Sensors for detecting glucose and lactate, and methods for determining aerobic and anaerobic work thresholds.

Abstract

This disclosure describes a lactate-responsive sensor, a sensing system incorporating the lactate-responsive sensor, and a method of using the same, which are useful for continuously monitoring lactate levels and determining lactate thresholds (both aerobic and anaerobic thresholds). This disclosure also relates to an analyte sensor for continuously detecting glucose and lactate levels.

Description

Technical Field

[0001] The present invention relates to a sensor for detecting glucose and lactic acid, and a method for determining an aerobic work threshold and an anaerobic work threshold.

Background Art

[0002] Data-driven training protocols are becoming increasingly important for both world-class athletes and other individuals interested in improving fitness and athletic performance. Lactic acid concentration in blood or other body fluids is often used to determine an athlete's fitness level, guide sports training, and measure the impact of training in preparation for competition. In particular, the anaerobic lactate work threshold, which characterizes an individual's aerobic-anaerobic transition zone, is the most widely used metric for guiding efficient and effective training, especially in endurance sports.

[0003] Although external sensors are available for determining lactic acid levels, the results provided by these sensors are often inaccurate. Invasive blood collection may be required to obtain more reliable lactic acid levels, but this approach can be inconvenient or painful to perform on an individual during a workout routine or training protocol. Furthermore, even a rapid blood collection (e.g., from an earlobe) may require at least a short stoppage in an individual's workout routine, which can lead to suboptimal workout efficiency.

[0004] Furthermore, glucose monitoring is another important component in sports training that provides athletes with real-time information such as energy status, fatigue, and timing of refueling for optimal training.

[0005] Therefore, there is a need for a sensor that provides continuous lactate monitoring, as well as glucose monitoring, without the inaccuracies associated with current sensors or invasive blood sampling associated with more accurate technologies, enabling rapid, accurate, and continuous monitoring of an individual's metabolic profile during sports training and exercise by tracking glucose and lactate levels in real time. [Overview of the project]

[0006] This disclosure describes lactate-responsive sensors, sensing systems incorporating lactate-responsive sensors, and methods of using them, which are useful for monitoring lactate levels and determining lactate thresholds (both aerobic and anaerobic thresholds). These sensors and sensing systems provide a quick and convenient way to obtain reliable lactate levels, including lactate thresholds, and provide individuals with useful information regarding running pace, heart rate, and / or power corresponding to aerobic or anaerobic thresholds.

[0007] In some embodiments, the disclosure relates to a sensor that detects both glucose and lactate levels. This sensor can provide continuous, real-time feedback on both glucose and lactate levels during training and competition, which may help maximize performance.

[0008] This disclosure is, Substrate and A first working electrode located on the substrate, A second working electrode located on the substrate, A lactate-responsive sensing area is positioned on the surface of the first working electrode, A glucose-responsive sensing area is positioned on the surface of the second working electrode, A first membrane that is permeable to lactic acid and covers the lactic acid-responsive sensing area, The device comprises a second membrane that is permeable to glucose and covers the glucose-responsive sensing area and the lactate-responsive sensing area, This relates to an analyte sensor configured to be partially inserted into an individual's skin.

[0009] In some embodiments, the lactate-responsive sensing area may include lactate oxidase. In some embodiments, the lactic acid-responsive sensing area may include a first polymer and a first electron transfer agent.

[0010] In some embodiments, the first electron transfer agent may be covalently bonded to the first polymer. In some embodiments, the glucose-responsive sensing area may include glucose oxidase.

[0011] In some embodiments, the glucose-responsive sensing area may include a second polymer and a second electron transfer agent. In some embodiments, the second electron transfer agent may be covalently bonded to the second polymer.

[0012] In some embodiments, the sensor may further include a reference electrode and a counter electrode. In some embodiments, the first and second films may have different compositions. The disclosure also discloses a method for monitoring lactate levels in an individual, comprising: exposing an analyte sensor of a sensing system to a fluid, the analyte sensor comprising: a substrate; a first working electrode located on the substrate; a second working electrode located on the substrate; a lactate-responsive sensing area disposed on the surface of the first working electrode; a glucose-responsive sensing area disposed on the surface of the second working electrode; a first membrane permeable to lactate covering the lactate-responsive sensing area; and a second membrane permeable to glucose covering the glucose-responsive sensing area and the lactate-responsive sensing area, 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; acquiring a first signal above the redox potential of the lactate-responsive sensing area, the signal being proportional to the lactate concentration in the fluid; and correlating the signal with the lactate concentration in the fluid.

[0013] In some embodiments, the method may further include acquiring a second signal that is greater than or equal to the redox potential of a glucose-responsive sensing area, wherein the signal is proportional to the glucose concentration in the fluid, and correlating the second signal with the glucose concentration in the fluid.

[0014] In some embodiments, the lactate-responsive sensing area may include lactate oxidase. In some embodiments, the lactic acid-responsive sensing area may include a first polymer and a first electron transfer agent.

[0015] In some embodiments, the first electron transfer agent may be covalently bonded to the first polymer. In some embodiments, the glucose-responsive sensing area may include glucose oxidase.

[0016] In some embodiments, the glucose-responsive sensing area may include a second polymer and a second electron transfer agent. In some embodiments, the second electron transfer agent may be covalently bonded to the second polymer.

[0017] In some embodiments, the sensor may further include a reference electrode and a counter electrode. In some embodiments, the first and second films may have different compositions. This disclosure also discloses a method for determining an anaerobic threshold in an individual, comprising: continuously measuring a signal indicating the concentration of lactate in the individual's bodily fluids using a sensing system equipped with a lactate-responsive sensor; communicating 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 as disclosed herein.

[0018] In some embodiments, the individual may undergo a lactate threshold test. In some embodiments, the lactate threshold test may be a step test involving a gradual increase in power.

[0019] In some embodiments, the anaerobic working threshold may be determined by the processor using a broken bar model. In some embodiments, the anaerobic working threshold may be determined by the processor using the D-max method.

[0020] In some embodiments, the anaerobic working threshold may be determined by the processor using a modified D-max method. This disclosure also discloses a method for determining an aerobic work threshold in an individual, comprising: continuously measuring a signal indicating the concentration of lactate in the individual's bodily fluids using a sensing system equipped with a lactate-responsive sensor; communicating the signal indicating the lactate concentration measured by the lactate-responsive sensor to a processor; and determining an anaerobic work threshold based on the signal indicating the lactate concentration. In some embodiments, the sensor may be any sensor as disclosed herein.

[0021] In some embodiments, the individual may undergo a lactate work threshold test. In some embodiments, the lactate work threshold test may be a step test involving a stepwise increase in power.

[0022] In some embodiments, the aerobic work threshold may be defined as a fixed value. In some embodiments, the aerobic work threshold may be defined as baseline lactate concentration plus about 0.5 mM lactate.

[0023] In some embodiments, the aerobic work threshold may be defined as baseline lactate concentration plus about 1 mM lactate. In some embodiments, the aerobic work threshold may be determined by a processor using a log-log model.

[0024] In some embodiments, the aerobic work threshold may be determined by a processor using segmented regression analysis. Further embodiments and advantages of the present disclosure are set forth in part in the following description, and may be derived from the description, or may be learned by practicing the present disclosure.

[0025] It should be understood that both the foregoing summary of the invention and the following detailed description are merely exemplary and illustrative, and are not intended to limit the scope of the claims. Brief Description of the Drawings

[0026] [Figure 1] An exemplary plot of lactate levels as a function of physical activity of various intensities is shown. [Figure 2A] , shows a diagram of an exemplary sensing system that can incorporate the lactate-responsive sensor of the present disclosure. [Figure 2B] A block diagram of processing electronics that can be associated with one or more components of the sensing system is shown. [Figure 3A] A cross-sectional view of an exemplary two-electrode analyte sensor configuration having a single working electrode is shown. [Figure 3B] A diagram illustrating an exemplary three-electrode analyte sensor configuration is shown. [Figure 3C] A diagram illustrating an exemplary three-electrode analyte sensor configuration is shown. [Figure 3D] A cross-sectional view of an exemplary two-electrode analyte sensor configuration having a single working electrode is shown. [Figure 3E] A diagram illustrating an exemplary three-electrode analyte sensor configuration is shown. [Figure 3F] A diagram illustrating an exemplary three-electrode analyte sensor configuration is shown. [Figure 4] A cross-sectional view of an analyte sensor having glucose-responsive sensing areas and lactate-responsive sensing areas on separate working electrodes is shown. [Figure 5A] A cross-sectional view of an exemplary analyte sensor configuration having two working electrodes, a counter electrode, and a reference electrode is shown. [Figure 5B] A cross-sectional view of an exemplary analyte sensor configuration having two working electrodes, a counter electrode, and a reference electrode is shown. [Figure 6] This disclosure describes several embodiments of analyte sensors for detecting glucose and lactate. [Figure 7] A diagram of an enzyme system that can be used to detect glucose is shown herein. [Figure 8] A diagram of an enzyme system that can be used to detect lactic acid is shown herein. [Figure 9] This shows the lactate concentration as a power plot for determining the anaerobic threshold using the D-max model. [Figure 10A] This shows the lactate concentration as a power plot for determining the anaerobic threshold using a broken bar model. [Figure 10B] This shows the linear regression model error using a power plot to determine the anaerobic work threshold using a broken bar model. [Figure 11]The graph shows the lactate levels detected by the sensor over 128 hours, compared to a blood lactate test using a finger-prick or earlobe-prick blood sample. [Figure 12] The graph shows glucose levels detected by sensors over 77 hours, compared to a blood glucose test using a finger-prick blood sample. [Figure 13] This plot shows threshold detection using a blood lactate test versus threshold detection using a glucose / lactate dual sensor. [Figure 14] The table shows the results of comparing the determination of the anaerobic work threshold using sensors and blood tests. [Modes for carrying out the invention]

[0027] The headings provided herein are not intended to limit the various embodiments of this disclosure, but may be defined by referring to this disclosure as a whole. Since the scope of this disclosure is limited only by the appended claims, it should also be understood that the terms used herein are intended solely to describe and not to limit specific embodiments.

[0028] definition For convenience, the meanings of some terms and phrases used in this specification, the examples, and the appended claims are provided below. Unless otherwise stated or implied by the context, the following terms and phrases have the meanings provided below. Since the scope of this art is limited only by the claims, the definitions are provided to help describe specific embodiments and are not intended to limit the claimed art. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this art belongs. In the event of any apparent inconsistency between the use of a term in the art and its definition provided herein, the definition provided herein shall prevail.

[0029] The articles “a,” “an,” and “the” are used herein to refer to one or more (i.e., at least one) grammatical objects of the article. For example, “an element” means one or more elements.

[0030] As used herein, the term “approximately” means within an acceptable margin of error for a particular value as determined by those skilled in the art, which depends in part on how the value is measured or determined, i.e., on the limits of the measuring system. For example, “approximately” may mean a standard deviation of 3 or less or greater than 3, according to convention in the art. Alternatively, “approximately” may mean a range of up to 20% (e.g., up to 10%, up to 5%, or up to 1%) of a given value.

[0031] The term "at least" preceding a number or a set of numbers is understood, as is clear from the context, to include the number related to the term "at least," and all subsequent numbers or integers that may logically be included. When "at least" precedes a set of numbers or a range, it is understood that "at least" can modify each of the numbers in that set or range. For example, "at least 3" means at least 3, at least 4, at least 5, etc. When "at least" precedes a component in a method step, that component is included in the step, but any additional components are optional.

[0032] As used herein, terms such as “comprises,” “comprising,” “having,” “including,” and “containing” are open-ended terms meaning “including, but not limited to.” To the extent that a given embodiment disclosed herein “includes” certain elements, it should be understood that this disclosure also specifically intends to and disclose embodiments that “essentially consist of” those elements and embodiments that “consist of” those elements.

[0033] As used herein, terms such as "consists essentially of" and "consisting essentially of" should be interpreted as semi-closed terms meaning that no other components that substantially affect the basic and novel features of the embodiment are included.

[0034] As used herein, terms such as "consists of" and "consisting of" should be interpreted as closed terms; therefore, an embodiment "consisting of" a particular set of elements excludes any elements, steps, or components not specified in that embodiment.

[0035] As used herein, the term “measure” and its variations may encompass the meanings of other terms such as “determine,” “calculate,” and their variations.

[0036] As used herein, “analyte” refers to the enzyme substrate that is being measured or detected. The analyte may be derived from, for example, a biological fluid and may be tested in vivo, ex vivo, or in vitro.

[0037] As used herein, “sensor” is a device configured to detect the presence of an analyte in a sample and / or measure its level via electrochemical oxidation and reduction reactions on the sensor. These reactions are converted into electrical signals that can be correlated to the amount, concentration, or level of the analyte in the sample.

[0038] As used herein, “working electrode” is an electrode on which the analyte (or a second compound whose level depends on the level of the analyte) is electrooxidized or electroreduced, with or without the action of an electron transfer agent.

[0039] As used herein, “counter electrode” refers to an electrode paired with the working electrode, through which a current equal in magnitude and opposite in sign to the current passing through the working electrode passes. In the context of embodiments of this disclosure, unless otherwise indicated or unless a reference electrode is also present, the term “counter electrode” is intended to include both a) a counter electrode and b) a counter electrode that also functions as a reference electrode (i.e., a pair / reference electrode), and if a reference electrode is also present, the term “counter electrode” is intended to refer simply to the counter electrode.

[0040] As used herein, the term “reference electrode” refers to an electrode whose potential is known and which can be used as a reference against which the working electrode potential is evaluated or measured. In the context of embodiments of this disclosure, unless otherwise indicated or unless a counter electrode is also present, the term “reference electrode” is intended to include both a) a reference electrode and b) a reference electrode that also functions as a counter electrode (i.e., a pair / reference electrode), and if a counter electrode is also present, the term “reference electrode” is intended to refer simply to the reference electrode.

[0041] As used herein, a component is “immobilized” or “bonded” to a polymer and / or sensor, for example, if the component is captured on or within a component of a polymer, sol-gel matrix, membrane, and / or sensor, or covalently bonded to, ionically bonded to, electrostatically bonded to, or coordinately bonded to, a component of the polymer and / or sensor, thereby reducing or preventing its movement.

