SENSOR FOR DETECTING GLUCOSE AND LACTIC ACID AND METHOD FOR DETERMINING Aerobic AND Aerobic thresholds

Abstract

This disclosure describes lactic acid responsive sensors, sensing systems including lactic acid responsive sensors, and methods of use thereof that facilitate continuous monitoring of lactic acid levels and determination of lactic acid thresholds (aerobic and anaerobic thresholds). The present disclosure also relates to analyte sensors for continuously detecting glucose and lactic acid levels.

Description

[0001] background

[0002] Data-driven training programs are becoming increasingly important for world-class athletes and others interested in improving their physical fitness and athletic performance. Lactate concentrations in blood or other bodily fluids are frequently used to determine an athlete's fitness level, develop training plans, and measure the impact of training on competition preparation. Specifically, the anaerobic lactate threshold (which characterizes an individual's aerobic-anaerobic transition zone) is the most widely used indicator to guide efficient and effective training, especially in endurance sports.

[0003] External sensors can be used to measure lactate levels, but these sensors often provide inaccurate results. For more reliable lactate levels, invasive blood draws may be necessary, but this method can be inconvenient or painful for individuals who are exercising or training. Furthermore, even quick blood draws (such as from the earlobe) may require at least a brief interruption to an individual's workout routine, potentially leading to inefficient workouts.

[0004] In addition, glucose monitoring is another important component of sports training, providing athletes with real-time information such as energy status, fatigue levels, and optimal replenishment times for training.

[0005] Therefore, there is a need for sensors that provide continuous lactate monitoring, avoiding the inaccuracies associated with current sensors or the invasive blood draws associated with more accurate technologies, and provide glucose monitoring so that glucose and lactate levels can be tracked in real time, thereby enabling rapid and accurate continuous monitoring of an individual's metabolic status during exercise training and workouts.

[0006] Brief Overview

[0007] This disclosure describes lactate-responsive sensors, sensing systems incorporating lactate-responsive sensors, and methods of using them, which facilitate the monitoring of lactate levels and the determination of lactate thresholds (aerobic and anaerobic thresholds). These sensors and sensing systems provide a rapid and convenient method to obtain reliable lactate levels, including lactate thresholds, thereby providing individuals with valuable information about running speed, heart rate, and / or power, corresponding to aerobic or anaerobic thresholds.

[0008] In some particle design schemes, this disclosure relates to a sensor for detecting glucose and lactate levels. This sensor can continuously and in real-time provide feedback on glucose and lactate levels during training and competition, which can help maximize athletic performance.

[0009] This disclosure relates to an analyte sensor, which includes

[0010] Base;

[0011] The first working electrode is located on the substrate;

[0012] The second working electrode is located on the substrate;

[0013] A lactic acid-responsive sensing region is disposed on the surface of the first working electrode; and

[0014] A glucose-responsive sensing area is disposed on the surface of the second working electrode;

[0015] A first lactic acid-permeable membrane covering the lactic acid-responsive sensing region; and

[0016] A glucose-permeable second membrane covering the glucose-responsive sensing region and the lactate-responsive sensing region.

[0017] The sensor is configured to be partially inserted into the individual's skin.

[0018] In some embodiments, the lactate-responsive sensing region may contain lactate oxidase.

[0019] In some embodiments, the lactic acid-responsive sensing region may comprise a first polymer and a first electron transfer reagent.

[0020] In some embodiments, the first electron transfer reagent may be covalently bonded to the first polymer.

[0021] In some embodiments, the glucose-responsive sensing region may contain glucose oxidase.

[0022] In some embodiments, the glucose-responsive sensing region may include a second polymer and a second electron transfer reagent.

[0023] In some embodiments, the second electron transfer agent may be covalently bonded to the second polymer.

[0024] In some implementations, the sensor may further include a reference electrode and a counter electrode.

[0025] In some embodiments, the first membrane and the second membrane may have different compositions.

[0026] This disclosure also discloses a method for monitoring lactate levels in an individual, the method comprising exposing an analyte sensor of a sensing system to a fluid, wherein the analyte sensor comprises a substrate; a first working electrode located on the substrate; a second working electrode located on the substrate; a lactate-responsive sensing region disposed on a surface of the first working electrode; and a glucose-responsive sensing region disposed on a surface of the second working electrode; a lactate-permeable first membrane covering the lactate-responsive sensing region; and a glucose-permeable second membrane covering the glucose-responsive sensing region and the lactate-responsive sensing region, wherein the sensor is configured to be partially inserted into the individual's skin; applying a potential to the first working electrode of the analyte sensor; obtaining a first signal at a redox potential or higher of the lactate-responsive sensing region, the signal being proportional to the concentration of lactate in the fluid; and correlating the signal with the concentration of lactate in the fluid.

[0027] In some embodiments, the method may further include obtaining a second signal at the redox potential or higher of the glucose-responsive sensing region, the signal being proportional to the concentration of glucose in the fluid; and correlating the second signal with the concentration of glucose in the fluid.

[0028] In some embodiments, the lactate-responsive sensing region may contain lactate oxidase.

[0029] In some embodiments, the lactic acid-responsive sensing region may comprise a first polymer and a first electron transfer reagent.

[0030] In some embodiments, the first electron transfer reagent may be covalently bonded to the first polymer.

[0031] In some embodiments, the glucose-responsive sensing region may contain glucose oxidase.

[0032] In some embodiments, the glucose-responsive sensing region may include a second polymer and a second electron transfer reagent.

[0033] In some embodiments, the second electron transfer agent may be covalently bonded to the second polymer.

[0034] In some implementations, the sensor may further include a reference electrode and a counter electrode.

[0035] In some embodiments, the first membrane and the second membrane may have different compositions.

[0036] This disclosure also discloses a method for determining an anaerobic threshold in an individual, the method comprising continuously measuring a signal indicating the lactate concentration in a biofluid of the individual using a sensing system including a lactate-responsive sensor; transmitting the signal indicating the lactate concentration measured by the lactate-responsive sensor to a processor; and determining an anaerobic threshold based on the signal indicating the lactate concentration. In some embodiments, the sensor may be any sensor disclosed herein.

[0037] In some implementations, the individual may be performing a lactate threshold test.

[0038] In some implementations, the lactate threshold test may be a step test with progressively increasing power.

[0039] In some implementations, the processor may use a broken stick model to determine the anaerobic threshold.

[0040] In some implementations, the processor may use the D-max method to determine the anaerobic threshold.

[0041] In some implementations, the processor may use a modified D-max method to determine the anaerobic threshold.

[0042] This disclosure also discloses a method for determining an aerobic threshold in an individual, the method comprising continuously measuring a signal indicating lactate concentration in a biofluid of the individual using a sensing system including a lactate-responsive sensor; transmitting the signal indicating lactate concentration measured by the lactate-responsive sensor to a processor; and determining an anaerobic threshold based on the signal indicating lactate concentration. In some embodiments, the sensor may be any sensor disclosed herein.

[0043] In some implementations, the individual may be performing a lactate threshold test.

[0044] In some implementations, the lactate threshold test may be a step test with progressively increasing power.

[0045] In some implementations, the aerobic threshold can be defined as a fixed value.

[0046] In some implementations, the aerobic threshold can be defined as baseline lactate concentration + approximately 0.5 mM lactate.

[0047] In some implementations, the aerobic threshold can be defined as baseline lactate concentration + approximately 1 mM lactate.

[0048] In some implementations, the processor may use a log-log model to determine the aerobic threshold.

[0049] In some implementations, the processor may use piecewise regression analysis to determine the aerobic threshold.

[0050] Further embodiments and advantages of this disclosure will be set forth in part in the description which follows, and will be derived from the description or may be learned by practice of this disclosure.

[0051] It should be understood that the foregoing summary and the following detailed description are merely exemplary and explanatory, and do not limit the scope of the claims. Brief description of the attached diagram

[0053] Figure 1 This diagram illustrates how lactate levels vary with different intensities of physical activity.

[0054] Figure 2A A simplified diagram of an exemplary sensing system is shown, which may include the lactic acid responsive sensor of this disclosure.

[0055] Figure 2B A block diagram of a processing electronic device is shown, which may be associated with one or more components of a sensing system.

[0056] Figure 3A A simplified cross-sectional view of an exemplary dual-electrode analyte sensor configuration with a single working electrode is shown.

[0057] Figure 3B and 3C A simplified diagram of an exemplary three-electrode analyte sensor configuration is shown.

[0058] Figure 3D A simplified cross-sectional view of an exemplary dual-electrode analyte sensor configuration with a single working electrode is shown.

[0059] Figure 3E and 3F A simplified diagram of an exemplary three-electrode analyte sensor configuration is shown.

[0060] Figure 4 A simplified cross-sectional view of an analyte sensor with glucose-responsive and lactate-responsive sensing regions on separate working electrodes is shown.

[0061] Figure 5A A simplified cross-sectional view of an exemplary analyte sensor configuration is shown.

[0062] Figure 5B A simplified cross-sectional view of an exemplary analyte sensor configuration is shown.

[0063] Figure 6 An analyte sensor for detecting glucose and lactic acid according to certain embodiments of this disclosure is shown.

[0064] Figure 7 A simplified diagram of an enzyme system that can be used to detect glucose according to the disclosure herein is shown.

[0065] Figure 8 A simplified diagram of an enzyme system that can be used to detect lactate according to the disclosure herein is shown.

[0066] Figure 9 The graph shows the relationship between lactate concentration and power when the anaerobic threshold is determined using the D-max model.

[0067] Figure 10A The graph shows the relationship between lactate concentration and power when the anaerobic threshold is determined using the broken rod model.

[0068] Figure 10B The graph shows the relationship between error and power in a linear regression model used to determine the anaerobic threshold via the broken stick model.

[0069] Figure 11 A graph showing the lactate levels detected by the sensor over 128 hours compared to blood lactate tests using finger-prick or earlobe puncture blood samples.

[0070] Figure 12 A graph showing glucose levels detected by the sensor over 77 hours compared to a blood glucose test using a finger-prick blood sample.

[0071] Figure 13 A graph showing the detection threshold via blood lactate testing compared to the detection threshold via a glucose / lactic acid dual sensor is displayed.

[0072] Figure 14 A table showing a comparison of results obtained by measuring the anaerobic threshold using sensors and blood tests.

[0073] Detailed description

[0074] The headings provided herein are not intended to limit the various embodiments of this disclosure, which can be defined by referring to the entire specification. It should also be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting, as the scope of this disclosure will be limited only by the appended claims.

[0075] definition

[0076] For convenience, the meanings of certain terms and phrases used in the specification, embodiments, and appended claims are provided below. Unless otherwise stated or implied in the context, the following terms and phrases include the meanings provided below. These definitions are provided to aid in the description of particular embodiments and are not intended to limit the claimed technology, as its scope is limited only by the claims. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the technology pertains. If there is a significant difference between the use of a term in the art and its definition provided herein, the definition provided in the specification shall prevail.

[0077] The articles “a / an,” “a / an,” and “the” are used in this text to indicate one or more (i.e., at least one) grammatical object of the article. For example, “an element” refers to one or more elements.

[0078] As used herein, the term “about” means within an acceptable range of error for a particular value as determined by one of ordinary skill in the art, depending in part on how the value is measured or determined, i.e., the limitations of the measurement system. For example, “about” can mean within three or more standard deviations, according to practice in the art. Alternatively, “about” can refer to a range of up to 20% (e.g., up to 10%, up to 5%, or up to 1%) of a given value.

[0079] The term "at least" preceding a number or series of numbers should be understood to include the number associated with the term "at least," as well as any subsequent numbers or integers that are logically included and which are clearly apparent from the context. When "at least" appears before a series of numbers or a range, it should be understood that "at least" can modify each number in that series or range. For example, "at least 3" means at least 3, at least 4, at least 5, etc. When "at least" precedes a component of a method step, that component is included in that step, while other components are optional.

[0080] The terms “comprising,” “having,” “including,” and “containing” used herein are open-ended terms meaning “including, but not limited to”. With respect to the fact that a given embodiment disclosed herein “comprising” certain elements, it should be understood that this disclosure also specifically considers and discloses embodiments “consisting substantially of those elements” and “composed of those elements.”

[0081] The terms “consists essentially of” and “consisting essentially of” used in this document should be interpreted as semi-closed terms, meaning that they do not include other components that substantially affect the basic and novel features of an implementation.

[0082] The terms “consists of” and “consisting of” used in this document should be interpreted as closed terms. Therefore, an implementation “consisting of a specific set of elements” excludes any elements, steps, or components not specified in that implementation.

[0083] The term “measurement” and its variants used in this article may encompass the meanings of corresponding terms such as “determine”, “calculate” and their variants.

[0084] As used in this article, "analyte" refers to an enzyme substrate to be measured or detected. The analyte may be derived from, for example, biological fluids and may be tested in vivo, in vitro, or in vitro.

[0085] As used herein, a “sensor” is a device configured to detect the presence and / or measure the level of an analyte in a sample via electrochemical oxidation and reduction reactions on the sensor. These reactions are converted into electrical signals that can be correlated with the amount, concentration, or level of the analyte in the sample.

[0086] The “working electrode” used in this article is an electrode that performs electro-oxidation or electro-reduction of the analyte (or a second compound whose level depends on the analyte level) with or without the presence of an electron transfer reagent.

[0087] As used herein, “counter electrode” refers to an electrode that is paired with the working electrode, through which the current flowing is equal in magnitude and opposite in sign to the current flowing through the working electrode. For certain embodiments of this disclosure, the term “counter electrode” includes a) a counter electrode and b) a counter electrode that also serves as a reference electrode (i.e., counter / reference electrode), unless otherwise indicated, or unless a reference electrode is also present, in which case the term “counter electrode” means only the counter electrode.

[0088] As used herein, the term "reference electrode" refers to an electrode whose potential is known and can be used as a reference for evaluating or measuring the potential of a working electrode. In the context of embodiments of this disclosure, the term "reference electrode" includes a) a reference electrode and b) a reference electrode that also serves as a counter electrode (i.e., a counter / reference electrode), unless otherwise indicated, or unless a counter electrode is also present, in which case the term "reference electrode" means only a reference electrode.

[0089] The components used in this article are “fixed” or “attached” to polymers and / or sensors, for example, when the components are trapped on, trapped in, covalently bonded, ionicly bonded, electrostatically bonded or coordinately bonded to polymers, sol-gel matrices, membranes and / or sensor components, thereby reducing or preventing flowability.

[0090] The term "electron transfer reagent" as used in this article refers to a compound that directly or in synergistic with other electron transfer reagents transfers electrons between the analyte and the working electrode. An example of an electron transfer reagent is a redox medium.

[0091] The term "redox medium" as used in this article refers to an electron transfer agent used to transfer electrons between an analyte, a reduced or oxidized analyte, an enzyme, and an electrode. This transfer can be direct or via one or more other electron transfer agents. Redox media comprising a polymer backbone can also be referred to as "redox polymers."

