Micro biosensor and its determination method

Abstract

The present invention provides a measuring method for extending the service life of a micro biosensor, wherein the micro biosensor is used to measure a physiological signal associated with a physiological parameter of an analyte, and comprises two working electrodes at least partially covered by a chemical reagent and two pairs of electrodes having silver and silver halide, wherein the silver halide has an initial amount. The measuring method comprises the following cyclic steps: applying a measuring voltage to drive one of the two working electrodes during the measuring period to measure the physiological signal and obtain the physiological parameter, and the silver halide of one of the two pairs of electrodes is consumed by a consumption amount; stopping applying the measuring voltage; applying a recharge voltage to drive one of the two pairs of electrodes during the recharge period, so that the silver halide of one of the two pairs of electrodes is recharged by a recharge amount, wherein each time after obtaining a physiological parameter, the sum of each recharge amount and each initial amount minus each consumption amount is controlled within the range of each initial amount plus or minus a specific value.

Description

Technical Field

[0001] The present invention relates to a micro biosensor and a measuring method thereof, and in particular to a micro biosensor and a measuring method thereof which can extend the service life of the micro biosensor.

[0002] Prior Art

[0003] The population of diabetic patients is growing rapidly, and with it comes an increasing emphasis on the need to monitor changes in glucose in the body. As a result, many studies have begun to develop implantable continuous glucose monitoring (CGM) systems to address the inconvenience in patients' lives caused by repeated blood sampling and testing multiple times a day.

[0004] In the field of enzyme-based biosensor CGM systems, biochemical reaction signals depending on the concentration of the analyte are converted into measurable physical signals, such as optical or electrochemical signals. For glucose determination, the electrochemical reaction, for example, glucose oxidase (GOx) catalyzes the glucose reaction to generate gluconolactone and reduced enzymes. Subsequently, the reduced enzymes will transfer electrons with oxygen in the biological fluid in the body to generate hydrogen peroxide (H2O2). Finally, the glucose concentration is quantified by catalyzing the oxidation reaction of the product H2O2. The reaction formula is as follows.

[0005] Glucose+GOx(FAD)→GOx(FADH2)+Gluconolactone

[0006] GOx(FADH2)+O2→GOx(FAD)+H2O2

[0007] In the above reaction, FAD (Flavin Adenine Dinucleotide) is the active center of GOx.

[0008] Users usually wear CGM for a long time, such as more than 14 days, so miniaturization becomes an inevitable trend. The basic structure of CGM includes: (a) a biosensor, which is used to measure physiological signals corresponding to the glucose concentration of the human body; and (b) a transmitter, which is used to transmit these physiological signals. The biosensor can be a two-electrode system or a three-electrode system. In a biosensor with a three-electrode system, a working electrode (WE), a counter electrode (CE) and a reference electrode (RE) are included. The biosensor with a two-electrode system includes a working electrode (WE) and a counter electrode (CE), in which the counter electrode also has the function of a reference electrode, so it is sometimes also called a counter / reference electrode (R / C). The reference electrode in the biosensor with a three-electrode system and the counter electrode as a reference electrode in the biosensor with a two-electrode system are suitable materials for stable measurement of glucose concentration, such as silver / silver chloride (Ag / AgCl). However, after the sensor is implanted in the body, when the working electrode undergoes an oxidation reaction to measure the glucose concentration, the corresponding reference electrode (RE) or the counter / reference electrode (C / R) undergoes a reduction reaction, resulting in the reduction of silver chloride to silver, which causes the silver chloride to be consumed. In addition, if the sensor implanted in the body is a two- or three-electrode system sensor, the silver chloride on the reference electrode will be lost due to the dissociation of silver chloride in the body fluid, which will cause the drift problem of the reference voltage. However, in the two-electrode system, the counter / reference electrode (R / C) participates in the reaction, and its silver chloride consumption is higher than that of the three-electrode system. Therefore, the service life of the sensor is limited by the content of silver chloride on the counter electrode and / or the reference electrode.

[0009] There are also many inventions proposed to address the problem of the service life of biosensors. Taking a two-electrode system as an example, the consumption of AgCl in the electrode is about 1.73 millicoulombs (mC) per day at an average sensing current of 20 nanoamperes (nA). Assuming that the length, width and height of the electrode are 3.3 mm, 0.25 mm and 0.01 mm respectively, and the originally designed electrode capacity is only 6mC, its stable measurement state can be maintained for at most three days. However, if the service life is to be extended, if the biosensor is to be implanted subcutaneously for continuous 16 days of glucose monitoring, the capacity of the electrode must be at least 27.68mC. Without changing the width and thickness, the length of the electrode in the prior art may need to be as long as 15.2mm. Therefore, the prior art attempts to lengthen the length of the electrode to more than 10mm, and in order to avoid implantation deep into the subcutaneous tissue, these biosensors need to be implanted at an oblique angle. Therefore, it causes larger implantation wounds and higher infection risks to patients, and due to the long implantation length, the pain during implantation is also more significant.

[0010] US 8,620,398 describes a biosensor, which is mainly a three-electrode system. Although the reference electrode basically does not participate in the chemical reaction, silver chloride is still gradually consumed naturally in the body environment, but the consumption rate is slower than that of the two-electrode system. The article discloses that it will not be regenerated until the AgCl is exhausted. That is to say, when the measurement signal is unstable, that is, when the measured signal is already noise, the program of recharging AgCl will be started to restore AgCl to the amount required for multiple measurements. Then until the next noise occurs, AgCl needs to be recharged again. It can be understood that US 8,620,398 considers that AgCl will be consumed in the measurement and recharges AgCl when the biosensor fails. However, the measurement value at the time of failure is no longer reliable. It is necessary to wait for the biosensor to complete the AgCl recharging program to obtain the correct measurement value, temporarily adopt the blood sampling measurement method, or directly skip this measurement. This problem is always very troubling for patients or people who need to know the blood sugar concentration at that time. In addition, since this type of biosensor needs to cope with multiple measurements at least several times in a row or even for several days, a larger amount of AgCl capacity must be prepared, which inevitably causes the problem of a longer implant length of the biosensor. It also does not propose a biosensor that can provide uninterrupted measurements, have a shorter implant length, and have a longer service life by using real-time AgCl recharging.

[0011] US9351677B2 is mainly a two-electrode system, where the counter / reference electrode (R / C) participates in the chemical reaction, so silver chloride is consumed along with the electrochemical reaction. The article proposes an analyte sensor with increased AgCl capacity, which uses H2O2 to regenerate the AgCl on the reference electrode. However, since H2O2 is easily reduced to H2O or oxidized to O2, it is not easy to exist stably in the human body. Therefore, during the regeneration / recharge period, the concentration of H2O2 in the body may not be sufficient to stably recharge a sufficient amount of AgCl, and relatively speaking, the biosensor needs to be configured with a larger AgCl electrode size, and its implant end is also as long as 12mm.

[0012] Therefore, the present invention provides a biosensor that can be charged immediately to provide uninterrupted measurement, can stably recharge AgCl, extend its service life, and has a small size of the miniaturized implant end, which can also reduce the manufacturing cost of the product. These functions can solve the problems that are difficult to overcome in the aforementioned known technologies.

[0013] In view of the deficiencies in the known technology, the applicant of this case, after careful experiments and research, and with a spirit of perseverance, finally conceived this case, which can overcome the deficiencies of the previous technology. The following is a brief description of this case. Summary of the invention

[0014] Through the recharging technology of the present invention, the micro biosensor of the present invention has a prolonged service life and the size of the electrode signal sensing section can be reduced, thereby reducing biological toxicity. In addition, the reduction in electrode size particularly refers to shortening the length of the implant end of the sensor, thereby reducing the user's implant pain. In addition, the device of the present invention including four electrodes can provide a more flexible and efficient operation mode.

[0015] One of the purposes of the present invention is to provide a method for measuring an analyte that can extend the service life of a micro biosensor, the biosensor is used to be implanted subcutaneously to measure a physiological signal of a physiological parameter associated with the analyte in a biological fluid, the biosensor includes a first and a second working electrode and a first and a second pair of electrodes, each of the working electrodes is at least partially covered by a chemical reagent and is used to produce an electrochemical reaction with the analyte, and an electrode material of each pair of electrodes includes silver and silver chloride. The method includes the following steps: a) performing a first measurement step, including: i. applying a first measurement potential difference between the first working electrode and the first pair of electrodes during a first measurement period ii. removing the first measurement potential difference, stopping the first measurement step, and outputting a first physiological parameter after the first physiological signal is calculated; b) executing a first recharge step, including: i. applying a first recharge potential difference between the first pair of electrodes and one of the first or second working electrodes during a first recharge period, so that the first pair of electrodes has a first oxidation reaction, and the first pair of electrodes has a first consumption corresponding to the first physiological signal. The method comprises the steps of: i. applying a first measuring potential difference between one of the first and second working electrodes and the second pair of electrodes during a second measuring period, so that a voltage of one of the first and second working electrodes is higher than a voltage of the second pair of electrodes, so that a second oxidation reaction occurs in one of the first and second working electrodes, and the silver chloride has a first recharge amount, wherein the first recharge amount corresponds to the first consumption; and ii. removing the first recharge potential difference and stopping the first recharge step; c) performing a second measuring step, including: i. applying the first measuring potential difference between one of the first and second working electrodes and the second pair of electrodes during a second measuring period, so that a voltage of one of the first and second working electrodes is higher than a voltage of the second pair of electrodes, so that the first oxidation reaction occurs in one of the first and second working electrodes, and the silver chloride has a first recharge amount, wherein the first recharge amount corresponds to the first consumption; The second pair of electrodes is provided with a second pair of electrodes, wherein the ... silver chloride is provided with a second pair of electrodes, wherein the silver chloride is provided with a second pair of electrodes, wherein the second pair of electrodes is provided with a second pair of electrodes, wherein the silver chloride is provided with a second pair of electrodes, wherein the second pair of electrodes is provided with a second pair of electrodes, wherein the silver chloride is provided with a second pair of electrodes, wherein the second pair of electrodes is provided with a second pair of electrodes, wherein the silver chloride is provided with a second pair of electrodes, wherein the second pair of electrodes is provided with a second pair of electrodes, wherein the silver chloride is provided with a second pair of electrodes, wherein the second pair of electrodes is provided with a second pair of electrodes, wherein the silver chloride is provided with a second pair of electrodes, wherein the silver chloride is provided with a second pair of electrodes, wherein the silver chloride is provided with a second pair of electrodes, wherein the silver chloride is provided with a second pair of electrodes, wherein the silver chloride is provided with a second pair of electrodes, wherein the silver chloride is provided with a second pair of electrodes, wherein the silver chloride is provided with a second pair of electrodes, wherein the silver chloride is provided with a second pair of electrodes,Remove the first recharge potential difference and stop the second recharge step; and e) repeatedly perform the following steps a2) to d2) in sequence: a2) perform an Mth measurement step identical to step a) to obtain the Mth physiological signal and output an Mth physiological parameter, and the silver chloride of the first pair of electrodes has an Mth consumption corresponding to the Mth physiological signal; b2) perform an Mth recharge step identical to step b) to make the silver chloride of the first pair of electrodes have an Mth recharge amount and the Mth recharge amount corresponds to the Mth consumption; c2) perform the same as step c) An Nth measurement step to obtain the Nth physiological signal and output an Nth physiological parameter, and the silver chloride of the second pair of electrodes has an Nth consumption corresponding to the Nth physiological signal; and d2) performing an Nth silver chloride recharge step identical to step d) so that the silver chloride of the second pair of electrodes has an Nth recharge amount, and the Nth recharge amount corresponds to the Nth consumption, wherein: an amount of the silver chloride on each pair of electrodes is controlled within a safety inventory range, so that the next physiological signal and the next physiological parameter obtained in the next measurement step maintain a stable proportional relationship.