[0042] As used herein, “electron transfer agent” is a compound that carries electrons between the analyte and the working electrode, either directly or in cooperation with other electron transfer agents. An example of an electron transfer agent is a redox mediator.

[0043] As used herein, “redox mediator” is an electron transfer agent for transporting electrons between an analyte, an enzyme that reduces the analyte or an enzyme that oxidizes the analyte, and an electrode, either directly or via one or more further electron transfer agents. Redox mediators containing a polymer backbone may also be called “redox polymers.”

[0044] As used herein, “sensing area” is a component of a sensor containing components that facilitate the electrolysis of an analyte. The sensing area may contain components such as an oxidation-reduction mediator (e.g., an electron transfer agent or an oxidation-reduction polymer), a catalyst that catalyzes the reaction of the analyte to produce a reaction at the working electrode (e.g., an analyte-specific enzyme), or both an electron transfer agent and a catalyst. In some embodiments of the present disclosure, the sensor includes a sensing area that is positioned in close proximity to or on the working electrode in a non-leaching manner. In some embodiments of the present disclosure, the sensing area may be positioned continuously or discontinuously on the working electrode. The sensing area is considered to be “continuously positioned” on the working electrode if the sensing area is applied in a manner that is not interrupted across the surface of the working electrode, i.e., in a single spot or line, etc. The sensing area is considered to be “discontinuously positioned” on the working electrode if the sensing area is applied on the working electrode as at least two distinct shapes, such as two spots, two lines, one spot and one line, or multiple (e.g., an array) spots, lines, or a combination thereof. The number of discontinuous applications of sensing areas as a series of spots and / or lines is not considered particularly limiting, but may range from 2 to about 10 (e.g., including 2, 3, 4, 5, 6, 7, 8, 9, or 10, about 3 to about 8, or about 4 to about 6). In some embodiments, the sensing areas are arranged continuously on the working electrode. In some embodiments, the sensing areas are arranged discontinuously on the working electrode.

[0045] As used herein, “sensing element” is an application or region of an analyte-specific enzyme placed in a sensing area. Thus, the sensing element can interact with the analyte. The sensing area may have two or more sensing elements constituting an analyte detection area placed on the working electrode. In some embodiments, the sensing element comprises an analyte-specific enzyme and an electron transfer agent (e.g., an electron transfer agent). In some embodiments, the sensing element comprises an analyte-specific enzyme, a redox mediator, and a crosslinking agent.

[0046] As used herein, "crosslinking agent" or "crosslinker" 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 at least two parts of the same molecule together (intramolecular crosslinking). Crosslinking agents having more than two reactive groups can perform both intermolecular and intramolecular crosslinking simultaneously.

[0047] The term "patient" refers to a living animal and therefore includes, for example, living mammals and living humans. The term "user" may be used herein as a term that encompasses the term "patient."

[0048] Sensors and detection systems Lactate is produced in vivo during exercise or other activities, particularly during strenuous physical activity or exercise, via the glycolysis of glucose. Glycolysis provides energy to help an individual maintain their current activity level. Lactate levels in an individual are typically characterized as existing within three distinct zones, as shown in Figure 1. At lower activity levels (intensity), lactate remains low, and the rates of lactate production and lactate clearance remain fairly balanced, with lactate levels remaining relatively constant at or near a fixed baseline concentration, possibly with only a slight increase in concentration, up to a point called the aerobic threshold (LT1) during moderate / strenuous exercise. After LT1, lactate levels can generally increase linearly during high-intensity exercise up to a point called the anaerobic threshold (LT2). After LT2, lactate levels generally show an accelerating increase.

[0049] This disclosure describes lactate-responsive sensors and sensing systems incorporating lactate-responsive sensors that are useful for monitoring lactate levels and determining lactate thresholds, i.e., 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 both glucose and lactate. In some embodiments, sensors that detect both glucose and lactate levels, and systems having them, can provide continuous real-time feedback on both glucose and lactate levels during training and competition, which can help maximize performance.

[0050] In some embodiments, the sensor is configured to detect lactic acid levels. In some embodiments, the sensor is configured to measure lactic acid levels approximately every second, every three seconds, every five seconds, every ten seconds, every fifteen seconds, every twenty seconds, every thirty seconds, every forty-five seconds, every minute, every 1.5 minutes, every two minutes, every three minutes, every five minutes, every ten minutes, every fifteen minutes, every twenty minutes, every thirty minutes, every forty-five minutes, every hour, every hour, every two hours, or every three hours.

[0051] In some embodiments, the sensor is configured to communicate a signal indicating the lactic acid level to a processor. In some embodiments, the sensor may be a sensor as described in this disclosure. In some embodiments, the sensor may be a sensor as disclosed in U.S. Patent No. 10,392,647, U.S. Patent Application Publication No. 2019 / 0320947, and / or U.S. Patent Application Publication No. 2022 / 0125354, each disclosure of which is incorporated herein by reference in whole.

[0052] In some embodiments, the system may include various sensing components, such as a processor and / or coding instructions (algorithms) therein, which are adapted to process sensor data received from a lactate sensor and determine multiple lactate concentrations therefrom. The processor and / or coding instructions may then analyze the lactate concentrations to determine an individual's aerobic and anaerobic work thresholds.

[0053] In some embodiments, the system may comprise a lactate-responsive sensor configured to detect lactate in vivo, and a processor located within a cloud server, remote terminal, or local terminal, which is communicatively coupled to the lactate-responsive sensor. Cloud or server-based communication also falls within the scope of the systems disclosed herein. As used herein, the term “local terminal” refers to a user interface that is physically adjacent to the system in which the lactate-responsive sensor is located. For example, in some embodiments, the processor may be adjacent to the housing of the lactate-responsive sensor. As used herein, the term “remote terminal” refers to a user interface that is not located in the same physical space as the lactate-responsive sensor. In some embodiments, the remote terminal and its processor may be communicatively coupled to the lactate-responsive sensor or the network. In some embodiments, the individual interacting with the system may not be able to see the output of the lactate-responsive sensor. In other embodiments, the individual can view the sensor output (e.g., lactate concentration) in real time or near real time on a remote or local visible display, etc. The remote terminal may include, for example, a dedicated reader device, a dedicated fitness monitoring device (e.g., Fitbit), a smartphone, or a smartwatch.

[0054] In some embodiments, the processor may be configured to receive signals from a lactate-responsive sensor. Upon receiving signals from the sensor, the processor may be further configured to determine a plurality of lactate concentrations and to determine a lactate work threshold (both aerobic and anaerobic work thresholds) based on the plurality of lactate concentrations. The processor may further signal the individual wearing the sensor or another party when a predetermined lactate level is reached, such as an aerobic and anaerobic work threshold, a specified lactate concentration, a multiple of a plurality of baseline lactate concentrations, or a percentage of a peak lactate concentration. The output of the processor may be numerical and / or graphic. Notification to the wearer of the lactate-responsive sensor or other party may be auditory, tactile (tactile), or any combination thereof.

[0055] In some embodiments, the activity-sensing region of a lactate-responsive sensor may be located at any suitable in vivo location. Suitable locations include, but are not limited to, intravenous, subcutaneous, or cutaneous locations. Intravenous sensors may have the advantage of directly analyzing lactate in the blood, but they are invasive and may be painful for an individual to wear for extended periods. Subcutaneous and cutaneous analyte sensors may be less painful for an individual to wear due to their shallower penetration, and can often provide sufficient measurement accuracy. In some embodiments, a lactate-responsive sensor suitable for use in this disclosure may be a cutaneous sensor configured to examine an individual's skin fluid. In some embodiments, a lactate-responsive sensor suitable for use in this disclosure may be configured to examine an individual's interstitial fluid. As used herein, the term “interrogate” refers to the act of measuring parameters of a sample.

[0056] In some embodiments, the sensor may extend from a housing configured for external attachment to the skin of an individual performing a given physical activity. The external location where the lactate-responsive sensor is placed is not considered particularly limiting and may 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 can be used to monitor a single exercise event, such as performing a comparison between lactate concentrations measured at two different external locations. One sensor may be located at a site of active muscle use (e.g., on the thigh during cycling), and the other sensor may be located at a site with minimal active muscle use during the exercise event (e.g., on the arm during cycling), thereby enabling determination of the rate of lactate diffusion from the bloodstream into other interstitial tissues. If necessary, the outputs from one or both sensor locations may also be cross-referenced with blood lactate levels obtained from finger or earlobe punctures.

[0057] Figure 2A shows a diagram of an exemplary system in which the lactate-responsive sensor of this disclosure may be incorporated. As shown, the system 100 includes a sensor control device 102 and a reader device 120, configured to communicate with each other via a local communication path or link 140, which may be wired or wireless, unidirectional or bidirectional, and encrypted or unencrypted. The reader device 120 may, according to some embodiments, constitute an output medium for viewing the lactate concentration and warnings or notifications determined by the sensor 104 or its associated processor, and for enabling one or more user inputs. Alternatively, the reader device 120 may generate an output invisible to the user. The reader device 120 may be a multipurpose smartphone or a dedicated electronic reader. Although only one reader device 120 is shown, multiple reader devices 120 may be present in certain examples. According to some embodiments, a suitable processor may be incorporated into the reader device 120. The reader device 120 may also communicate with the remote terminal 170 and / or the trusted computer system 180 via communication paths / links 141 and / or 142, respectively, which may also be wired or wireless, one-way or two-way, and encrypted or unencrypted. The reader device 120 may also, or alternatively, communicate with the network 150 (e.g., a cellular network, the internet, or a cloud server) via communication path / link 151. The network 150 may further be communicably coupled to the remote terminal 170 via communication path / link 152 and / or the trusted computer system 180 via communication path / link 153. Alternatively, the sensor 104 may communicate directly with the remote terminal 170 and / or the trusted computer system 180 without the presence of the intervening reader device 120. For example, according to some embodiments, the sensor 104 may communicate with a remote terminal 170 and / or a trusted computer system 180 via a direct communication link to a network 150, as described in U.S. Patent Application Publication No. 2011 / 0213225 (which is incorporated herein by reference in its entirety).Each communication path or link 141, 142, 151, 152 and / or 153 may use any suitable electronic communication protocol, such as Near Field Communication (NFC), Radio Frequency Identification (RFID), Bluetooth® or Bluetooth® Low Energy protocol, Wi-Fi, or a cellular network. The remote terminal 170 and / or trusted computer system 180 may, according to some embodiments, be accessible to parties other than the primary user who are interested in the primary user's lactate concentration or lactate clearance rate, such as a personal trainer or coach. The reader device 120 may comprise a display 122 and an optional input component 121. The display 122 may, according to some embodiments, comprise a touchscreen interface.

[0058] In some embodiments, the sensor control device 102 may include a sensor 104 that, while positioned in vivo, comes into contact with the user's bodily fluids and senses the level of an analyte contained therein. The sensor may be part of the sensor control device, which includes electronics and a power supply that reside on the user's body and enable and control the analyte sensing. The sensor control device 102 and its variations may also be referred to as a “sensor control unit,” an “on-body electronics” device or unit, an “on-body” device or unit, or a “sensor data communication” device or unit. In some embodiments, the sensor control device 102 includes a sensor housing 103 that can house the circuitry and power supply for operating the sensor 104. Optionally, the power supply and / or active circuitry may be omitted. A processor (not shown in Figure 2A) may be communicatively coupled to the sensor 104, and the processor may be physically located within the sensor housing 103 or the reader device 120. In some embodiments, the sensor 104 protrudes from the underside of the sensor housing 103 and extends through an adhesive layer 105 that, according to some embodiments, is adapted to adhere the sensor housing 103 to a tissue surface such as skin.

[0059] Figure 2B shows a block diagram of processing electronics that may be associated with one or more components of a sensing system, such as within a reader device 120. Alternatively, such functions may be associated with one or more of the network 150, a remote terminal 170, or a trusted computer system 180. As shown, the processing electronics 190 directly or indirectly receives signals emitted from the sensor control device 102. The signals may be processed using algorithms associated with the processor 191 and / or memory 192. The lactic acid concentration determined therein may be stored in memory 192 and / or exported to an output device 193, which may be a display or an external storage medium in various embodiments. Guidance, advice, etc., may also be determined using the processor 191 and exported to the output device 193, as further described herein.

[0060] The sensor 104 is adapted to be at least partially inserted into tissue of interest, such as within the dermis or subcutaneous tissue of the skin. The sensor 104 may comprise a sensor of sufficient length to be inserted to a desired depth in a given tissue. In some embodiments, the sensor may comprise a proximal portion configured to be positioned above the user's skin and a distal portion configured to be positioned percutaneously through the user's skin and to be in contact with body fluids. In some embodiments, the distal portion is configured to detect analytes in body fluids. In some embodiments, the proximal portion may be electrically coupled to processing electronics. In some embodiments, the processing electronics are located within the electronics housing of the sensor control device. According to one or more embodiments, the sensor may include a sensing region or sensing area that is active for sensing lactate, and may include a lactate-responsive enzyme. According to some embodiments, the sensing region or sensing area may include a polymer material to which the lactate-responsive enzyme is covalently bonded. In some embodiments of the present disclosure, lactate can be monitored in any biological fluid of interest, such as skin fluid, plasma, blood, lymph, synovial fluid, cerebrospinal fluid, saliva, bronchoalveolar lavage, and amniotic fluid. In some embodiments, the lactate-responsive sensor of the present disclosure may be adapted to examine skin fluid or interstitial fluid.

[0061] An introducer may be present temporarily to facilitate the introduction of the sensor 104 into the tissue. In exemplary embodiments, the introducer may comprise a needle. It should be noted that other types of introducers, such as a sheath or blade, may be present in alternative embodiments. More specifically, the needle or similar introducer may be present temporarily in close proximity to the sensor 104 before insertion and then withdrawn. While present, the needle or other introducer can facilitate the insertion of the sensor 104 into the tissue by opening an access path for the sensor 104 to advance. For example, according to some embodiments, the needle may facilitate penetration of the epidermis as an access path to the dermis, thereby enabling the implantation of the sensor 104. After opening the access path, the needle or other introducer may be withdrawn so as not to represent a sharp object hazard. In some embodiments, the needle may be solid or hollow, beveled or not beveled, and / or have a circular or non-circular cross-section. In some embodiments, the needle may be equivalent to an acupuncture needle in terms of cross-sectional diameter and / or tip design, for example, having a cross-sectional diameter of about 250 microns. However, it should be recognized that a suitable needle may have a larger or smaller cross-sectional diameter if required for a particular application.