[0092] As used herein, a “sensing region” is a component of a sensor that includes components that facilitate the electrolysis of the analyte. The sensing region may include components such as a redox medium (e.g., an electron transfer reagent or redox polymer), a catalyst (e.g., an analyte-specific enzyme), etc., which catalyze the reaction of the analyte to produce a response at the working electrode, or may include both an electron transfer reagent and a catalyst. In some embodiments of this disclosure, the sensor includes a sensing region that is non-leachingly disposed near or on the working electrode. In some embodiments of this disclosure, the sensing region may be disposed continuously or discontinuously on the working electrode. A sensing region is considered “continuously disposed” on the working electrode when it is applied to the surface of the working electrode in an uninterrupted manner, i.e., a single point or line, etc. A sensing region is considered “discontinuously disposed” on the working electrode when it is applied to the working electrode in at least two discrete shapes, such as two points, two lines, a point and a line, or multiple (e.g., an array) points, lines, or combinations thereof. There is no particular limitation on the number of sensing areas that are discontinuously applied in the form of a series of points and / or lines, but it can be in the range of 2 to about 10 (e.g., 2, 3, 4, 5, 6, 7, 8, 9, or 10, including about 3 to about 8 or about 4 to about 6). In some embodiments, the sensing areas are continuously disposed on the working electrode. In some embodiments, the sensing areas are discontinuously disposed on the working electrode.

[0093] As used herein, a "sensing element" is an application or region of an analyte-specific enzyme disposed together with a sensing region. Therefore, the sensing element is capable of interacting with the analyte. A sensing region may have more than one sensing element, which together constitute an analyte detection region disposed on the working electrode. In some embodiments, the sensing element comprises an analyte-specific enzyme and an electron transfer reagent (e.g., an electron transfer agent). In some embodiments, the sensing element comprises an analyte-specific enzyme, a redox medium, and a cross-linking agent.

[0094] As used herein, "crosslinking agent" or "crosslinking reagent" is a molecule containing at least two (e.g., 2, 3, or 4) reactive groups (e.g., terminal functional groups) that can link at least two molecules together (intermolecular crosslinking) or link at least two parts of the same molecule together (intramolecular crosslinking). Crosslinking agents having more than two reactive groups can be capable of both intermolecular and intramolecular crosslinking simultaneously.

[0095] The term "patient" refers to a living animal and therefore encompasses, for example, living mammals and living humans. The term "user" may be used herein as a term that encompasses the term "patient".

[0096] Sensors and sensing systems

[0097] Lactic acid is produced in the body during exercise or other activities through the glycolysis of glucose, especially during strenuous physical activity or training. Glycolysis provides energy to help individuals maintain their current activity level. Lactic acid levels in an individual are typically characterized as falling within three distinct regions, such as... Figure 1 As shown. At lower activity levels (intensities), lactate levels remain low and the rates of lactate production and clearance remain fairly balanced, causing lactate levels to remain relatively constant at or near a fixed baseline concentration, with possible slight increases, until reaching a point known as the aerobic threshold (LT1) during moderate / high-intensity exercise. After LT1, lactate levels typically increase linearly until reaching a point known as the anaerobic threshold (LT2) during high-intensity exercise. After LT2, lactate levels typically show an accelerated increase.

[0098] This disclosure describes lactate-responsive sensors and sensing systems incorporating lactate-responsive sensors, which facilitate the monitoring of lactate levels and the determination of lactate thresholds, namely aerobic and anaerobic thresholds. In some embodiments, the lactate-responsive sensor is a sensor that detects both lactate and glucose levels. In some embodiments, the system is a continuous lactate monitoring system. In some embodiments, the system is a system for monitoring glucose and lactate. In some embodiments, the system can continuously monitor glucose and lactate. In some embodiments, the sensor that detects glucose and lactate levels, and the system incorporating it, can provide continuous, real-time feedback on glucose and lactate levels during training and competition, which helps to maximize performance.

[0099] In some embodiments, the sensor is configured to detect lactate levels. In some embodiments, the sensor is configured to measure lactate levels approximately every second, approximately every 3 seconds, approximately every 5 seconds, approximately every 10 seconds, approximately every 15 seconds, approximately every 20 seconds, approximately every 30 seconds, approximately every 45 seconds, approximately every minute, approximately every 1.5 minutes, approximately every 2 minutes, approximately every 3 minutes, approximately every 5 minutes, approximately every 10 minutes, approximately every 15 minutes, approximately every 20 minutes, approximately every 30 minutes, approximately every 45 minutes, approximately every hour, approximately every 2 hours, or approximately every 3 hours.

[0100] In some embodiments, the sensor is configured to transmit a signal indicating lactate levels to a processor. In some embodiments, the sensor may be the sensor described in this disclosure. In some embodiments, the sensor may be a sensor disclosed in US 10,392,647, US 2019 / 0320947 and / or US 2022 / 0125354, the entire contents of which are incorporated herein by reference.

[0101] In some implementations, the system may include various sensing components, such as a processor and / or coded instructions (algorithms) therein, adapted to process sensor data received from a lactate sensor and determine multiple lactate concentrations therefrom. The processor and / or coded instructions can then analyze the lactate concentrations to determine an individual's aerobic and anaerobic thresholds.

[0102] In some embodiments, the system may include a lactate-responsive sensor configured to detect lactate in the body and a processor located in a cloud server, remote terminal, or local terminal, which communicates with the lactate-responsive sensor. Cloud- or server-based communication is also within the scope of the systems disclosed herein. The term "local terminal" as used herein refers to a user interface physically connected to the system containing the lactate-responsive sensor. For example, in some embodiments, the processor may be connected to the housing of the lactate-responsive sensor. The term "remote terminal" as used herein refers to a user interface not in the same physical space as the lactate-responsive sensor. In some embodiments, the remote terminal and its processor may communicate with the lactate-responsive sensor or a network. In some embodiments, the individual interacting with the system may be unaware of the output of the lactate-responsive sensor. In other embodiments, the individual may see the sensor output (e.g., lactate concentration) in real time or near real time, such as on a remotely or locally viewable display. The remote terminal may include, for example, a dedicated reader device, a dedicated fitness monitoring device (e.g., Fitbit), a smartphone, or a smartwatch.

[0103] In some embodiments, the processor may be configured to receive signals from a lactate-responsive sensor. The processor may also be configured to determine multiple lactate concentrations upon receiving the signal from the sensor and to determine lactate thresholds (aerobic and anaerobic thresholds) based on the multiple lactate concentrations. The processor may also signal to the individual wearing the sensor or other relevant party when a predetermined lactate level (e.g., aerobic and anaerobic thresholds, a specified lactate concentration, a multiple of baseline lactate concentration, or a fraction of peak lactate concentration) has been reached. The processor's output may be numerical and / or graphical. The notification sent to the wearer of the lactate-responsive sensor or other relevant party may be auditory, tactile (haptic), or any combination thereof.

[0104] In some embodiments, the active sensing area of ​​the lactate-responsive sensor can be located at any suitable location within the body. Suitable locations may include, but are not limited to, intravenous, subcutaneous, or dermal locations. Intravenous sensors may have the advantage of directly analyzing lactate in the blood, but they are invasive and may sometimes cause pain to the wearer for extended periods. Subcutaneous and dermal analyte sensors often cause less pain to the wearer due to their shallower penetration depth and can provide sufficient measurement accuracy in many cases. In some embodiments, the lactate-responsive sensor suitable for this disclosure may be a dermal sensor configured to detect an individual's dermal fluid. In some embodiments, the lactate-responsive sensor suitable for this disclosure may be configured to detect an individual's interstitial fluid. The term "detection" as used herein refers to the act of measuring a sample parameter.

[0105] In some embodiments, the sensor may extend from a housing configured for external wear on the skin of an individual performing a specific physical activity. The external location of the lactate-responsive sensor is not considered particularly limited and can depend on the type of physical activity being performed. In some embodiments, the lactate-responsive sensor may be placed on the biceps, triceps, upper back, lower back, chest, buttocks, abdomen, thigh, or calf. In some embodiments, multiple lactate-responsive sensors may be used to monitor a single movement event, such as comparing lactate concentrations measured at two different external locations. One sensor may be placed on a site of high muscle activity (e.g., the thigh during cycling), and another sensor may be placed on a site of low muscle activity during exercise (e.g., the arm during cycling), thereby determining the rate at which lactate diffuses from the bloodstream into other interstitial tissues. If desired, the outputs from one or two sensor locations may be cross-referenced with blood lactate readouts obtained from finger or earlobe punctures.

[0106] Figure 2AA simplified diagram of an exemplary system is shown, which may include the lactate-responsive sensor of this disclosure. As shown, system 100 includes a sensor control device 102 and a readout device 120, configured to communicate with each other via a local communication path or link 140, which may be wired or wireless, one-way or two-way, encrypted or unencrypted. According to some embodiments, the readout device 120 may serve as an output medium for viewing lactate concentrations and alarms or notifications determined by sensor 104 or its associated processor, and for allowing input from one or more users. Alternatively, the readout device 120 may produce outputs that are not visible to the user. The readout device 120 may be a multi-function smartphone or a dedicated e-reader. Although only one readout device 120 is shown, multiple readout devices 120 may be present in some cases. According to some embodiments, a suitable processor may also be integrated into the readout device 120. The readout device 120 can also communicate with the remote terminal 170 and / or the trusted computer system 180 via communication paths / links 141 and / or 142, respectively. These communication paths / links 141 and / or 142 can be wired or wireless, one-way or two-way, encrypted or unencrypted. The readout device 120 can also, or alternatively, communicate with the network 150 (e.g., a mobile phone network, the Internet, or a cloud server) via communication path / link 151. The network 150 can further communicate with the remote terminal 170 via communication path / link 152, and / or with the trusted computer system 180 via communication path / link 153. Alternatively, the sensor 104 can communicate directly with the remote terminal 170 and / or the trusted computer system 180 without the intermediate readout device 120. For example, according to some embodiments, sensor 104 may communicate with remote terminal 170 and / or trusted computer system 180 via a direct communication link with network 150, as described in U.S. Patent Application Publication 2011 / 0213225 (which is incorporated herein by reference in its entirety). For each communication path or link 141, 142, 151, 152, and / or 153, any suitable electronic communication scheme may be used, such as Near Field Communication (NFC), Radio Frequency Identification (RFID), Bluetooth® or Bluetooth Low Energy® schemes, WiFi, mobile phone networks, etc. According to some embodiments, other parties besides the primary user (such as individual trainers or coaches) may access remote terminal 170 and / or trusted computer system 180, and these other parties may be interested in the primary user's lactate concentration or lactate clearance rate. Readout device 120 may include display 122 and optional input component 121. According to some embodiments, display 122 may include a touchscreen interface.

[0107] In some embodiments, sensor control device 102 may include sensor 104, which, when placed inside the body, contacts the user's bodily fluids and senses the level of analyte contained therein. This sensor may be part of a sensor control device located on the user's body and contains electronic components and a power supply capable of realizing and controlling analyte sensing. Sensor control device 102 and variations thereof may also be referred to as a "sensor control unit," a "human body electronics" device or unit, a "human body" device or unit, or a "sensor data communication" device or unit. In some embodiments, sensor control device 102 includes a sensor housing 103, which may house circuitry and a power supply for operating sensor 104. Optionally, the power supply and / or active circuitry may be omitted. Processor (in...) Figure 2A (Not shown) can be communicatively connected to sensor 104, and the processor is physically located within sensor housing 103 or readout device 120. In some embodiments, sensor 104 protrudes from the bottom of sensor housing 103 and extends through adhesive layer 105, which, according to some embodiments, is adapted to adhere sensor housing 103 to a tissue surface, such as skin.

[0108] Figure 2B A block diagram of a processing electronics device is shown, which may be associated with one or more components of a sensing system, such as within a readout device 120. Alternatively, this functionality may be associated with one or more of a network 150, a remote terminal 170, or a trusted computer system 180. As shown, the processing electronics device 190 receives signals directly or indirectly from the sensor control device 102. These signals may be processed using algorithms associated with a processor 191 and / or a memory 192. The lactic acid concentration thus determined may be stored in the memory 192 and / or output to an output device 193, which in various embodiments may be a display or an external storage medium. The processor 191 may also be used to determine guidance, recommendations, etc., and similarly export them to the output device 193, as further described herein.

[0109] Sensor 104 is adapted to be at least partially inserted into tissue of interest, such as within the dermis of the skin or in subcutaneous tissue. Sensor 104 may comprise a sensor of sufficient length to be inserted to a desired depth into a given tissue. In some embodiments, the sensor may comprise a proximal portion configured to be positioned above the user's skin, and the distal portion configured to percutaneously penetrate the user's skin and contact bodily fluids. In some embodiments, the distal portion is configured to detect an analyte in the bodily fluids. In some embodiments, the proximal portion may be electrically coupled to a processing electronics device. In some embodiments, the processing electronics device is disposed within an electronic housing of a sensor control device. According to one or more embodiments, the sensor may comprise a sensing region or sensing area for sensing lactate and may comprise a lactate-responsive enzyme. According to some embodiments, the sensing region or sensing area may comprise a polymeric material covalently bonded to a lactate-responsive enzyme. In some embodiments of this disclosure, lactate in any biological fluid of interest, such as dermal fluid, plasma, blood, lymph, synovial fluid, cerebrospinal fluid, saliva, bronchoalveolar lavage fluid, amniotic fluid, etc., can be monitored. In some embodiments, the lactate-responsive sensor of this disclosure can be used to detect dermal fluid or interstitial fluid.

[0110] The introducer may be present temporarily to facilitate the insertion of sensor 104 into the tissue. In an exemplary embodiment, the introducer may comprise a needle. It should be appreciated that in alternative embodiments, other types of introducers, such as sheaths or blades, may be present. More specifically, a needle or similar introducer may be temporarily placed near sensor 104 before insertion and then withdrawn after insertion. When present, the needle or other introducer may facilitate insertion of sensor 104 into the tissue by opening an access channel for sensor 104. For example, according to some embodiments, the needle may facilitate penetration of the epidermis as a channel into the dermis, thereby allowing implantation of sensor 104. After opening the access channel, the needle or other introducer may be withdrawn to avoid the risk of sharps injury. In some embodiments, the needle may be solid or hollow, beveled or non-beveled, and / or have an annular or non-annular cross-section. In some embodiments, the cross-sectional diameter and / or tip design of the needle may be comparable to that of an acupuncture needle, for example, it may have a cross-sectional diameter of about 250 micrometers. However, it should be appreciated that suitable needles may have a larger or smaller cross-sectional diameter if required by a particular application.

[0111] In some embodiments, the needle tip may be tilted to the end of the sensor 104, such that the needle first penetrates the tissue and opens an access channel for the sensor 104. In some embodiments, the sensor 104 may be located within the cavity or recess of the needle, with the needle again opening an access channel for the sensor 104. In either case, the needle is withdrawn after convenient insertion.

[0112] According to certain embodiments of this disclosure, sensor 104 may employ a two-electrode or three-electrode detection mode. The three-electrode mode may include a working electrode, a counter electrode, and a reference electrode. The two-electrode mode may include a working electrode and a second electrode, wherein the second electrode acts as both the counter electrode and the reference electrode (i.e., counter electrode / reference electrode). In both two-electrode and three-electrode detection modes, the sensing area or sensing region of sensor 104 may be in contact with the working electrode. In some embodiments, the electrodes may be at least partially stacked on top of each other, as described in more detail below. In some embodiments, the various electrodes may be spaced apart from each other at the insertion tail of sensor 104.

