH of Garbsen, Germany. Laser systems, LPX-400, LPX-300 or LPX-200 laser systems commercially available from Lambda Physik AG of Gottingen, Germany, and International of Colorado Springs, Co. A chrome plated quartz mask commercially available from International Phototool Company.

In the microline laser 200-4 laser system (FIGS. 5-6), the laser source 411 is an LPX-200 KrF-UV-laser. However, high wavelength UV lasers can be used. The laser source 411 operates at 248 nm with a pulse energy of 600 mJ, and a pulse repetition frequency of 50 Hz. The intensity of the laser beam 412 can be infinitely adjusted between 3% and 92% by a dielectric beam attenuator (not shown). The beam profile is 27x15 mm 2 (0.62 square inches) and the pulse duration is 25 ns. The layout on the mask 414 is equally projected by the optical element beam expander, homogenizer, and field lens (not shown). The performance of the homogenizer is determined by measuring the energy profile. Imaging lens 416 transmits the structure of mask 414 to ribbon 420. The imaging ratio is 2: 1 to remove large areas in one hand, but to maintain an energy density below the removal point of the chrome mask applied in the other hand. Although 2: 1 imaging is shown, certain other ratios are possible depending on the desired design requirements. Ribbon 420 moves as shown by arrow 425 to cause the plurality of layout segments to be removed in series.

Positioning of mask 414, movement of ribbon 420, and laser energy are computer controlled. As shown in FIG. 5, the laser beam 412 is projected onto the ribbon 420 and removed. Light 412 passing through the transparent area or window 418 of the mask 414 removes metal from the ribbon 420. The chrome coated area 424 of the mask 414 blocks the laser light 412 and prevents its removal from that area, resulting in a structure plated on the ribbon 420 surface. Referring to FIG. 6, the complete structure of the electrical component may require an additional removal step through the second mask 414 ′. Depending on the size of the lens and the electrical component to be removed, only a single removal step or two or more removal steps may be necessary. In addition, instead of multiple masks, multiple fields can be formed in the same mask.

Specifically, a non-limiting second example of a suitable removal device 410 '(FIG. 7) is a custom laser system commercially available from LPKF Laser Electronic GmbH of Garbsen, Germany. , The Stable energy eximer laser (STEEL) laser system commercially available from Lambda Physik AG of Gottingen, Germany, and the international phototool of Colorado Springs, Co. Chromium plated quartz mask commercially available from International Phototool Company. The laser system exhibits 1000 mJ pulse energy at 308 nm wavelength. In addition, the laser system has a frequency of 100 Hz. The device 410 'can be configured to produce a two pass biosensor as shown in FIGS. 5 and 6, but preferably the lens allows the formation of a 10x40 mm pattern in a single pass at 25 ns. do.

Although not combined with a particular theory, laser pulses or beams 412 that penetrate the masks 414, 414 ′, 414 ″ are absorbed within the surface 402 of less than 1 μm in the ribbon 420. Photons of the beam 412 have sufficient energy to cause photodissociation and rapid breakdown of chemical bonds at the metal / polymer interface. This abrupt chemical bond breakdown causes a rapid pressure increase in the absorbing region and the force member (metal film 403) and exits from the polymer base surface. Since the typical pulse duration is about 20 to 25 ns, the interaction with the material causes a sudden and thermal damage to the edges of the conductive material 403, thereby minimizing the periphery of the structure. As intended by the present invention, the edges of the electrical components have high edge characteristics and accurate position.

The energy density used to remove the metal from the ribbon 420 is determined by the material on which the ribbon 420 is formed, the adhesion of the metal film to the base material, the thickness of the metal film, and the film on the base such as, for example, support and deposition. Follow the possible treatments used to locate them. The energy density level for gold is about 50 to about 90 mJ / cm 2 on KALADEX ^® , about 100 to 120 mJ / cm 2 on polyimide and about 60 to 120 mJ / cm 2 on MELINEX ^® . Energy density levels below or above the above mentioned energy density levels are suitable for other base materials according to the invention.