[0016] Another object of the present invention is to provide a method for measuring an analyte that can extend the service life of a biosensor. The biosensor is implanted subcutaneously to measure a physiological signal associated with a physiological parameter of the analyte, and includes two working electrodes and two pairs of electrodes arranged on a substrate, each of the working electrodes is at least partially covered by a chemical reagent, each of the pairs of electrodes has an electrode material including silver and a silver halide, and each of the silver halide has an initial amount. The method includes the following steps: applying a measuring voltage to drive one of the two working electrodes during a first measuring period to measure the physiological signal to obtain the physiological parameter, and the silver halide of one of the two pairs of electrodes is consumed by a consumption amount; stopping applying the measuring voltage; applying a recharge during a first recharge period. A charging voltage is applied to drive one of the two pairs of electrodes, so that the amount of silver halide in one of the two pairs of electrodes is recharged by a recharge amount; during a second measurement period, the measurement voltage is applied to drive one or the other of the two working electrodes to measure another physiological signal to obtain another physiological parameter, and the silver halide in the other of the two pairs of electrodes is consumed by a consumption amount; application of the measurement voltage is stopped; and during a second recharge period, the recharge voltage is applied to drive the other of the two pairs of electrodes, so that the amount of silver halide in the other of the two pairs of electrodes is recharged by a recharge amount; wherein after each physiological parameter is obtained, during each recharge period, a value of the sum of each recharge amount and each initial amount minus each consumption amount is controlled within a range of each initial amount plus or minus a specific value.

[0017] Another object of the present invention is to provide an implantable micro biosensor with a long service life and a small electrode size, which is used to measure a physiological signal of a physiological parameter associated with an analyte in a living body, the biosensor comprising: a substrate; a chemical reagent; two working electrodes, arranged on the substrate, each comprising a first signal sensing section, at least partially covered by the chemical reagent, and during a specific measurement period, one of the two working electrodes is driven to generate an oxidation reaction to measure a physiological signal of the analyte and to generate the physiological parameter; and two pairs of electrodes, arranged at The substrate includes a second signal sensing section having a size, and the two pairs of electrodes each have an electrode material including silver and a silver halide, wherein each silver halide has an initial amount, and during the specific measurement period, each silver halide is consumed by a consumption amount, wherein; after each physiological parameter is obtained, during a recharging period, one of the two pairs of electrodes is driven, and the amount of the silver halide of the driven pair of electrodes is recharged by a recharging amount, wherein a value of the sum of each recharging amount and each initial amount minus each consumption amount is controlled within a range of each initial amount plus or minus a specific value. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The above-mentioned objects and advantages of the present invention will become more immediately apparent to those having ordinary knowledge in the art after referring to the following detailed description and the accompanying drawings.

[0019] [ Figure 1 ] is a schematic diagram of the physiological signal measuring device of the present invention.

[0020] [ Figure 2A ] is a front schematic diagram of the first embodiment of the micro biosensor of the present invention.

[0021] [ Figure 2B ] is a schematic diagram of the back side of the first embodiment of the micro biosensor of the present invention.

[0022] [ Figure 2C ] for the present invention Figure 2A Schematic diagram of the cross section along line A-A'.

[0023] [ Figure 3A ] is a cross-sectional schematic diagram of the second embodiment of the micro biosensor of the present invention.

[0024] [ Figure 3B ] is a cross-sectional schematic diagram of the third embodiment of the micro biosensor of the present invention.

[0025] [ Figure 3C ] is a cross-sectional schematic diagram of the fourth embodiment of the micro biosensor of the present invention.

[0026] [ Figure 4A] is a constant voltage circuit in the present invention that can execute measurement mode and recharge mode according to the first method.

[0027] [ Figure 4B ] is a constant voltage circuit in the present invention that can execute measurement mode and recharge mode according to the second method.

[0028] [ Figure 4C ] is a constant voltage circuit in the present invention that can execute measurement mode and recharge mode according to the third method.

[0029] [ Figure 5A ] is a current schematic diagram of the constant voltage circuit of the present invention alternating between the measurement mode and the recharging mode in the first manner.

[0030] [ Figure 5B ] is a current schematic diagram of the constant voltage circuit of the present invention alternating between the measurement mode and the recharging mode in the second manner.

[0031] [ Figure 5C ] is a current schematic diagram of the constant voltage circuit of the present invention alternating between the measurement mode and the recharging mode in a third manner.

[0032] [ Figure 5D ] is a current schematic diagram of the constant voltage circuit of the present invention alternating between the measurement mode and the recharging mode in the fourth manner.

[0033] [ Figure 5E ] is a current schematic diagram of the constant voltage circuit of the present invention alternating between the measurement mode and the recharge mode in the fifth manner.

[0034] [ Fig. 5F ] is a current schematic diagram of the constant voltage circuit of the present invention alternating between the measurement mode and the recharging mode in the sixth manner.

[0035] [ Figure 6 ] is a constant current circuit with step switching that can perform measurement mode and recharging mode in the present invention.

[0036] [ Figure 7 ] is a constant current circuit in the present invention that can execute stepless switching between the measurement mode and the recharging mode.

[0037] [ Fig. 8A ] is a voltage schematic diagram of the constant current circuit of the present invention alternating between the measurement mode and the recharge mode in the first manner.

[0038] [ Figure 8B ] is a voltage schematic diagram of the constant current circuit of the present invention alternating between the measurement mode and the recharging mode in the second manner.

[0039] [ Figure 8C ] is a voltage schematic diagram of the constant current circuit of the present invention alternating between the measurement mode and the recharge mode in the third manner.

[0040] [ Fig.8D ] is a schematic diagram of the constant current circuit of the present invention alternating between the measurement mode and the recharging mode in a third manner.

[0041] [ Fig. 9A ] is a schematic diagram of a constant current or constant voltage circuit of the present invention performing a measurement mode and a recharging mode according to one embodiment.

[0042] [ Fig. 9B ] is a schematic diagram of the constant current or constant voltage circuit of the present invention performing a measurement mode and a recharging mode according to another embodiment.

[0043] [ Fig.10 ] is a method for determining an analyte according to one embodiment of the present invention.

[0044] [ Fig.11 ] is a method for determining an analyte according to another embodiment of the present invention. DETAILED DESCRIPTION

[0045] The invention proposed in this case can be fully understood by the following embodiments, so that those with ordinary knowledge in the relevant technical field can complete it. However, the implementation of this case is not limited to its implementation form by the following embodiments. Those with ordinary knowledge in the relevant technical field can still deduce other embodiments based on the spirit of the embodiments other than those disclosed, and these embodiments should all fall within the scope of the present invention.

[0046] Unless otherwise limited in specific examples, the following definitions apply to terms used throughout the specification.

[0047] The term "amount" refers to the capacity (Capacity) of silver halide (AgX) or silver chloride (AgCl) in the electrode, and is preferably expressed in units of microcoulomb (μC), millicoulomb (mC) or coulomb (C), but is not limited to being expressed in terms of weight percentage concentration wt%, molar number, molar concentration, etc.

[0048] See also Figure 1, which is a schematic diagram of the physiological signal measuring device of the present invention. The physiological signal measuring device 10 of the present invention can be implanted subcutaneously to measure the physiological signals of the physiological parameters associated with the analyte in the biological fluid. The physiological signal measuring device 10 of the present invention includes a micro biosensor 400 and a sensing unit 200, wherein the sensing unit 200 is electrically connected to the micro biosensor 400, and has a processor 210, a power supply 220, a power supply 220, a circuit switching unit 230, a temperature sensing unit 240 and a communication unit 250. The power supply 220 controls the circuit switching unit 230 through the processor 210 to provide voltage to the micro biosensor 400 for measuring the physiological signal, and the temperature sensing unit 240 measures the biological body temperature, so the temperature measurement signal and the physiological signal measured by the micro biosensor 400 will be transmitted to the processor 210, and then the processor 210 calculates the physiological signal into a physiological parameter. The communication unit 250 can perform wired or wireless transmission with the user device 20.