[0113] In some embodiments, the sensor may include a sensing region (e.g., a lactate-responsive sensing region). In some embodiments, the sensor may include different types of sensing regions (e.g., glucose-responsive and lactate-responsive sensing regions) located on a single working electrode or on two or more separate working electrodes. According to certain embodiments of this disclosure and as further described herein, a single-working-electrode sensor configuration may employ a two-electrode or three-electrode detection mode. Figure 3A and 3D A simplified cross-sectional view of an exemplary dual-electrode analyte sensor configuration with a single working electrode is shown, which is compatible with the use in some embodiments disclosed herein. As shown, analyte sensors 200 and 203 include a substrate 212 disposed between a working electrode 214 and a counter / reference electrode 216. Alternatively, the working electrode 214 and the counter / reference electrode 216 may be located on the same side of the substrate 212, with a dielectric material (configuration not shown) sandwiched in between. In some embodiments, sensor 200 includes a sensing region 218 (i.e., a lactate-responsive sensing region) disposed on the surface of the working electrode 214. In some embodiments, sensor 203 includes sensing regions 218a and 218b (i.e., a glucose-responsive sensing region and a lactate-responsive sensing region) laterally spaced apart from each other on the surface of the working electrode 214. In some embodiments, sensing region 218a may be disposed continuously or discontinuously on the working electrode for detecting the analyte. In some embodiments, the sensing region 218b may be continuously or discontinuously disposed on the working electrode for detecting the analyte. The analyte sensor 200 can determine lactic acid using any one of coulometric, amperometric, voltammetric, or potentiochemical detection techniques. The analyte sensor 203 can determine glucose and lactic acid using any one of coulometric, amperometric, voltammetric, or potentiochemical detection techniques.

[0114] A three-electrode sensor configuration may include a working electrode, a counter electrode, and a reference electrode when a single working electrode is present in the analyte sensor. A related two-electrode sensor configuration may include a working electrode and a second electrode, wherein the second electrode can serve as both a counter electrode and a reference electrode (i.e., a counter / reference electrode). In both two-electrode and three-electrode sensor configurations, a first analyte-responsive sensing region and a second analyte-responsive sensing region may be disposed on a single working electrode. In any sensor configuration disclosed herein, the various electrodes may at least partially stack (layer) on each other and / or be laterally spaced apart on the sensor. A suitable sensor configuration may be a substantially flat or substantially cylindrical shape, wherein the first analyte-responsive sensing region and the second analyte-responsive sensing region are laterally spaced apart on the working electrode. In all sensor configurations disclosed herein, the individual electrodes may be electrically isolated from each other by a dielectric material or a similar insulator.

[0115] In some embodiments, the sensor may include two or more working electrodes and at least one additional electrode (i.e., at least one additional electrode, at least two additional electrodes, etc.). When one additional electrode is present, it can serve as a counter electrode / reference electrode for each working electrode. When two additional electrodes are present, one of the additional electrodes can serve as a counter electrode for each working electrode, and the other additional electrode can serve as a reference electrode for each working electrode. Figures 3B-3C Figures 3E-3F illustrate simplified diagrams of exemplary three-electrode analyte sensor configurations, which are also compatible with the uses of certain embodiments disclosed herein. The three-electrode analyte sensor configurations can be used with... Figure 3A and 3D The configuration of the analyte sensor 200 shown is similar, except that additional electrodes 217 are included in analyte sensors 201, 202, 204, and 205. Figures 3B-3C (and 3E-3F). With the addition of the auxiliary electrode 217, the counter electrode / reference electrode 216 can then serve as either a counter electrode or a reference electrode, and the auxiliary electrode 217 performs other unconsidered electrode functions. The working electrode 214 continues to perform its original function. The auxiliary electrode 217 can be disposed on the working electrode 214 or the electrode 216, separated from both by a dielectric material layer. For example, as Figure 3B As shown, dielectric layers 219a, 219b, and 219c space electrodes 214, 216, and 217 apart from each other and provide electrical isolation. Alternatively, as Figure 3CAs shown, at least one of electrodes 214, 216, and 217 can be located on opposite surfaces of substrate 212. Therefore, in some embodiments, electrode 214 (working electrode) and electrode 216 (counter electrode) can be located on opposite surfaces of substrate 212, while electrode 217 (reference electrode) can be located on one of electrodes 214 or 216 and separated from them by a dielectric material. A reference material layer 230 (e.g., Ag / AgCl) can be present on electrode 217, and the location of the reference material layer 230 is not limited to... Figure 3B and 3C The location shown. (Compared to) Figure 3A Similar to the sensor 200 shown, the sensing region 218 in analyte sensors 201 and 202 can be continuously or discontinuously positioned on the working electrode for detecting lactic acid. Furthermore, analyte sensors 201 and 204 can determine lactic acid using any of the following methods: coulometric, amperometric, voltammetric, or potentiochemical detection techniques.

[0116] Similar to analyte sensor 200, membrane 220 may also cover sensing regions 218 and 218a, 218b in analyte sensors 201, 202, 204, and 205, as well as other sensor components, thereby acting as a mass transfer limiting membrane. In some embodiments, additional electrode 217 may be covered by membrane 220. Although Figures 3B-3C Figures 3E-3F depict all electrodes 214, 216, and 217 covered by membrane 220; however, it should be recognized that in some embodiments, only the working electrode 214 may be covered. Furthermore, the thickness of membrane 220 at each of electrodes 214, 216, and 217 may be the same or different. (Comparison with dual-electrode analyte sensor configurations...) Figure 3A and 3D Similarly, in Figures 3B-3C In the sensor configurations of 3E-3F, one or two surfaces of the analyte sensors 201, 202, 204, and 205 may be covered by the membrane 220, or the entire analyte sensors 201, 202, 204, and 205 may be covered.

[0117] Figure 4 A simplified cross-sectional view of an exemplary analyte sensor configuration is shown, featuring two working electrodes, a reference electrode, and a counter electrode, compatible with applications in certain embodiments disclosed herein. Figure 4As shown, the analyte sensor 300 includes working electrodes 304 and 306 disposed on opposite surfaces of a substrate 302. Sensing region 310a is disposed on the surface of working electrode 304, and sensing region 310b is disposed on the surface of working electrode 306. The analyte sensor 300 may include additional sensing regions that are laterally spaced apart from each other on the surfaces of working electrodes 304 and / or 306. According to certain embodiments of this disclosure, sensing regions 310a and 310b may be lactate-responsive and glucose-responsive sensing regions, respectively. Counter electrode 320 is electrically isolated from working electrode 304 by dielectric layer 322, and reference electrode 321 is electrically isolated from working electrode 306 by dielectric layer 323. Outer dielectric layers 330 and 332 are located on reference electrode 321 and counter electrode 320, respectively. Figure 4The layers present in the sensor 300 may sequentially include an outer dielectric layer 332, a counter electrode 320, a dielectric layer 322, a working electrode 304, a substrate 302, a working electrode 306, a dielectric layer 323, a reference electrode 321, and an outer dielectric layer 330. The layers may be (partially) stacked on top of each other, with a portion of each layer near its edge that is not covered by adjacent layers. For example, the substrate 302 may extend beyond (not covered by) the respective ends of the working electrodes 304 and 306. The working electrodes 304 and 306 may extend beyond (not covered by) the ends of the dielectric layers 322 and 333. The portions of the working electrodes 304 and 306 extending beyond the ends of the dielectric layers 322 and 333 may provide space for sensing regions 310a and 310b, respectively. In any embodiment described herein, the substrate 302 may extend to the distal tip of the sensor, thereby separating the layers on either side of the substrate 302. According to various embodiments, membrane 340 has a first membrane portion 340a and a second membrane portion 340b, which respectively cover at least sensing regions 310a and 310b, and other components of analyte sensor 300 or the entire analyte sensor 300 are optionally also covered by the first membrane portion 340a and / or the second membrane portion 340b. Similarly, membrane 340 may be continuous, but its composition may differ within the first membrane portion 340a and the second membrane portion 340b (i.e., on sensing regions 310a and 310b) to achieve different permeability values ​​for differentiated modulation of analyte flux at each location. For example, different membrane formulations may be sprayed and / or printed onto opposite surfaces of analyte sensor 300. Impregnation coating techniques are also applicable, particularly for depositing at least a portion of a bilayer membrane on one of sensing regions 310a and 310b. Therefore, according to certain embodiments of this disclosure, one of the first membrane portion 340a and the second membrane portion 340b may comprise a bilayer membrane, and the other of the first membrane portion 340a and the second membrane portion 340b may comprise a monolayer polymer membrane. In some embodiments, the analyte sensor 300 can determine glucose and lactic acid by any of coulometric, amperometric, voltammetric, or potentiochemical detection techniques. The above description of the membranes also applies to any sensor embodiment described herein.

[0118] Figure 5AA simplified diagram of an exemplary four-electrode analyte sensor configuration is shown, which is compatible with the uses disclosed herein. As shown, sensor 206 includes a substrate 212 disposed between working electrodes 214a and 214b. Alternatively, working electrodes 214a and 214b may be located on the same side of substrate 212, with a dielectric material sandwiched in between (configuration not shown). Analyte-specific responsive sensing regions 218a and / or 218b (e.g., glucose-responsive sensing regions and lactate-responsive sensing regions) may be disposed as at least one layer on at least a portion of working electrodes 214a and / or 214b. As further discussed herein, the analyte-responsive sensing regions may be disposed continuously or discontinuously on the working electrodes for detecting the analyte. A reference electrode may be disposed on either working electrode 214a or 214b, separated from it by a dielectric material layer. A counter electrode may be disposed on the opposite side of working electrode 214a or 214b, separated from it by a dielectric material layer. For example, such as Figure 5A As shown, dielectric layers 219b and 219c space electrodes 214a, 214b, 216, and 217 apart from each other and provide electrical isolation. Outer dielectric layers 219a and 219d are located on the reference electrode 216 and the counter electrode 217. In other embodiments, at least one of electrodes 214a, 214b, 216, and 217 may be located on opposite surfaces of the substrate 212 (configuration not shown).

[0119] In some embodiments, electrode 214a (working electrode) and electrode 216 (counter electrode) may be located on opposite surfaces of substrate 212, similar to electrode 217 (reference electrode), and working electrode 214b may be located on opposite surfaces of the substrate, such as... Figure 5A As shown. The reference material layer 230 (e.g., Ag / AgCl) may be present on the reference electrode 216, and the location of the reference material layer 230 is not limited to... Figure 5A The location is shown. Additionally, the analyte sensor 206 can determine the analyte using any of the following methods: coulometric, amperometric, voltammetric, or potentiochemical detection techniques. Although Figure 5A It is depicted that all electrodes 214a, 214b, 216, and 217 are covered by membrane 220; however, it should be recognized that in some embodiments, only the working electrodes 214a and 214b may be covered. Furthermore, in any of the embodiments described herein, the thickness of membrane 220 at each of electrodes 214a, 214b, 216, and 217 may be the same or different. Similar to the dual-electrode analyte sensor configuration, in... Figure 5A In the sensor configuration shown, one or two surfaces of the analyte sensor 206 can be covered by the membrane 220, or the entire analyte sensor 206 can be covered. Therefore, Figure 5AThe multi-electrode sensor configurations shown should be understood as not limiting the embodiments disclosed herein, and alternative electrodes and / or layer configurations are still within the scope of this disclosure.

[0120] In some embodiments (including any of the embodiments in Figures 3-6), the substrate is formed of any suitable inert material. In some embodiments, the substrate is biocompatible. Examples of suitable substrates include titanium, carbon-based substrates (e.g., cellulose, polylactic acid), and plastic substrates (e.g., polyethylene terephthalate, polyethylene, polypropylene, polymethyl methacrylate, polysulfone, polydimethylsiloxane, polyvinyl chloride, etc.). The substrate may be disposed between the working electrode and the counter and / or reference electrode.

[0121] In some embodiments (including any of the embodiments in Figures 3-6), the dielectric layer may comprise a suitable dielectric material that can be formed into a solid. In one embodiment, the insulating layer may be formed of ceramic, mica, glass, barium strontium titanate, plastics (e.g., polystyrene, polytetrafluoroethylene, polyethylene terephthalate, polyethylene, polypropylene, polymethyl methacrylate, polysulfone, polydimethylsiloxane, polyvinyl chloride) or metal oxides (e.g., silicon dioxide, alumina, titanium dioxide, zirconium oxide, tantalum oxide, etc.).

[0122] In some embodiments (including any of the embodiments in Figures 3-6), membrane 220 optionally covers at least the analyte-responsive sensing regions 218a and 218b and covers some or all of the working electrodes 214a and / or 214b and / or the reference electrode 216 and / or the counter electrode 217, or according to some embodiments, covers the entire analyte sensor 202. One or both sides of the analyte sensor 202 may be covered by membrane 220. Membrane 220 may comprise one or more polymer membrane materials capable of limiting the analyte flux to the sensing regions 218 (i.e., membrane 220 is a mass transport limiting membrane with a certain degree of permeability to the analyte). The composition and thickness of membrane 220 may be varied to facilitate the desired analyte flux to the analyte-responsive sensing regions 218a, 218b, thereby providing the desired signal strength and stability.

[0123] Figure 5B and Figure 6A simplified diagram of an exemplary four-electrode analyte sensor configuration is shown, which is compatible with the uses disclosed herein. As shown, the analyte sensor 232 includes a substrate 212 disposed between a working electrode 214a and a counter electrode 216. The working electrodes 214a and 214b are located on the same side of the substrate 212, and a dielectric material 219b is sandwiched between the working electrodes 214a and 214b. The counter electrode 216 and a reference electrode 217 are located on opposite sides of the substrate 212, and a dielectric material 219c is sandwiched between the counter electrode 216 and the reference electrode 217. An analyte-specific responsive sensing region 218a (e.g., a lactate-responsive sensing region) may be disposed as at least one layer on at least a portion of the working electrode 214a. An analyte-specific responsive sensing region 218b (e.g., a glucose-responsive region) may be disposed as at least one layer on at least a portion of the working electrode 214b. Sensing region 218a (e.g., lactate-responsive sensing region) may be located further distal to end A than analyte-specific responsive sensing region 218b (e.g., glucose-responsive sensing region). As further discussed herein, analyte-responsive sensing regions 218a and 218b may be disposed continuously or discontinuously on the working electrode used for analyte detection. Figure 5B As shown, dielectric layers 219b and 219c space electrodes 214a, 214b, 216, and 217 apart and provide electrical isolation. Outer dielectric layers 219a and 219d are located on the working electrode 214b and the counter electrode 217. A reference material layer 230 (e.g., Ag / AgCl) (not shown) may be present on the reference electrode 216 or at other suitable locations on the sensor. Figure 5B The sensor 232 may contain, in sequence, an outer dielectric layer 219a, a working electrode 214b, a dielectric layer 219b, a working electrode 214a, a substrate 212, a reference electrode 216, a dielectric layer 219c, a counter electrode 217, and an outer dielectric layer 219d. The layers may be (partially) stacked on top of each other, with a portion of each layer near the end of that layer not covered by adjacent layers. For example, in... Figure 6 As shown, the lactate-responsive sensing region can be continuously disposed on the working electrode 214a, while the glucose-responsive sensing region can be discontinuously disposed on the working electrode 214b. Furthermore, the analyte sensors 206 and 232 can determine the analyte using any of the following methods: coulometric method, amperometric method, voltammetric method, or potentiochemical detection technique.