[0062] In some embodiments, the tip of the needle may be angled across the end of the sensor 104 so that the needle first penetrates the tissue and opens an access path for the sensor 104. In some embodiments, the sensor 104 may be located within the lumen or groove of the needle, and the needle similarly opens an access path for the sensor 104. In any case, the needle is withdrawn after facilitating insertion.

[0063] The sensor 104 may use a two-electrode or three-electrode sensing motif according to some embodiments of the present disclosure. The three-electrode motif may comprise a working electrode, a counter electrode, and a reference electrode. The two-electrode motif may comprise a working electrode and a second electrode, the second electrode functioning as both a counter electrode and a reference electrode (i.e., a counter / reference electrode). In both the two-electrode and three-electrode sensing motifs, the sensing region or sensing area of ​​the sensor 104 may be in contact with the working electrode. In some embodiments, the electrodes may be stacked at least partially on each other, as will be described in more detail below. In some embodiments, the various electrodes may be spaced apart from each other on the insertion tail of the sensor 104.

[0064] In some embodiments, the sensor may include a sensing area (e.g., a lactate-responsive sensing area). In some embodiments, the sensor may have different types of sensing areas (e.g., a glucose-responsive sensing area and a lactate-responsive sensing area) on a single working electrode or on two or more separate working electrodes. The single working electrode sensor configuration may employ a two-electrode or three-electrode detection motif, as further described herein, according to some embodiments of the present disclosure. Figures 3A and 3D show cross-sectional views of exemplary two-electrode analyte sensor configurations having a single working electrode, suitable for use in some embodiments of the present disclosure. As shown, analyte sensors 200 and 203 include a substrate 212 positioned between a working electrode 214 and a pair / reference electrode 216. Alternatively, the working electrode 214 and the pair / reference electrode 216 may be positioned on the same side of the substrate 212 with a dielectric material interposed between them (configuration not shown). In some embodiments, the sensor 200 includes a sensing area 218 (i.e., a lactate-responsive sensing area) which may be positioned on the surface of the working electrode 214. In some embodiments, the sensor 203 includes sensing areas 218a and 218b (i.e., a glucose-responsive sensing area and a lactate-responsive sensing area) that are spaced laterally apart from each other on the surface of the working electrode 214. In some embodiments, sensing area 218a may be continuously or discontinuously arranged on the working electrode for the detection of the analyte. In some embodiments, sensing area 218b may be continuously or discontinuously arranged on the working electrode for the detection of the analyte. The lactate sensor 200 may be operable to assay the analyte by coulometry, amperometry, voltammetry, or potentiometric electrochemical detection. The lactate sensor 203 may be operable to assay glucose and lactate by coulometry, amperometry, voltammetry, or potentiometric electrochemical detection.

[0065] When a single working electrode is present within the analyte sensor, a three-electrode sensor configuration may comprise a working electrode, a counter electrode, and a reference electrode. A related two-electrode sensor configuration may comprise a working electrode and a second electrode, the second electrode may function as both a counter electrode and a reference electrode (i.e., a counter / reference electrode). In both two-electrode and three-electrode sensor configurations, both the first analyte responsive sensing area and the second analyte responsive sensing area may be located on a single working electrode. In any sensor configuration disclosed herein, the various electrodes may be at least partially stacked (layered) and / or laterally spaced apart from each other on the sensor. A suitable sensor configuration may have a substantially flat or substantially cylindrical shape, with the first and second analyte responsive sensing areas laterally spaced apart on the working electrode. In all sensor configurations disclosed herein, the various electrodes may be electrically insulated from each other by a dielectric material or similar insulator.

[0066] In some embodiments, the sensor may comprise two or more working electrodes and at least one additional electrode (i.e., at least one additional electrode, at least two additional electrodes, etc.). If one additional electrode is present, that additional electrode may function as a pair / reference electrode for each of the multiple working electrodes. If two additional electrodes are present, one of the additional electrodes may function as a pair electrode for each of the multiple working electrodes, and the other of the additional electrodes may function as a reference electrode for each of the multiple working electrodes. Figures 3B-3C and 3E-3F illustrate exemplary three-electrode analyte sensor configurations, which are also adapted for use in some embodiments of the disclosure herein. The three-electrode analyte sensor configuration may be similar to that shown for analyte sensor 200 in Figures 3A and 3D, except that analyte sensors 201, 202, 204, and 205 (Figures 3B-3C and 3E-3F) include an additional electrode 217. With the additional electrode 217, the pair / reference electrode 216 can then function as either a pair electrode or a reference electrode, and the additional electrode 217 can perform other electrode functions not otherwise considered. The working electrode 214 continues to perform its original function. The additional electrode 217 may be placed on either the working electrode 214 or electrode 216 with a dielectric material isolation layer in between. For example, as shown in Figure 3B, dielectric layers 219a, 219b, and 219c isolate electrodes 214, 216, and 217 from each other and provide electrical insulation. Alternatively, at least one of electrodes 214, 216, and 217 may be located on the opposite side of the substrate 212, as shown in Figure 3C. Therefore, in some embodiments, the electrodes 214 (working electrode) and 20216 (counter electrode) can be located on opposite sides of the substrate 212, and the electrode 217 (reference electrode) can be located on one of the electrodes 214 or 216 and separated therefrom by the dielectric material. The reference material layer 230 (e.g., Ag / AgCl) may be present on the electrode 217, and the position of the reference material layer 230 is not limited to the positions shown in Figures 3B and 3C.Similar to sensor 200 shown in Figure 3A, the sensing areas 218 in analyte sensors 201 and 202 may be continuously or discontinuously positioned on the working electrode for detecting lactic acid. Furthermore, analyte sensors 201 and 204 may be operable to assay lactic acid by coulometry, amperometry, voltammetry, or potentiometric electrochemical detection.

[0067] Similar to the analyte sensor 200, the film 220 may also cover the sensing areas 218 and 218a, 218b in the analyte sensors 201, 202, 204, and 205, as well as other sensor components, thereby acting as a mass transfer limiting film. In some embodiments, an additional electrode 217 may be covered with the film 220. Figures 3B-3C and 3E-3F show electrodes 214, 216, and 217 all covered with the film 220, but it should be noted that in some embodiments, only the working electrode 214 may be covered. Furthermore, the thickness of the film 220 on each of electrodes 214, 216, and 217 may be the same or different. As shown in the two-electrode analyte sensor configuration (Figures 3A and 3D), one or both sides of the analyte sensors 201, 202, 204, and 205 may be covered with the film 220 in the sensor configurations of Figures 3B-3C and 3E-3F, or the entire analyte sensors 201, 202, 204, and 205 may be covered.

[0068] Figure 4 shows a cross-sectional view of an exemplary analyte sensor configuration having two working electrodes, a reference electrode, and a counter electrode, suitable for use in some embodiments of the disclosure herein. As shown in Figure 4, the analyte sensor 300 includes working electrodes 304 and 306 positioned on opposite sides of a substrate 302. Sensing area 310a is positioned on the surface of working electrode 304, and sensing area 310b is positioned on the surface of working electrode 306. The analyte sensor 300 may also include further sensing areas on the surface(s) of the working electrode(s) 304 and / or 306, which may be spaced laterally apart from each other. According to some embodiments of the disclosure, sensing areas 310a and 310b may be lactate-responsive sensing areas and glucose-responsive sensing areas, respectively. The counter electrode 320 is electrically insulated from the working electrode 304 by a dielectric layer 322, and the reference electrode 321 is electrically insulated from the working electrode 306 by a dielectric layer 323. The outer dielectric layers 330 and 332 are positioned on the reference electrode 321 and the counter electrode 320, respectively. The layers present in the sensor 300 of Figure 4 may include, in this order, the outer dielectric layer 332, the counter electrode 320, the dielectric layer 322, the working electrode 304, the substrate 302, the working electrode 306, the dielectric layer 323, the reference electrode 321, and the outer dielectric layer 330. The layers can be stacked (partially) on each other, and portions of each layer near the edges of the layers are not covered by adjacent layers. For example, the substrate 302 may extend beyond the respective ends of the working electrodes 304 and 306 (and not cover them). The working electrodes 304 and 306 may extend beyond the ends of the dielectric layers 322 and 333 (and not cover them). The portions of the working electrodes 304 and 306 that extend beyond the ends of the dielectric layers 322 and 333 may provide space for sensing areas 310a and 310b, respectively. In any embodiment described herein, the substrate 302 may extend to the distal tip of the sensor so as to separate the layers on either side of the substrate 302.The membrane 340 has a first membrane portion 340a and a second membrane portion 340b, which, according to various embodiments, separately cover at least the sensing areas 310a and 310b, respectively, and other components of the analyte sensor 300 or the entire analyte sensor 300 are optionally also covered with the first membrane portion 340a and / or the second membrane portion 340b. In this case as well, the membrane 340 is continuous but compositionally different within the first membrane portion 340a and the second membrane portion 340b (i.e., on the sensing areas 310a and 310b), giving each other different permeability values ​​to differentially regulate the flow of the analyte at each location. For example, different membrane formulations may be sprayed and / or printed onto the opposite surface of the analyte sensor 300. Immersion coating techniques may also be suitable, in particular, for depositing at least a portion of a two-layer membrane on one of the sensing areas 310a and 310b. Accordingly, according to some embodiments of the present 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 single-membrane polymer. In some embodiments, the analyte sensor 300 may be operable to assay glucose and lactate by any of coulometry, amperometry, voltammetry, or potentiometric electrochemical detection. The above description of the membrane applies equally to any embodiment of the sensor described herein.

[0069] Figure 5A shows a diagram of an exemplary four-electrode analyte sensor configuration suitable for use in the disclosure herein. As shown, the sensor 206 comprises a substrate 212 positioned between working electrodes 214a and 214b. Alternatively, the working electrodes 214a and 214b may be positioned on the same side of the substrate 212, with a dielectric material sandwiched between them (configuration not shown). Analyte-specific responsive sensing areas 218a and / or 218b (e.g., glucose-responsive sensing area and lactate-responsive sensing area) may be positioned as at least one layer on at least a portion of the working electrodes 214a and / or 214b. The analyte-responsive sensing areas may be positioned continuously or discontinuously on the working electrodes for analyte detection, as further discussed herein. A reference electrode may be positioned on either the working electrodes 214a or 214b, with a separatory layer of dielectric material between them. The counter electrode may be located on the other side of the working electrode 214a or 214b, with a dielectric isolation layer between them. For example, as shown in Figure 5A, dielectric layers 219b and 219c separate electrodes 214a, 214b, 216, and 217 from each other, providing electrical insulation. The 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 the opposite side of the substrate 212 (configuration not shown).

[0070] In some embodiments, electrodes 214a (working electrode) and 216 (counter electrode) may be located on the opposite side of the substrate 212 as electrode 217 (reference electrode), and the working electrode 214b may be located on the opposite side of the substrate as shown in Figure 5A. A 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 the location shown in Figure 5A. Furthermore, the analyte sensor 206 may be operable to assay the analyte by any of the following methods: coulometry, amperometry, voltammetry, or potentiometric electrochemical detection. Although Figure 5A shows electrodes 214a, 214b, 216, and 217 all coated with film 220, it should be noted that in some embodiments, only the working electrodes 214a and 214b may be coated. Furthermore, the thickness of the film 220 on each of electrodes 214a, 214b, 216, and 217 may be the same or different in any of the embodiments described herein. As in the two-electrode analyte sensor configuration, one or both sides of the analyte sensor 206 may be covered with the film 220 in the sensor configuration of Figure 5A, or the entire analyte sensor 206 may be covered. Thus, the multi-electrode sensor configuration shown in Figure 5A should be understood as not limiting the embodiments disclosed herein, and alternative electrode and / or layer configurations remain within the scope of this disclosure.

[0071] In some embodiments (including any of the embodiments in Figures 3 to 6), the substrate is formed from 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 placed between the working electrode and the pair and / or reference electrode.

[0072] In some embodiments (including any of the embodiments in Figures 3 to 6), the dielectric layer may include a suitable dielectric material that can form a solid. For example, the insulating layer may be formed from porcelain (ceramics), 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., silica, alumina, titania, zirconia, tantalum oxide, etc.).

[0073] In some embodiments (including any of the embodiments in Figures 3 to 6), the film 220 optionally covers at least the analyte-responsive sensing areas 218a and 218b, some or all of the working electrodes 214a and / or 214b and / or the reference electrode 216 and / or counter electrode 217, or, according to some embodiments, the entire analyte sensor 202. One or both sides of the analyte sensor 202 may be covered with the film 220. The film 220 may comprise one or more polymer film materials having the ability to restrict the flow of analyte to the sensing areas 218 (i.e., the film 220 is a mass transfer restricting film with some permeability to the analyte being measured). The composition and thickness of the film 220 may be varied to facilitate the flow of a desired analyte to the analyte-responsive sensing areas 218a and 218b, thereby providing a desired signal intensity and stability.