[0049] See also Figure 2A and 2B , which is a schematic diagram of the front and back of the first embodiment of the micro biosensor of the present invention. The micro biosensor 400 of the present invention includes a substrate 410, a first working electrode 420, a second working electrode 430, a first pair of electrodes 440 and a second pair of electrodes 450 disposed on the substrate 410, and a chemical reagent 460 (such as Figure 2C As shown). The material of the substrate 410 can be any material known to be suitable for use as an electrode substrate and preferably has flexibility and insulating properties, such as but not limited to: polymer materials such as polyester and polyimide. The aforementioned polymer materials can be used alone or in combination. The substrate 410 has a surface 411 (i.e., a first surface), an opposite side surface 412 (i.e., a second surface) opposite to the surface 411, a first end 413 and a second end 414, and the substrate 410 is divided into three areas, namely a signal output area 415 close to the first end 413, a sensing area 416 close to the second end 414, and a connection area 417 located between the signal output area 415 and the sensing area 416. The first working electrode 420 and the second working electrode 430 are disposed on the surface 411 of the substrate 410, and extend from the first end 413 of the substrate 410 to the second end 414. The first working electrode 420 includes a first signal output section 421 located in the signal output region 415 of the substrate 410, and a first signal sensing section 422 located in the sensing region 416 of the substrate 410. The second working electrode 430 includes a second signal output section 431 located in the signal output region 415 of the substrate 410, and a second signal sensing section 432 located in the sensing region 416 of the substrate 410.

[0050] The first pair of electrodes 440 and the second pair of electrodes 450 are disposed on opposite side surfaces 412 of the substrate 410 and extend from the first end 413 to the second end 414 of the substrate 410. The first pair of electrodes 440 includes a third signal output section 441 located in the signal output region 415 of the substrate 410 and a third signal sensing section 442 located in the sensing region 416 of the substrate 410, and the second pair of electrodes 450 includes a fourth signal output section 451 located in the signal output region 415 of the substrate 410 and a fourth signal sensing section 452 located in the sensing region 416 of the substrate 410. The materials on the surfaces of the first pair of electrodes 440 and the second pair of electrodes 450 include silver and silver halide, wherein the silver halide is preferably silver chloride or silver iodine, so that the first pair of electrodes 440 and the second pair of electrodes 450 also function as reference electrodes, that is, the first pair of electrodes 440 and the second pair of electrodes 450 of the present invention can (1) form an electronic circuit with the first working electrode 420 or the second working electrode 430, so that the current on the first working electrode 420 or the second working electrode 430 is smooth, so as to ensure that the oxidation reaction occurs on the first working electrode 420 or the second working electrode 430; and (2) provide a stable relative potential as a reference potential. Therefore, the first working electrode 420, the second working electrode 430, the first pair of electrodes 440 and the second pair of electrodes 450 of the present invention form a four-electrode system. In order to further reduce the cost and improve the biocompatibility of the biosensor of the present invention, the silver / silver halide can be mixed with carbon for use, for example, the silver / silver halide is mixed into carbon glue, and the silver halide content is sufficient to allow the first pair of electrodes 440 and the second pair of electrodes 450 to stably perform the set measurement action. The surfaces of the first pair of electrodes 440 and the second pair of electrodes 450 can also be covered with a conductive material to prevent the dissolution of the silver halide, thereby protecting the first pair of electrodes 440 and the second pair of electrodes 450, wherein the conductive material is mainly a conductive material that does not affect the measurement performance of the working electrode, for example, the conductive material is carbon.

[0051] In another embodiment, the biosensor is not limited to a wire-type or stacked electrode structure.

[0052] In another embodiment of the present invention, before the biosensor is prepared to be shipped out of the factory for sale, the initial amount of silver halide can be zero. In this case, there is no silver halide on the first pair of electrodes 440 and / or the second pair of electrodes 450 of the biosensor. During the initial recharge period after the biosensor is subcutaneously implanted in the patient's body and before the first measurement is taken, the silver coated on the first pair of electrodes 440 and / or the second pair of electrodes 450 through oxidation can be recharged with the initial amount of silver halide on the first pair of electrodes 440 and / or the second pair of electrodes 450.

[0053] The chemical reagent 460 covers at least the first signal sensing segment 422 of the first working electrode 420. In another embodiment, the chemical reagent 460 covers at least the first signal sensing segment 422 and the second signal sensing segment 432 of the first working electrode 420 and the second working electrode 430. In another embodiment, the chemical reagent 460 covers the signal sensing segments 422, 432, 442, 452 of all electrodes. In another embodiment, the first pair of electrodes 440 and / or the second pair of electrodes 450 may not be covered by the chemical reagent 460. The sensing area 416 of the micro biosensor 400 can be implanted subcutaneously so that the first signal sensing segment 422 and the second signal sensing segment 432 can measure the physiological signal associated with the analyte in the biological fluid, and the physiological signal will be transmitted to the first signal output segment 421 and the second signal output segment 431 respectively, and then transmitted to the processor 210 by the first output segment 421 and the second output segment 431 to obtain the physiological parameter. In addition to being obtained from the sensor unit 200 , the physiological parameters can also be transmitted to the user device 20 via wireless / wired communication. Common user devices 20 are, for example, smart phones, physiological signal receivers, or blood glucose meters.

[0054] See also Figure 2C , which is Figure 2A Schematic cross-sectional view along line AA' in FIG. 4 , wherein line AA' is a cross-sectional line from the sensing region 416 of the micro biosensor 400. Figure 2CIn the embodiment, the first working electrode 420 and the second working electrode 430 are arranged on the surface 411 of the substrate 410, the first pair of electrodes 440 and the second pair of electrodes 450 are arranged on the opposite side surface 412 of the substrate 410, and the surfaces of the first working electrode 420, the second working electrode 430, the first pair of electrodes 440 and the second pair of electrodes 450 are covered with a chemical reagent 460. Basically, the chemical reagent 460 covers at least a portion of the surface of one working electrode. The micro biosensor 400 of the present invention performs a measurement step during the measurement period and a recharge step during the recharge period. During the measurement step, the first working electrode 420 or the second working electrode 430 can be selected to measure the physiological signal, and during the recharge step, the first working electrode 420 or the second working electrode 430 helps the first pair of electrodes 440 or the second pair of electrodes 450 to recharge the silver halide. Therefore, in this embodiment, when the measurement step is performed, the voltage of the first working electrode 420 or the second working electrode 430 is higher than the voltage of the first pair of electrodes 440 or the second pair of electrodes 450, so that the current flows from the first working electrode 420 or the second working electrode 430 to the first pair of electrodes 440 or the second pair of electrodes 450, thereby causing the first working electrode 420 or the second working electrode 430 to undergo an oxidation reaction (i.e., an electrochemical reaction between the first working electrode 420 or the second working electrode 430, the chemical reagent 460 and the analyte) to measure the physiological signal, and the first pair of electrodes 440 or the second pair of electrodes 450 to undergo a reduction reaction, so that the silver halide in the first pair of electrodes 440 or the second pair of electrodes 450 is consumed and dissociated into silver (Ag) and halide ions (X - ). Since the silver halide in the first pair of electrodes 440 or the second pair of electrodes 450 is consumed, it is necessary to recharge the silver halide in the first pair of electrodes 440 or the second pair of electrodes 450 to perform the next measurement step. When the recharging step is performed, the voltage of the first pair of electrodes 440 or the second pair of electrodes 450 is higher than the voltage of the first working electrode 420 or the second working electrode 430, so that the current flows from the first pair of electrodes 440 or the second pair of electrodes 450 to the first working electrode 420 or the second working electrode 430, thereby causing the first pair of electrodes 440 or the second pair of electrodes 450 to undergo an oxidation reaction so that silver combines with halide ions to recharge the silver halide. For detailed measurement steps and recharging steps, see Fig.10 illustrate.

[0055] See also Figure 3A , which is a cross-sectional schematic diagram of a second embodiment of the micro biosensor of the present invention. The second embodiment is a variation of the electrode configuration of the first embodiment. In this embodiment, Figure 3AAs shown, the first working electrode 420 and the first pair of electrodes 440 of the micro biosensor 400 of the present invention are disposed on the surface 411 of the substrate 410, the second working electrode 430 and the second pair of electrodes 450 are disposed on the opposite side surface 412 of the substrate 410, and the surfaces of the first working electrode 420, the second working electrode 430, the first pair of electrodes 440 or the second pair of electrodes 450 are covered with a chemical reagent 460. Similarly, during the measurement step, the first working electrode 420 or the second working electrode 430 can be selected to measure the physiological signal, and during the recharging step, the first working electrode 420 or the second working electrode 430 can also be selected to help recharge the silver halide to the first pair of electrodes 440 or the second pair of electrodes 450. Therefore, in this embodiment, when the measurement step is performed, the current flows from the first working electrode 420 or the second working electrode 430 to the first pair of electrodes 440 or the second pair of electrodes 450, thereby causing the first working electrode 420 or the second working electrode 430 to undergo an oxidation reaction to measure the physiological signal, and the first pair of electrodes 440 or the second pair of electrodes 450 to undergo a reduction reaction to consume the silver halide in the first pair of electrodes 440 or the second pair of electrodes 450 and dissociate into silver (Ag) and halide ions (X - When the recharging step is performed, the current flows from the first pair of electrodes 440 or the second pair of electrodes 450 to the first working electrode 420 or the second working electrode 430, thereby causing an oxidation reaction in the first pair of electrodes 440 or the second pair of electrodes 450 to combine silver with halide ions to recharge silver halide.