[0124] In some implementations, sensor 232 may contain two membranes 220, 222. For example, in... Figure 5BAs seen, membrane 222 may cover only a portion of the working electrode 214a, which includes sensing region 218a (e.g., a lactate-responsive sensing region). Membrane 220 may cover sensing regions 218a (e.g., a lactate-responsive sensing region) and sensing region 218b (e.g., a glucose-responsive sensing region). Membrane 220 may also cover counter electrode 216 and reference electrode 217 on opposite sides of substrate 212. Therefore, sensing region 218a (e.g., a lactate-responsive sensing region) may have a bilayer membrane comprising membranes 222 and 220, while sensing region 218b may have only a single layer membrane 220. Although Figure 5B The diagram depicts all electrodes 214a, 214b, 216, and 217 covered by membrane 220; however, it should be understood that in some embodiments, only the working electrodes 214a and 214b may be covered. Furthermore, the thickness of membranes 220 and 222 at each of electrodes 214a, 214b, 216, and 217 may be the same or different. Similar to the dual-electrode analyte sensor configuration, in... Figure 5B In the sensor configuration, one or two surfaces of the analyte sensor 232 can be covered by the membrane 220, or the entire analyte sensor 232 can be covered. Therefore, Figure 5A and 5B The multi-electrode sensor configurations shown should be understood as not limiting the embodiments disclosed herein, and alternative electrodes and / or layer configurations are still within the scope of this disclosure.

[0125] Membrane 222 can be dip-coated onto sensing region 218a (e.g., a lactic acid-responsive sensing region). For example, sensor 232 can be partially immersed in the membrane solution such that only the end region near the distal end A (which includes sensing region 218a but not sensing region 218b) is immersed in the membrane solution. The application of membrane 222 can be completed in a single dip-coating process, or multiple dips in the membrane solution may be required to obtain a dense membrane. A larger portion of sensor 232 (which includes sensing regions 218a and 218b) can then be immersed in different membrane solutions. Thus, sensing region 218a, located closer to the distal end A, can have a bilayer membrane, while sensing region 218b, closer to sensing region 218a, has a single layer membrane. This dip-coating has several advantages. First, two sensing regions can be distributed on one side of substrate 212 without flipping the substrate 212, which simplifies the manufacturing process and improves efficiency. Secondly, this impregnation method allows the same membrane impregnation equipment to be used to treat membranes 222 and 220, simply by changing the membrane solution and adjusting the impregnation depth.

[0126] In some embodiments, membrane 222 may comprise at least one crosslinked polyvinylpyridine homopolymer or copolymer. Membrane 222 may be a one-component membrane or a multi-component membrane. According to some embodiments of this disclosure, a multi-component membrane embodiment may comprise a bilayer or homogeneous mixture of crosslinked polyvinylpyridine and another polymer. Suitable polyvinylpyridine copolymers contained in membrane 222 may comprise up to about 25% comonomer (based on the total amount of monomers in the copolymer), such as about 0.1% to about 5% comonomer, or about 5% to about 15% comonomer, or about 15% to about 25% comonomer, or about 1% to about 10% comonomer. There are no particular limitations on suitable comonomers, provided that the mass transfer limiting membrane provides sufficient lactic acid permeability to provide an analyte sensitivity of about 1 nA / mM or greater when exposed to lactic acid. In some embodiments, according to certain embodiments, the polyvinylpyridine copolymer may be different from a polyvinylpyridine-co-styrene copolymer. The crosslinking of the membrane polymer of the membrane 222 disclosed herein can be achieved by functionalization with a bicyclic oxide, such as polyethylene glycol diglycidyl ether (PEGDGE) or glycerol triglycidyl ether. In some embodiments, the membrane 222 may comprise polyvinylpyridine and a crosslinking agent, such as polyethylene glycol diglycidyl ether (PEGDGE), for example, PEGDGE 400.

[0127] In some embodiments, membrane 220 may be a membrane comprising a crosslinked polymer containing heterocyclic nitrogen groups, such as polymers of polyvinylpyridine and polyvinylimidazole. In some embodiments, membrane 220 may comprise polyurethane, or polyether urethane, or chemically related materials, or a membrane made of silicone, etc.

[0128] In some embodiments, membranes can be formed by in-situ crosslinking polymers (including those discussed above) in a buffer solution (e.g., an alcohol buffer solution), said polymer being modified with a zwitterionic moiety, a non-pyridine copolymer component, and optionally another moiety (which is hydrophilic or hydrophobic, and / or has other desired properties). In some embodiments, the modified polymer can be made from a precursor polymer containing heterocyclic nitrogen groups. For example, the precursor polymer can be polyvinylpyridine or polyvinylimidazole. Optionally, hydrophilic or hydrophobic modifiers can be used to “fine-tune” the permeability of the resulting membrane to the target analyte. Optional hydrophilic modifiers such as poly(ethylene glycol), hydroxyl or polyhydroxyl modifiers, and any combination thereof can be used to enhance the biocompatibility of the polymer or the resulting membrane.

[0129] In some embodiments, membrane 220 may comprise polymers including, but not limited to, poly(styrene-co-maleic anhydride), dodecylamine, and poly(propylene glycol)-block-poly(ethylene glycol)-block-poly(propylene glycol) (2-aminopropyl ether) crosslinked with poly(propylene glycol)-block-poly(ethylene glycol)-block-poly(propylene glycol) bis(2-aminopropyl ether); poly(N-isopropylacrylamide); copolymers of poly(ethylene oxide) and poly(propylene oxide); polyvinylpyridine; derivatives of polyvinylpyridine; polyvinylimidazole; derivatives of polyvinylimidazole; and the like; and any combination thereof. In some embodiments, the membrane may comprise a polyvinylpyridine-co-styrene polymer, wherein a portion of the pyridine nitrogen atom is functionalized with a non-crosslinked poly(ethylene glycol) tail, and a portion of the pyridine nitrogen atom is functionalized with an alkyl sulfonic acid group. In some embodiments, membrane 220 may comprise the polymers shown below.

[0130]

[0131] In some embodiments, membrane 222 may comprise polyvinylpyridine and a crosslinking agent, such as polyethylene glycol diglycidyl ether (PEGDGE), for example, PEGDGE 400. In some embodiments, membrane 220 may comprise polyvinylpyridine-co-styrene and a crosslinking agent, such as PEGDGE, for example, PEGDGE 400, or glycerol triglycidyl ether. In some embodiments, membrane 222 may comprise polyvinylpyridine and a crosslinking agent, such as PEGDGE, for example, PEGDGE 400, and membrane 220 may comprise polyvinylpyridine-co-styrene and a crosslinking agent, such as PEGDGE, for example, PEGDGE 400, or glycerol triglycidyl ether.

[0132] In some embodiments, the sensing region 218a may contain a lactate-responsive enzyme. More specifically, according to certain embodiments of this disclosure, the lactate-responsive enzyme may contain lactate dehydrogenase or lactate oxidase. Figure 8 A simplified diagram of an enzyme system that can be used to detect lactate according to the disclosure herein is shown. In some embodiments, such as in Figure 8 As shown, the electron transfer medium can facilitate the transfer of electrons from lactate to the working electrode 214a during the redox reaction. The electrons transferred during this reaction provide the basis for lactate detection at the working electrode. Changes in signal intensity (e.g., current) at the working electrode 214a can be proportional to lactate concentration and / or the activity of lactate-responsive enzymes.

[0133] In some embodiments, the sensing region 218a may further comprise a stabilizer for lactate dehydrogenase or lactate oxidase, such as catalase or albumin. According to some embodiments, a lactate-responsive enzyme (such as lactate dehydrogenase or lactate oxidase) may be covalently bonded to the polymer comprising the sensing region 218. Covalent bonding immobilizes the lactate-responsive enzyme within the sensing region 218a.

[0134] In some embodiments, lactate oxidase may be present in the sensing region in an amount ranging from about 0.05 μg to about 5 μg, or about 0.1 μg to about 4 μg, or about 0.2 μg to about 3 μg, or about 0.5 μg to about 2 μg. The amount of lactate oxidase present, in terms of weight percentage of the sensing region, may be about 10% to about 90% of the weight of the sensing region, or about 25% to about 75% of the weight of the sensing region, or about 30% to about 60% of the weight of the sensing region.

[0135] According to some embodiments, the albumin within the sensing area may comprise human serum albumin. In some embodiments, non-human albumin, such as bovine serum albumin, may be used satisfactorily.

[0136] According to the disclosure herein, albumin can be incorporated into the sensing region in an amount sufficient to stabilize lactate-responsive enzymes, particularly lactate oxidase. In more specific embodiments, albumin can be present in the sensing region in an amount ranging from about 0.05 μg to about 5 μg, or about 0.1 μg to about 2 μg, or about 0.2 μg to about 1.5 μg, or about 0.3 μg to about 0.8 μg. The amount of albumin present can be about 25% to about 75% of the weight of the sensing region, or about 30% to about 60% of the weight of the sensing region, in terms of weight percentage of the sensing region. In some embodiments, the weight ratio of lactate oxidase to albumin can be in the range of about 10:1 to about 1:10 (w / w), or about 5:1 to about 1:5, or about 5:1 to about 1:1, or about 2:1 to about 1:1, or about 1:1 to about 1:5, or about 1:1 to about 1:2. In some embodiments, the weight ratio of lactate oxidase to albumin can be about 2:1. In some implementations, the weight ratio of lactate oxidase to albumin can be approximately 1:1.

[0137] In some embodiments, sensing region 218a may comprise a redox medium, which may comprise a polymer and an electron transfer reagent. In some embodiments, the electron transfer reagent may be a low-potential osmium complex electron transfer medium. In some embodiments, the polymer is covalently bonded to a lactate-responsive enzyme (such as lactate dehydrogenase or lactate oxidase) and a low-potential osmium complex electron transfer medium, as disclosed, for example, in U.S. Patent Nos. 6,134,461, 6,605,200, 6,736,957, 7,501,053, and 7,754,093, the disclosures of each of which are incorporated herein by reference in their entirety. Other suitable examples of electron transfer media combining an electron transfer medium and a polymer may include those described in U.S. Patent Nos. 8,444,834, 8,268,143, and 6,605,201 (the disclosures of which are incorporated herein by reference in their entirety).

[0138] The electron transfer medium facilitates the transfer of electrons from lactate to the working electrode 214a during the redox reaction. Changes in signal intensity (e.g., current) at the working electrode 214 can be proportional to the lactate concentration and / or the activity of lactate-responsive enzymes. According to some embodiments, a calibration factor (e.g., via a processor) can be applied to determine the lactate concentration from the signal intensity. Suitable electron transfer media include electroreducible and electrooxidizable ions, complexes, or molecules with redox potentials several hundred millivolts higher or lower than those of a standard calomel electrode (SCE). Other suitable electron transfer media may comprise metal compounds or complexes such as ruthenium, iron (e.g., polyvinylferrocene), or cobalt. Suitable ligands for metal complexes may include, for example, bidentate or higher-dentate ligands, such as, for example, bipyridine, biimidazole, phenanthroline, or pyridyl (imidazole). Other suitable bidentate ligands may include, for example, amino acids, oxalic acid, acetylacetone, diaminoalkanes, or o-diaminoaromatics. In metal complexes, any combination of monodentate, bidentate, tridentate, tetradentate, or higher dentate ligands can exist to achieve a complete coordination sphere.

[0139] The polymer in the redox medium can be any suitable polymer capable of transferring electrons between the electron transfer reagent and the working electrode. For example, the polymer can be poly(4-vinylpyridine), poly(1-vinylimidazole), poly(thiophene), poly(aniline), poly(pyrrole), poly(acetylene), poly(acrylic acid), styrene / maleic anhydride copolymer, methyl vinyl ether / maleic anhydride copolymer, poly(vinylbenzyl chloride), poly(allylamine), poly(lysine), poly(acrylamide-co-1-vinylimidazole), poly(4-vinylpyridine) quaternized with a carboxylpentyl group, and poly(sodium 4-styrene sulfonate). These polymers can be considered precursor polymers because they are further modified to immobilize (e.g., link) the electron transfer complex. In some embodiments, the polymer may comprise a poly(4-vinylpyridine), poly(1-vinylimidazole), poly(thiophene), poly(aniline), poly(pyrrole), or poly(acetylene) backbone. In other embodiments, the polymer may comprise repeating polymer or copolymer units, which may contain at least one (e.g., 1, 2, 3, 4, 5, or 6) side-chain pyridyl, imidazole, or both pyridyl and imidazole groups. For example, suitable polymers include partially or fully quaternized poly(4-vinylpyridine) and poly(1-vinylimidazole), wherein the quaternized pyridyl and imidazole groups can be used to form spacers by reacting with an electron transfer agent (e.g., complexation).

[0140] Suitable polymers included in sensing region 218a include, but are not limited to, polyvinylpyridine (e.g., poly(4-vinylpyridine)), polyimide (e.g., poly(1-vinylimide)), or any copolymer thereof. Exemplary copolymers include, for example, copolymers containing monomer units such as styrene, acrylamide, methacrylamide, or acrylonitrile.

[0141] Covalent bonding of the lactate-responsive enzyme to the polymer or other matrix (e.g., sol-gel) in sensing region 218a can be achieved by introducing a crosslinking agent using a suitable crosslinking reagent. Suitable crosslinking reagents for reacting with free amino groups in the enzyme (e.g., with free amines in lysine) may include crosslinking reagents such as, for example, polyethylene glycol diglycidyl ether (PEGDGE) or other polyepoxides, cyanuric chloride, N-hydroxysuccinimide, imine esters, epichlorohydrin, or derivatives thereof. Suitable crosslinking reagents for reacting with free carboxylic acid groups in the enzyme may include, for example, carbodiimide.

[0142] In some embodiments, the redox medium may comprise an osmium complex bonded to a polymer or copolymer of poly(1-vinylimidazole) or poly(4-vinylpyridine). The poly(4-vinylpyridine)-based polymer is a prepolymer, as shown in the following structure, which has been modified to link the osmium complex (e.g., a poly(biimidizyl)osmium complex):

[0143] ,

[0144] Where n can be 2, n It can be 17, and n It can be 1. Other reactive groups and / or spacer groups can be used.

[0145] In some embodiments, the electronic redox medium may comprise an osmium-containing poly(4-vinylpyridine)-based polymer, as shown below.

[0146] ,

[0147] Where n is 2, n It is 17, and n It is 1.

[0148] While the lactate-responsive enzyme and / or electron transfer medium can be covalently bonded to the polymer or other suitable matrix in sensing region 218a, other binding modalities may also be suitable. In some embodiments, the lactate-responsive enzyme and / or the electron transfer medium may bind to the polymer or other matrix ionicly or coordinately. For example, a charged polymer may ionicly bind to a lactate-responsive enzyme or electron transfer medium with an opposite charge. In still other embodiments, the lactate-responsive enzyme and / or the electron transfer medium may be physically encapsulated within the polymer or other matrix of sensing region 218a.