Patterning of the area of the ribbon 420 is accomplished using masks 414, 414 ′. Each mask 414 414 ′ illustratively includes a mask field 422 that includes an accurate two-dimensional representation of a predetermined portion of the electrode component pattern to be formed. 5 shows a mask field 422 that includes contact pads and portions of traces. As shown in FIG. 6, the second mask 414 ′ includes an electrode pattern comprising a finger and a second corresponding portion of the trace. As discussed above, depending on the size of the area to be removed, the mask 414 may comprise a complete illustration of the electrode pattern (FIG. 7), or portions of a pattern other than those shown in FIGS. 5 and 6. Preferably, in the first aspect of the invention, the wide field contains the total size of the test strip (FIG. 7) such that the entire pattern of electrical components on the test strip is simultaneously removed. Alternatively, as shown in FIGS. 5 and 6, portions of the entire biosensor are run continuously.

Although the mask 414 is discussed below, the discussion applies to the masks 414 ', 414 " except as otherwise indicated. Referring to FIG. 5, the area 424 of the mask field 422 protected by chromium prevents the laser beam 412 penetration into the ribbon 420. The transparent area or window 418 of the mask field 422 allows the laser beam 412 to penetrate the mask 414 and press against a predetermined area of the ribbon 420. As shown in FIG. 5, the transparent area 418 of the mask field 422 corresponds to the area of the ribbon 420 from which the conductive material 403 is removed.

In addition, the mask field 422 has a length shown by line 430 and a width shown by line 432. Given a 2: 1 imaging ratio of LPX-200, the length 430 of the mask is twice the length of the patterned length 434, and the width 432 of the mask is patterned on the ribbon 420 Twice the width 436. Lens 416 reduces the size of laser beam 412 that strikes ribbon 420. The relative dimensions and patterning of the mask field 422 can be modified in accordance with the present invention. Mask 414 '(FIG. 6) is used to complete the two-dimensional illustration of the electrical component.

With continued reference to FIG. 5, in the laser ablation apparatus 410, the excimer laser source 411 emits a beam 412, which passes through a chrome coated quartz mask 414. The mask field 422 reflects a portion of the laser beam 412, penetrates the other portion of the beam, and creates a pattern on the gold film pressed by the laser beam 412. The ribbon 420 may be stationary relative to the device 410 or may move continuously on a roll through the device 410. Accordingly, the non-limiting moving speed of the ribbon 420 is about 0 m / min to about 100 m / min, more preferably about 30 m / min to about 60 m / min. The moving speed 420 of the ribbon 420 is limited only by the selected equipment 410 and may exceed 100 m / min depending on the pulse duration of the laser source 411 in accordance with the present invention.

After the pattern of the mask 414 is created on the ribbon 420, the ribbon is rewound and transported through the device 410 with the mask 414 ′ (FIG. 6). Alternatively, laser device 410 may be located in series in accordance with the present invention. Thus, by using masks 414, 414 ′, a large area of ribbon 420 uses a step-and-repeat process that includes multiple mask fields 422 in the same mask area. Patterned to enable the economic production of complex electrode patterns and other electrical components on the substrate of the base, the precise edges of the electrode components, and the removal of large amounts of metal film from the base material.

The second embodiment of the present invention shown in FIGS. 8 and 9 improves on the prior art by providing operation on the test strip and I-R drop compensation of the counter electrode leads. 8 schematically shows the configuration of a test strip of the second embodiment of the present invention, typically indicated at 800. The test strip 800 comprises a bottom substrate 12 coated on its top surface with a 50 nm conductive gold layer (eg, by the method of non-limiting examples such as sputtering or deposition). The electrodes connecting the traces and contact pads are patterned on the conductive layer by laser ablation treatment as described above. For example, actuation 814a, actuation sense 826a, opposing 216a, and opposing sense 224a electrodes are formed as shown and each is traced by respective traces 814c, 826c, 216c and 224c, respectively. Can be coupled to the measuring contact pads 814b, 826b, 216b, and 224b. These contact pads 814b, 826b, 216b, and 224b provide a conductive area on the test strip 800 so that after the test strip 800 is inserted into the test meter, the contactor contacts of the test meter (not shown) are provided. Contact by