[0056] See also Figure 3B , which is a cross-sectional schematic diagram of the third embodiment of the micro biosensor of the present invention. In the third embodiment, the first working electrode 420 of the micro biosensor 400 of the present invention is disposed on the surface 411 of the substrate 410, the second working electrode 430, the first pair of electrodes 440 and the second pair of electrodes 450 are disposed on the opposite side surface 412 of the substrate 410, and the surface of the first working electrode 420, the second working electrode 430, the first pair of electrodes 440 or the second pair of electrodes 450 is covered with a chemical reagent 460. In addition to being disposed between the two pairs of electrodes, the second working electrode 430 can also be disposed at the leftmost or rightmost side position (not shown in the figure). In this embodiment, during the measurement step, the first working electrode 420 or the second working electrode 430 can be selected to measure the physiological signal, and during the recharging step, the first working electrode 420 or the second working electrode 430 can also be selected to help recharge the silver halide to the first pair of electrodes 440 or the second pair of electrodes 450.

[0057] See also Figure 3C, which is a cross-sectional schematic diagram of the fourth embodiment of the micro biosensor of the present invention. In the fourth embodiment, the first working electrode 420 and the second working electrode 430 of the micro biosensor 400 of the present invention are disposed on the surface 411 of the substrate 410, the second working electrode 430 is U-shaped and is adjacent to and surrounds the side of the first working electrode 420, the first pair of electrodes 440 and the second pair of electrodes 450 are disposed on the opposite side surface 412 of the substrate 410, and the surfaces of the first working electrode 420, the second working electrode 430, the first pair of electrodes 440 and the second pair of electrodes 450 are covered with a chemical reagent 460. In this embodiment, during the measurement step, the first working electrode 420 or the second working electrode 430 can be selected to measure the physiological signal, and during the recharging step, the first working electrode 420 or the second working electrode 430 can also be selected to help recharge the silver halide to the first pair of electrodes 440 or the second pair of electrodes 450.

[0058] above Figure 2C-3C The detailed electrode stack is omitted, and only the electrode positions are indicated. Figure 2C-3C Basically, the chemical reagent 460 covers at least a portion of the surface of the first working electrode 420.

[0059] In any of the above embodiments, the materials of the first working electrode 420 and the second working electrode 430 include but are not limited to: carbon, platinum, aluminum, gallium, gold, indium, iridium, iron, lead, magnesium, nickel, manganese, molybdenum, osmium, palladium, rhodium, silver, tin, titanium, zinc, silicon, zirconium, mixtures of the aforementioned elements, or derivatives of the aforementioned elements (such as alloys, oxides or metal compounds, etc.). Preferably, the materials of the first working electrode 420 and the second working electrode 430 are noble metals, derivatives of noble metals or combinations thereof. More preferably, the first working electrode 420 and the second working electrode 430 are platinum-containing materials. In another embodiment, the electrode material of the second working electrode 430 is selected from a material having a lower sensitivity to hydrogen peroxide than the first working electrode 420, such as carbon.

[0060] In any of the above embodiments, in order to prevent the silver electrode material from being disconnected due to excessive chlorination, a layer of conductive material (such as carbon) may be added between the opposite side surface 412 of the substrate 410 and the silver of the first pair of electrodes 440 and the second pair of electrodes 450. However, if the bottom layer of the first pair of electrodes 440 and the second pair of electrodes 450 is carbon, the resistance at the switch may be too high. Therefore, another conductive layer may be added between the carbon conductive material and the opposite side surface 412 of the substrate 410, such as silver, to reduce the impedance of the signal output end, so that the first pair of electrodes 440 and the second pair of electrodes 450 of the present invention are conductive layers, carbon layers, and silver / silver halide layers in order from the opposite side surface 412 of the substrate 410.

[0061] Since the micro biosensor 400 of the present invention has two working electrodes and two counter electrodes, the micro biosensor 400 can use the second working electrode 430 and the second counter electrode 450 to perform the recharging step while using the first working electrode 420 and the first counter electrode 440 to perform the measuring step. Or, for example, the first working electrode 420 can be used to continuously perform the measuring step while the second working electrode 430 can be used to help the first counter electrode 440 or the second counter electrode 450 to perform the recharging step.

[0062] Constant voltage circuit switching applications

[0063] Please refer to Figures 4A-4C , which respectively show the constant voltage circuits of the present invention that can perform the measurement mode and the recharge mode according to different methods. The measurement mode can be started and stopped by applying the measurement potential difference Vl and removing the measurement potential difference Vl, respectively, and the corresponding current is represented by Ia. In the constant voltage circuit, the first working electrode W1 is controlled by the switch S1, the first pair of electrodes R / C1 is controlled by the switches S5 and S6, the second working electrode W2 is controlled by the switches S2 and S7, and the second pair of electrodes R / C2 is controlled by the switches S3 and S4. Through the control of the above switches, there can be a variety of flexible operating methods, which are illustrated by the following examples.

[0064] like Figure 4AAs shown, in the measurement mode, during the measurement period T1, a measurement potential difference V1 is applied between the first working electrode W1 and the first pair of electrodes R / C1, so that the voltage of the first working electrode W1 is higher than the voltage of the first pair of electrodes R / C1. At this time, switches S1 and S6 are in a closed circuit state, and switch S5 is in an open circuit state. The first working electrode W1 is +V1, and the first pair of electrodes R / C1 is grounded, so that the first working electrode W1 undergoes an oxidation reaction and undergoes an electrochemical reaction with the chemical reagent and the analyte to output a physiological signal Ia. At the same time, the AgCl of the first pair of electrodes R / C1 has a consumption corresponding to the physiological signal Ia. In the recharge mode, it can be started and stopped by applying the recharge potential difference V2 and removing the recharge potential difference V2, respectively, and the corresponding current is represented by Ib. V2 is a fixed value between 0.1V and 0.8V, preferably a fixed value between 0.2V and 0.5V. In the recharge mode, the recharge potential difference V2 is applied between the second working electrode W2 and the second pair of electrodes R / C2 for the recharge period t2, so that the voltage of the second pair of electrodes R / C2 is higher than the voltage of the second working electrode W2. At this time, switches S4 and S7 are in an open circuit state, while switches S2 and S3 are in a closed circuit state, the second pair of electrodes R / C2 is +V2, and the second working electrode W2 is grounded, so that the Ag on the second pair of electrodes R / C2 undergoes an oxidation reaction, and the AgCl on the second pair of electrodes R / C2 is recharged to a recharge amount. The recharge potential difference V2 in the constant voltage circuit is a fixed voltage, and the measured output current is Ib. The present invention defines the capacity (Capacity, unit coulomb, represented by the symbol "C") of AgCl by calculating the area under the current curve, so the consumption of AgCl in the measurement mode is Ia*Tl, and the recharge amount of AgCl in the recharge mode is Ib*t2. Therefore, the recharge amount of AgCl can be controlled by adjusting the application time t2 of the recharge potential difference V2. In other words, under the premise that the AgCl on the first or second pair of electrodes R / C1 or R / C2 is kept within the safety stock, the recharge amount can be equal to or not equal to (including approximately similar, greater than or less than) the consumption amount. Figure 4A The timing of the measurement mode and the timing of the recharge mode are overlapped while being performed simultaneously. The control of the above-mentioned switch can also be transformed into other forms of circuits to have a variety of flexible operating methods. In some preferred embodiments, the timing of the measurement mode and the timing of the recharge mode can be performed simultaneously and can also be partially overlapped or not overlapped.

[0065] Figure 4B-4C similar Figure 4A , the only difference is Figure 4B Shown is an embodiment of using W2 and R / C2 for measurement and using W1 and R / C1 for refilling; and Figure 4C The embodiment shown is one in which W1 and R / C2 are used for measurement and W2 and R / C1 are used for recharging. In some preferred embodiments, the constant voltage circuit is alternately switched to Figure 4Aand Figure 4B In some preferred embodiments, the constant voltage circuit is alternately switched to Figure 4A and Figure 4C In the above manner, the first pair of electrodes R / C1 and the second pair of electrodes R / C2 can be consumed and recharged in turn, so that the AgCl on the two pairs of electrodes can be kept within the safety inventory. In some preferred embodiments, the constant voltage circuit can have a third voltage source to control the recharge voltage difference to be different from the measurement voltage difference.

[0066] By controlling the application of voltage difference and the switching of switches, such as Figures 4A-4C The constant voltage circuit shown can also alternately perform a measurement mode and a recharge mode. Figures 5A-5D The current schematic diagrams of the constant voltage circuit in different ways of alternately performing the measurement mode and the recharge mode are shown. As shown in the figure, between the multiple measurement periods T1 is a period T2 during which no measurement is performed. In some preferred embodiments, T2 is a fixed value. Figures 5A-5D The horizontal axis is time, the V1 line represents the application and removal of the measured potential difference V1, and the V2 line represents the application and removal of the recharged potential difference V2. Figure 5A In a preferred embodiment, V2 and T2 are both fixed values, and the application time t2 of V2 (i.e., the recharging period) is a variable value. The recharging period t2 is dynamically adjusted between 0 and T2 according to the physiological signal Ia measured in the measurement mode and the measurement period T1. Figure 5A As shown in , t2 may be t2', t2", or t2'... In other words, the recharging period t2 may be changed according to the consumption of AgCl. If the consumption of AgCl is large, a longer recharging time may be required to keep the AgCl on the first pair of electrodes R / C1 within the safety stock. For example, the amount of AgCl recharged during t2" will be greater than the amount of AgCl recharged during t2'.

[0067] Please refer to Figure 5B In another preferred embodiment, V2, T2 and t2 are all fixed values, where t2 = T2. That is, the measurement mode and the recharge mode are seamlessly alternated, and the period when no measurement is performed is the recharge period. Please refer to Figure 5C and 5D In some preferred embodiments, V2, T2 and t2 are all fixed values, wherein t2 is a fixed value greater than 0 and less than T2, for example, t2 = 1 / 2 of T2, 2 / 5 of T2, 3 / 5 of T2, etc. Figure 5C and 5D The difference is that Figure 5C In the middle, after each measurement mode ends, a buffer time (buffer time = T2-t2) will pass before the recharge mode begins; Figure 5DIn the embodiment, the recharge mode starts immediately after each measurement mode ends without buffering time, and a period of time is left between the end of each recharge mode and the start of the next measurement mode. In some preferred embodiments, t2 is less than T2, and t2 can be any time period during T2.