[0149] In some embodiments, sensing region 218b may comprise a redox medium, which may comprise a polymer and an electron transfer reagent. Suitable polymers and electron transfer reagents discussed for the first sensing region 218a are also applicable to the second sensing region 218b. In some embodiments, the electron transfer reagent may be a low-potential osmium complex electron transfer medium. In some embodiments, the polymer is covalently bonded to a glucose-responsive enzyme (such as glucose oxidase) and the low-potential osmium complex electron transfer medium. Figure 7A simplified diagram of an enzyme system that can be used to detect glucose according to the disclosure herein is shown. An electron transfer medium facilitates the transfer of electrons from glucose to the working electrode 214b during a redox reaction. Changes in signal intensity (e.g., current) at the working electrode 214b can be proportional to glucose concentration and / or the activity of a glucose-responsive enzyme. According to certain embodiments, a calibration factor can be applied (e.g., via a processor) to determine the glucose concentration from the signal intensity.

[0150] In some embodiments, the first sensing region 218a may comprise a lactate-responsive enzyme, such as lactate oxidase, and the second sensing region 218b may comprise a glucose-responsive enzyme, such as glucose oxidase, as well as suitable electron transfer reagents and polymers discussed in more detail above. According to some embodiments, the sensor may be adapted to detect glucose and lactate and may comprise a first working electrode 214a having the first sensing region 218a disposed thereon and a second working electrode having the second sensing region 218b disposed thereon, and a mass transfer limiting membrane covering the first and second sensing regions on the working electrodes, wherein the first sensing region 218a comprises a polymer, albumin, and a lactate-responsive enzyme (e.g., lactate oxidase) covalently bonded to the polymer, and the second sensing region 218b comprises a glucose-responsive enzyme (e.g., glucose oxidase) covalently bonded to the polymer. In some embodiments, the first and second electron transfer reagents may be different from each other. In some embodiments, the mass transfer limiting membrane may comprise at least one cross-linked polyvinylpyridine homopolymer or copolymer. The composition of the mass transfer limiting membranes can be the same or different, wherein the mass transfer limiting membranes cover each sensing region. In some embodiments, the mass transfer limiting membrane covering the second sensing region can be a single component (containing a single membrane polymer), and the mass transfer limiting membrane covering the first sensing region can be multi-component (containing two or more different membrane polymers, one of which is a polyvinylpyridine homopolymer or copolymer), as a bilayer or homogeneous mixture.

[0151] In some implementations, the sensors discussed herein can be configured to be partially inserted into an individual's skin. Working electrodes are positioned on the sensor and can be inserted into the tissue for the analysis of lactate and glucose within the tissue. No particular limitations are considered to apply to suitable tissues, and specific examples are discussed in more detail above. Similarly, considerations for deploying sensors at specific locations or depths within tissues have been discussed above.

[0152] A detection method for determining glucose and lactic acid using the sensor disclosed herein may include: exposing the analyte sensor to a fluid containing glucose and lactic acid; applying a potential to a first working electrode and a second working electrode; obtaining a first signal at a redox potential or higher in the lactic acid-responsive sensing region, wherein the first signal is proportional to the concentration of lactic acid in the fluid; obtaining a second signal at a redox potential or higher in the glucose-responsive sensing region, wherein the second signal is proportional to the concentration of glucose in the fluid; and correlating the first signal with the concentration of lactic acid in the fluid and the second signal with the concentration of glucose in the fluid.

[0153] In some implementations, the signal associated with each sensing region can be correlated with the corresponding glucose or lactate concentration by consulting a lookup table or calibration curve for each analyte. The lookup table for each analyte can be populated by measuring samples with multiple known analyte concentrations and recording the sensor response for each analyte at each concentration. Similarly, the calibration curve for each analyte can be determined by plotting the analyte sensor response versus concentration and identifying a suitable calibration function within the calibration range (e.g., through regression, particularly linear regression).

[0154] The processor can determine which sensor response value in the lookup table is closest to the measured value of the sample with an unknown analyte concentration, and then report the analyte concentration accordingly. In some embodiments, if the sensor response value of the sample with an unknown analyte concentration falls between the values ​​recorded in the lookup table, the processor can interpolate between the two lookup table values ​​to estimate the analyte concentration. The interpolation method can assume a linear concentration change between the two values ​​reported in the lookup table. Interpolation can be used when the sensor response differs sufficiently from a given value in the lookup table (e.g., a deviation of about 10% or greater).

[0155] Similarly, according to some implementations, the processor can input the sensor response value of a sample with an unknown analyte concentration into the corresponding calibration function. The processor can then report the analyte concentration accordingly.

[0156] In some implementations, the sensors described herein can also be configured to analyze other analytes. Other analytes of interest in the field of sports training include, for example, cardiac stress markers, inflammatory markers, pyruvate, pH, triglycerides, free fatty acids, and hormones such as insulin, glucagon, cortisol, adrenaline, noradrenaline, testosterone, HGH, IFG1, and BDNF.

[0157] In some implementations, the sensing system may include additional functions suitable for monitoring physical activity. These additional functions may optionally include, for example, a heart rate monitor, a heart rate variability monitor, a blood oxygen monitor, a power meter, an accelerometer, a pedometer, a measure of the rate of perceived exertion by the user, etc.

[0158] It should be understood that the sensing systems and sensors disclosed herein may include additional features and / or functions, which are not necessarily described herein for the sake of brevity. Therefore, the above description of the sensing systems and sensors should be considered exemplary and non-limiting in nature.

[0159] method

[0160] This paper also discloses methods for monitoring lactate levels in individuals and methods for determining aerobic and anaerobic thresholds in individuals. The methods disclosed herein can rapidly and conveniently obtain reliable lactate levels related to indicators such as power and heart rate (even if there is a lag in the response of changes in interstitial fluid lactate concentration to changes in power or heart rate), and determine lactate thresholds, thereby providing individuals with valuable information about running speed, heart rate, and / or power corresponding to aerobic or anaerobic thresholds.

[0161] In some embodiments, the method for monitoring lactate levels in an individual includes exposing an analyte sensor of a sensing system to a fluid. In some embodiments, the sensor may be any sensor disclosed herein. In some embodiments, the sensor may be a sensor disclosed in US 10,392,647, US 2019 / 0320947, and / or US 2022 / 0125354 (the disclosures of each of these are incorporated herein by reference in their entirety). In some embodiments, the analyte sensor is the sensor described in association with Figures 3-6. In some embodiments, the analyte sensor is... Figure 5B and Figure 6The sensor is described in association. In some embodiments, the method further includes: applying a potential to the working electrode of the sensor; obtaining a first signal at a redox potential or higher in a lactate-responsive sensing region (e.g., a first sensing region), the signal being proportional to the concentration of lactate in the fluid; and correlating the signal with the concentration of lactate in the fluid. In some embodiments, the method further includes obtaining a second signal at a redox potential or higher in a glucose-responsive sensing region (e.g., a second sensing region), the second signal being proportional to the concentration of glucose in the fluid; and correlating the second signal with the concentration of glucose in the fluid. In some embodiments, each sensing region has a redox potential, and the redox potential of the glucose-responsive sensing region is sufficiently separated from that of the lactate-responsive sensing region, thereby allowing the glucose-responsive sensing region and the lactate-responsive sensing region to generate signals independently.

[0162] In some embodiments, the method for determining an aerobic threshold, an anaerobic threshold, or both aerobic and anaerobic thresholds may include continuously measuring a signal indicating the concentration of lactate in a biofluid within an individual using a sensing system comprising a lactate-responsive sensor. As discussed above, in some embodiments, the sensor may be any sensor disclosed herein or one of the aforementioned references. In some embodiments, the measurement of multiple lactate concentrations is performed while the individual is in a state where a lactate threshold test is being conducted to determine aerobic and anaerobic thresholds. In some embodiments, the lactate threshold test may be a step test with a gradual increase in exercise intensity. In some embodiments, the lactate threshold test may involve running at a low speed (e.g., on a treadmill) and then gradually increasing the running speed until exhaustion or near exhaustion. In some embodiments, the lactate threshold test may involve cycling at a low speed (e.g., on a stationary bike) and then gradually increasing the cycling speed until exhaustion or near exhaustion. In some embodiments, the gradual increase may be defined based on power. In some embodiments, the gradual increase may be approximately 1 W, approximately 2 W, approximately 3 W, approximately 4 W, approximately 5 W, approximately 6 W, approximately 7 W, approximately 8 W, approximately 9 W, approximately 10 W, approximately 15 W, approximately 20 W, approximately 25 W, approximately 30 W, approximately 35 W, approximately 40 W, approximately 45 W, or approximately 50 W. In some embodiments, the lactate threshold test may collect lactate concentration data related to power or heart rate.

[0163] In some embodiments, the sensor is configured to perform measurements approximately every second, approximately every 3 seconds, approximately every 5 seconds, approximately every 10 seconds, approximately every 15 seconds, approximately every 20 seconds, approximately every 30 seconds, approximately every 45 seconds, approximately every minute, approximately every 1.5 minutes, approximately every 2 minutes, approximately every 3 minutes, approximately every 5 minutes, approximately every 10 minutes, approximately every 15 minutes, approximately every 20 minutes, approximately every 30 minutes, approximately every 45 minutes, approximately every hour, approximately every 2 hours, or approximately every 3 hours. In some embodiments, the method may further include transmitting a signal indicating the lactate concentration measured by the lactate-responsive sensor to a processor. In some embodiments, the processor may be configured to receive the signal from the lactate-responsive sensor and determine the lactate concentration from the received signal. In some embodiments, the processor is further configured to determine an individual's aerobic threshold, anaerobic threshold, or both aerobic and anaerobic thresholds based on the signal indicating lactate concentration from the lactate-responsive sensor. In some embodiments, the processor may further signal to the individual wearing the sensor or other relevant party when the aerobic or anaerobic threshold has been reached. In some implementations, the processor's output can be numerical and / or graphical. Notification to the wearer or other relevant party of the lactate-responsive sensor can be auditory, tactile, or any combination thereof.

[0164] In some embodiments, the method may include determining an individual's baseline lactate concentration based on multiple lactate concentration measurements. The baseline lactate concentration may vary from individual to individual. In some embodiments, the baseline lactate concentration may be in the range of about 0.5 mM to about 2 mM, about 0.5 mM to about 1.5 mM, or about 0.5 mM to about 1 mM. The baseline lactate concentration may be determined before reaching the anaerobic threshold and / or after the lactate concentration has stabilized again following reaching the anaerobic threshold.

[0165] In some embodiments, the aerobic threshold may be a fixed value and is defined as the power or heart rate at which an initial increase of about 0.5 mM or about 1 mM (or other predetermined suitable value) in lactate concentration is observed from the baseline concentration. In some embodiments, the processor is configured to determine the baseline concentration from the lactate measurement and to determine the aerobic threshold by increasing the baseline lactate concentration by about 0.5 mM or about 1 mM, such that the aerobic threshold can be defined based on (i) the lactate concentration and (ii) the power or heart rate associated with that lactate concentration.

[0166] In some embodiments, the processor is configured to determine an aerobic threshold based on multiple lactate concentrations using a log-log model. In some embodiments, the log-log model may include plotting lactate levels versus intensity (e.g., power or heart rate) on a logarithmic scale. In some embodiments, the log-log model may further include dividing the graph into two parts and performing piecewise regression analysis. Each segment can be connected at the breakpoint by a best-fit line. In some embodiments, the piecewise regression analysis may include minimizing the sum of squared errors (SSE) (also known as the residual sum of squares (RSS)), for example, by changing the membership of data points in each group. In some embodiments, the breakpoint provides an aerobic threshold based on (i) lactate concentration and (ii) intensity (e.g., power or heart rate).

[0167] In some embodiments, the anaerobic threshold can be defined as power or heart rate at a fixed lactate concentration of 4 mM. In some embodiments, the processor is configured to determine the anaerobic threshold using a multinomial regression model based on multiple lactate concentrations. In some embodiments, the processor is configured to determine the anaerobic threshold using a D-max method based on multiple lactate concentrations, such as in... Figure 9 As shown in the diagram. In some embodiments, the D-max method may include performing regression analysis to determine the best-fit line (e.g., a regression curve) based on multiple plots of lactate concentration versus power or heart rate. In some embodiments, a third-order polynomial function may provide the best-fit line (e.g., a regression curve) based on multiple plots of lactate concentration versus power or heart rate. In some embodiments, the D-max method may further include finding a linear equation that links the first measured lactate concentration (e.g., the starting point) to the last measured lactate concentration (e.g., the ending point). In some embodiments, the D-max method may further include finding the D-max point on the best-fit line (e.g., the regression curve) that is furthest from the straight line connecting the first measured lactate concentration (e.g., the starting point) and the last measured lactate concentration (e.g., the ending point), wherein the D-max point lies on the tangent to the curve parallel to the straight line connecting the first measured lactate concentration (e.g., the starting point) and the last measured lactate concentration (e.g., the ending point). In some implementations, the D-max point provides an anaerobic threshold based on (i) lactate concentration and (ii) power or heart rate.

[0168] In some embodiments, the processor is configured to determine an anaerobic threshold based on multiple lactate concentrations using a modified D-max method. In some embodiments, the modified D-max method is similar to the D-max method described above, except that the starting point is a lactate concentration of 0.4 mM (or other suitable starting point). That is, in some embodiments, the modified D-max method may include finding a linear equation that connects the 0.4 mM lactate concentration (e.g., the starting point) to the last measured lactate concentration (e.g., the endpoint). In some embodiments, the modified D-max method may include performing regression analysis to determine the best-fit line (e.g., a regression curve) based on multiple plots of lactate concentration versus power or heart rate. In some embodiments, a third-order polynomial function may provide the best-fit line (e.g., a regression curve) based on plotted multiple lactate concentration versus power or heart rate plots. In some embodiments, the improved D-max method further includes finding a D-max point on the fitted line (e.g., a regression curve) that is furthest from the straight line connecting the 0.4 mM lactate concentration (e.g., the starting point) and the last measured lactate concentration (e.g., the ending point), and that the point lies on the tangent to a curve parallel to the straight line connecting the 0.4 mM lactate concentration (e.g., the starting point) and the last measured lactate concentration (e.g., the ending point). In some embodiments, the D-max point provides an anaerobic threshold based on (i) lactate concentration and (ii) power or heart rate.

[0169] In some embodiments, the processor is configured to determine the anaerobic threshold using a piecewise linear regression model based on multiple lactate concentrations. In some embodiments, the processor is configured to determine the anaerobic threshold using a broken-bar model based on multiple lactate concentrations, as in... Figures 10A-10B As shown in the diagram. In some embodiments, the broken rod model may involve dividing multiple lactate concentrations into two groups of data and performing regression analysis to find the best-fit line connecting each group of data at the breakpoint. In some embodiments, finding the best-fit line for each group of data may include minimizing the sum of squared errors (SSE) (also known as the residual sum of squared errors (RSS)), for example, by minimizing between the two groups of data points by changing the membership of the data points in each group. In some embodiments, the breakpoint provides an anaerobic threshold based on (i) lactate concentration and (ii) power or heart rate.