With the exception of the addition of the actuation sense electrode 826a, the contact pads 826b, and the traces 826c, the test strip 800 of FIG. 8 is substantially the same as the test strip 200 of the first embodiment of FIG. same. The provision of the actuation sense line 826 allows the test meter to compensate for any I-R drop caused by the contact resistance of the connection to the contact pads 814b and 216b, and to compensate for the trace resistance of the traces 814c and 216c.

9 shows a schematic electrical circuit diagram of an electrode compensation circuit (usually indicated by 900) of a second embodiment mounted in a test meter. As shown, when the test strip 800 is inserted into the test meter, the circuit is connected to the contact pads 826b, 814b, 216b, and 224b. As will be appreciated by those skilled in the art, the potential is applied to the counter electrode contact pad 216b, and a current proportional to the amount of analyte present in the sample of the organism applied to the reactant 18 has a counter electrode 216b and a working electrode 814a. Occurs between). Current from the working electrode 814a is sent to the working electrode contact pad 814b by the working electrode trace 814c and to the current-voltage amplifier 310. The analog output voltage of the amplifier 310 is converted into a digital signal by the A / D 312. The digital signal is processed by the microprocessor 314 according to a pre-stored program to determine the concentration of the analyte associated with the sample of the organism applied to the test strip 800. The concentration is displayed to the user by the LCD output device 316.

The microprocessor 314 outputs a digital signal indicative of the potential applied to the counter electrode contact pad 216b. The digital signal is converted into an analog voltage signal (reference voltage source) by the D / A 318. The analog signal of the D / A 318 serves as the first input of the OP amplifier 320. The second input of the OP amplifier 320 is connected to the output of the OP amplifier 910. The OP amplifier 910 is connected to another amplifier configuration using a mechanical amplifier. The first input of the OP amplifier 910 is connected to the operating sense electrode contact pad 826b, and the second input of the OP amplifier 910 is connected to the opposing sense electrode contact pad 224b. The output of the OP amplifier 320 is connected to the opposing electrode contact pad 216b. When the biosensor test strip 800 is connected to the test meter, the first input of the OP amplifier 910 is connected to the operational sense trace 826c and the second input is connected to the opposite sense trace 224c. The output of the OP amplifier is connected to the counter electrode trace. In this configuration, the OP amplifier 910 acts as a differential amplifier.

OP amplifier 320 is coupled in a voltage follower configuration, and the amplifier regulates its output (within the physical limitations of operation) until the voltage indicated at the second output is equal to the commanded voltage indicated at the first input. The two inputs of the OP amplifier 910 are high impedance inputs so that there is no current flowing substantially in the opposing sense line 224 or the operating sense line 826. Since there is no substantially flowing current, any resistance in the opposing sense line 224 or the operating sense line 826 does not cause a potential drop, and the voltage representing the input of the OP amplifier 910 is substantially between the measuring cells. (I.e., between the counter electrode 216a and the working electrode 814a). Since the OP amplifier 910 is connected in a differential amplifier shape, the output of the OP amplifier represents the voltage between the measuring cells.

OP amplifier 320 operates to adjust the output (i.e., the potential applied to opposing electrode contact pad 216b) until the substantial potential representing between the measuring cells becomes equal to the potential commanded by microprocessor 314. do. The OP amplifier 320 automatically compensates for any potential drop caused by the vortex resistance at the counter electrode trace 216c, the counter electrode pad 216b, the working electrode trace 814c, and the working electrode contact 814b. Therefore, the potential shown between the measurement cells is a desired potential. The calculation of the analyte concentration in the sample of the organism is more accurate from the current generated by the working electrode.