[0074] Figures 5B and 6 illustrate exemplary four-electrode analyte sensor configurations suitable for use in the disclosure herein. As shown, the analyte sensor 232 comprises a substrate 212 positioned between a working electrode 214a and a counter electrode 216. The working electrodes 214a and 214b are positioned on the same side of the substrate 212, with a dielectric material 219b sandwiched between the working electrodes 214a and 214b. The counter electrode 216 and reference electrode 217 are positioned on the opposite side of the substrate 212, with a dielectric material 219c sandwiched between the counter electrode 216 and the reference electrode 217. An analyte-specific responsive sensing area 218a (e.g., a lactate-responsive sensing area) may be positioned as at least one layer on at least a portion of the working electrode 214a. An analyte-specific responsive sensing area 218b (e.g., a glucose-responsive sensing area) may be positioned as at least one layer on at least a portion of the working electrode 214b. The sensing area 218a (e.g., a lactate-responsive sensing area) may be located closer to the distal end A than the analyte-specific responsive sensing area 218b (e.g., glucose-responsive). The analyte-responsive sensing areas 218a and 218b may be arranged continuously or discontinuously on the working electrode(s) for analyte detection, as will be further discussed herein. As shown in Figure 5B, dielectric layers 219b and 219c separate the electrodes 214a, 214b, 216, and 217 from each other and provide electrical insulation. The 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 another preferred location on the sensor. The layers present in the sensor 232 in Figure 5B may comprise, in this order, 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 can be (partially) stacked on top of each other, and a portion of each layer near the edge of the layer is not covered by the adjacent layer. As shown in Figure 6, the lactate-responsive sensing area may be continuously arranged on the working electrode 214a, and the glucose-responsive sensing area may be discontinuously arranged on the working electrode 214b.Furthermore, the analyte sensors 206 and 232 may be capable of assaying the analyte by any of the following methods: coulometry, amperometry, voltammetry, or potentiometric electrochemical detection.

[0075] In some embodiments, the sensor 232 may include two membranes 220, 222. As shown in Figure 5B, membrane 222 may cover only a portion of the working electrode 214a, including a sensing area 218a (e.g., a lactate-responsive sensing area). Membrane 220 may cover both sensing area 218a (e.g., a lactate-responsive sensing area) and sensing area 218b (e.g., glucose-responsive). Membrane 220 may also cover the counter electrode 216 and reference electrode 217 on the opposite side of the substrate 212. Thus, sensing area 218a (e.g., a lactate-responsive sensing area) may have a bilayer membrane including membranes 222 and 220, while sensing area 218b may have only a single layer membrane 220. Figure 5B shows electrodes 214a, 214b, 216, and 217 all coated with film 220, but it should be noted that in some embodiments, only working electrodes 214a and 214b may be coated. Furthermore, the thicknesses of films 220 and 222 on each of electrodes 214a, 214b, 216, and 217 may be the same or different. As in the two-electrode analyte sensor configuration, one or both sides of the analyte sensor 232 may be coated with film 220 in the sensor configuration of Figure 5B, or the entire analyte sensor 232 may be coated. Therefore, the multi-electrode sensor configurations shown in Figures 5A and 5B should be understood as not limiting the embodiments disclosed herein, and alternative electrode and / or layer configurations remain within the scope of this disclosure.

[0076] The film 222 can be immersion-coated onto the sensing area 218a (e.g., a lactate-responsive sensing area). For example, the sensor 232 may be partially immersed in the film solution such that only the end region near the distal end A, which includes the sensing area 218a but does not include the sensing area 218b, is immersed in the film solution. The application of the film 222 may be achieved in a single immersion procedure, or multiple immersions in the film solution may be required to obtain a high-density film. Then, a larger portion of the sensor 232, including both sensing areas 218a and 218b, may be immersed in different film solutions. Thus, the sensing area 218a, which is located closer to the distal end A, may have a double-layer film, while the sensing area 218b, which is proximal to the sensing area 218a, may have a single-layer film. Immersion coating in this method has several advantages. Firstly, distributing both sensing areas to one side of the substrate 212 without the need to invert the substrate 212 simplifies the manufacturing process and improves efficiency. Secondly, this immersion method allows the use of the same membrane immersion apparatus for both membranes 222 and 220, simply by changing the membrane solution and adjusting the immersion depth.

[0077] In some embodiments, the membrane 222 may comprise at least a crosslinked polyvinylpyridine homopolymer or copolymer. The membrane 222 may be single-component or multi-component. Embodiments of a multi-component membrane may comprise a bilayer or homogeneous mixture of crosslinked polyvinylpyridine and another polymer, according to some embodiments of the present disclosure. Suitable polyvinylpyridine copolymers for inclusion in the membrane 222 may comprise up to about 25% comonomers (based on the total amount of monomers in the copolymer), such as about 0.1% to about 5% comonomers, or about 5% to about 15% comonomers, or about 15% to about 25% comonomers, or about 1% to about 10% comonomers. Suitable comonomers are not particularly limited, as long as they provide sufficient lactic acid permeability to provide analyte sensitivity of about 1 nA / mM or more when the mass transfer limiting membrane is exposed to lactic acid. In some embodiments, the polyvinylpyridine copolymer may differ from the polyvinylpyridine-co-styrene copolymer according to some embodiments. With respect to film 222, the crosslinking of the film polymer disclosed herein may occur via functionalization with bis-epoxides such as polyethylene glycol diglycidyl ether (PEGDGE) or glycerol triglycidyl ether. In some embodiments, film 222 may comprise polyvinylpyridine and a crosslinking agent such as polyethylene glycol diglycidyl ether (PEGDGE), e.g., PEGDGE400.

[0078] In some embodiments, the membrane 220 may be a membrane comprising a crosslinked polymer containing heterocyclic nitrogen groups, such as polyvinylpyridine and polyvinylimidazole polymers. In some embodiments, the membrane 220 may also include a membrane made of polyurethane, or polyether urethane, or a chemically related material, or silicone.

[0079] In some embodiments, the membrane may be formed in situ by crosslinking a polymer, including those discussed above, in a buffer solution (e.g., an alcohol buffer solution), modified with a zwitterionic moiety, a nonpyridine copolymer component, and optionally another moiety that is either hydrophilic or hydrophobic and / or has other desirable properties. In some embodiments, the modified polymer may be made from a precursor polymer containing heterocyclic nitrogen groups. For example, the precursor polymer may be polyvinylpyridine or polyvinylimidazole. Optionally, hydrophilic or hydrophobic modifiers may be used to "fine-tune" the permeability of the resulting membrane to the analyte of interest. Hydrophilic modifiers such as poly(ethylene glycol), hydroxyl modifiers or polyhydroxyl modifiers, and any combination thereof, may be used to enhance the biocompatibility of the polymer or the resulting membrane.

[0080] In some embodiments, the film 220 may include, but is not limited to, polymers containing poly(styrene-com-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 any combination thereof. In some embodiments, the film may include a polyvinylpyridine-co-styrene polymer in which some of the pyridine nitrogen atoms are functionalized with uncrosslinked poly(ethylene glycol) tails and some of the pyridine nitrogen atoms are functionalized with alkylsulfonic acid groups. In some embodiments, the film 220 may include the polymers shown below.

[0081] [ka]

[0082] In some embodiments, membrane 222 may contain polyvinylpyridine and a crosslinking agent such as polyethylene glycol diglycidyl ether (PEGDGE), for example PEGDGE400. In some embodiments, membrane 220 may contain polyvinylpyridine-co-styrene and a crosslinking agent such as PEGDGE, for example PEGDGE400, or glycerol triglycidyl ether. In some embodiments, membrane 222 may contain polyvinylpyridine and a crosslinking agent such as PEGDGE, for example PEGDGE400, and membrane 220 may contain polyvinylpyridine-co-styrene and a crosslinking agent such as PEGDGE, for example PEGDGE400, or glycerol triglycidyl ether.

[0083] In some embodiments, the sensing area 218a may include a lactate-responsive enzyme. More specifically, according to some embodiments of the present disclosure, the lactate-responsive enzyme may include lactate dehydrogenase or lactate oxidase. Figure 8 shows a diagram of an enzyme system that can be used to detect lactate according to the present disclosure. In some embodiments, an electron transfer mediator can facilitate the transfer of electrons from lactate to the working electrode 214a during a redox reaction, as shown in Figure 8. The electrons transferred during this reaction provide the basis for lactate detection at the working electrode. The change in signal intensity (e.g., current) at the working electrode 214a may be proportional to the lactate concentration and / or the activity of the lactate-responsive enzyme.

[0084] In some embodiments, the sensing area 218a may further contain 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 containing the sensing area 218. The covalent bond immobilizes the lactate-responsive enzyme to the sensing area 218a.

[0085] In some embodiments, lactate oxidase may be present in the sensing area in amounts 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. With respect to the weight percentage of the sensing area, lactate oxidase may be present in amounts ranging from about 10% to about 90% by weight of the sensing area, or about 25% to about 75% by weight of the sensing area, or about 30% to about 60% by weight of the sensing area.

[0086] According to some embodiments, the albumin in the sensing area may include human serum albumin. In some embodiments, non-human albumin, such as bovine serum albumin, may be used in sufficient quantities.

[0087] Albumin may be incorporated into the sensing area in an amount sufficient to stabilize a lactate-responsive enzyme, particularly lactate oxidase, according to the disclosure herein. In more specific embodiments, albumin may be present in the sensing area in amounts 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. With respect to the weight percentage of the sensing area, albumin may be present in amounts ranging from about 25% to about 75% by weight of the sensing area, or about 30% to about 60% by weight of the sensing area. In certain embodiments, the weight ratio of lactate oxidase to albumin may range from 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 may be about 2:1. In some embodiments, the weight ratio of lactate oxidase to albumin may be about 1:1.

[0088] In some embodiments, the sensing area 218a may include a polymer and a redox mediator which may include an electron transfer agent. In some embodiments, the electron transfer agent may be a low-potential osmium complex electron transfer mediator. In some embodiments, the polymer is covalently bonded to both a lactate-responsive enzyme such as lactate dehydrogenase or lactate oxidase and a low-potential osmium complex electron transfer mediator, as disclosed in, for example, U.S. Patents 6,134,461, 6,605,200, 6,736,957, 7,501,053, and 7,754,093 (these disclosures are incorporated herein by reference in their entirety). Other suitable examples of electron transfer mediators and polymer-bonded electron transfer mediators are those described in U.S. Patents No. 8,444,834, No. 8,268,143, and No. 6,605,201 (these disclosures are incorporated herein by reference in their entirety).

[0089] Electron transfer mediators can facilitate the transfer of electrons from lactate to the working electrode 214a during a redox reaction. Changes in signal intensity (e.g., current) at the working electrode 214 may be proportional to the lactate concentration and / or the activity of the lactate-responsive enzyme. According to some embodiments, a calibration coefficient may be applied (e.g., by a processor) to determine the lactate concentration from the signal intensity. Suitable electron transfer mediators include electroreducible and electrooxidizing ions, complexes, or molecules having redox potentials several hundred millivolts higher or lower than the redox potential of the standard calomel electrode (SCE). Other suitable electron transfer mediators may include, for example, metal compounds or complexes of ruthenium, iron (e.g., polyvinylferrocene), or cobalt. Suitable ligands for metal complexes include, for example, bidentate ligands such as bipyridine, biimidazole, phenanthroline, or pyridyl(imidazole), or even polydentate ligands. Other suitable bidentate ligands include, for example, amino acids, oxalic acid, acetylacetone, diaminoalkanes, or o-diaminoarenes. Any combination of monodentate, bidentate, tridentate, or quaternate or more ligands can be present in the metal complex to achieve a complete coordination sphere.

[0090] The polymer in the redox mediator can be any suitable polymer that enables the transfer of electrons between the electron transfer agent and the working electrode. For example, the polymer may 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 carboxypentyl groups, and poly(4-sodium styrenesulfonate). These polymers can be considered precursor polymers in that they are further modified to immobilize (e.g., bind) electron transfer complexes. In some embodiments, the polymer may comprise a poly(4-vinylpyridine), poly(1-vinylimidazole), poly(thiophene), poly(aniline), poly(pyrrole), or poly(acetylene) skeleton. In other embodiments, the polymer may comprise a polymer or copolymer repeating unit comprising at least one (e.g., 1, 2, 3, 4, 5, or 6) pendant pyridinyl groups, imidazolyl groups, or both pyridinyl and imidazolyl groups. Suitable polymers, for example, include partially or fully quaternized poly(4-vinylpyridine) and poly(1-vinylimidazole), where the quaternized pyridine and imidazole groups can be used to form spacers by reaction with electron transfer agents (e.g., complex formation with electron transfer agents), respectively.

[0091] Suitable polymers for inclusion in the sensing area 218a include, but are not limited to, polyvinylpyridine (e.g., poly(4-vinylpyridine)), polyimidazole (e.g., poly(1-vinylimidazole)), or any copolymer thereof. Suitable exemplary copolymers include, for example, copolymers containing monomer units such as styrene, acrylamide, methacrylamide, or acrylonitrile.

[0092] Covalent bonding of a lactate-responsive enzyme to a polymer or other matrix (e.g., sol-gel) in the sensing area 218a may occur via a crosslinking agent introduced with a suitable crosslinking material. Suitable crosslinking materials for reaction with free amino groups in the enzyme (e.g., free amines in lysine) include, for example, polyethylene glycol diglycidyl ether (PEGDGE) or other polyepoxides, cyanuryl chloride, N-hydroxysuccinimide, imide esters, epichlorohydrin, or their derivatized variants. Suitable crosslinking materials for reaction with free carboxylic acid groups in the enzyme include, for example, carbodiimide.

[0093] In some embodiments, the redox mediator may include an osmium complex bonded to a poly(1-vinylimidazole) or poly(4-vinylpyridine) polymer or copolymer. The poly(4-vinylpyridine) polymer is a prepolymer modified to bond an osmium complex (e.g., poly(biimidizyl)osmium complex) as shown in the following structure.

[0094] [ka]

[0095] In the formula, n can be 2, n' can be 17, and n'' can be 1. Other reactive groups and / or spacer groups may be used. In some embodiments, the electronic redox mediator may include an osmium-containing poly(4-vinylpyridine) polymer, as shown below.

[0096] [ka]

[0097] In the equation, n is 2, n' is 17, and n'' is 1. Lactate-responsive enzymes and / or electron transfer mediators may be covalently bound to the polymer or other suitable matrix in the sensing area 218a, but other association means may be equally suitable. In some embodiments, the lactate-responsive enzymes and / or electron transfer mediators may be ionically or coordinationally bound to the polymer or other matrix. For example, a charged polymer may be ionically bound to a conversely charged lactate-responsive enzyme or electron transfer mediator. In yet another embodiment, the lactate-responsive enzymes and / or electron transfer mediators may be physically incorporated into the polymer or other matrix in the sensing area 218a.