[0068] Please refer to Figure 5E and 5F , which shows a current schematic diagram of the constant voltage circuit of the present invention alternating between the measurement mode and the recharge mode in different ways. Figure 5E and 5F In the figure, the horizontal axis is time, the vertical axis is current, and the curve represents the physiological parameter value curve converted from the measured physiological signal Ia. Figure 5A , V2 and T2 are fixed values, and t2 is a variable value during the recharging period. Figure 5E and 5F In the figure, the white area under the curve represents the consumption of AgCl in the measurement mode (Ia*Tl), and the oblique line area represents the recharge amount of AgCl in the recharge mode (Ib*t2). As can be seen from the figure, in order to make Ib*t2 close to Ia*Tl or within a certain range of Ia*Tl, the recharge period t2 is dynamically adjusted between 0 and T2 according to the measured physiological signal Ia and the measurement period T1. As needed, the front section of the period (T2) when the measurement mode is not executed can be selected (such as Figure 5E as shown) or the latter part (as shown Fig. 5F as shown) to enter the recharge mode.

[0069] Constant current circuit switching application with step switching

[0070] Please refer to Figure 6 , which shows a constant current circuit with step switching that can perform measurement mode and recharging mode in the present invention. The constant current circuit with step switching repeatedly cycles between measurement mode and recharging mode. Figure 4ASimilar, so no further description is given here. The main difference is that the recharge mode can be started and stopped by applying the recharge potential difference V2 (V2 is a variable value) and removing the recharge potential difference V2, and the corresponding current is represented by Ib. Taking the recharge mode performed on the second working electrode W2 and the second pair of electrodes R / C2 as an example, the recharge potential difference V2 is applied between the second working electrode W2 and the second pair of electrodes R / C2 for the recharge period t2. At this time, switches S2 and S3 are in a closed circuit state, switch S2 and at least one switch corresponding to I_F1 to I_Fn in part of the constant current circuit 61 are in a closed circuit state, the second working electrode W2 is grounded, and the second pair of electrodes R / C2 is +V2, so that the Ag on the second pair of electrodes R / C2 undergoes an oxidation reaction and recharges AgCl. In this embodiment, the constant current circuit with segment switching can selectively switch to I_F1, I_F2, I_F3…I_Fn by controlling the multiple switches corresponding to I_F1 to I_Fn to adjust the required recharge potential difference V2 and output current Ib. In the recharge mode, the recharge amount of AgCl can be controlled by adjusting the recharge potential difference V2 and its application time t2 according to the size of the physiological signal Ia and the measurement period T1. In other words, under the premise that the AgCl on the first or second pair of electrodes R / C1 or R / C2 is kept within the safety inventory, the recharge amount can be made equal to or not equal to (including approximately similar, greater than or less than) the consumption. In another embodiment, part of the constant current circuit 61 can be set to connect the second pair of electrodes R / C2.

[0071] Application of stepless switching constant current circuit switching

[0072] Please refer to Figure 7 , which shows a constant current circuit that can perform stepless switching between a measurement mode and a recharging mode in the present invention. Figures 4A-4C Similarly, the recharge mode is Figure 6 Similar, so I won’t repeat it here. Figure 7 and Figure 6 The embodiments of Figure 7 In the constant current circuit, the stepless switching part of the constant current circuit 71 outputs a fixed current Ib by controlling a digital-to-analog converter (DAC).

[0073] Please refer to Figures 8A-8C , which shows a voltage schematic diagram of the constant current circuit of the present invention alternating between the measurement mode and the recharge mode in different ways. Figures 8A-8C The horizontal axis is time, the V1 line represents the application and removal of the measured potential difference V1, and the V2 line represents the application and removal of the recharged potential difference V2. Fig. 8AIn a preferred embodiment, T2 is a fixed value, and V2 and the application time t2 of V2 (i.e., the recharging period) are variable values. The recharging period t2 is dynamically adjusted between 0 and T2 according to the physiological signal Ia measured in the measurement mode and the measurement period T1. Fig. 8A As shown in , t2 can be t2', t2", or t2'... In other words, the recharging period t2 can be changed according to the consumption of AgCl. If the consumption of AgCl is large, the recharging time can be longer to keep the AgCl on the first pair of electrodes R / C1 within the safety stock.

[0074] Please refer to Figure 8B In another preferred embodiment, V2 is a variable value, T2 and t2 are both fixed values, wherein t2 is a fixed value greater than 0 and less than T2, such as t2=1 / 2 of T2, 2 / 5 of T2, 3 / 7 of T2, etc. In this embodiment, V2 is dynamically adjusted according to the consumption of AgCl in the physiological signal measurement step (i.e., in the measurement mode). One embodiment of the dynamic adjustment method is as follows. Using, for example, the above-mentioned constant current circuit with segment switching, the circuit has n fixed current sources and n switches, and each fixed current source corresponds to a switch. In the recharge mode, according to the consumption of AgCl, at least one of the n switches is selected to be turned on (even if the switch is in a closed circuit state) to output a fixed current value. When t2 is a fixed value during the recharge period, the recharge amount of AgCl can be controlled by selecting different fixed current outputs.

[0075] Please refer to Figure 8C In another preferred embodiment, V2 is a variable value, T2 and t2 are both fixed values, where t2 = T2. That is, the measurement mode and the recharge mode are seamlessly alternated, and the period when no measurement is performed is the recharge period.

[0076] Compared with the constant current circuit with stepless switching, the constant current circuit with segmented switching can control multiple current paths through multiple switches, so that it can be recharged with segmented constant current according to the required current amount, which is more power-saving and can reduce costs. In addition, whether it is a constant voltage circuit or a constant current circuit, the potential difference can come from a DC power supply or an AC power supply, preferably a DC power supply.

[0077] FIG. 5A to FIG. 8CThe embodiments all describe the operation mode of alternating and cyclically performing the measuring step and the refilling step, that is, there is an AgCl refilling step between each measuring step. This method can better ensure that AgCl remains within the safety stock amount. However, in some preferred embodiments, Y times of AgCl refilling can be selectively combined during N times of measuring, where Y≤N, so that the cumulative refill amount of AgCl can still be kept within the safety stock range. The measuring step and the refilling step do not necessarily need to be performed in an alternating and cyclical manner. A refilling step can also be performed after several measuring steps, or after a predetermined measuring time. For example, a refilling step can be performed after 10 measurements, or a refilling step can be performed after the cumulative measuring time reaches 1 hour.

[0078] Please refer to Fig.8D , which shows that the constant current circuit of the present invention is similar to Figure 8C Schematic diagram of alternating between the measurement mode and the recharging mode. Fig.8D In FIG. 1 , the curve represents the physiological parameter value curve converted from the measured physiological signal Ia, and is similar to Figure 8C , T2 and t2 are fixed values, and V2 is a variable value. Fig.8D In the figure, the white area under the curve represents the consumption of AgCl in the measurement mode (Ia*Tl), and the oblique line area represents the recharged amount of AgCl in the recharge mode (Ib*t2). It can be seen from the figure that in order to make Ib*t2 close to Ia*Tl or within a certain range of Ia*Tl, the recharge potential difference V2 is dynamically adjusted according to the consumption of AgCl.

[0079] in addition Figure 5E , 5F and Fig.8D Although the timing of outputting each physiological parameter value after each physiological signal measurement step is not shown, the physiological parameter value is not limited to being output when the measurement is completed or during the recharging period, and the AgCl recharging step is not limited to being executed after each physiological parameter is output or after the physiological signal is obtained.

[0080] In the aforementioned embodiment of using the constant current or constant voltage circuit of the present invention to alternately perform the measurement mode and the recharge mode, the working electrode used in the measurement mode and the recharge mode can be either the first working electrode W1 or the second working electrode W2, and the counter electrode used in the measurement mode can also be either the first counter electrode R / C1 or the second counter electrode R / C2, but the counter electrode used in the recharge mode is preferably the counter electrode used in the previous measurement mode. Two exemplary embodiments are described below. Example 1 is performed in chronological order: (a) using W1 / W2 (indicating one of W1 and W2) and R / C1 for measurement, (b) using the other of W1 / W2 and R / C1 for recharge, (c) using one of W1 / W2 and R / C2 for measurement, (d) using the other of W1 / W2 and R / C2 for recharge, and repeating steps (a)-(d). Example 2 repeats steps (a), (b), (a), (b), (c), (d), (c), (d) in chronological order.

[0081] Please refer to Fig. 9A and 9B , which is a schematic diagram showing different embodiments of the constant current or constant voltage circuit of the present invention performing a measurement mode and a recharge mode at the same time. Fig. 9A and 9B The horizontal axis is time, the line V1 represents the application and removal of the measuring potential difference V1, and the line V2 represents the application and removal of the recharging potential difference V2. Since there are two counter electrodes and two working electrodes in the present invention, the measuring step and the recharging step can be performed simultaneously. Fig. 9A In the embodiment, the first combination formed by the first working electrode W1 and the first pair of electrodes R / C1 and the second combination formed by the second working electrode W2 and the second pair of electrodes R / C2 perform the measurement and recharging steps in turn. That is, when the first combination is used for the measurement step, the second combination is used for the recharging step, and vice versa. Fig. 9B In some preferred embodiments, the first working electrode W1 is fixed for the measurement step, the second working electrode W2 is fixed for the recharging step, and the two counter electrodes are used alternately between the measurement step and the recharging step. In some preferred embodiments, multiple T1s do not overlap with each other. In some preferred embodiments, multiple t2s do not overlap with each other. In some preferred embodiments, T1 and t2 overlap (indicates starting and ending at the same time) or partially overlap. Fig. 9A and 9B It is shown that the first measurement (using R / C1) is not accompanied by the refilling step, and the refilling (refilling R / C1) is performed simultaneously when the second measurement (using R / C2) is performed. However, the refilling step (refilling R / C2) can also be performed simultaneously when the first measurement (using R / C1) is performed.