10, in combination with FIG. 8, not only provides IR drop compensation of the working electrode and the counter electrode line, but also ensures that the test meter can compensate for the IR drop, so that the two resistors of the working electrode and the counter electrode line are pre-set. A third embodiment of the present invention is shown which improves on the prior art by providing an inspection that does not exceed a defined limit. FIG. 10 shows a schematic electrical circuit diagram of an electrode compensation circuit (typically denoted by 1000) of a third embodiment mounted in a test meter. The electrode compensation circuit 1000 works in conjunction with the test strip 800 of FIG. 8. As shown, when the test strip 800 is inserted into the test meter, the circuit is connected to the contact pads 826b, 814b, 216b, and 224b. As will be appreciated by those skilled in the art, the potential is applied to the counter electrode contact pad 216b, and a current proportional to the amount of analyte present in the sample of the organism applied to the reactant 18 is applied to the counter electrode 216a and the working electrode 814a. Between). Current from the working electrode 814a is transmitted to the working electrode contact pad 814b by the working electrode trace 814c and provided to the current-voltage amplifier 310. When the switch 1004 is in the closed position, the output of the current-voltage amplifier 310 is used for the input of the mechanical amplifier 1002 formed into a buffer having unity gain. The analog output voltage of the amplifier 1002 is converted into a digital signal by the A / D 312. The digital signal is then processed by the microprocessor 314 in accordance with a prestored program to determine the concentration of the analyte in the sample of the organism used in the test strip 800. This concentration is displayed to the user by the LCD output device 316.

The microprocessor 314 also outputs a digital signal indicative of the potential used for the counter electrode contact pad 216b. The digital signal is converted into an analog voltage signal by the D / A 318. The analog output of the D / A 318 is used at the input of the OP amplifier 320 formed of a voltage follower when the switch 1006 is in the position shown. The output of the OP amplifier 320 is connected to the opposing electrode contact pad 216b and measures the body fluid of the organism applied to the reactant 18. In addition, if the switches 1006, 1008 and 1010 are in the position shown in FIG. 10, the circuit is configured as in FIG. 9 and can be used to automatically compensate for eddy current resistance and contact resistance as described above with respect to FIG. 9.

In order to measure the amount of eddy current resistance in the counter electrode line 216, the switch 1008 is placed in the position shown in FIG. 10, the switch 1006 is placed in the opposite position shown in FIG. 10, and the switch 1010 ) Is closed. The OP amplifier 320 acts as a buffer with unity gain and uses a potential on the counter electrode contact pad 216b through a known resistor R _nom . This resistance generates a current to flow in the opposite electrode line 216 and the opposite sense line 224 sensed by the current-voltage amplifier 310, and is connected to the current sense line through the switch 1010. The output of the current-voltage amplifier 310 is provided to the microprocessor 314 via the A / D 312. Knowing the value of R _nom , the microprocessor 314 can calculate the value of the desired vortex resistance in the opposite sense line 224 and the opposite electrode line 216. This vortex resistance value is compared with a predetermined limit value stored in the test meter to determine whether physical damage has occurred to the test strip 800 or whether non-conductive accumulation is present on the contact pad. 800) These tests can be compared to sizes that cannot be used reliably. In such a case, the test meter may be programmed to inform the user that an alternative test strip should be inserted into the test meter before proceeding with the test.

In order to measure the amount of eddy current resistance in the working electrode line 814, the switches 1006 and 1008 are placed in opposite positions to the position shown in FIG. 10, and the switch 1010 is opened. The OP amplifier 320 acts as a buffer with unity gain and uses the potential through the known resistor R _nom to the operating sense contact pads 826b. This resistance generates a current that flows in the working sensor line 826 and the working electrode line 814 as sensed by the current-voltage amplifier 310. The output of the current-voltage amplifier 320 is provided to the microprocessor 314 via the A / D 312. Knowing the value of R _nom , the microprocessor 314 can calculate the value of the desired vortex resistance in the operating sense line 826 and the working electrode line 814. This vortex resistance value is compared with a predetermined limit value stored in the test meter to determine whether physical damage has occurred to the test strip 800 or whether non-conductive accumulation is present on the contact pad. 800) These tests can be compared to sizes that cannot be used reliably. In such a case, the test meter may be programmed to inform the user that an alternative test strip should be inserted into the test meter before proceeding with the test.