[0098] In some embodiments, the sensing area 218b may include a redox mediator that may contain a polymer and an electron transfer agent. Suitable polymers and electron transfer agents described with respect to the first sensing area 218a are also suitable for the second sensing area 218b. In some embodiments, the electron transfer agent may be a low-potential osmium complex electron transfer mediator. In some embodiments, the polymer is covalently bonded to both a glucose-responsive enzyme, such as glucose oxidase, and the low-potential osmium complex electron transfer mediator. Figure 7 shows a diagram of an enzyme system that can be used to detect glucose according to the disclosure herein. The electron transfer mediator can facilitate the transfer of electrons from glucose to the working electrode 214b during a redox reaction. The change in signal intensity (e.g., current) at the working electrode 214b may be proportional to the glucose concentration and / or the activity of the glucose-responsive enzyme. According to some embodiments, a calibration coefficient may be applied (e.g., by a processor) to determine the glucose concentration from the signal intensity.

[0099] In some embodiments, in addition to the preferred electron transfer agents and polymers discussed in more detail above, the first sensing area 218a may contain a lactate-responsive enzyme such as lactate oxidase, and the second sensing area 218b may contain a glucose-responsive enzyme such as glucose oxidase. According to some embodiments, the sensor may be suitable for detecting glucose and lactate and may comprise a first working electrode 214a on which the first sensing area 218a is located, a second working electrode on which the second sensing area 218b is located, and a mass transfer limiting membrane covering the first and second sensing areas on the working electrode, wherein the first sensing area 218a contains a polymer, albumin, and a lactate-responsive enzyme (e.g., lactate oxidase) covalently bonded to the polymer, and the second sensing area 218b contains a glucose-responsive enzyme (e.g., glucose oxidase) covalently bonded to the polymer. In some embodiments, the first and second electron transfer agents may be different from each other. In some embodiments, the mass transfer restriction membrane may comprise at least a crosslinked polyvinylpyridine homopolymer or copolymer. The composition of the mass transfer restriction membrane may be the same or different when the membrane covers each sensing area. In some embodiments, the mass transfer restriction membrane covering the second sensing area may be single-component (containing a single membrane polymer), while the mass transfer restriction membrane covering the first sensing area may be multi-component (containing two or more different membrane polymers, one of which is a polyvinylpyridine homopolymer or copolymer), and may be either a bilayer or a homogeneous mixture.

[0100] In some embodiments, the sensors discussed herein may be configured to be partially inserted into an individual's skin. Working electrodes are positioned on the sensor and inserted into tissue to facilitate the analysis of lactate and glucose within it. Suitable tissues are not considered particularly limited, and specific examples are described in more detail above. Similarly, considerations for positioning the sensor at a specific location or depth within the tissue are described above.

[0101] A detection method for assaying glucose and lactate using the sensor disclosed herein may include: exposing the analyte sensor to a fluid containing glucose and lactate; applying potentials to a first working electrode and a second working electrode; acquiring a first signal above the redox potential of a lactate-responsive sensing area, wherein the first signal is proportional to the concentration of lactate in the fluid; acquiring a second signal above the redox potential of a glucose-responsive sensing area, wherein the second signal is proportional to the concentration of glucose in the fluid; and correlating the first signal with the concentration of lactate in the fluid and the second signal with the concentration of glucose in the fluid.

[0102] In some embodiments, the signal associated with each sensing area may be correlated to the corresponding concentration of glucose or lactate by referring to a lookup table or calibration curve for each analyte. The lookup table for each analyte can be data-inputted by assaying multiple samples with known analyte concentrations and recording the sensor response at each concentration for each analyte. Similarly, the calibration curve for each analyte may be determined (e.g., by regression, particularly linear regression) by plotting the analyte sensor response for each analyte as a function of concentration and determining a suitable calibration function over a calibration range.

[0103] The processor may determine which sensor response value in the lookup table is closest to the sensor response value measured for a sample with an unknown analyte concentration, and then report the analyte concentration accordingly. In some embodiments, if the sensor response value for a sample with an unknown analyte concentration falls between the recorded values ​​in the lookup table, the processor may interpolate between the two lookup table values ​​to estimate the analyte concentration. The interpolation may assume a linear concentration change between the two values ​​reported in the lookup table. Interpolation may be employed when the sensor response differs by a sufficient amount from a given value in the lookup table, such as a variation of about 10% or more.

[0104] Similarly, according to some embodiments, the processor may input the sensor response value of a sample having an unknown analyte concentration into a corresponding calibration function. The processor may then report the analyte concentration accordingly.

[0105] In some embodiments, the sensors described herein may also be configured to analyze other analytes. Further analytes that may be targeted in the field of sports training include, for example, markers of cardiac stress, markers of inflammation, pyruvate, pH, triglycerides, free fatty acids, and hormones such as insulin, glucagon, cortisol, epinephrine, norepinephrine, testosterone, HGH, IFG1, and BDNF.

[0106] In some embodiments, the sensing system may incorporate additional functionality appropriate for monitoring physical activity. Optional additional functionality may include, for example, a heart rate monitor, a heart rate variability monitor, a blood oxygen monitor, a power meter, an accelerometer, a pedometer, and a measurement of the rate of exertion as perceived by the user.

[0107] It should be understood that the sensing systems and sensors disclosed herein may have additional features and / or functions not necessarily described herein for the sake of brevity. Therefore, the foregoing descriptions of sensing systems and sensors should be considered illustrative and non-limiting in nature.

[0108] method Also disclosed herein are methods for monitoring lactate levels in an individual, and methods for determining an individual's aerobic and anaerobic work thresholds. The methods disclosed herein enable a rapid and convenient method for obtaining reliable lactate levels correlated with metrics such as power and heart rate, despite delays in interstitial fluid lactate concentration changes in response to power or heart rate changes, and for determining lactate work thresholds to provide an individual with useful information regarding running pace, heart rate, and / or power corresponding to aerobic or anaerobic work thresholds.

[0109] In some embodiments, a method for monitoring lactic acid 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 as disclosed herein. In some embodiments, the sensor may be a sensor as disclosed in U.S. Patent No. 10,392,647, U.S. Patent Application Publication No. 2019 / 0320947, and / or U.S. Patent Application Publication No. 2022 / 0125354, each disclosure of which is incorporated herein by reference in whole. In some embodiments, the analyte sensor is the sensor described in relation to Figures 3–6. In some embodiments, the analyte sensor is the sensor described in relation to Figures 5B and 6. In some embodiments, the method further includes applying a potential to the working electrode of the sensor and acquiring a first signal above the redox potential of a lactic acid-responsive sensing area (e.g., a first sensing area), the signal being proportional to the lactic acid concentration in the fluid, and correlating the signal with the lactic acid concentration in the fluid. In some embodiments, the method further includes acquiring a second signal that is greater than or equal to the redox potential of a glucose-responsive sensing area (e.g., a second sensing area), wherein the second signal is proportional to the glucose concentration in the fluid, and correlating the second signal with the glucose concentration in the fluid. In some embodiments, each sensing area has a redox potential, and the redox potential of the glucose-responsive sensing area is sufficiently separated from the redox potential of the lactate-responsive sensing area, allowing for independent generation of signals from the glucose-responsive and lactate-responsive sensing areas.

[0110] In some embodiments, a method for determining an aerobic threshold, an anaerobic threshold, or both aerobic and anaerobic thresholds may include continuously measuring signals indicating the concentration of lactate in the body fluids within an individual in vivo using a sensing system equipped with a lactate-responsive sensor. As described above, in some embodiments, the sensor may be any sensor as disclosed herein or a sensor disclosed in one of the publications referenced above. In some embodiments, measuring multiple lactate concentrations is performed when an individual is undergoing a lactate threshold test to determine their 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 include running at a lower speed (e.g., on a treadmill) and then gradually increasing the speed to exhaustion or near exhaustion. In some embodiments, the lactate threshold test may include cycling at a lower speed (e.g., on a stationary bicycle) and then gradually increasing the speed to exhaustion or near exhaustion. In some embodiments, the stepwise increase may be defined based on power. In some embodiments, the stepwise increase may be about 1W, about 2W, about 3W, about 4W, about 5W, about 6W, about 7W, about 8W, about 9W, about 10W, about 15W, about 20W, about 25W, about 30W, about 35W, about 40W, about 45W, or about 50W. In some embodiments, a lactate threshold test may collect lactate concentration data against power or heart rate.

[0111] In some embodiments, the sensor is configured to take measurements approximately every 1 second, 3 seconds, 5 seconds, 10 seconds, 15 seconds, 20 seconds, 30 seconds, 45 seconds, 1 minute, 1.5 minutes, 2 minutes, 3 minutes, 5 minutes, 10 minutes, 15 minutes, 20 minutes, 30 minutes, 45 minutes, 1 hour, 2 hours, or 3 hours. In some embodiments, the method may further include communicating 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 a 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 the lactate concentration from the lactate-responsive sensor. In some embodiments, the processor may further signal the individual wearing the sensor or another party when an aerobic or anaerobic threshold is reached. In some embodiments, the processor's output may be numerical and / or graphical. Notification to the wearer of the lactate-responsive sensor or other party may be auditory, tactile (tactile), or any combination thereof.

[0112] In some embodiments, the method may include determining an individual's baseline lactate concentration based on multiple lactate concentration measurements. Baseline lactate concentrations may vary from person to person. In some embodiments, baseline lactate concentrations may range from approximately 0.5 mM to approximately 2 mM, approximately 0.5 mM to approximately 1.5 mM, or approximately 0.5 mM to approximately 1 mM. Baseline lactate concentrations may be determined before reaching the anaerobic threshold and / or after reaching the anaerobic threshold and once the lactate concentration has stabilized again.

[0113] In some embodiments, the aerobic threshold may be a fixed value and may be defined as the power or heart rate at which an initial increase of about 0.5 mM or about 1 mM (or another predetermined preferred value) is observed from the baseline lactate concentration. In some embodiments, the processor is configured to determine the aerobic threshold by determining the baseline concentration from the lactate measurement and adding about 0.5 mM or about 1 mM to the baseline lactate concentration, so that the aerobic threshold may be defined with respect to (i) the lactate concentration and (ii) the power or heart rate correlated with that lactate concentration.

[0114] In some embodiments, the processor is configured to determine an aerobic work threshold based on multiple lactate concentrations using a log-log model. In some embodiments, the log-log model may include plotting lactate levels against intensity (e.g., power or heart rate) on a logarithmic scale. In some embodiments, the log-log model may further include dividing the plot into two segments and performing segmented regression analysis. Each segment may have a best-fitted line connected by breakpoints. In some embodiments, the segmented regression analysis may include minimizing the sum of squared errors (SSE), also known as the sum of squared residuals (RSS), for example, by varying the membership of data points within each group. In some embodiments, the breakpoints provide an aerobic work threshold with respect to (i) lactate concentration and (ii) intensity (e.g., power or heart rate).

[0115] In some embodiments, the anaerobic threshold may 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 based on multiple lactate concentrations using a polynomial regression model. In some embodiments, the processor is configured to determine the anaerobic threshold based on multiple lactate concentrations using the D-max method shown in Figure 9. In some embodiments, the D-max method may include performing a regression analysis to determine a best-fitted line (e.g., a regression curve) based on multiple lactate concentrations plotted against power or heart rate. In some embodiments, a cubic polynomial function may provide the best-fitted line (e.g., a regression curve) based on multiple lactate concentrations plotted against power or heart rate. In some embodiments, the D-max method may further include finding a linear equation from the first measured lactate concentration (e.g., a starting point) to the last measured lactate concentration (e.g., an ending point). In some embodiments, the D-max method may further include finding the D-max point on the best-fitted line (e.g., regression curve) furthest from the line connecting the first measured lactate concentration (e.g., start point) to the last measured lactate concentration (e.g., end point), where the D-max point lies tangent to a curve parallel to the line connecting the first measured lactate concentration (e.g., start point) to the last measured lactate concentration (e.g., end point). In some embodiments, the D-max point provides an anaerobic threshold with respect to (i) lactate concentration and (ii) power or heart rate.

[0116] In some embodiments, the processor is configured to determine the 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 another suitable starting point). That is, in some embodiments, the modified D-max method may include finding a linear equation that connects a lactate concentration of 0.4 mM (e.g., the starting point) to the last measured lactate concentration (e.g., the ending point). 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 lactate concentrations plotted against power or heart rate. In some embodiments, a cubic polynomial function may provide the best-fit line (e.g., a regression curve) based on multiple lactate concentrations plotted against power or heart rate. In some embodiments, the modified D-max method further includes finding a D-max point on a fitted line (e.g., a regression curve) that is furthest from a straight line connecting a 0.4 mM lactate concentration (e.g., a start point) to the last measured lactate concentration (e.g., an end point) and is tangent to a curve parallel to the straight line connecting a 0.4 mM lactate concentration (e.g., a start point) to the last measured lactate concentration (e.g., an end point). In some embodiments, the D-max point provides an anaerobic threshold with respect to (i) lactate concentration and (ii) power or heart rate.

[0117] In some embodiments, the processor is configured to determine an anaerobic working threshold based on multiple lactate concentrations using a piecewise linear regression model. In some embodiments, the processor is configured to determine an anaerobic working threshold based on multiple lactate concentrations using a broken stick model, as shown in Figures 10A-10B. In some embodiments, the broken stick model may include dividing the multiple lactate concentrations into two data groups and performing regression analysis to find the best-fitted line for each data group connected by breakpoints. In some embodiments, finding the best-fitted line for each data group may include minimizing the sum of squared errors (SSE), also known as the sum of squared residuals (RSS), across both groups of data points by varying the membership of the data points within each group. In some embodiments, the breakpoints provide an anaerobic working threshold with respect to (i) lactate concentration and (ii) power or heart rate.