[0170] In some embodiments, the method may include repeating the lactate threshold test with smaller power or heart rate increments to improve aerobic or anaerobic threshold determination. In some embodiments, an initial lactate threshold test may be performed by measuring lactate in 25-watt increments, and the lactate threshold test may be repeated using smaller increments (e.g., 20-watt or 10-watt increments). In some embodiments, an initial lactate threshold test may be performed by measuring lactate in 20-watt increments, and the lactate threshold test may be repeated using smaller increments (e.g., 10-watt or 5-watt increments).

[0171] In some embodiments, the method may further include repeating the lactate threshold test after approximately 1 week, approximately 2 weeks, approximately 3 weeks, approximately 4 weeks, approximately 5 weeks, approximately 6 weeks, approximately 7 weeks, approximately 8 weeks, approximately 9 weeks, approximately 10 weeks, approximately 12 weeks, approximately 14 weeks, approximately 16 weeks, approximately 1 month, approximately 2 months, approximately 3 months, approximately 4 months, approximately 5 months, approximately 6 months, approximately 9 months, or approximately 1 year. In some embodiments, the processor is configured to compare the aerobic and anaerobic thresholds determined from a previous lactate threshold test with the results of a most recently performed test. The processor's output may be numerical and / or graphical to track progress. Notification to the wearer of the lactate-responsive sensor or other relevant parties may be auditory, tactile, or any combination thereof.

[0172] The following implementation plan further illustrates the contents of this disclosure.

[0173] (1) An analyte sensor comprising:

[0174] Base;

[0175] The first working electrode is located on the substrate;

[0176] The second working electrode is located on the substrate;

[0177] A lactic acid-responsive sensing region is disposed on the surface of the first working electrode; and

[0178] A glucose-responsive sensing area is disposed on the surface of the second working electrode;

[0179] A first lactic acid-permeable membrane covering the lactic acid-responsive sensing region; and

[0180] A glucose-permeable second membrane covering the glucose-responsive sensing region and the lactate-responsive sensing region.

[0181] The sensor is configured to be partially inserted into the individual's skin.

[0182] (2) (1) Analyte sensor, wherein the lactate responsive sensing region contains lactate oxidase.

[0183] (3) (1) or (2) of the analyte sensor, wherein the lactic acid responsive sensing region comprises a first polymer and a first electron transfer reagent.

[0184] (4) (3) Analyte sensor, wherein the first electron transfer reagent is covalently bonded to the first polymer.

[0185] (5) (3) or (4) of the analyte sensor, wherein the first electron transfer reagent comprises an osmium complex.

[0186] (6) Analyte sensor of any one of (3-5), wherein the first polymer is a polymer based on poly(4-vinylpyridine).

[0187] An analyte sensor of any one of (7) (3-6), wherein the lactic acid responsive sensing region further comprises a first crosslinking agent.

[0188] (8) (7) Analyte sensor, wherein the first crosslinking agent is polyethylene glycol diglycidyl ether (PEGDGE).

[0189] An analyte sensor of any one of (9) (1-8), wherein the glucose-responsive sensing region comprises glucose oxidase.

[0190] An analyte sensor of any one of (10) (1-9), wherein the glucose-responsive sensing region comprises a second polymer and a second electron transfer reagent.

[0191] (11) (10) analyte sensor, wherein the second electron transfer reagent is covalently bonded to the second polymer.

[0192] (12) (10) or (11) of the analyte sensor, wherein the second electron transfer reagent comprises an osmium complex.

[0193] An analyte sensor of any one of (13) (10-12), wherein the second polymer is a polymer based on poly(4-vinylpyridine).

[0194] An analyte sensor of any one of (14) (10-13), wherein the glucose-responsive sensing region further comprises a second crosslinking agent.

[0195] (15) (14) Analyte sensor, wherein the second crosslinking agent is PEGDGE.

[0196] (16) (1-15) Analyte sensor, wherein the sensor further comprises a reference electrode.

[0197] (17) (1-16) Analyte sensor, wherein the sensor further comprises a counter electrode.

[0198] (18) (1-17) analyte sensor, wherein the first membrane and the second membrane have different compositions.

[0199] (19) (1-18) Analyte sensor, wherein the first membrane comprises a polyvinylpyridine homopolymer or copolymer.

[0200] (20) (19) analyte sensors, wherein the first membrane further comprises a first crosslinking agent.

[0201] (21) (20) Analyte sensor, wherein the first crosslinking agent is polyethylene glycol diglycidyl ether (PEGDGE).

[0202] (22) (1-21) analyte sensor, wherein the second membrane comprises a polyvinylpyridine-co-styrene polymer.

[0203] (23) (22) Analyte sensor, wherein the second membrane further comprises a second crosslinking agent.

[0204] (24) (23) Analyte sensor, wherein the second crosslinking agent is glycerol triglycidyl ether.

[0205] (25) A method for monitoring lactate levels in an individual, the method comprising:

[0206] The analyte sensor of the sensing system is exposed to a fluid; wherein the analyte sensor comprises:

[0207] Base;

[0208] The first working electrode is located on the substrate;

[0209] The second working electrode is located on the substrate;

[0210] A lactic acid-responsive sensing region is disposed on the surface of the first working electrode; and

[0211] A glucose-responsive sensing area is disposed on the surface of the second working electrode;

[0212] A first lactic acid-permeable membrane covering the lactic acid-responsive sensing region; and

[0213] A glucose-permeable second membrane covering the glucose-responsive sensing region and the lactate-responsive sensing region.

[0214] The sensor is configured to be partially inserted into the individual's skin;

[0215] A potential is applied to the first working electrode of the analyte sensor;

[0216] A first signal is obtained at the redox potential or higher of the lactic acid responsive sensing region, the signal being proportional to the concentration of lactic acid in the fluid; and

[0217] The signal is correlated with the concentration of lactic acid in the fluid.

[0218] The methods of (26) and (25) further include:

[0219] A second signal is obtained at the redox potential or higher in the glucose-responsive sensing region, the signal being proportional to the concentration of glucose in the fluid; and

[0220] The second signal is correlated with the concentration of glucose in the fluid.

[0221] The method of (27), (25) or (26), wherein the lactate-responsive sensing region comprises lactate oxidase.

[0222] The method of any one of (28) (25-27), wherein the lactic acid responsive sensing region comprises a first polymer and a first electron transfer reagent.

[0223] (29) (28) method, wherein the first electron transfer reagent is covalently bonded to the first polymer.

[0224] The method of (30), (28) or (29), wherein the first electron transfer reagent comprises an osmium complex.

[0225] The method of any one of (31) (28-30), wherein the first polymer is a polymer based on poly(4-vinylpyridine).

[0226] The method of any one of (32) (28-31), wherein the lactic acid responsive sensing region further comprises a first crosslinking agent.

[0227] (33) (32) method, wherein the first crosslinking agent is PEGDGE.

[0228] The method of any one of (34) (25-33), wherein the glucose-responsive sensing region comprises glucose oxidase.

[0229] The method of any one of (35) (25-34), wherein the glucose-responsive sensing region comprises a second polymer and a second electron transfer reagent.

[0230] (36) (35) method, wherein the second electron transfer reagent is covalently bonded to the second polymer.

[0231] The method of (37), (35), or (36), wherein the second electron transfer reagent comprises an osmium complex.

[0232] The method of any one of (38) (35-37), wherein the second polymer is a polymer based on poly(4-vinylpyridine).

[0233] The method of any one of (39) (35-38), wherein the glucose-responsive sensing region further comprises a second crosslinking agent.

[0234] (40) (39) method, wherein the second crosslinking agent is PEGDGE.

[0235] (41) (25-40) method, wherein the sensor further comprises a reference electrode.

[0236] (42) (25-41) method, wherein the sensor further comprises a counter electrode.

[0237] (43) (25-42) method, wherein the first membrane and the second membrane have different compositions.

[0238] (44) (25-43) of the method, wherein the first membrane comprises a polyvinylpyridine isomer or copolymer.

[0239] (45) (44) method, wherein the first membrane further comprises a first crosslinking agent.

[0240] (46) (45) method, wherein the first crosslinking agent is polyethylene glycol diglycidyl ether (PEGDGE).

[0241] (47) (25-46) method, wherein the second membrane comprises a polyvinylpyridine-co-styrene polymer.

[0242] (48) (47) method, wherein the second membrane further comprises a second crosslinking agent.

[0243] (49) (48) method, wherein the second crosslinking agent is glyceryl triglycidyl ether.

[0244] (50) A method for determining an anaerobic threshold in an individual, the method comprising:

[0245] A sensing system incorporating a lactate-responsive sensor is used to continuously measure signals indicating the concentration of lactate in biological fluids within an individual.

[0246] The signal indicating lactate concentration, measured by the lactate-responsive sensor, is transmitted to the processor;

[0247] The anaerobic threshold is determined based on the signal indicating lactate concentration.

[0248] (51) (50) method, wherein the individual is undergoing a lactate threshold test.

[0249] (52) (51) method, wherein the lactate threshold test is a step test with gradually increasing power.

[0250] The method of any one of (53) (50-52), wherein the processor uses a broken stick model to determine the anaerobic threshold.

[0251] The method of any one of (54) (50-53), wherein the processor uses the D-max method to determine the anaerobic threshold.

[0252] The method of any one of (55) (50-54), wherein the processor uses the improved D-max method to determine the anaerobic threshold.

[0253] (56) The method of any one of (50-55), wherein the continuous measurement of the signal indicating lactate concentration comprises measuring the signal indicating lactate concentration approximately every 10 seconds, approximately every 15 seconds, approximately every 20 seconds, approximately every 30 seconds, approximately every 45 seconds, approximately every minute, approximately every 1.5 minutes, approximately every 2 minutes, approximately every 3 minutes, approximately every 5 minutes, approximately every 10 minutes, approximately every 15 minutes, approximately every 20 minutes, approximately every 30 minutes, approximately every 45 minutes, approximately every hour, approximately every 2 hours, or approximately every 3 hours.

[0254] The method of any one of (57) (50-56), wherein the continuous measurement of the signal indicating lactate concentration comprises a signal indicating lactate concentration measured approximately every minute.

[0255] The method of any one of (58) (50-55), wherein the lactic acid responsive sensor is any one of (1-24).

[0256] (59) A method for determining an aerobic threshold in an individual, the method comprising:

[0257] A sensing system incorporating a lactate-responsive sensor continuously measures a signal indicating the concentration of lactate in the biological fluid of the individual.

[0258] The signal indicating lactate concentration, measured by the lactate-responsive sensor, is transmitted to the processor;

[0259] The aerobic threshold is determined based on the signal indicating lactate concentration.

[0260] (60) (59) methods, wherein the individual is undergoing a lactate threshold test.

[0261] The method of (61) (60), wherein the lactate threshold test is a step test with gradually increasing power.

[0262] The method of any one of (62) (59-61), wherein the aerobic threshold is defined as a fixed value.

[0263] (63) (62) method, wherein the aerobic threshold is defined as baseline lactate concentration + about 0.5 mM lactate.

[0264] (64) (62) method, wherein the aerobic threshold is defined as baseline lactate concentration + about 1 mM lactate.

[0265] The method of any one of (65) (59-61), wherein the processor uses a log-log model to determine the aerobic threshold.

[0266] The method of any one of (66) (59-61), wherein the processor uses piecewise regression analysis to determine the aerobic threshold.

[0267] The method of any one of (67) (59-66), wherein the continuous measurement of the signal indicating lactate concentration comprises measuring the signal indicating lactate concentration approximately every 10 seconds, approximately every 15 seconds, approximately every 20 seconds, approximately every 30 seconds, approximately every 45 seconds, approximately every minute, approximately every 1.5 minutes, approximately every 2 minutes, approximately every 3 minutes, approximately every 5 minutes, approximately every 10 minutes, approximately every 15 minutes, approximately every 20 minutes, approximately every 30 minutes, approximately every 45 minutes, approximately every hour, approximately every 2 hours, or approximately every 3 hours.

[0268] The method of any one of (68) (59-67), wherein the continuous measurement of the signal indicating lactate concentration comprises a signal indicating lactate concentration measured approximately every minute.

[0269] The method of any one of (69) (59-68), wherein the lactic acid responsive sensor is any one of (1-24).

[0270] (70) A sensor control device comprising a sensor of any one of (1-24) and a processor communicatively coupled to said sensor.

[0271] (71) (70) sensor control device, wherein the sensor is configured to continuously measure a signal indicating the concentration of lactic acid in the biological fluid of the individual and transmit the signal indicating the concentration of lactic acid to the processor.

[0272] (72) (71) sensor control device, wherein the processor is configured to determine an aerobic threshold, an anaerobic threshold, or both based on the signal indicating lactate concentration.

[0273] (73) (72) sensor control device, wherein the user is conducting a lactate threshold test.

[0274] (74) (73) sensor control device, wherein the lactate threshold test is a step test with gradually increasing power.

[0275] A sensor control device of any one of (75) (72-74), wherein the processor uses a broken stick model to determine the anoxic threshold.

[0276] A sensor control device of any one of (76) (72-74), wherein the processor uses the D-max method to determine the anaerobic threshold.

[0277] A sensor control device of any one of (77) (72-74), wherein the processor uses an improved D-max method to determine the anaerobic threshold.

[0278] A sensor control device of any one of (78) (72-77), wherein the aerobic threshold is defined as a fixed value.

[0279] (79) (79) sensor control device, wherein the aerobic threshold is defined as baseline lactate concentration + approximately 0.5 mM lactate.

[0280] (80) (79) sensor control device, wherein the aerobic threshold is defined as baseline lactate concentration + approximately 1 mM lactate.

[0281] A sensor control device of any one of (81) (72-78), wherein the processor uses a log-log model to determine the aerobic threshold.

[0282] A sensor control device of any one of (82) (72-78), wherein the processor uses piecewise regression analysis to determine the aerobic threshold.

[0283] (83) A sensor control device of any one of (70-82), wherein the sensor is configured to continuously measure a signal indicating lactic acid concentration approximately every 10 seconds, approximately every 15 seconds, approximately every 20 seconds, approximately every 30 seconds, approximately every 45 seconds, approximately every minute, approximately every 1.5 minutes, approximately every 2 minutes, approximately every 3 minutes, approximately every 5 minutes, approximately every 10 minutes, approximately every 15 minutes, approximately every 20 minutes, approximately every 30 minutes, approximately every 45 minutes, approximately every hour, approximately every 2 hours, or approximately every 3 hours.

[0284] A sensor control device of any one of (84) (70-83), wherein the sensor is configured to continuously measure a signal indicating lactic acid concentration approximately every minute.

[0285] (85) A sensing system comprising a sensor control device and a readout device of any one of (70-84).

[0286] (86) An analyte sensor comprising:

[0287] It is configured to be located in the proximal portion above the user's skin, and

[0288] A distal portion configured to percutaneously penetrate the user's skin, the distal portion comprising:

[0289] Base;

[0290] The first working electrode is located on the substrate;

[0291] The second working electrode is located on the substrate;

[0292] A lactic acid-responsive sensing region is disposed on the surface of the first working electrode; and

[0293] A glucose-responsive sensing area is disposed on the surface of the second working electrode;

[0294] A first lactic acid-permeable membrane covering the lactic acid-responsive sensing region; and

[0295] A glucose-permeable second membrane covering the glucose-responsive sensing region and the lactate-responsive sensing region.