All publications, conventional applications, and other documents described herein are incorporated herein by reference individually and in their entirety.

Although the present invention has been illustrated and described in detail in the drawings and the foregoing description, the description is by way of example and not limitation. Preferred embodiments, and certain other embodiments, are shown to help further illustrate the use or formation of the preferred embodiments. All variations and modifications within the spirit of the invention are preferably protected.

Claims (27)

A biosensor system for detecting a concentration of an analyte using a biosensor test strip, wherein the biosensor test strip 800 includes: Working electrode 814b, A working electrode trace 814c operatively connected to the working electrode 814a, An actuation sense trace 826c operatively connected to the actuation electrode 814a, Counter electrode 216a, A counter electrode trace 216c operatively connected to the counter electrode 216a, An opposing sense trace 224c operatively connected to the opposing electrode 216a, The system, A test meter having an interface for receiving the biosensor test strip 800, A differential amplifier 910 having a first and a second differential amplifier 910 input and a differential amplifier 910 output, the first differential amplifier 910 input being operatively connected to the operational sense trace 826c; And the second differential amplifier (910) input is operatively connected to the opposite sense trace (224c) and the differential amplifier (910) output is operatively connected to the opposite electrode trace (216c). The method of claim 1, A reference voltage source 318 with a reference voltage output, and Further comprising an OP amplifier 320 having a first and a second OP amplifier 320 input and an OP amplifier 320 output, The first OP amplifier 320 input is operatively connected to the reference voltage output, the second OP amplifier 320 input is operatively connected to the differential amplifier 910 output, and the OP amplifier 320 output is the A biosensor system, operatively connected to the counter electrode trace 216c. 3. A biosensor system according to claim 2, wherein the reference voltage source (318) is a digital-to-analog converter (318). 3. A biosensor system according to claim 2, further comprising an analog-to-digital converter (312) having an operative connection input to the actuation electrode (814a). The method of claim 4, wherein Said analog-to-digital converter 312 having an analog input and a digital output; And a current-voltage amplifier (310), the input being operatively connected to the working electrode trace (814c) and the output is operatively connected to the analog-to-digital converter (312) input. The method of claim 5, A microprocessor 314 having a microprocessor 314 input operatively coupled to the analog-to-digital converter 312 and providing a microprocessor 314 reference voltage control output, and And a reference voltage source (318) further comprising a reference voltage source (318) control input operatively coupled to the microprocessor (314) reference control output. 7. The apparatus of claim 6, wherein the microprocessor 314 further comprises a display control output to indicate the concentration of the analyte, The system, And an output indication 316 operatively connected to the microprocessor 314 display control output, wherein the indication of the concentration of the analyte is provided to the user via the output indication 316. . As a biosensor system, Biosensor test strip 800, Working electrode 814a, A working electrode trace 814c operatively connected to the working electrode 814a, An actuation sense trace 826c operatively connected to the actuation electrode 814a, Counter electrode 216a, A counter electrode trace 216c operatively connected to the counter electrode 216a, A counter sense trace 224c operatively connected to the counter electrode 216a, A test meter operatively connected to the biosensor test strip 800, The test meter, A differential amplifier 910 having a first and a second differential amplifier 910 input and a differential amplifier 910 output, the first differential amplifier 910 input being operatively connected to the operational sense trace 826c, The second differential amplifier 910 input is a differential amplifier 910 operatively connected to the opposite sense trace 224c, A reference voltage source 318, and A voltage follower amplifier (320) having a first and a second voltage follower (320) input and a voltage follower (320) output, the first voltage follower (320) input being the reference voltage source (318). A voltage follower that is operatively connected to the second voltage follower 320 input is operatively connected to the differential amplifier 910 output, and the voltage follower 320 output is operatively connected to the counter electrode trace 216c. Biosensor system comprising a war amplifier. A method of applying a stimulus of a desired size to a sample of a creature under test in a measurement cell of a test strip 800, the method comprising: Applying a stimulus to the test strip 800, Measuring a magnitude of a voltage difference generated through the measurement cell in response to the stimulus, and Adjusting the magnitude of the stimulus on the test strip (800) such that the voltage difference produced through the measurement cell has a magnitude substantially equal to the desired magnitude. 