[0118] In some embodiments, the method may include repeating lactate threshold tests with smaller incremental increases in power or heart rate to refine the determination of the aerobic or anaerobic threshold. In some embodiments, the initial lactate threshold test may be performed by measuring lactate in 25-watt increments, and the lactate threshold test may be repeated using smaller incremental increases, e.g., 20-watt or 10-watt increments. In some embodiments, the initial lactate threshold test may be performed by measuring lactate in 20-watt increments, and the lactate threshold test may be repeated using smaller incremental increases, e.g., 10-watt or 5-watt increments.

[0119] In some embodiments, the method may further include repeating the lactate threshold test for about 1 week, 2 weeks, 3 weeks, 4 weeks, 5 weeks, 6 weeks, 7 weeks, 8 weeks, 9 weeks, 10 weeks, 12 weeks, 14 weeks, 16 weeks, 1 month, 2 months, 3 months, 4 months, 5 months, 6 months, 9 months, or about 1 year. In some embodiments, the processor is configured to compare the aerobic and anaerobic thresholds determined from previous lactate threshold tests with the results from the most recent test. The processor output may be numerical and / or graphical for tracking progress. Notification to the wearer of the lactate-responsive sensor or other parties may be auditory, tactile (tactile), or any combination thereof.

[0120] This disclosure is further illustrated by the following embodiments. (1) Substrate and A first working electrode located on the substrate, A second working electrode located on the substrate, A lactate-responsive sensing area is disposed on the surface of the first working electrode, A glucose-responsive sensing area is disposed on the surface of the second working electrode, A first film that is permeable to lactic acid covers the lactic acid-responsive sensing area, The system comprises a second membrane that is permeable to glucose and covers the glucose-responsive sensing area and the lactate-responsive sensing area, An analyte sensor configured to be partially inserted into an individual's skin.

[0121] (2) The analyte sensor according to (1), wherein the lactic acid-responsive sensing area contains lactate oxidase. (3) The analyte sensor according to (1) or (2), wherein the lactic acid-responsive sensing area comprises a first polymer and a first electron transfer agent.

[0122] (4) The analyte sensor according to (3), wherein the first electron transfer agent is covalently bonded to the first polymer. (5) The analyte sensor according to (3) or (4), wherein the first electron transfer agent comprises an osmium complex.

[0123] (6) The analyte sensor according to any one of (3) to (5), wherein the first polymer is a poly(4-vinylpyridine) polymer. (7) The analyte sensor according to any one of (3) to (6), wherein the lactic acid-responsive sensing area further comprises a first crosslinking agent.

[0124] (8) The analyte sensor according to (7), wherein the first crosslinking agent is polyethylene glycol diglycidyl ether (PEGDGE). (9) The analyte sensor according to any one of (1) to (8), wherein the glucose-responsive sensing area contains glucose oxidase.

[0125] (10) The analyte sensor according to any one of (1) to (9), wherein the glucose-responsive sensing area comprises a second polymer and a second electron transfer agent. (11) The analyte sensor according to (10), wherein the second electron transfer agent is covalently bonded to the second polymer.

[0126] (12) The analyte sensor according to (10) or (11), wherein the second electron transfer agent comprises an osmium complex. (13) The analyte sensor according to any one of (10) to (12), wherein the second polymer is a poly(4-vinylpyridine) polymer.

[0127] (14) The analyte sensor according to any one of (10) to (13), wherein the glucose-responsive sensing area further comprises a second crosslinking agent. (15) The analyte sensor according to (14), wherein the second crosslinking agent is PEGDGE.

[0128] (16) The analyte sensor according to (1) to (15), wherein the sensor further includes a reference electrode. (17) The analyte sensor according to (1) to (16), wherein the sensor further includes a counter electrode.

[0129] (18) The analyte sensor according to (1) to (17), wherein the first membrane and the second membrane have different compositions. (19) The analyte sensor according to (1) to (18), wherein the first membrane comprises a polyvinylpyridine homopolymer or copolymer.

[0130] (20) The analyte sensor according to (19), wherein the first membrane further comprises a first crosslinking material. (21) The analyte sensor according to (20), wherein the first crosslinking substance is polyethylene glycol diglycidyl ether (PEGDGE).

[0131] (22) The analyte sensor according to (1) to (21), wherein the second membrane comprises a polyvinylpyridine-costyrene polymer. (23) The analyte sensor according to (22), wherein the second film further comprises a second crosslinking material.

[0132] (24) The analyte sensor according to (23), wherein the second crosslinking substance is glycerol triglycidyl ether. (25) Exposing the analyte sensor of the sensing system to a fluid, the analyte sensor is base material, A first working electrode located on the substrate, A second working electrode located on the substrate, A lactate-responsive sensing area disposed on the surface of the first working electrode, A glucose-responsive sensing area disposed on the surface of the second working electrode, A first film that is permeable to lactic acid, covering the lactic acid-responsive sensing area, and The glucose-responsive sensing area and the lactate-responsive sensing area are covered by a second membrane that is permeable to glucose, The sensor is configured to be partially inserted into the skin of an individual, and is exposed to, Applying a potential to the first working electrode of the analyte sensor, The acquisition of a first signal that is greater than or equal to the oxidation-reduction potential of the lactic acid-responsive sensing area, wherein the signal is proportional to the lactic acid concentration in the fluid. A method for monitoring lactic acid levels in an individual, comprising correlating the signal with the lactic acid concentration in the fluid.

[0133] (26) To acquire a second signal that is greater than or equal to the redox potential of the glucose-responsive sensing area, wherein the signal is proportional to the glucose concentration in the fluid. The method according to (25), further comprising correlating the second signal with the glucose concentration in the fluid.

[0134] (27) The method according to (25) or (26), wherein the lactate-responsive sensing area contains lactate oxidase. (28) The method according to any one of (25) to (27), wherein the lactic acid-responsive sensing area comprises a first polymer and a first electron transfer agent.

[0135] (29) The method according to (28), wherein the first electron transfer agent is covalently bonded to the first polymer. (30) The method according to (28) or (29), wherein the first electron transfer agent comprises an osmium complex.

[0136] (31) The method according to any one of (28) to (30), wherein the first polymer is a poly(4-vinylpyridine) polymer. (32) The method according to any one of (28) to (31), wherein the lactic acid-responsive sensing area further comprises a first crosslinking agent.

[0137] (33) The method according to (32), wherein the first crosslinking agent is PEGDGE. (34) The method according to any one of (25) to (33), wherein the glucose-responsive sensing area contains glucose oxidase.

[0138] (35) The method according to any one of (25) to (34), wherein the glucose-responsive sensing area comprises a second polymer and a second electron transfer agent. (36) The method according to (35), wherein the second electron transfer agent is covalently bonded to the second polymer.

[0139] (37) The method according to (35) or (36), wherein the second electron transfer agent comprises an osmium complex. (38) The method according to any one of (35) to (37), wherein the second polymer is a poly(4-vinylpyridine) polymer.

[0140] (39) The method according to any one of (35) to (38), wherein the glucose-responsive sensing area further comprises a second crosslinking agent. (40) The method according to (39), wherein the second crosslinking agent is PEGDGE.

[0141] (41) The method according to (25) to (40), wherein the sensor further includes a reference electrode. (42) The method according to (25) to (41), wherein the sensor further includes a counter electrode. (43) The method according to (25) to (42), wherein the first film and the second film have different compositions.

[0142] (44) The method according to (25) to (43), wherein the first film comprises a polyvinylpyridine homopolymer or copolymer. (45) The method according to (44), wherein the first film further comprises a first crosslinking material.

[0143] (46) The method according to (45), wherein the first crosslinking substance is polyethylene glycol diglycidyl ether (PEGDGE). (47) The method according to (25) to (46), wherein the second membrane comprises a polyvinylpyridine-co-styrene polymer.

[0144] (48) The method according to (47), wherein the second film further comprises a second crosslinking material. (49) The method according to (48), wherein the second crosslinking substance is glycerol triglycidyl ether.

[0145] (50) Using a sensing system equipped with a lactate-responsive sensor, continuously measure a signal indicating the lactate concentration in the body fluids of an individual, The signal indicating the lactic acid concentration measured by the lactic acid responsive sensor is communicated to the processor, A method for determining an anaerobic threshold in an individual, comprising determining the anaerobic threshold based on the signal indicating lactic acid concentration.

[0146] (51) The method according to (50), wherein the individual is performing a lactate threshold test. (52) The lactate threshold test is a step test with a gradual increase in power, as described in (51).

[0147] (53) The method according to any one of (50) to (52), wherein the anaerobic work threshold is determined by the processor using a broken bar model. (54) The method according to any one of (50) to (53), wherein the anaerobic work threshold is determined by the processor using the D-max method.

[0148] (55) The method according to any one of (50) to (54), wherein the anaerobic work threshold is determined by the processor using a modified D-max method. (56) The method according to any one of (50) to (55), wherein the continuous measurement of a signal indicating lactate concentration includes measuring a signal indicating lactate concentration approximately every 10 seconds, every 15 seconds, every 20 seconds, every 30 seconds, every 45 seconds, every 1 minute, every 1.5 minutes, every 2 minutes, every 3 minutes, every 5 minutes, every 10 minutes, every 15 minutes, every 20 minutes, every 30 minutes, every 45 minutes, every 1 hour, every 2 hours, or every 3 hours.

[0149] (57) The method according to any one of (50) to (56), wherein the continuous measurement of a signal indicating lactate concentration includes measuring a signal indicating lactate concentration approximately every minute. (58) The method according to any one of (50) to (55), wherein the lactic acid-responsive sensor is the sensor described in any one of (1) to (24).

[0150] (59) Using a sensing system equipped with a lactate-responsive sensor, continuously measure a signal indicating the lactate concentration in an individual's biological fluids, The signal indicating the lactic acid concentration measured by the lactic acid responsive sensor is communicated to the processor, A method for determining an aerobic work threshold in an individual, comprising determining the aerobic work threshold based on the signal indicating lactic acid concentration.

[0151] (60) The method according to (59), wherein the individual is performing a lactate threshold test. (61) The method according to (60), wherein the lactate work threshold test is a step test with a gradual increase in power.

[0152] (62) The method according to any one of (59) to (61), wherein the aerobic work threshold is defined as a fixed value. (63) The method according to (62), wherein the aerobic work threshold is defined as baseline lactate concentration + approximately 0.5 mM lactate.

[0153] (64) The method according to (62), wherein the aerobic work threshold is defined as baseline lactate concentration + approximately 1 mM lactate. (65) The method according to any one of (59) to (61), wherein the aerobic work threshold is determined by the processor using a log-log model.

[0154] (66) The method according to any one of (59) to (61), wherein the aerobic work threshold is determined by the processor using segmented regression analysis. (67) The method according to any one of (59) to (66), wherein the continuous measurement of a signal indicating lactate concentration includes measuring a signal indicating lactate concentration approximately every 10 seconds, every 15 seconds, every 20 seconds, every 30 seconds, every 45 seconds, every 1 minute, every 1.5 minutes, every 2 minutes, every 3 minutes, every 5 minutes, every 10 minutes, every 15 minutes, every 20 minutes, every 30 minutes, every 45 minutes, every 1 hour, every 2 hours, or every 3 hours.

[0155] (68) The method according to any one of (59) to (67), wherein the continuous measurement of a signal indicating lactate concentration includes measuring a signal indicating lactate concentration approximately every minute. (69) The method according to any one of (59) to (68), wherein the lactic acid-responsive sensor is the sensor described in any one of (1 to 24).

[0156] A sensor control device comprising a sensor described in any one of (70)(1) to (24) and a processor communicatively coupled to the sensor. (71) A sensor control device of (70), wherein the sensor is configured to continuously measure a signal indicating the concentration of lactic acid in an individual's biological fluid and to communicate the signal indicating the lactic acid concentration to the processor.

[0157] (72) The sensor control device according to (71), wherein the processor is configured to determine an aerobic working threshold, an anaerobic working threshold, or both, based on the signal indicating the lactic acid concentration.

[0158] (73) The user is performing a lactate threshold test using the sensor control device described in (72). (74) The lactic acid work threshold test is a step test with a gradual increase in power, as described in (73) for the sensor control device.

[0159] (75) The sensor control device according to any one of (72) to (74), wherein the anaerobic work threshold is determined by the processor using a broken bar model. (76) The sensor control device according to any one of (72) to (74), wherein the anaerobic work threshold is determined by the processor using the D-max method.

[0160] (77) The sensor control device according to any one of (72) to (74), wherein the anaerobic work threshold is determined by the processor using a modified D-max method. (78) The sensor control device according to any one of (72) to (77), wherein the aerobic work threshold is defined as a fixed value.

[0161] (79) The sensor control device according to (79), wherein the aerobic work threshold is defined as baseline lactate concentration + approximately 0.5 mM lactate. (80) The sensor control device according to (79), wherein the aerobic work threshold is defined as baseline lactate concentration + approximately 1 mM lactate.

[0162] (81) The sensor control device according to any one of (72) to (78), wherein the aerobic work threshold is determined by the processor using a log-log model. (82) The sensor control device according to any one of (72) to (78), wherein the aerobic work threshold is determined by the processor using segmented regression analysis.

[0163] (83) A sensor control device according to any one of (70) to (82), wherein the sensor is configured to continuously measure a signal indicating lactic acid concentration at intervals of approximately 10 seconds, 15 seconds, 20 seconds, 30 seconds, 45 seconds, 1 minute, 1.5 minutes, 2 minutes, 3 minutes, 5 minutes, 10 minutes, 15 minutes, 20 minutes, 30 minutes, 45 minutes, 1 hour, 2 hours, or 3 hours.

[0164] (84) The sensor control device according to any one of (70) to (83), wherein the sensor is configured to continuously measure a signal indicating lactic acid concentration at intervals of approximately one minute. A sensing system comprising a sensor control device described in any one of (85)(70) to (84) and a reader device.

[0165] (86) A proximal portion configured to be positioned on the user's skin, A distal portion configured to be positioned transcutaneously through the user's skin, base material, A first working electrode located on the substrate, A second working electrode located on the substrate, A lactate-responsive sensing area disposed on the surface of the first working electrode, A glucose-responsive sensing area disposed on the surface of the second working electrode, A first film that is permeable to lactic acid, covering the lactic acid-responsive sensing area, and An analyte sensor comprising: a distal portion having a second membrane that is permeable to glucose and covers the glucose-responsive sensing area and the lactate-responsive sensing area.