[0296] (87) (86) analyte sensors, wherein the lactate-responsive sensing region contains lactate oxidase.

[0297] An analyte sensor of (88), (86), or (87), wherein the lactic acid responsive sensing region comprises a first polymer and a first electron transfer reagent.

[0298] (89) (88) analyte sensor, wherein the first electron transfer reagent is covalently bonded to the first polymer.

[0299] (90) (88) or (89) of an analyte sensor, wherein the first electron transfer reagent comprises an osmium complex.

[0300] An analyte sensor of any one of (91) (88-90), wherein the first polymer is a polymer based on poly(4-vinylpyridine).

[0301] An analyte sensor of any one of (92) (88-91), wherein the lactic acid responsive sensing region further comprises a first crosslinking agent.

[0302] (93) (92) Analyte sensor, wherein the first crosslinking agent is PEGDGE.

[0303] An analyte sensor of any one of (94) (86-93), wherein the glucose-responsive sensing region comprises glucose oxidase.

[0304] An analyte sensor of any one of (95) (86-94), wherein the glucose-responsive sensing region comprises a second polymer and a second electron transfer reagent.

[0305] (96) (95) analyte sensors, wherein the second electron transfer reagent is covalently bonded to the second polymer.

[0306] (97) (95) or (96) of the analyte sensor, wherein the second electron transfer reagent comprises an osmium complex.

[0307] An analyte sensor of any one of (98) (95-97), wherein the second polymer is a polymer based on poly(4-vinylpyridine).

[0308] An analyte sensor of any one of (99) (95-98), wherein the glucose-responsive sensing region further comprises a second crosslinking agent.

[0309] (100) (99) analyte sensor, wherein the second crosslinking agent is PEGDGE.

[0310] (101) (86-100) analyte sensors, wherein the sensor further comprises a reference electrode.

[0311] (102) (86-101) analyte sensor, wherein the sensor further comprises a counter electrode.

[0312] (103) (86-102) analyte sensors, wherein the first membrane and the second membrane have different compositions.

[0313] (104) (86-103) analyte sensors, wherein the first membrane comprises a polyvinylpyridine homopolymer or copolymer.

[0314] (105) (104) analyte sensors, wherein the first membrane further comprises a first crosslinking agent.

[0315] (106) (105) Analyte sensor, wherein the first crosslinking agent is PEGDGE.

[0316] (107) (86-106) analyte sensors, wherein the second membrane comprises a polyvinylpyridine-co-styrene polymer.

[0317] (108) (107) analyte sensors, wherein the second membrane further comprises a second crosslinking agent.

[0318] (109) (108) Analyte sensor, wherein the second crosslinking agent is glycerol triglycidyl ether.

[0319] (110) A method for monitoring lactate levels in a user, the method comprising:

[0320] The analyte sensor of the sensing system is exposed to a fluid. The analyte sensor includes a proximal portion configured to be located above the user's skin and a distal portion configured to percutaneously penetrate the user's skin. The distal portion includes:

[0321] Base;

[0322] The first working electrode is located on the substrate;

[0323] The second working electrode is located on the substrate;

[0324] A lactic acid-responsive sensing region is disposed on the surface of the first working electrode; and

[0325] A glucose-responsive sensing area is disposed on the surface of the second working electrode;

[0326] A first lactic acid-permeable membrane covering the lactic acid-responsive sensing region; and

[0327] A glucose-permeable second membrane covering the glucose-responsive sensing region and the lactate-responsive sensing region;

[0328] A potential is applied to the first working electrode of the analyte sensor;

[0329] A first signal is obtained at the redox potential or higher of the lactic acid responsive sensing region, the signal being proportional to the concentration of lactic acid in the fluid; and

[0330] The signal is correlated with the concentration of lactic acid in the fluid.

[0331] The method of (111) (110) further includes:

[0332] A second signal is obtained at the redox potential or higher in the glucose-responsive sensing region, the signal being proportional to the concentration of glucose in the fluid; and

[0333] The second signal is correlated with the concentration of glucose in the fluid.

[0334] The method of (112), (110), or (111), wherein the lactate-responsive sensing region comprises lactate oxidase.

[0335] The method of any one of (113) (110-112), wherein the lactic acid responsive sensing region comprises a first polymer and a first electron transfer reagent.

[0336] (114) (113) method, wherein the first electron transfer reagent is covalently bonded to the first polymer.

[0337] The method of (115), (113), or (114), wherein the first electron transfer reagent comprises an osmium complex.

[0338] The method of any one of (116) (113-115), wherein the first polymer is a polymer based on poly(4-vinylpyridine).

[0339] The method of any one of (117) (113-116), wherein the lactic acid responsive sensing region further comprises a first crosslinking agent.

[0340] The method of (118) (115), wherein the first crosslinking agent is PEGDGE.

[0341] The method of any one of (119) (110-118), wherein the glucose-responsive sensing region comprises glucose oxidase.

[0342] The method of any one of (120) (110-119), wherein the glucose-responsive sensing region comprises a second polymer and a second electron transfer reagent.

[0343] The method of (121) (120), wherein the second electron transfer reagent is covalently bonded to the second polymer.

[0344] The method of (122), (120), or (121), wherein the second electron transfer reagent comprises an osmium complex.

[0345] The method of any one of (123) (120-122), wherein the second polymer is a polymer based on poly(4-vinylpyridine).

[0346] The method of any one of (124) (120-123), wherein the glucose-responsive sensing region further comprises a second crosslinking agent.

[0347] The method of (125) (124), wherein the second crosslinking agent is PEGDGE.

[0348] The method of (126) (110-125), wherein the sensor further comprises a reference electrode.

[0349] The method of (127) (110-126), wherein the sensor further comprises a counter electrode.

[0350] (128) (110-127) method, wherein the first membrane and the second membrane have different compositions.

[0351] (129) (110-128) method, wherein the first membrane comprises a polyvinylpyridine isomer or copolymer.

[0352] The method of (130) (129), wherein the first membrane further comprises a first crosslinking agent.

[0353] The method of (131) (130), wherein the first crosslinking agent is polyethylene glycol diglycidyl ether (PEGDGE).

[0354] (132) (110-131) method, wherein the second membrane comprises a polyvinylpyridine-co-styrene polymer.

[0355] The method of (133) (132), wherein the second membrane further comprises a second crosslinking agent.

[0356] The method of (134) (133), wherein the second crosslinking agent is glyceryl triglycidyl ether.

[0357] (135) A method for determining an anaerobic threshold in an individual, the method comprising:

[0358] A sensing system incorporating a lactate-responsive sensor is used to continuously measure signals indicating the concentration of lactate in biological fluids within an individual.

[0359] The signal indicating lactate concentration, measured by the lactate-responsive sensor, is transmitted to the processor; and

[0360] The processor determines the anaerobic threshold based on the signal indicating lactate concentration.

[0361] The methods of (136) and (135) wherein the individual is undergoing a lactate threshold test.

[0362] The method of (137) (136), wherein the lactate threshold test is a step test with gradually increasing power.

[0363] The method of any one of (138) (135-137), wherein the processor uses a broken stick model to determine the anaerobic threshold.

[0364] The method of any one of (139) (135-137), wherein the processor uses the D-max method to determine the anaerobic threshold.

[0365] The method of any one of (140) (135-137), wherein the processor uses the improved D-max method to determine the anaerobic threshold.

[0366] The method of any one of (141) (135-140), wherein the continuous measurement of the signal indicating lactate concentration comprises measuring the signal indicating lactate concentration approximately every 10 seconds, approximately every 15 seconds, approximately every 20 seconds, approximately every 30 seconds, approximately every 45 seconds, approximately every minute, approximately every 1.5 minutes, approximately every 2 minutes, approximately every 3 minutes, approximately every 5 minutes, approximately every 10 minutes, approximately every 15 minutes, approximately every 20 minutes, approximately every 30 minutes, approximately every 45 minutes, approximately every hour, approximately every 2 hours, or approximately every 3 hours.

[0367] The method of any one of (142) (135-141), wherein the continuous measurement of the signal indicating lactate concentration comprises measuring the signal indicating lactate concentration approximately every minute.

[0368] The method of any one of (143) (135-142), wherein the lactic acid responsive sensor is a sensor of any one of (1-24).

[0369] The method of any one of (144) and (135-142), wherein the lactic acid responsive sensor is a sensor of any one of (86-109).

[0370] (145) A method for determining an aerobic threshold in an individual, the method comprising:

[0371] A sensing system incorporating a lactate-responsive sensor continuously measures a signal indicating the concentration of lactate in the biological fluid of the individual.

[0372] The signal indicating lactic acid concentration is transmitted to the processor;

[0373] The aerobic threshold is determined based on the signal indicating lactate concentration.

[0374] The methods of (146) and (145) wherein the individual is undergoing a lactate threshold test.

[0375] The method of (147) (146), wherein the lactate threshold test is a step test with gradually increasing power.

[0376] The method of any one of (148) (145-147), wherein the aerobic threshold is defined as a fixed value.

[0377] The method of (149) (148) wherein the aerobic threshold is defined as baseline lactate concentration + approximately 0.5 mM lactate.

[0378] The method of (150) (148) wherein the aerobic threshold is defined as baseline lactate concentration + approximately 1 mM lactate.

[0379] The method of any one of (151) (145-147), wherein the processor uses a log-log model to determine the aerobic threshold.

[0380] The method of any one of (152) (145-147), wherein the processor uses piecewise regression analysis to determine the aerobic threshold.

[0381] The method of any one of (153) (145-152), wherein the continuous measurement of the signal indicating lactate concentration comprises measuring the signal indicating lactate concentration approximately every 10 seconds, approximately every 15 seconds, approximately every 20 seconds, approximately every 30 seconds, approximately every 45 seconds, approximately every minute, approximately every 1.5 minutes, approximately every 2 minutes, approximately every 3 minutes, approximately every 5 minutes, approximately every 10 minutes, approximately every 15 minutes, approximately every 20 minutes, approximately every 30 minutes, approximately every 45 minutes, approximately every hour, approximately every 2 hours, or approximately every 3 hours.

[0382] The method of any one of (154) (145-153), wherein the continuous measurement of the signal indicating lactate concentration comprises a signal indicating lactate concentration measured approximately every minute.

[0383] The method of any one of (155) (145-154), wherein the lactic acid responsive sensor is a sensor of any one of (1-24).

[0384] The method of any one of (156) and (145-154), wherein the lactic acid responsive sensor is a sensor of any one of (86-109).

[0385] (157) A sensor control device comprising a sensor of any one of (81-104) and a processor communicatively coupled to said sensor.

[0386] (158) (157) sensor control device, wherein the sensor is configured to continuously measure a signal indicating the concentration of lactic acid in a user’s biofluid and transmit the signal indicating the concentration of lactic acid to the processor.

[0387] (159) (158) sensor control device, wherein the processor is configured to determine an aerobic threshold, an anaerobic threshold, or both based on the signal indicating lactate concentration.

[0388] (160) (159) sensor control device, wherein the user is conducting a lactate threshold test.

[0389] (161) (160) sensor control device, wherein the lactate threshold test is a step test with gradually increasing power.

[0390] A sensor control device of any one of (162) (159-161), wherein the processor uses a broken stick model to determine the anoxic threshold.

[0391] A sensor control device of any one of (163) (159-161), wherein the processor uses the D-max method to determine the anaerobic threshold.

[0392] A sensor control device of any one of (164) (159-161), wherein the processor uses an improved D-max method to determine the anaerobic threshold.

[0393] A sensor control device of any one of (165) (159-164), wherein the aerobic threshold is defined as a fixed value.

[0394] (166) (165) sensor control device, wherein the aerobic threshold is defined as baseline lactate concentration + approximately 0.5 mM lactate.

[0395] (167) (153) sensor control device, wherein the aerobic threshold is defined as baseline lactate concentration + approximately 1 mM lactate.

[0396] A sensor control device of any one of (168) (159-164), wherein the processor uses a log-log model to determine the aerobic threshold.

[0397] A sensor control device of any one of (169) (159-164), wherein the processor uses piecewise regression analysis to determine the aerobic threshold.

[0398] A sensor control device of any one of (170) (157-169), wherein the sensor is configured to continuously measure a signal indicating lactic acid concentration approximately every 10 seconds, approximately every 15 seconds, approximately every 20 seconds, approximately every 30 seconds, approximately every 45 seconds, approximately every minute, approximately every 1.5 minutes, approximately every 2 minutes, approximately every 3 minutes, approximately every 5 minutes, approximately every 10 minutes, approximately every 15 minutes, approximately every 20 minutes, approximately every 30 minutes, approximately every 45 minutes, approximately every hour, approximately every 2 hours, or approximately every 3 hours.

[0399] A sensor control device of any one of (171) (157-170), wherein the sensor is configured to continuously measure a signal indicating lactic acid concentration approximately every minute.

[0400] (172) A sensing system comprising a sensor control device of any one of (157-171).

[0401] (173) A sensor control device comprising:

[0402] A lactate-responsive sensor comprising a proximal portion configured to be located above a user's skin and a distal portion configured to percutaneously pass through the user's skin and contact the user's biofluid, wherein the lactate-responsive sensor is configured to continuously measure a signal indicating the concentration of lactate in the user's biofluid and transmit the signal indicating the lactate concentration to a processor.

[0403] The processor is configured to determine an aerobic threshold, an anaerobic threshold, or both, based on the signal indicating lactate concentration.

[0404] (174) (173) sensor control device, wherein the user is conducting a lactate threshold test.

[0405] (175) (174) sensor control device, wherein the lactate threshold test is a step test with gradually increasing power.

[0406] A sensor control device of any one of (176) (173-175), wherein the processor uses a broken stick model to determine the anoxic threshold.

[0407] A sensor control device of any one of (177) (173-175), wherein the processor uses the D-max method to determine the anaerobic threshold.

[0408] A sensor control device of any one of (178) (173-175), wherein the processor uses an improved D-max method to determine the anaerobic threshold.

[0409] A sensor control device of any one of (179) (173-168), wherein the aerobic threshold is defined as a fixed value.

[0410] (180) (179) sensor control device, wherein the aerobic threshold is defined as baseline lactate concentration + approximately 0.5 mM lactate.

[0411] (181) (179) sensor control device, wherein the aerobic threshold is defined as baseline lactate concentration + approximately 1 mM lactate.

[0412] A sensor control device of any one of (182) (173-178), wherein the processor uses a log-log model to determine the aerobic threshold.

[0413] A sensor control device of any one of (183) (173-178), wherein the processor uses piecewise regression analysis to determine the aerobic threshold.

[0414] A sensor control device of any one of (184) (173-183), wherein the sensor is configured to continuously measure a signal indicating lactic acid concentration approximately every 10 seconds, approximately every 15 seconds, approximately every 20 seconds, approximately every 30 seconds, approximately every 45 seconds, approximately every minute, approximately every 1.5 minutes, approximately every 2 minutes, approximately every 3 minutes, approximately every 5 minutes, approximately every 10 minutes, approximately every 15 minutes, approximately every 20 minutes, approximately every 30 minutes, approximately every 45 minutes, approximately every hour, approximately every 2 hours, or approximately every 3 hours.