10. The method of claim 9, further comprising using a device having a high input impedance to measure the voltage difference generated through the measurement cell in response to the stimulus. 12. The method of claim 10, wherein said device with high input impedance comprises a differential amplifier (910). 10. The method of claim 9, wherein the test strip 800 comprises a counter electrode 216a and a working electrode 814a, the method comprising: Comparing the measured potential difference between the measurement cell and the desired reference voltage, Using a comparison of the potential difference between the measurement cell and the desired reference voltage to adjust the voltage between the counter electrode (216a) and a working electrode (814a). 13. The method of claim 12, wherein the desired reference voltage is provided by a microprocessor (314) in which a voltage reference is controlled. 14. The method of claim 13, wherein the microprocessor (314) having a controlled voltage reference further comprises a digital-to-analog converter (318). 10. The method of claim 9, further comprising using an opposing sense line (224) and an operating sense line (826) to sense the potential difference between the measurement cells. A method of measuring an analyte using a test strip 800 comprising a measuring cell, a counter electrode 216a, and a working electrode 814a, the method comprising: Receiving the test strip 800 in the biosensor device, Applying a stimulus to the counter electrode 216a to create a potential through the measurement cell, Measuring a potential difference generated through said measuring cell by said application of said stimulus, Adapting the stimulus applied to the counter electrode based on the measured potential difference produced through the measurement cell. The method of claim 16, wherein the test strip 800, Working electrode 814a, An actuation sense contact pad 826b operatively connected to the actuation electrode 814a, A working electrode contact pad 814b operatively connected to the working electrode 814a, Counter electrode 216a, An opposite electrode contact pad 216b operatively connected to the opposite electrode 216a, and Further comprising an opposing sense contact pad 224b operatively connected to the opposing electrode 216a, The method, Receiving an operating sense contact pad 826b potential from the operating electrode 814a from the operating sense contact pad 826b, Receiving an opposite sense contact pad 224b potential from the opposite electrode 216a from the opposite sense contact pad 224b, Comparing the working sense contact pad (224b) potential with the opposite sense contact pad (224b) potential to measure the potential through the measuring cell. A method of measuring the eddy current impedance of one or more traces of a biosensor test strip 800, wherein the biosensor test strip 800 comprises: Working electrode 814a, A working electrode trace 814c operatively connected to the working electrode 814a, The actuation sense trace 826c operatively connected to the actuation electrode 814a, Counter electrode 216a, A counter electrode trace 216c operatively connected to the counter electrode 216a, An opposing sense trace 224c operatively connected to the opposing electrode 216b, The method, The operating sense trace 826c and the working electrode trace 814c to form a series circuit equal to the impedance of the known resistor and the operating sense trace 826c and the series circuit impedance including the operating electrode trace 814c impedance. Selectively placing a resistor having a known impedance in series with Selectively applying a stimulus to generate a current through the series circuit, Measuring a current flowing through the series circuit, Using the current measurement to calculate the eddy current impedance of one or more traces of the biosensor test strip (800). 19. The method of claim 18, wherein the series circuit impedance is used to determine whether the biosensor test strip (800) is damaged. A method of measuring the eddy current impedance of one or more traces of a biosensor test strip 800, wherein the biosensor test strip 800 comprises: Working electrode 814a, A working electrode trace 814c operatively connected to the working electrode 814a, The actuation sense trace 826c operatively connected to the actuation electrode 814a, Counter electrode 216a, A counter electrode trace 216c operatively connected to the counter electrode 216a, An opposing sense trace 224c operatively connected to the opposing electrode 216b, The method, The counter sense trace 224c and the counter electrode trace 216c to form a series circuit having a series circuit impedance including the impedance of the known resistor and the counter sense trace 224c impedance and the counter electrode trace 216c impedance. Selectively placing a resistor having a known impedance in series with Selectively applying a stimulus to generate a current through the series circuit, Measuring a current flowing through the series circuit, Using the current measurement to calculate the eddy current impedance of one or more traces of the biosensor test strip (800). 