[0166] (87) The analyte sensor according to (86), wherein the lactic acid-responsive sensing area contains lactate oxidase. (88) The analyte sensor according to (86) or (87), wherein the lactic acid-responsive sensing area comprises a first polymer and a first electron transfer agent.

[0167] (89) The analyte sensor according to (88), wherein the first electron transfer agent is covalently bonded to the first polymer. (90) The analyte sensor according to (88) or (89), wherein the first electron transfer agent comprises an osmium complex.

[0168] (91) The analyte sensor according to any one of (88) to (90), wherein the first polymer is a poly(4-vinylpyridine) polymer. (92) The analyte sensor according to any one of (88) to (91), wherein the lactic acid-responsive sensing area further comprises a first crosslinking agent.

[0169] (93) The analyte sensor according to (92), wherein the second crosslinking agent is PEGDGE. (94) The analyte sensor according to any one of (86) to (93), wherein the glucose-responsive sensing area contains glucose oxidase.

[0170] (95) The analyte sensor according to any one of (86) to (94), wherein the glucose-responsive sensing area comprises a second polymer and a second electron transfer agent. (96) The analyte sensor according to (95), wherein the second electron transfer agent is covalently bonded to the second polymer.

[0171] (97) The analyte sensor according to (95) or (96), wherein the second electron transfer agent comprises an osmium complex. (98) The analyte sensor according to any one of (95) to (97), wherein the second polymer is a poly(4-vinylpyridine) polymer.

[0172] (99) The analyte sensor according to any one of (95) to (98), wherein the glucose-responsive sensing area further comprises a second crosslinking agent. (100) The analyte sensor according to (99), wherein the second crosslinking agent is PEGDGE.

[0173] (101) The analyte sensor according to (86) to (100), wherein the sensor further includes a reference electrode. (102) The analyte sensor according to (86) to (101), wherein the sensor further includes a counter electrode.

[0174] (103) The analyte sensor according to (86) to (102), wherein the first film and the second film have different compositions. (104) The analyte sensor according to (86) to (103), wherein the first membrane comprises a polyvinylpyridine homopolymer or copolymer.

[0175] (105) The analytical sensor according to (104), wherein the first membrane further comprises a first crosslinking material. (106) The analyte sensor according to (105), wherein the first crosslinking material is PEGDGE.

[0176] (107) The analyte sensor according to (86) to (106), wherein the second membrane comprises a polyvinylpyridine-co-styrene polymer. (108) The analyte sensor according to (107), wherein the second membrane further comprises a second crosslinking material.

[0177] (109) The analyte sensor according to (108), wherein the second crosslinking substance is glycerol triglycidyl ether. (110) Exposing an analyte sensor of a sensing system to a fluid, wherein the analyte sensor comprises a proximal portion configured to be positioned on the user's skin and a distal portion configured to be positioned transcutaneously through the user's skin, the distal portion base material, A first working electrode located on the substrate, A second working electrode located on the substrate, A lactate-responsive sensing area disposed on the surface of the first working electrode, A glucose-responsive sensing area disposed on the surface of the second working electrode, A first film that is permeable to lactic acid, covering the lactic acid-responsive sensing area, and The device comprises a second membrane that is permeable to glucose and covers the glucose-responsive sensing area and the lactate-responsive sensing area, and is exposed to exposure. Applying a potential to the first working electrode of the analyte sensor, The acquisition of a first signal that is greater than or equal to the oxidation-reduction potential of the lactic acid-responsive sensing area, wherein the signal is proportional to the lactic acid concentration in the fluid. A method for monitoring a user's lactic acid level, comprising correlating the aforementioned signal with the lactic acid concentration in the fluid.

[0178] (111) To acquire a second signal that is greater than or equal to the redox potential of the glucose-responsive sensing area, wherein the signal is proportional to the glucose concentration in the fluid. The method according to (110), further comprising correlating the second signal with the glucose concentration in the fluid.

[0179] (112) The method according to (110) or (111), wherein the lactate-responsive sensing area contains lactate oxidase. (113) The method according to any one of (110) to (112), wherein the lactic acid-responsive sensing area comprises a first polymer and a first electron transfer agent.

[0180] (114) The method according to (113), wherein the first electron transfer agent is covalently bonded to the first polymer. (115) The method according to (113) or (114), wherein the first electron transfer agent comprises an osmium complex.

[0181] (116) The method according to any one of (113) to (115), wherein the first polymer is a poly(4-vinylpyridine) polymer. (117) The method according to any one of (113) to (116), wherein the lactic acid-responsive sensing area further comprises a first crosslinking agent.

[0182] (118) The method according to (115), wherein the first crosslinking agent is PEGDGE. (119) The method according to any one of (110) to (118), wherein the glucose-responsive sensing area contains glucose oxidase.

[0183] (120) The method according to any one of (110) to (119), wherein the glucose-responsive sensing area comprises a second polymer and a second electron transfer agent. (121) The method according to (120), wherein the second electron transfer agent is covalently bonded to the second polymer.

[0184] (122) The method according to (120) or (121), wherein the second electron transfer agent comprises an osmium complex. (123) The method according to any one of (120) to (122), wherein the second polymer is a poly(4-vinylpyridine) polymer.

[0185] (124) The method according to any one of (120-123), wherein the glucose-responsive sensing area further comprises a second crosslinking agent. (125) The method according to (124), wherein the second crosslinking agent is PEGDGE.

[0186] (126) The method according to (110) to (125), wherein the sensor further includes a reference electrode. (127) The method according to (110) to (126), wherein the sensor further includes a counter electrode.

[0187] (128) The method according to (110) to (127), wherein the first film and the second film have different compositions. (129) The method according to (110) to (128), wherein the first film comprises a polyvinylpyridine homopolymer or copolymer.

[0188] (130) The method according to (129), wherein the first film further comprises a first crosslinking material. (131) The method according to (130), wherein the first crosslinking substance is polyethylene glycol diglycidyl ether (PEGDGE).

[0189] (132) The method according to (110) to (131), wherein the second membrane comprises a polyvinylpyridine-costyrene polymer. (133) The method according to (132), wherein the second film further comprises a second crosslinking material.

[0190] (134) The method according to (133), wherein the second crosslinking substance is glycerol triglycidyl ether. (135) Using a sensing system equipped with a lactate-responsive sensor, continuously measure a signal indicating the lactate concentration in an individual's biological fluids, The signal indicating the lactic acid concentration measured by the lactic acid responsive sensor is communicated to the processor, A method for determining an anaerobic work threshold in an individual, comprising determining an anaerobic work threshold based on a signal indicating lactic acid concentration using the processor.

[0191] (136) The method according to (135), wherein the individual is performing a lactate threshold test. (137) The method according to (136), wherein the lactate work threshold test is a step test with a gradual increase in power.

[0192] (138) The method according to any one of (135) to (137), wherein the anaerobic work threshold is determined by the processor using a broken bar model. (139) The anaerobic work threshold is determined by the processor using the D-max method, according to any one of (135) to (137).

[0193] (140) The method according to any one of (135) to (137), wherein the anaerobic work threshold is determined by the processor using a modified D-max method. (141) The method according to any one of (135) to (140), wherein the continuous measurement of a signal indicating lactate concentration includes measuring a signal indicating lactate concentration approximately every 10 seconds, every 15 seconds, every 20 seconds, every 30 seconds, every 45 seconds, every 1 minute, every 1.5 minutes, every 2 minutes, every 3 minutes, every 5 minutes, every 10 minutes, every 15 minutes, every 20 minutes, every 30 minutes, every 45 minutes, every 1 hour, every 2 hours, or every 3 hours.

[0194] (142) The method according to any one of (135) to (141), wherein the continuous measurement of a signal indicating lactate concentration includes measuring a signal indicating lactate concentration approximately every minute. (143) The method according to any one of (135) to (142), wherein the lactic acid-responsive sensor is the sensor described in any one of (1) to (24).

[0195] (144) The method according to any one of (135) to (142), wherein the lactic acid-responsive sensor is the sensor described in any one of (86) to (109). (145) Using a sensing system equipped with a lactate-responsive sensor, continuously measure a signal indicating the lactate concentration in an individual's biological fluids, The signal indicating the lactic acid concentration is communicated to the processor, A method for determining an aerobic work threshold in an individual, comprising determining the aerobic work threshold based on the signal indicating lactic acid concentration.

[0196] (146) The method according to (145), wherein the individual is performing a lactate threshold test. (147) The method according to (146), wherein the lactate work threshold test is a step test with a gradual increase in power.

[0197] (148) The method according to any one of (145) to (147), wherein the aerobic work threshold is defined as a fixed value. (149) The method according to (148), wherein the aerobic work threshold is defined as baseline lactate concentration + approximately 0.5 mM lactate.

[0198] (150) The method according to (148), wherein the aerobic work threshold is defined as baseline lactate concentration + approximately 1 mM lactate. (151) The aerobic work threshold is determined by the processor using a log-log model, according to any one of (145) to (147).

[0199] (152) The method according to any one of (145) to (147), wherein the aerobic work threshold is determined by the processor using segmented regression analysis. (153) The method according to any one of (145) to (152), wherein the continuous measurement of a signal indicating lactate concentration includes measuring a signal indicating lactate concentration approximately every 10 seconds, every 15 seconds, every 20 seconds, every 30 seconds, every 45 seconds, every 1 minute, every 1.5 minutes, every 2 minutes, every 3 minutes, every 5 minutes, every 10 minutes, every 15 minutes, every 20 minutes, every 30 minutes, every 45 minutes, every 1 hour, every 2 hours, or every 3 hours.

[0200] (154) The method according to any one of (145) to (153), wherein the continuous measurement of a signal indicating lactate concentration includes measuring a signal indicating lactate concentration approximately every minute. (155) The method according to any one of (145) to (154), wherein the lactic acid-responsive sensor is the sensor described in any one of (1) to (24).

[0201] (156) The method according to any one of (145) to (154), wherein the lactic acid-responsive sensor is the sensor described in any one of (86) to (109). A sensor control device comprising a sensor described in any one of (157)(81) to (104) and a processor communicatively coupled to the sensor.

[0202] (158) A sensor control device according to (157), wherein the sensor is configured to continuously measure a signal indicating the lactic acid concentration in the user's biological fluid and to communicate the signal indicating the lactic acid concentration to the processor.

[0203] (159) The sensor control device according to (158), wherein the processor is configured to determine an aerobic working threshold, an anaerobic working threshold, or both, based on the signal indicating a lactic acid concentration.

[0204] (160) The user is performing a lactate threshold test with the sensor control device described in (159). (161) The lactic acid work threshold test is a step test with a gradual increase in power, as described in (160) for the sensor control device.

[0205] (162) The sensor control device according to any one of (159) to (161), wherein the anaerobic work threshold is determined by the processor using a broken bar model. (163) The sensor control device according to any one of (159) to (161), wherein the anaerobic work threshold is determined by the processor using the D-max method.

[0206] (164) The sensor control device according to any one of (159) to (161), wherein the anaerobic work threshold is determined by the processor using a modified D-max method. (165) The sensor control device according to any one of (159) to (164), wherein the aerobic work threshold is defined as a fixed value.

[0207] (166) The sensor control device according to (165), wherein the aerobic work threshold is defined as baseline lactate concentration + approximately 0.5 mM lactate. (167) The sensor control device according to (153), wherein the aerobic work threshold is defined as baseline lactate concentration + approximately 1 mM lactate.

[0208] (168) The sensor control device according to any one of (159) to (164), wherein the aerobic work threshold is determined by the processor using a log-log model. (169) The sensor control device according to any one of (159) to (164), wherein the aerobic work threshold is determined by the processor using segmented regression analysis.

[0209] (170) A sensor control device according to any one of (157) to (169), wherein the sensor is configured to continuously measure a signal indicating lactic acid concentration at intervals of approximately 10 seconds, 15 seconds, 20 seconds, 30 seconds, 45 seconds, 1 minute, 1.5 minutes, 2 minutes, 3 minutes, 5 minutes, 10 minutes, 15 minutes, 20 minutes, 30 minutes, 45 minutes, 1 hour, 2 hours, or 3 hours.

[0210] (171) The sensor control device according to any one of (157) to (170), wherein the sensor is configured to continuously measure a signal indicating lactic acid concentration at intervals of approximately one minute. A sensing system comprising a sensor control device as described in any one of (172), (157), or (171).

[0211] (173) A lactate-responsive sensor comprising a proximal portion configured to be positioned on the user's skin and a distal portion configured to be positioned transcutaneously through the user's skin and to be in contact with the user's biological fluid, wherein the lactate-responsive sensor is configured to continuously measure a signal indicating the lactate concentration in the user's biological fluid and to communicate the signal indicating the lactate concentration to a processor, A sensor control device comprising: a processor configured to determine an aerobic working threshold, an anaerobic working threshold, or both, based on the signal indicating lactic acid concentration.

[0212] (174) The user is performing a lactate threshold test using the sensor control device described in (173). (175) The lactic acid work threshold test is a step test with a gradual increase in power, as described in (174) for the sensor control device.

[0213] (176) The sensor control device according to any one of (173) to (175), wherein the anaerobic work threshold is determined by the processor using a broken bar model. (177) The sensor control device according to any one of (173) to (175), wherein the anaerobic work threshold is determined by the processor using the D-max method.

[0214] (178) The sensor control device according to any one of (173) to (175), wherein the anaerobic work threshold is determined by the processor using a modified D-max method. (179) The aerobic work threshold is defined as a fixed value, as described in any one of (173) to (168), for the sensor control device.

[0215] (180) The sensor control device according to (179), wherein the aerobic work threshold is defined as baseline lactate concentration + approximately 0.5 mM lactate. (181) The sensor control device according to (179), wherein the aerobic work threshold is defined as baseline lactate concentration + approximately 1 mM lactate.

[0216] (182) The sensor control device according to any one of (173) to (178), wherein the aerobic work threshold is determined by the processor using a log-log model. (183) The sensor control device according to any one of (173) to (178), wherein the aerobic work threshold is determined by the processor using segmented regression analysis.