[0082] Please refer to Fig.10, which shows a method for determining an analyte according to an embodiment of the present invention, by which the service life of a micro biosensor can be extended. The micro biosensor can be, for example, Figure 2A -The micro biosensor shown in FIG. 3 is used for implantation under the skin to measure physiological signals of physiological parameters associated with the analyte in a biological fluid (such as tissue fluid). Fig.10 In the embodiment of the present invention, the analyte may be glucose in tissue fluid, the physiological parameter is the glucose value (or concentration) in the human body, and the physiological signal is the current value measured by the micro biosensor. In this embodiment, the method for determining the analyte includes repeatedly and cyclically performing a determination step (S901) and a recharging step (S902). The determination step (S901) includes using the aforementioned constant voltage or constant current circuit to perform the aforementioned determination mode during the determination period T1 to output a physiological signal (i.e., a current value), while the AgCl of the electrode has a consumption corresponding to the current value. The determination step (S901) also includes stopping the determination step by stopping the aforementioned determination mode, and the current value is calculated to output a physiological parameter (i.e., a glucose value).

[0083] In the determination step (S901), the chemical reaction formula is as follows:

[0084] The following oxidation reaction is performed at the first working electrode 420 or the second working electrode 430:

[0085]

[0086]

[0087] The following reduction reaction is performed at the first pair of electrodes 440 or the second pair of electrodes 450:

[0088]

[0089] The recharging step (S902) includes using the aforementioned constant voltage or constant current circuit to perform the aforementioned recharging mode during the recharging period, so that the AgCl of the counter electrode has a recharging amount corresponding to the consumption amount, thereby controlling the amount of AgCl on the counter electrode within the safety stock range. In this way, the potential difference between the working electrode and the counter electrode can be kept stable, so that the obtained current value can still maintain a stable proportional relationship with the glucose value (if the detection substance is other analytes, it may also be a proportional relationship or an inverse relationship). In other words, the next current value obtained in the next measurement step can maintain a stable proportional relationship with the next glucose value. The recharging step (S902) also includes stopping the recharging step by stopping the aforementioned recharging mode. After the recharging step (S902) is completed, the measurement step (S901) is executed in a loop until N measurement steps (S901) and N recharging steps (S902) are executed. In some preferred embodiments, the measuring step (S901) and the recharging step (S902) are performed simultaneously, at different times, or partially overlapped. In some preferred embodiments, the N measuring steps do not overlap with each other. In some preferred embodiments, the N recharging steps do not overlap with each other.

[0090] In the recharging step (S902), the chemical reaction formula is as follows:

[0091] The following reduction reaction is performed at the first working electrode 420 or the second working electrode 430:

[0092]

[0093]

[0094]

[0095]

[0096] The positive potential at the first pair of electrodes 440 or the second pair of electrodes 450 causes the first pair of electrodes 440 or the second pair of electrodes 450 to perform the following oxidation reaction:

[0097]

[0098] The Ag on the counter electrode is oxidized to Ag + , and Cl from organisms - or Cl after oxidation (or dissociation) of AgCl - Combined to form AgCl, so that part or all of the AgCl consumed during the measurement period T1 is returned to the counter electrode.

[0099] The human body can obtain chloride ions and iodide ions through iodized salt, so the available halide ions include at least chloride ions and iodide ions for recharging silver halide.

[0100] The following embodiments are for a cycle of N measurement steps (S901) and N recharging steps (S902), wherein the physiological parameter mentioned is preferably a glucose value, and the physiological signal mentioned is preferably a current value. According to certain preferred embodiments, each measurement potential difference V1 is applied during the measurement period T1, and each recharging potential difference V2 is applied during the recharging period t2, and the measurement period T1 is a fixed value, which can be a time value within 3 seconds, within 5 seconds, within 10 seconds, within 15 seconds, within 30 seconds, within 1 minute, within 2 minutes, within 5 minutes or within 10 minutes. According to certain preferred embodiments, it is preferably a time value within 30 seconds. According to certain preferred embodiments, the measurement period T1 is a fixed value, and can be 2.5 seconds, 5 seconds, 15 seconds, 30 seconds, 1 minute, 2.5 minutes, 5 minutes, 10 minutes or 30 minutes, preferably 30 seconds. According to certain preferred embodiments, each measurement period T1 plus each recharging period t2 is a fixed value. According to some preferred embodiments, each recharge potential difference V2 has a fixed voltage value, and each recharge period t2 is dynamically adjusted according to the consumption of AgCl each time (e.g. Figure 5A As shown). According to certain preferred embodiments, each output physiological parameter is obtained by calculating each physiological signal at a single measurement time point in each measurement period T1. According to certain preferred embodiments, each output physiological parameter is obtained by calculating a mathematical operation value of multiple physiological signals at multiple measurement time points in each measurement period T1. The aforementioned mathematical operation values ​​are, for example, cumulative values, average values, medians, average values ​​of medians, etc. According to certain preferred embodiments, by controlling each recharge amount to be equal to or not equal to (including approximately similar, greater than or less than) each consumption amount, the amount of AgCl in the counter electrode is controlled within the safety stock range, so that the next physiological signal and the next physiological parameter obtained in the next measurement step maintain a stable proportional relationship. According to certain preferred embodiments, the step of removing each measurement potential difference V1 is to disconnect the circuit configured to connect the working electrode and the counter electrode, or to set each measurement potential difference V1 to 0. In other words, the power may be turned off to make the measuring circuit open circuit; or, a voltage of 0 volt may be applied between the working electrode and the counter electrode, wherein the operation time of either operation is 0.01 to 0.5 seconds. The step of removing the measuring potential difference V1 can avoid the generation of a Λ-shaped physiological signal. According to some preferred embodiments, the step of removing each recharge potential difference V2 is to disconnect the circuit configured to connect the working electrode and the counter electrode, or to set each recharge potential difference V2 to 0.

[0101] According to some preferred embodiments, the sensor needs to undergo a warm-up period after being implanted in the human body so that the sensor can reach equilibrium and stability in the body and then stably present a physiological signal that is positively correlated with the concentration of the analyte. Therefore, in the measurement step (S901), the measurement voltage is continuously applied until the measurement period T1 ends, and the measurement period T1 is controlled so that the physiological signal and the physiological parameters of the analyte reach a stable proportional relationship. Therefore, the measurement period T1 can be a variable value or a combination of a variable value and a fixed value (for example, a variable value + a fixed value, the variable value can be 1 hour, 2 hours, 3 hours, 6 hours, 12 hours or 24 hours, and the fixed value can be, for example, 30 seconds).

[0102] Please refer to Figure 5A -F. Fig. 8A -D and Fig.10 The present invention uses voltage applied to the counter electrode R / C to measure the reaction current of the counter electrode during a period, and obtains the initial capacity of AgCl by mathematically calculating the reaction current during the period, for example, by calculating the area under the reaction current curve to define the initial capacity of AgCl, also known as the initial amount or initial coulomb amount (C initial ), the following description is based on quantity. The counter electrode R / C contains Ag and AgCl. When the percentage of AgCl (X% AgCl) is known, the Ag percentage (Y% Ag = 100% - X% AgCl) can be calculated. In each measurement step (S901), the area under the current curve of the working electrode W is calculated to define the consumption of AgCl each time (in terms of C consume The AgCl of the electrode R / C has a consumption C corresponding to the physiological signal Ia. consume , that is, C consume =Ia*T1. In each recharging step (S902), the recharging amount of AgCl (in C) is defined by calculating the area under the current curve of the counter electrode R / C. replenish C replenish =Ib*t2, t2 is between 0 and T2.

[0103] The following describes the calculation method of the AgCl safety stock. In certain preferred embodiments, the safety stock interval is presented as the ratio of Ag to AgCl. The present invention uses the coulomb amount (C) measured at the electrode to reflect the ratio of Ag to AgCl. In certain preferred embodiments, the ratio of Ag to AgCl is 99.9%:0.1%, 99%:1%, 95%:5%, 90%:10%, 70%:30%, 50%:50%, 40%:60% or 30:70%, so that AgCl has a certain amount on the electrode without being consumed, so that each physiological signal measurement step can be performed stably. The remaining amount of AgCl is the sum of the recharge amount and the initial amount minus the consumption amount. In certain preferred embodiments, the remaining amount of AgCl varies within a range, that is, the remaining amount of AgCl is controlled within the range of the initial amount plus or minus a specific value (X value), that is, (C replenish +C initial )-C consume =C initial ±X, where 0 <X<100%C initial , 10%C initial <X≤90%C initial , or 0.5%C initial <X≤50%C initial In some preferred embodiments, the residual amount of AgCl may gradually decrease, gradually increase, or change steadily or randomly within a range but still be within the range.

[0104] Please refer to Fig.11 , which shows a method for determining an analyte according to another embodiment of the present invention, by which the service life of the micro biosensor can be extended and the amount of silver and silver halide materials used in the electrode can be reduced. The micro biosensor can be, for example, Figure 2A -The micro biosensor shown in FIG3 is used for implantation under the skin to measure physiological signals of physiological parameters associated with the analyte in biological fluid (e.g., tissue fluid). The electrode material of the counter electrode of the micro biosensor includes silver and silver halide. Fig.11 In the embodiment of the present invention, the analyte may be glucose in tissue fluid, the physiological parameter is the glucose value in the human body, and the physiological signal is the current value measured by the micro-biosensor. Only two cycles of this embodiment are described below. The method of this embodiment begins with the following steps: during a first measurement period, a measurement voltage is applied to drive the first or second working electrode W1 / W2 to measure a physiological signal for obtaining the physiological parameter, wherein the silver halide of the first or second pair of electrodes R / C1 or R / C2 (assuming the first pair of electrodes R / C1) is consumed by a consumption amount (S1101).