21. The method of claim 20, wherein at least one of the indicators of the calculated impedance is used to determine whether the biosensor test strip (800) is damaged. A method of using a biosensor meter to measure the eddy current impedance of one or more traces of a biosensor test strip 800, wherein the biosensor test strip 800 is: Working electrode 814a, A working electrode trace 814c operatively connected to the working electrode 814a, The actuation sense trace 826c operatively connected to the actuation electrode 814a, Counter electrode 216a, A counter electrode trace 216c operatively connected to the counter electrode 216a, An opposing sense trace 224c operatively connected to the opposing electrode 216b, The biosensor meter comprises a biosensor meter test strip interface, The biosensor meter test strip interface,      Working electrode contact pad 814b,      Working sense contact pad 826b,      Counter electrode contact pads 216b, and      An opposing sense contact pad 224b, The method, Receiving the test strip 800 in the biosensor meter, The working electrode trace 814c is operatively connected to the working electrode contact pad 814b, the working sense trace 826c is operatively connected to the working sense contact pad 826b, and the counter electrode trace 216c is And operatively connect the test strip 800 to the biosensor meter test strip interface such that the opposing sense trace 224c is operatively connected to the opposing sense trace 224b. step, The operating sense trace 826c and the working electrode trace 814c to form a series circuit equal to the impedance of the known resistor and the operating sense trace 826c and the series circuit impedance including the operating electrode trace 814c impedance. Selectively converting a resistor having a known impedance in series with Providing a stimulus to generate a current through the series circuit, Measuring a current flowing through the series circuit, and Using a current measurement to calculate the working electrode trace (814c) impedance and the working sense trace (826c) impedance. 23. The method of claim 22, further comprising using the series circuit impedance to determine whether the test strip (800) is damaged. 24. The method of claim 23, further comprising indicating an indicator of usefulness of the test strip (800). A method of using a biosensor meter to measure the eddy current impedance of one or more traces of a biosensor test strip 800, wherein the biosensor test strip 800 is: Working electrode 814a, A working electrode trace 814c operatively connected to the working electrode 814a, The actuation sense trace 826c operatively connected to the actuation electrode 814a, Counter electrode 216a, A counter electrode trace 216c operatively connected to the counter electrode 216a, An opposing sense trace 224c operatively connected to the opposing electrode 216b, The biosensor meter includes a biosensor meter test strip interface, The biosensor meter test strip interface,      Working electrode contact pad 814b,      Working sense contact pad 826b,      Counter electrode contact pads 216b, and      An opposing sense contact pad 224b, The method, Receiving the test strip 800 in the biosensor meter, The working electrode trace 814c is operatively connected to the working electrode contact pad 814b, the working sense trace 826c is operatively connected to the working electrode contact pad 826b, and the counter electrode trace 216c is And operatively connect the test strip 800 to the biosensor meter test strip interface such that the opposing sense trace 224c is operatively connected to the opposing sense trace 224b. step, The counter sense trace 224c and the counter electrode trace 216c to form a series circuit equal to the impedance of the known resistor and the series circuit impedance including the counter sense trace 224c impedance and the counter electrode trace 216c impedance. Selectively placing a resistor having a known impedance in series with Selectively applying a stimulus to generate a current through the series circuit, Measuring a current flowing through the series circuit, and Using a current measurement to calculate an indicator of the opposite sense trace (224c) impedance and the operating sense trace (216c) impedance. 26. The method of claim 25 including using one or more indicators of the impedance of the series circuit to determine whether the test strip (800) is damaged. 27. The method of claim 26, further comprising indicating an indicator of usefulness of the test strip (800).

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