[0217] (184) A sensor control device according to any one of (173) to (183), wherein the sensor is configured to continuously measure a signal indicating lactic acid concentration at intervals of approximately 10 seconds, 15 seconds, 20 seconds, 30 seconds, 45 seconds, 1 minute, 1.5 minutes, 2 minutes, 3 minutes, 5 minutes, 10 minutes, 15 minutes, 20 minutes, 30 minutes, 45 minutes, 1 hour, 2 hours, or 3 hours.

[0218] (185) A sensor control device according to any one of (173) to (184), wherein the sensor is configured to continuously measure a signal indicating lactic acid concentration at intervals of approximately one minute. (186) The distal portion Substrate and A first working electrode located on the substrate, A second working electrode located on the substrate, A lactate-responsive sensing area is disposed on the surface of the first working electrode, A glucose-responsive sensing area is disposed on the surface of the second working electrode, a first membrane that covers the lactic acid-responsive sensing area and is permeable to lactic acid; a second membrane that covers the glucose-responsive sensing area and the lactic acid-responsive sensing area and is permeable to glucose, the sensor control device according to any one of (173) to (185).

[0219] (187) The sensor control device according to (186), wherein the lactic acid-responsive sensing area comprises lactate oxidase. (188) The sensor control device according to (186) or (187), wherein the lactic acid-responsive sensing area comprises a first polymer and a first electron transfer agent.

[0220] (189) The sensor control device according to (188), wherein the first electron transfer agent is covalently bonded to the first polymer. (190) The sensor control device according to (188) or (189), wherein the first electron transfer agent comprises an osmium complex.

[0221] (191) The sensor control device according to any one of (188) to (190), wherein the first polymer is a poly(4-vinylpyridine)-based polymer. (192) The sensor control device according to any one of (188) to (191), wherein the lactic acid-responsive sensing area further comprises a first crosslinking agent.

[0222] (193) The sensor control device according to (192), wherein the first crosslinking agent is PEGDGE. (194) The sensor control device according to any one of (186) to (193), wherein the glucose-responsive sensing area comprises glucose oxidase.

[0223] (195) The sensor control device according to any one of (186) to (194), wherein the glucose-responsive sensing area comprises a second polymer and a second electron transfer agent. (196) The sensor control device according to (195), wherein the second electron transfer agent is covalently bonded to the second polymer.

[0224] (197) The sensor control device according to (195) or (196), wherein the second electron transfer agent comprises an osmium complex. (198) The sensor control device according to any one of (195) to (197), wherein the second polymer is a poly(4-vinylpyridine) polymer.

[0225] (199) The sensor control device according to any one of (195) to (198), wherein the glucose-responsive sensing area further comprises a second crosslinking agent. (200) The sensor control device according to (199), wherein the second crosslinking agent is PEGDGE.

[0226] (201) The sensor control device according to (186) to (200), further comprising a reference electrode. (202) The sensor control device according to (186-201), further comprising a counter electrode.

[0227] (203) The sensor control device according to (186) to (202), wherein the first film and the second film have different compositions. (204) The sensor control device according to (186) to (203), wherein the first film comprises a polyvinylpyridine homopolymer or copolymer.

[0228] (205) The sensor control device according to (204), wherein the first film further comprises a first crosslinking material. (206) The sensor control device according to (205), wherein the first crosslinking material is PEGDGE.

[0229] (207) The sensor control device according to (186) to (206), wherein the second membrane comprises a polyvinylpyridine-co-styrene polymer. (208) The sensor control device according to (207), wherein the second film further comprises a second crosslinking material.

[0230] (209) The sensor control device according to (208), wherein the second crosslinking material is glycerol triglycidyl ether. Examples The embodiments presented below are provided for illustrative purposes only, and the embodiments described herein should not be construed as being limited to these embodiments. Rather, the embodiments should be construed as encompassing all possible variations that become apparent as a result of the teachings provided herein.

[0231] Example 1 A post-hoc analysis of results from 103 individuals and 286 evaluable sensors in four previous clinical studies was performed to assess the accuracy of anaerobic lactate threshold (LT2) determination using simultaneous glucose monitoring with a subcutaneous lactate / glucose dual biosensor. The lactate / glucose sensor design is shown in Figure 6. To be eligible to participate in the clinical trial, individuals had to agree to routinely engage in at least approximately 150 minutes of moderate-intensity aerobic physical activity or at least approximately 75 minutes of vigorous-intensity aerobic physical activity per week at the time of the trial, and to engage in moderate and / or vigorous physical activity during clinic visits as needed. In addition, individuals who regularly used a bicycle in their exercise regimen were preferred.

[0232] The individual performed one of two tests on a stationary bicycle, as described below. The first test was based on an increasing-intensity exercise protocol that included the following phases. Baseline phase: Resting lactate levels were established before the individual began their required exercise routine; Gradual effort phase: Subjects completed up to eight intervals increasing in intensity (from 30 watts to 240 watts in 30-watt steps). Individuals proceeded to the sustained effort phase after (i) their lactate level reached 5.5 mM or higher, or (ii) after they completed all eight intervals. Individuals stopped at any point at their request or at the discretion of the principal investigator; Sustained effort phase: Subjects completed two intervals at approximately 85% of the maximum pace they could sustain, or 85% of the maximum effort achieved when a lactate level of 5.5 mM was determined by the sensor; Cool-down phase: Lactate monitoring was continued during the cool-down exercise while lactate levels decreased; Resting phase: Lactate monitoring was continued until lactate levels returned to baseline.

[0233] The incremental exercise protocol is summarized in Table 1.

[0234] [Table 1]

[0235] The second trial was based on an endurance exercise protocol that included the following phases. Baseline phase: Resting lactate levels were established before the individual began their required exercise routine; Exercise Phase: Subjects began exercising at 30W and then progressed to the next power setting (60, 90, 120, 150, 180, 210, and 240W) at 5-minute intervals, unless their lactate level exceeded 2.6mM. If the lactate level was 2.6mM or higher but less than 3.1mM, the power setting for the next step was +10W from the step just completed. If the lactate level was 3.1mM or higher but less than 4.5mM, the power setting for the next step depended on the lactate level prior to this result. Specifically, if the previous lactate result was less than 3.1mM (i.e., the lactate level had risen from the previous lactate result), the power setting for the next step was -10W from the step just completed. If the previous lactate result was approximately 3.1–4.5 mM (i.e., the lactate level was constant relative to the previous lactate result) or greater than 4.5 mM (i.e., the lactate level decreased from the previous lactate result), the power setting for the next step was the same as the step just completed; Rest phase: Lactate monitoring was continued until the lactate level returned to baseline.

[0236] The endurance exercise protocol is summarized in Table 2.

[0237]

Table 2

[0238] Figure 11 shows a graph of an individual's lactate level detected by the sensor over 128 hours, compared with a blood lactate test using a venous blood sample. Figure 12 shows a graph of glucose level of the same individual detected by the sensor over 77 hours, compared with a blood glucose test. The blood glucose test was performed using a YSI analyzer. The sensor was worn for 15 days and detected lactate levels and glucose levels with high correlation to those measured in blood samples.

[0239] As shown in Figure 13, the anaerobic threshold measurement value obtained by the sensor has a high correlation (R 2 of approximately 0.8) compared with that measured from blood samples. More than 88% of the anaerobic threshold measurement values obtained by the sensor are within 20% of the anaerobic threshold measurement values obtained by the blood lactate test, which has a low absolute error of approximately 10% (Figure 14).

[0240] Example 2 Formulation for lactate-responsive sensing area deposition: Lactate oxidase was combined with osmium-containing poly(4-vinylpyridine)-based polymer (Os-PVP) in an aqueous formulation as specified in Tables 3 and 4 shown below.

[0241]

Table 3

[0242]

Table 4

[0243] It should be understood that the section describing embodiments for carrying out the invention, rather than the section describing the summary and abstract of the invention, is intended to be used to interpret the claims. The section describing the summary and abstract of the invention may describe one or more exemplary embodiments of the invention as contemplated by the inventor(s) but may not describe all exemplary embodiments and is therefore not intended to limit the scope of the invention and the appended claims.

[0244] This disclosure is described above using functional components that demonstrate the implementation of specific functions and their relationships. The boundaries of these functional components are arbitrarily defined herein for the sake of clarity. Alternative boundaries may be defined, provided that the specified functions and their relationships are adequately performed.

[0245] The foregoing description of specific embodiments sufficiently reveals the general nature of the invention so that others can readily modify and / or adapt such specific embodiments for various uses without excessive experimentation and without departing from the general concept of the invention, by applying the knowledge of those skilled in the art. Such adaptations and modifications are therefore intended to be within the meaning and scope of equivalents of the disclosed embodiments, based on the teachings and guidance presented herein. It should be understood that the expressions or terms herein are for illustrative purposes only, not limiting purposes, and therefore should be interpreted by those skilled in the art in light of the teachings and guidance.

[0246] The breadth and scope of the present invention should not be limited by any of the exemplary embodiments described above, but should be defined solely in accordance with the following claims and their equivalents.

[0247] The claims in this application are different from the claims of the parent application or any other related application. Therefore, the applicant withdraws any abandonment of claims made in the parent application or any prior application related to this application. Accordingly, the examiner is advised that it may need to revisit any such previous abandonment and any references made to avoid it. Furthermore, the examiner should also be reminded that any abandonment made in this application should not be read against the parent application.

[0248] Where used herein, the phrase “in some embodiments” relating to a feature means that the feature may be present in any embodiment, provided that the feature is not obviously technically incompatible with that embodiment. Furthermore, any subset of features from one embodiment may be combined in any combination with any subset of features from any other embodiment, provided that such combination is not obviously technically incompatible.

Claims

1. Substrate and A first working electrode located on the substrate, A second working electrode located on the substrate, A lactate-responsive sensing area is disposed on the surface of the first working electrode, A glucose-responsive sensing area is disposed on the surface of the second working electrode, A first film that is permeable to lactic acid covers the lactic acid-responsive sensing area, The system comprises a second membrane that is permeable to glucose and covers the glucose-responsive sensing area and the lactate-responsive sensing area, An analyte sensor configured to be partially inserted into an individual's skin.

2. The analyte sensor according to claim 1, wherein the lactic acid-responsive sensing area contains lactate oxidase.

3. The analyte sensor according to claim 1 or 2, wherein the lactic acid-responsive sensing area comprises a first polymer and a first electron transfer agent.

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

5. The analyte sensor according to any one of claims 1 to 4, wherein the glucose-responsive sensing area includes glucose oxidase.

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

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

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

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

10. Exposing the analyte sensor of the sensing system to a fluid, wherein the analyte sensor base material, A first working electrode located on the substrate, A second working electrode located on the substrate, A lactate-responsive sensing area disposed on the surface of the first working electrode, A glucose-responsive sensing area disposed on the surface of the second working electrode, A first film that is permeable to lactic acid, covering the lactic acid-responsive sensing area, and The glucose-responsive sensing area and the lactate-responsive sensing area are covered by a second membrane that is permeable to glucose, The sensor is configured to be partially inserted into the individual's skin, and is exposed to, Applying a potential to the first working electrode of the analyte sensor, The acquisition of a first signal that is greater than or equal to the oxidation-reduction potential of the lactic acid-responsive sensing area, wherein the signal is proportional to the lactic acid concentration in the fluid. A method for monitoring lactic acid levels in an individual, comprising correlating the signal with the lactic acid concentration in the fluid.

11. The acquisition of a second signal having a redox potential greater than or equal to that of the glucose-responsive sensing area, wherein the signal is proportional to the glucose concentration in the fluid. The method according to claim 10, comprising correlating the second signal with the glucose concentration in the fluid.

12. The method according to claim 10 or 11, wherein the lactic acid-responsive sensing area contains lactate oxidase.

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

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

15. The method according to any one of claims 10 to 14, wherein the glucose-responsive sensing area includes glucose oxidase.

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

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

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

19. The method according to any one of claims 10 to 18, wherein the sensor tail is configured for insertion into tissue.

20. The method according to any one of claims 10 to 19, wherein the first film and the second film have different compositions.

21. Using a sensing system equipped with a lactate-responsive sensor, the system continuously measures signals indicating the lactate concentration in an individual's biological fluids, The signal indicating the lactic acid concentration measured by the lactic acid responsive sensor is communicated to the processor, A method for determining an anaerobic threshold in an individual, comprising determining the anaerobic threshold based on the signal indicating lactic acid concentration.

22. The method according to claim 21, wherein the individual is performing a lactate threshold test.

23. The method according to claim 22, wherein the lactate work threshold test is a step test involving a gradual increase in power.

24. The method according to any one of claims 21 to 23, wherein the anaerobic work threshold is determined by the processor using a broken bar model.

25. The method according to any one of claims 21 to 23, wherein the anaerobic work threshold is determined by the processor using the D-max method.

26. The method according to any one of claims 21 to 23, wherein the anaerobic work threshold is determined by the processor using a modified D-max method.

27. The method according to any one of claims 21 to 26, wherein the lactic acid-responsive sensor is the sensor according to any one of claims 1 to 9.

28. Using a sensing system equipped with a lactate-responsive sensor, the system continuously measures signals indicating the lactate concentration in an individual's biological fluids, The signal indicating the lactic acid concentration measured by the lactic acid responsive sensor is communicated to the processor, A method for determining an aerobic work threshold in an individual, comprising determining the aerobic work threshold based on the signal indicating lactic acid concentration.

29. The method according to claim 28, wherein the individual is performing a lactate threshold test.

30. The method according to claim 29, wherein the lactate work threshold test is a step test involving a gradual increase in power.

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

32. The method according to claim 31, wherein the aerobic work threshold is defined as baseline lactate concentration + approximately 0.5 mM lactate.

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

34. The method according to any one of claims 28 to 30, wherein the aerobic work threshold is determined by the processor using a log-log model.

35. The method according to any one of claims 28 to 30, wherein the aerobic work threshold is determined by the processor using segmented regression analysis.

36. The method according to any one of claims 28 to 35, wherein the lactic acid-responsive sensor is the sensor according to any one of claims 1 to 9.

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