[0415] A sensor control device of any one of (185) (173-184), wherein the sensor is configured to continuously measure a signal indicating lactic acid concentration approximately every minute.

[0416] The sensor control device of any one of (186) (173-185), wherein the remote portion comprises:

[0417] Base;

[0418] The first working electrode is located on the substrate;

[0419] The second working electrode is located on the substrate;

[0420] A lactic acid-responsive sensing region is disposed on the surface of the first working electrode; and

[0421] A glucose-responsive sensing area is disposed on the surface of the second working electrode;

[0422] A first lactic acid-permeable membrane covering the lactic acid-responsive sensing region; and

[0423] A glucose-permeable second membrane covering the glucose-responsive sensing region and the lactate-responsive sensing region.

[0424] (187) (186) sensor control device, wherein the lactate responsive sensing region contains lactate oxidase.

[0425] (188) (186) or (187) of a sensor control device, wherein the lactic acid responsive sensing region comprises a first polymer and a first electron transfer reagent.

[0426] (189) (188) sensor control device, wherein the first electron transfer reagent is covalently bonded to the first polymer.

[0427] (190) (188) or (189) of a sensor control device, wherein the first electron transfer reagent comprises an osmium complex.

[0428] A sensor control device of any one of (191) (188-190), wherein the first polymer is a polymer based on poly(4-vinylpyridine).

[0429] A sensor control device of any one of (192) (188-191), wherein the lactic acid responsive sensing region further comprises a first crosslinking agent.

[0430] (193) (192) sensor control device, wherein the first crosslinking agent is PEGDGE.

[0431] A sensor control device of any one of (194) (186-193), wherein the glucose-responsive sensing region comprises glucose oxidase.

[0432] A sensor control device of any one of (195) (186-194), wherein the glucose-responsive sensing region comprises a second polymer and a second electron transfer reagent.

[0433] (196) (195) sensor control device, wherein the second electron transfer reagent is covalently bonded to the second polymer.

[0434] (197) (195) or (196) of a sensor control device, wherein the second electron transfer reagent comprises an osmium complex.

[0435] A sensor control device of any one of (198) (195-197), wherein the second polymer is a polymer based on poly(4-vinylpyridine).

[0436] A sensor control device of any one of (199) (195-198), wherein the glucose-responsive sensing region further comprises a second crosslinking agent.

[0437] (200) (199) sensor control device, wherein the second crosslinking agent is PEGDGE.

[0438] (201) (186-200) sensor control device, wherein the sensor further includes a reference electrode.

[0439] (202) (186-201) sensor control device, wherein the sensor further includes a counter electrode.

[0440] (203) (186-202) sensor control device, wherein the first membrane and the second membrane have different compositions.

[0441] (204) (186-203) sensor control device, wherein the first membrane comprises a polyvinylpyridine homopolymer or copolymer.

[0442] (205) (204) sensor control device, wherein the first membrane further comprises a first crosslinking agent.

[0443] (206) (205) sensor control device, wherein the first crosslinking agent is PEGDGE.

[0444] (207) (186-206) sensor control device, wherein the second membrane comprises a polyvinylpyridine-co-styrene polymer.

[0445] (208) (207) sensor control device, wherein the second membrane further comprises a second crosslinking agent.

[0446] (209) (208) sensor control device, wherein the second crosslinking agent is glyceryl triglycidyl ether.

[0447] Example

[0448] The embodiments provided below are for illustrative purposes only, and the embodiments described herein should not in any way be construed as being limited to these embodiments. Rather, these embodiments should be construed as encompassing any and all variations that may be apparent from the teachings provided herein.

[0449] Example 1

[0450] A post-hoc analysis was performed on results from 103 individuals and 286 evaluable sensors in four previous clinical studies to determine the accuracy of using a subcutaneous lactate / glucose dual biosensor for simultaneous glucose monitoring to determine the anaerobic lactate threshold (LT2). The lactate / glucose sensor was designed as follows: Figure 6 As shown. To be eligible to participate in the clinical study, individuals must routinely engage in at least approximately 150 minutes of moderate-intensity physical activity or at least approximately 75 minutes of vigorous-intensity aerobic physical activity per week at the start of the study, and agree to engage in moderate-intensity and / or vigorous-intensity physical activity as required during clinic visits. Furthermore, individuals who regularly use cycling in their exercise program are preferred.

[0451] Individuals participated in one of two trials discussed below while riding a bicycle. The first trial was based on an incremental exercise program, which included the following phases:

[0452] - Baseline Phase Determine an individual's resting lactate levels before they begin the desired exercise program.

[0453] - Increasing Effort Phase Participants completed up to eight interval training sessions of progressively increasing intensity (from 30 watts to 240 watts, in 30-watt increments). Individuals entered the sustained effort phase after meeting either (i) a lactate level of 5.5 mM or higher, or (ii) completion of all eight interval training sessions. Individuals may stop at any time upon their own request or based on the researchers' judgment.

[0454] - Sustained effort phase: Subjects completed two interval training sessions at approximately 85% of their maximum sustained speed or 85% of their maximum effort when the sensor measured a lactate level of 5.5 mM.

[0455] - Cooling phase: During the cooling exercise, lactate monitoring continues as lactate levels decrease.

[0456] - Rest phase: Continue lactate monitoring until lactate levels return to baseline.

[0457] The incremental motion schemes are summarized in Table 1.

[0458] Table 1. Incremental Motion Scheme

[0459]

[0460] The second experiment was based on an endurance exercise program, which included the following phases:

[0461] - Baseline Phase Determine an individual's resting lactate levels before they begin the desired exercise program.

[0462] - Exercise Phase Subjects began exercise at 30 W and then continued at 5-minute intervals to the next power setting (60, 90, 120, 150, 180, 210, and 240 W) until lactate levels reached >2.6 mM. If lactate levels were ≥2.6 mM but <3.1 mM, the next power setting was increased by 10 W compared to the previous step. If lactate levels were ≥3.1 mM but <4.5 mM, the next power setting depended on the lactate level prior to that result. Specifically, if the previous lactate result was <3.1 mM (i.e., the lactate level was higher than the previous result), the next power setting was decreased by 10 W compared to the previous step. If the previous lactate result was between approximately 3.1 and 4.5 mM (i.e., the lactate level remained stable relative to the previous result) or >4.5 mM (i.e., the lactate level was lower than the previous result), the next power setting was the same as the previous step.

[0463] - Rest Phase Continue monitoring lactate levels until they return to baseline.

[0464] The endurance exercise program is summarized in Table 2.

[0465] Table 2. Endurance Exercise Program

[0466]

[0467] Figure 11 A graph showing the lactate levels of individuals detected by the sensor over 128 hours compared to a blood lactate test using venous blood samples. Figure 12 A graph showing glucose levels detected by the sensor over 77 hours for the same individual, compared to a blood glucose test, is displayed. The blood glucose test was performed using a YSI analyzer. The sensor was worn for 15 days, and the detected lactate and glucose levels were highly correlated with results measured using blood samples.

[0468] As in Figure 13 As shown, the anaerobic threshold measured by the sensor is highly correlated with the anaerobic threshold measured by the blood sample (R0). 2 (Approximately 0.8). Over 88% of the anaerobic thresholds measured by the sensor are within 20% of the anaerobic thresholds measured by the blood lactate test, with a low absolute error of approximately 10%. Figure 14 ).

[0469] Example 2

[0470] Formulations for lactic acid-responsive sensing region deposition:

[0471] Lactate oxidase was combined with an osmium-containing poly(4-vinylpyridine)-based polymer (Os-PVP) in the aqueous formulations shown in Tables 3 and 4 below.

[0472] Table 3. Formulation 1

[0473]

[0474] Table 4. Formulation 2

[0475]

[0476] It should be understood that the detailed description section, rather than the summary and abstract section, is intended to interpret the claims. The summary and abstract section may illustrate one or more (but not all) exemplary embodiments of the invention as conceived by the inventors, and is therefore not intended to limit the invention and the appended claims in any way.

[0477] The present disclosure has been described above using functional structural units to illustrate the implementation of specific functions and their relationships. For ease of description, the boundaries of these functional structural units have been arbitrarily defined. Alternative boundaries can be defined as long as the specific functions and their relationships are properly executed.

[0478] The above description of specific embodiments will fully reveal the general nature of the invention, enabling others to easily modify and / or adjust these specific embodiments for various applications without extensive experimentation by applying knowledge within the scope of the art, without departing from the general concept of the invention. Therefore, such adjustments and modifications are intended to fall within the meaning and scope of equivalents to the disclosed embodiments based on the teachings and guidance presented herein. It should be understood that phrases or terms in this document are for descriptive rather than limiting purposes, and the terminology or wording of this specification will be interpreted by those skilled in the art in light of the teachings and guidance.

[0479] The breadth and scope of this invention should not be limited by any of the above exemplary embodiments, but should be defined only by the following claims and their equivalents.

[0480] The claims in this application differ from those in the parent application or other related applications. Therefore, the applicant withdraws any abandonment of the scope of the claims made in the parent application or any prior application related to this application. Consequently, it is suggested that the examiner may need to reconsider any such prior abandonment and the relevant materials cited to avoid such abandonment. Furthermore, the examiner is reminded that any abandonment made in this application should not be construed as a supplement to or negation of the parent application.

[0481] As used herein, the phrase "in some embodiments" regarding a feature means that the feature may be present in any embodiment unless the feature is obviously technically incompatible with that embodiment. Furthermore, any subset of features from one embodiment may be combined with any subset of features from any other embodiment in any combination, unless such combination is obviously technically incompatible.

Claims

1. An analyte sensor comprising: Base; The first working electrode is located on the substrate; The second working electrode is located on the substrate; A lactic acid-responsive sensing area is disposed on the surface of the first working electrode; and A glucose-responsive sensing area is disposed on the surface of the second working electrode; A first lactic acid-permeable membrane covering the lactic acid-responsive sensing area; and A glucose-permeable second membrane covering the glucose-responsive sensing region and the lactate-responsive sensing region; The sensor is configured to be partially inserted into the individual's skin.

2. The analyte sensor of claim 1, wherein the lactate-responsive sensing region comprises lactate oxidase.

3. The analyte sensor of claim 1 or claim 2, wherein the lactic acid responsive sensing region comprises a first polymer and a first electron transfer reagent.

4. The analyte sensor of claim 3, wherein the first electron transfer reagent is covalently bonded to the first polymer.

5. The analyte sensor of any one of claims 1-4, wherein the glucose-responsive sensing region comprises glucose oxidase.

6. The analyte sensor of any one of claims 1-5, wherein the glucose-responsive sensing region comprises a second polymer and a second electron transfer reagent.

7. The analyte sensor of claim 6, wherein the second electron transfer reagent is covalently bonded to the second polymer.

8. The analyte sensor of any one of claims 1-7, wherein the sensor tail further comprises a reference electrode and a counter electrode.

9. The analyte sensor of any one of claims 1-8, wherein the first membrane and the second membrane have different compositions.

10. A method for monitoring lactate levels in an individual, the method comprising: The analyte sensor of the sensing system is exposed to a fluid; wherein the analyte sensor comprises: Base; The first working electrode is located on the substrate; The second working electrode is located on the substrate; A lactic acid-responsive sensing area is disposed on the surface of the first working electrode; and A glucose-responsive sensing area is disposed on the surface of the second working electrode; A first lactic acid-permeable membrane covering the lactic acid-responsive sensing area; and A glucose-permeable second membrane covering the glucose-responsive sensing region and the lactate-responsive sensing region. The sensor is configured to be partially inserted into the individual's skin; A potential is applied to the first working electrode of the analyte sensor; A first signal is obtained at the redox potential or higher of the lactic acid responsive sensing region, the signal being proportional to the concentration of lactic acid in the fluid; and The signal is correlated with the concentration of lactic acid in the fluid.

11. The method of claim 10, further comprising: A second signal is obtained at the redox potential or higher in the glucose-responsive sensing region, the signal being proportional to the concentration of glucose in the fluid; and The second signal is correlated with the concentration of glucose in the fluid.

12. The method of claim 10 or claim 11, wherein the lactate-responsive sensing region comprises lactate oxidase.

13. The method of any one of claims 10-12, wherein the lactic acid responsive sensing region comprises a first polymer and a first electron transfer reagent.

14. The method of claim 13, wherein the first electron transfer reagent is covalently bonded to the first polymer.

15. The method of any one of claims 10 to 14, wherein the glucose-responsive sensing region comprises glucose oxidase.

16. The method of any one of claims 10-15, wherein the glucose-responsive sensing region comprises a second polymer and a second electron transfer reagent.

17. The method of claim 16, wherein the second electron transfer agent is covalently bonded to the second polymer.

18. The method of any one of claims 10-17, wherein the sensor tail further comprises a reference electrode and a counter electrode.

19. The method of any one of claims 10-18, wherein the sensor tail is configured to be inserted into tissue.

20. The method of any one of claims 10-19, wherein the first membrane and the second membrane have different compositions.

21. A method for determining an anaerobic threshold in an individual, the method comprising: A sensing system incorporating a lactate-responsive sensor is used to continuously measure signals indicating the concentration of lactate in the biofluid within the individual; The signal indicating lactate concentration, measured by the lactate-responsive sensor, is transmitted to the processor; The anaerobic threshold is determined based on the signal indicating lactate concentration.

22. The method of claim 21, wherein the individual is undergoing a lactate threshold test.

23. The method of claim 22, wherein the lactate threshold test is a step test with progressively increasing power.

24. The method of any one of claims 21-23, wherein the processor uses a broken stick model to determine the anaerobic threshold.

25. The method of any one of claims 21-23, wherein the processor uses the D-max method to determine the anaerobic threshold.

26. The method of any one of claims 21-23, wherein the processor uses an improved D-max method to determine the anaerobic threshold.

27. The method of any one of claims 21-26, wherein the lactate responsive sensor is the sensor of any one of claims 1-9.

28. A method for determining an aerobic threshold in an individual, the method comprising: A sensing system incorporating a lactate-responsive sensor continuously measures a signal indicating the concentration of lactate in the biological fluid within the individual; The signal indicating lactate concentration, measured by the lactate-responsive sensor, is transmitted to the processor; The aerobic threshold is determined based on the signal indicating lactate concentration.

29. The method of claim 28, wherein the individual is undergoing a lactate threshold test.

30. The method of claim 29, wherein the lactate threshold test is a step test with progressively increasing power.

31. The method of any one of claims 28-30, wherein the aerobic threshold is defined as a fixed value.

32. The method of claim 31, wherein the aerobic threshold is defined as baseline lactate concentration + about 0.5 mM lactate.

33. The method of claim 31, wherein the aerobic threshold is defined as baseline lactate concentration + about 1 mM lactate.

34. The method of any one of claims 28-30, wherein the processor uses a log-log model to determine the aerobic threshold.

35. The method of any one of claims 28-30, wherein the processor uses piecewise regression analysis to determine the aerobic threshold.

36. The method of any one of claims 28-35, wherein the lactate-responsive sensor is the sensor of any one of claims 1-9.

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