[0105] Then stop applying the measurement voltage (S1102), and use the obtained physiological signal to obtain the physiological parameters (S1103). After obtaining the physiological parameters, apply the recharge voltage during the first recharge period to drive the electrode pair (i.e., the first electrode pair R / C1) used in S1101 and having the consumption amount, so that the amount of silver halide is recharged by a recharge amount (S1104), wherein the sum of the recharge amount and the initial amount minus the value of the consumption amount (i.e., the remaining amount mentioned above) is controlled within the range of the initial amount plus or minus a specific value. The above control step is achieved by controlling the recharge amount to be equal to or not equal to (including approximately similar, greater than or less than) the consumption amount to maintain the amount of silver halide within the safety inventory range. According to the reaction formula, the increase or decrease in the number of moles of silver halide corresponds to the increase or decrease in the number of moles of silver, so for the sake of convenience, the consumption of silver halide corresponds to the simulated increase in silver. In some preferred embodiments, the value of the remaining amount is controlled so that the ratio of the amount of silver halide to the amount of silver plus the amount of silver halide (AgCl / Ag+AgCl) is greater than 0 and less than 1, that is, there is only one amount of silver halide for the electrode, preferably between 0.01-0.99, between 0.1-0.9, between 0.2-0.8, between 0.3-0.7 or between 0.4-0.6. When the recharge amount is reached, the recharge voltage is stopped (S1105). Then, the process returns to step S1101, and during the second measurement period, a measurement voltage is applied to drive the first or second working electrode W1 / W2 to measure another physiological signal for obtaining another physiological parameter, wherein the silver halide of another electrode (i.e., the second electrode R / C2) is consumed by a consumption amount. Then, the measurement voltage is stopped (S1102), and the physiological signal obtained is used to obtain the physiological parameter (S1103). After obtaining the physiological parameters, a recharge voltage is applied during the second recharge period to drive the electrode used in S1101 and having the consumption amount (i.e., the second electrode R / C2), so that the amount of silver halide is recharged by a recharge amount (S1104). Then, the process returns to step S1001 to execute the next cycle.

[0106] The following describes a specific embodiment of the present invention, taking the biosensor service life of 16 days as an example to calculate the required electrode signal sensing section Ag / AgCl material size, for example, the average measurement current of the analyte measured each time is 30nA, the measurement period (T1) is 30 seconds, and the recharge period (t2) is 30 seconds. The daily consumption of AgCl (C consume / day )=1.3mC / day. Assuming the service life of the sensor is 16 days, the consumption of AgCl required for 16 days is 1.3x 16=20.8mC.

[0107] For example, the length of the counter electrode is 2.5 mm, which corresponds to the initial amount of AgCl C intial =10mC;

[0108] Without AgCl recharge, for a sensor life of 16 days, the electrode length required is at least:

[0109] C 16day / C consume / day＝ 20.8mC / 1.3mg / day=16mm

[0110] Therefore, without using the silver halide recharging method of the present invention, the length of the electrode must exceed 16 mm to extend the sensor life to 16 days.

[0111] In this embodiment, without using the silver halide recharging technology of the present invention, the electrode signal sensing section needs to be configured with a relatively large Ag / AgCl material size to achieve a sensor life of 16 days. Through the silver halide recharging method of the present invention, the silver halide recharging step is performed between two measurement steps, and the consumption and recharging of the silver halide can be repeatedly cycled in a short time (recharging as needed), so the amount of Ag / AgCl material in the sensor can be reduced, thereby miniaturizing the sensor. Therefore, the electrode signal sensing section material does not need to prepare a 16-day capacity of AgCl for consumption. For example, the sensor can be used for 16 days by preparing a capacity of AgCl for about 1 to 2 days, thereby achieving the effect of extending the service life of the sensor. The capacity of AgCl for 1 to 2 days also refers to the initial amount of AgCl, for example, between about 1.3 and 2.6 mC, of ​​the electrode before leaving the factory or performing the first measurement. The initial amount can also be other smaller or larger ranges. In other embodiments, different AgCl capacities may be prepared for 1 to 5 days, 1 to 3 days, 6 to 24 hours, 6 to 12 hours, etc. The material size of the electrode signal sensing segment only needs to have a capacity that allows each glucose measurement step to be stably performed and allows the measurement current to show a positive correlation with the glucose concentration in the body.

[0112] If the silver chloride recharging technology of the present invention is not used, the prior art would increase the electrode length / area to allow the sensor to reach the required number of days. Taking the prior art as an example, the length of the sensor implant end is about 12mm. Due to the long implantation length, in order to avoid implantation deep into the subcutaneous tissue, it needs to be implanted subcutaneously at an oblique angle, and the implantation wound is larger. For another example, the capacity of 1 to 2 days of AgCl is approximately between 1.3 and 2.6mC, which translates to a counter electrode length of 2.5 to 5mm for the 1 to 2 days. Compared to the 16mm counter electrode length required without the silver halide recharging method of the present invention, the present invention can effectively reduce the required counter electrode size. Through the silver halide recharging method of the present invention, the length of the implant end can be shortened, for example, the length can be reduced to no more than 10mm. In the present invention Figure 2A-2CThe lower half of the connection area 417 of the disclosed micro biosensor 400 to the second end 414 belongs to the short implant end 418 (eg Figure 2A and 2B As shown), and the implantation depth of the short implant end 418 must at least meet the depth at which the dermis can measure the glucose in the tissue fluid. Through the silver halide recharging method of the present invention, the longest side of the short implant end 418 is no more than 6 mm, so that the micro biosensor 400 can be partially implanted under the epidermis of the organism in a manner perpendicular to the epidermis of the organism. The longest side of the short implant end 418 is preferably no more than 5 mm, 4.5 mm, 3.5 mm or 2.5 mm. The short implant end 418 of the present invention includes a third signal sensing segment 442 and a fourth signal sensing segment 452, and the longest sides of the third signal sensing segment 442 and the fourth signal sensing segment 452 are no more than 6 mm, preferably 2-6 mm, 2-5 mm, 2-4.5 mm, 2-3.5 mm, 0.5-2 mm, 0.2-1 mm.

[0113] Therefore, compared with the situation where the silver halide recharging technology of the present invention is not used, the silver halide recharging method of the present invention can effectively extend the service life of the sensor, and can greatly reduce the use of Ag / AgCl materials on the electrode, so that the size of the electrode signal sensing section can be reduced. Due to the reduction in the use of Ag / AgCl materials on the electrode, the sensor can be miniaturized and the biotoxicity can be reduced. In addition, the reduction in electrode size specifically refers to shortening the length of the implant end of the sensor, thereby reducing the user's implant pain. In the device of the present invention including four electrodes, since measurement and recharging can be performed simultaneously, it can have a shorter electrode size and a more flexible and efficient operation mode compared to a device including two or three electrodes.

[0114]

Explanation of symbols

[0115] 10: Physiological signal measuring device

[0116] 20: User device

[0117] 200:Sensor unit

[0118] 210: Processor

[0119] 220: Power supply

[0120] 230: Circuit switching unit

[0121] 240: Temperature sensing unit

[0122] 250: Communication unit

[0123] 400:Micro Biosensor

[0124] 410:Substrate

[0125] 411: Surface

[0126] 412: Opposite surface

[0127] 413: First End

[0128] 414: Second End

[0129] 415:Signal output area

[0130] 416: Sensing area

[0131] 417: Connection area

[0132] 418: short implant end

[0133] 420: first working electrode

[0134] 321: First signal output section

[0135] 322: First signal sensing section

[0136] 430: second working electrode

[0137] 431: Second signal output section

[0138] 432: Second signal sensing segment

[0139] 440: first pair of electrodes

[0140] 441: Third signal output section

[0141] 442: Third signal sensing segment

[0142] 450: Second pair of electrodes

[0143] 451: Fourth signal output section

[0144] 452: Fourth signal sensing segment

[0145] 460: Chemical Reagents

[0146] 61: Partial constant current circuit with segment switching

[0147] 71: Partial constant current circuit with stepless switching

[0148] Steps S901, S902, S1101, S1102, S1103, S1104, S1105

Claims

1. A method for measuring an analyte by extending the service life of a micro biosensor, the biosensor being implanted subcutaneously to measure a physiological signal of a physiological parameter associated with the analyte in a biological fluid, the biosensor comprising a first and a second working electrode and a first and a second pair of electrodes, each of the working electrodes being at least partially covered by a chemical reagent and being used to produce an electrochemical reaction with the analyte, an electrode material of the first pair of electrodes and the second pair of electrodes comprising silver and silver chloride, the method comprising the following steps: a) performing a first determination step, comprising: During a first measurement period, a first measurement potential difference is applied between the first working electrode and the first pair of electrodes, so that a voltage of the first working electrode is higher than a voltage of the first pair of electrodes, so that a first oxidation reaction occurs at the first working electrode, and the first working electrode undergoes an electrochemical reaction with the chemical reagent and the analyte to output a first physiological signal, and at the same time, the silver chloride of the first pair of electrodes has a first consumption amount corresponding to the first physiological signal; as well as Removing the first measurement potential difference, stopping the first measurement step, and outputting a first physiological parameter after calculating the first physiological signal; b) performing a first recharging step, including: i. during a first recharge period, applying a first recharge potential difference between the first pair of electrodes and one of the first or second working electrodes, so that the voltage of the first pair of electrodes is higher than the voltage of one of the first or second working electrodes, thereby causing a second oxidation reaction to occur on the silver on the first pair of electrodes, and causing the silver chloride to have a first recharge amount, wherein the first recharge amount corresponds to the first consumption amount; and ii. removing the first recharge potential difference and stopping the first recharge step; c) performing a second determination step, comprising: i. during a second measurement period, applying the first measurement potential difference between one of the first and second working electrodes and the second pair of electrodes, so that a voltage of one of the first and second working electrodes is higher than a voltage of the second pair of electrodes, so that one of the first and second working electrodes undergoes the first oxidation reaction, and undergoes the electrochemical reaction with the chemical reagent and the analyte to output a second physiological signal, and at the same time, the silver chloride of the second pair of electrodes has a second consumption corresponding to the second physiological signal; and ii. removing the first measured potential difference, stopping the step of measuring the second physiological signal, and outputting a second physiological parameter after the second physiological signal is calculated; d) executing a second recharging step, comprising: i. during a second recharge period, applying a second recharge potential difference between the second pair of electrodes and the second working electrode, so that the voltage of the second pair of electrodes is higher than the voltage of the second working electrode, so that the silver on the second pair of electrodes undergoes the second oxidation reaction and the silver chloride has a second recharge amount; and ii. removing the first recharge potential difference and stopping the second recharge step; and e) Repeat the following steps a2) to d2) in sequence: a2) performing an Mth measuring step identical to step a) to obtain an Mth physiological signal and output an Mth physiological parameter, and the silver chloride of the first pair of electrodes has an Mth consumption corresponding to the Mth physiological signal; b2) performing an Mth recharging step identical to step b) so that the silver chloride of the first pair of electrodes has an Mth recharging amount and the Mth recharging amount corresponds to the Mth consumption amount; c2) performing an Nth measuring step identical to step c) to obtain an Nth physiological signal and output an Nth physiological parameter, and the silver chloride of the second pair of electrodes has an Nth consumption corresponding to the Nth physiological signal; and d2) performing an Nth silver chloride recharging step identical to step d) so that the silver chloride of the second pair of electrodes has an Nth recharging amount, and the Nth recharging amount corresponds to the Nth consumption amount, wherein: The amount of the silver chloride on the first pair of electrodes and the second pair of electrodes is controlled within a safety inventory range, so that the next physiological signal and the next physiological parameter obtained in the next measurement step maintain a stable proportional relationship.

2. The method as claimed in claim 1, wherein each of the first measuring potential differences is applied during the first measuring period and the second measuring period, respectively, the first recharge potential difference is applied during the first recharge period, and the second recharge potential difference is applied during the second recharge period, the first measuring period has a first measuring time, the second measuring period has a second measuring time, the first recharge period and the second recharge period have a recharge time, and the first measuring time and the second measuring time have a fixed measuring time value or a variable measuring time value.

3. The method of claim 2, wherein the first recharge potential difference and the second recharge potential difference have a fixed voltage value, and each recharge time is dynamically adjusted according to the respective consumption of silver chloride of the first pair of electrodes and the silver chloride of the second pair of electrodes.

4. The method of claim 2, wherein each recharge time is a fixed time value, and a value of each recharge voltage is dynamically adjusted according to the respective consumption of silver chloride of the first pair of electrodes and the silver chloride of the second pair of electrodes.

5. The method as claimed in claim 1, wherein the amount of silver chloride on the first pair of electrodes and the second pair of electrodes is controlled within a safety stock range, so that the next physiological signal and the next physiological parameter obtained in the next physiological signal measurement step maintain a stable proportional relationship, which is achieved by controlling the respective recharge amounts to be equal to the respective consumption amounts.

6. The method as claimed in claim 1, wherein the amount of silver chloride on the first pair of electrodes and the second pair of electrodes is controlled within a safety stock range, so that the next physiological signal and the next physiological parameter obtained in the next physiological signal measurement step maintain a stable proportional relationship, which is achieved by controlling the respective recharge amounts to be greater than the respective consumption amounts.

7. The method as claimed in claim 1, wherein the amount of silver chloride on the first pair of electrodes and the second pair of electrodes is controlled within a safety stock range, so that the next physiological signal and the next physiological parameter obtained in the next physiological signal measurement step maintain a stable proportional relationship, which is achieved by controlling the respective recharge amounts to be less than the respective consumption amounts.

8. The method of claim 1, wherein the amount of silver chloride on the first pair of electrodes and the second pair of electrodes is controlled within a safety stock range so that the next physiological signal and the next physiological parameter obtained in the next physiological signal measurement step maintain a stable proportional relationship, which is achieved by controlling the respective recharge amounts to be unequal to the respective consumption amounts.

9. The method of claim 1 , wherein a first content of the silver chloride of the first pair of electrodes at any time is calculated as a first ratio of an amount of the silver chloride of the first pair of electrodes to an amount of the silver plus the amount of the silver chloride, and a second content of the silver chloride of the second pair of electrodes is calculated as a second ratio of an amount of the silver chloride of the second pair of electrodes to an amount of the silver plus the amount of the silver chloride, and the first ratio and the second ratio are each a value greater than 0 and less than 1.

10. The method of claim 1, wherein the step of applying the first measured potential difference and the step of applying the second recharge potential difference are performed simultaneously, at different times, or partially overlapped, and the step of applying the first recharge potential difference and the step of applying the second recharge potential difference are performed simultaneously, at different times, or partially overlapped.

11. A method for measuring an analyte that can extend the service life of a biosensor, the biosensor being implanted subcutaneously to measure a physiological signal associated with a physiological parameter of the analyte, and comprising two working electrodes and two pairs of electrodes disposed on a substrate, each of the working electrodes being at least partially covered by a chemical reagent, the first pair of electrodes and the second pair of electrodes having an electrode material comprising silver and a silver halide, each of the silver halide having an initial amount, the method comprising the following steps: During a first measurement period, a measurement voltage is applied to drive one of the two working electrodes to measure the physiological signal to obtain the physiological parameter, and the silver halide of one of the two pairs of electrodes is consumed by a consumption amount; Stop applying the measuring voltage; During a first recharging period, a recharging voltage is applied to drive one of the two pairs of electrodes, so that an amount of the silver halide in one of the two pairs of electrodes is recharged by a recharging amount; During a second measurement period, the measurement voltage is applied to drive one or the other of the two working electrodes to measure another physiological signal to obtain another physiological parameter, and the silver halide of the other of the two pairs of electrodes is consumed by a consumption amount; Stop applying the measuring voltage; as well as During a second recharging period, the recharging voltage is applied to drive the other of the two pairs of electrodes, so that an amount of the silver halide in the other of the two pairs of electrodes is recharged by a recharging amount; in Whenever a physiological parameter is obtained, during the first charging period, the value of the sum of the first charging amount and the initial amount of the first charging period minus the consumption amount during the first charging period is controlled within a range of plus or minus a specific value from the initial amount of the first charging period. During the second charging period, the value of the sum of the second charging amount and the initial amount of the second charging period minus the consumption amount during the second charging period is controlled within a range of plus or minus a specific value from the initial amount of the second charging period.

12. The method according to claim 11, wherein the specific value is X, and X satisfies the following condition: 0 < X < 100% of the initial amount.

13. The method according to claim 11, wherein controlling the value of the sum of each charging amount and each initial amount minus each consumption amount consumed within a range of plus or minus the specific value from each initial amount is accomplished by controlling each charging amount to be equal to each consumption amount to maintain the amount of the silver halide within a safe inventory range.

14. The method according to claim 11, wherein controlling the value of the sum of each charging amount and each initial amount minus each consumption amount consumed within a range of plus or minus the specific value from each initial amount is accomplished by controlling each charging amount to be greater than each consumption amount to maintain the amount of the silver halide within a safe inventory range.

15. The method according to claim 11, wherein controlling the value of the sum of each charging amount and each initial amount minus each consumption amount consumed within a range of plus or minus the specific value from each initial amount is accomplished by controlling each charging amount to be less than each consumption amount to maintain the amount of the silver halide within a safe inventory range.

16. The method according to claim 11, wherein controlling the value of the sum of each charging amount and each initial amount minus each consumption amount consumed within a range of plus or minus the specific value from each initial amount is accomplished by controlling each charging amount not to be equal to each consumption amount to maintain the amount of the silver halide within a safe inventory range.

17. The method according to claim 11, wherein each initial amount is calculated as the ratio of the amount of silver halide of the first pair of electrodes and the second pair of electrodes to the sum of the amount of silver and the amount of silver halide, each ratio is a value greater than 0 and less than 1, and each measurement period does not overlap with each other.

18. An implantable micro-biosensor with both a long service life and a small counter electrode size, for measuring a physiological signal of a physiological parameter associated with an analyte in a living body, the implantable micro-biosensor comprising: a substrate; a chemical reagent; two working electrodes, disposed on the substrate, each including a first signal sensing section, at least partially covered by the chemical reagent, and during a specific measurement period, one of the two working electrodes is driven to undergo an oxidation reaction to measure a physiological signal of the analyte to generate the physiological parameter; and Two pairs of electrodes are disposed on the substrate, each including a second signal sensing section having a size, each of the two pairs of electrodes having an electrode material including silver and a silver halide, wherein each of the silver halide has an initial amount, and within the specific measurement period, each of the silver halide is consumed by a consumption amount, wherein; Each time after the physiological parameter is obtained, during a recharging period, one of the two pairs of electrodes is driven, so that the amount of silver halide of the driven pair of electrodes is recharged by a recharging amount, wherein the sum of each recharging amount and each initial amount minus a value of each consumed amount is controlled within a range of each initial amount plus or minus a specific value.

19. An implantable micro-biosensor as described in claim 18, wherein the value of the sum of each recharge amount and each initial amount minus each consumed amount is controlled so that the ratio of an amount of each silver halide to an amount of each silver plus a sum of the amount of each silver halide is greater than 0 and less than 1, the first pair of electrodes and the second pair of electrodes are at least partially covered by the chemical reagent, and the measurement periods do not overlap with each other.

20. An implantable micro-biosensor as described in claim 18, wherein the size of the two pairs of electrodes is adjusted based on the amount of the silver halide being sufficient to be maintained within a safe range, so that the length of each second signal sensing segment is not greater than 6 mm, a surface of each of the two pairs of electrodes is partially covered by a conductive material, and each two adjacent measurement periods include a pre-measurement period and a post-measurement period, during the pre-measurement period one of the two working electrodes and one of the two pairs of electrodes are driven, and during the post-measurement period one or the other of the two working electrodes is driven.

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