A non-invasive blood glucose detection method

Abstract

The present application belongs to the technical field of non-invasive blood glucose detection, and particularly relates to a non-invasive blood glucose detection method, comprising: attaching and fixing a blood glucose detection device on the skin of a subject to be detected, and then sequentially performing counter-ion electroosmotic extraction and electrochemical detection; wherein the extraction conditions comprise: an extraction current of 0.1-0.5 mA, an extraction voltage of 5-12 V, an extraction time of 5-30 min, an extraction current frequency of 1-4 kHz, and an extraction current duty cycle of 10-100%. By optimizing the extraction current, the extraction voltage, the extraction time, the extraction current frequency and the extraction current duty cycle, on the one hand, the extraction efficiency can be promoted, the detection accuracy can be improved, and on the other hand, the phenomenon of skin tingling or damage can be avoided, the stability of the extraction process at different times can be improved, and a high-accuracy measurement result can be obtained.

Description

Technical Field

[0001] This invention belongs to the field of non-invasive blood glucose detection technology, specifically relating to a non-invasive blood glucose detection method. Background Technology

[0002] Non-invasive blood glucose testing refers to the detection of subcutaneous tissue fluid without causing damage to human tissue. Existing research methods for non-invasive blood glucose testing are numerous and can be broadly categorized into three main types: those utilizing optical, thermal, and electrical principles. For tissue fluid testing in diabetic patients, besides blood glucose, other body fluids also contain significant amounts of glucose, with ISF (interstitial fluid of the skin) showing the closest glucose concentration to blood glucose levels. Electrical principles primarily utilize the correlation between other body fluids and blood glucose values. For example, glucose content in saliva, tears, sweat, and ISF can be measured. After calibration with standard blood glucose values, a data model is established to derive the measured value. Measurement of interstitial fluid glucose concentration mainly uses reverse iontophoresis (RI) for extraction and detection. For other body fluids, glucose sensors are generally used to directly detect their electrochemical properties.

[0003] Non-invasive glucose sensors based on sweat have been a subject of considerable research in recent years. Their advantages include convenient sampling, highly integrated and wearable devices, continuous measurement capabilities, and high comfort. However, sweat can only be detected and analyzed when it reaches the skin's surface, making timely and appropriate sweat collection a key limitation. Currently, most methods employ prolonged exercise, heating, pressure, and ionization stimulation to extract and collect sweat, but these all have drawbacks (e.g., prolonged sweating is unsuitable for diabetic patients, and heating and ionization stimulation can cause pain and discomfort). The low sugar content in sweat, leading to lower sensitivity and a certain hysteresis relative to blood glucose concentration, is also a major factor restricting their application.

[0004] Detecting glucose concentration in subcutaneous interstitial fluid is equivalent to monitoring blood glucose changes. Subcutaneous interstitial fluid is a bodily fluid containing glucose. Extraction of subcutaneous interstitial fluid using reverse iontophoresis extraction technology allows for the generation of blood glucose curves, which are of great reference value for patient medication. Currently, several research teams both domestically and internationally have established large-scale research projects on wearable medical devices, such as the Smart Shirt project at Georgia Institute of Technology, the MIThril project at MIT, the IST FP5 and FP6 projects in the European Union, and the "Guardian" and Health Shirt projects at the Chinese University of Hong Kong. Key universities in China, such as Tsinghua University, Zhejiang University, and Shanghai Jiao Tong University, are actively establishing pilot research projects on related wearable medical devices and have already made some progress.

[0005] The inventors of this invention previously disclosed a paper-based electrode detection platform for biochemical analysis and its preparation method in CN105954331B. This paper-based electrode detection platform uses biodegradable paper as the substrate material, prints carbon electrodes on the substrate material, and fixes an electron transfer medium and a recognition molecular layer on the surface of the carbon electrodes, resulting in a completely biodegradable paper-based electrode detection platform. Electrochemical tests show that the prepared biodegradable paper-based electrode detection platform has the same good electrochemical performance as its plastic substrate electrodes. The fully biodegradable paper-based electrode detection platform, used for glucose detection, has advantages such as high sensitivity, short detection time, small variability, and good stability. CN1973768A discloses a non-invasive blood glucose meter for closed-loop insulin injection, with a built-in wireless communication module. It combines an electrochemical electrode to extract subcutaneous tissue fluid to achieve non-invasive blood glucose detection and is coupled to an insulin pump via radio frequency wireless communication to guide insulin injection. The constant current source sampling circuit of this blood glucose meter can be combined with an electrochemical biosensor to continuously and non-invasively extract subcutaneous tissue fluid through human skin. The glucose concentration in the subcutaneous tissue fluid is detected by electrochemical methods, thereby obtaining the blood glucose concentration. The blood glucose information and time information are sent to the insulin pump through a radio frequency wireless communication module to guide insulin injection, realizing closed-loop control of blood glucose levels for diabetic patients. This can greatly reduce the suffering of diabetic patients and improve their quality of life.

[0006] However, in existing reverse ion permeation processes, the ISF glucose extraction rate is correlated with the current intensity. Increasing the ISF glucose extraction rate can effectively improve the accuracy of sensor detection. Therefore, the most common approach is to increase the current intensity, but prolonged monitoring can cause skin irritation and damage. Furthermore, in non-invasive blood glucose testing, the blood glucose value used for calibration is generally finger-prick blood or venous blood. When blood glucose levels change rapidly, the changes in blood glucose in the dermal tissue of the skin (i.e., the glucose concentration in the interstitial fluid of the skin tissue) lag behind the changes in blood glucose in peripheral or venous blood. The testing instrument can correct for this lag based on the body's metabolic rate. However, because existing detection methods inevitably cause some skin irritation and damage, uncontrollable simultaneous detection of blood glucose and ISF glucose can occur during measurement, affecting the calibration results and thus the accuracy of the test. For patients with hyperglycemia or hypoglycemia, such inaccurate test results are very dangerous.

[0007] Therefore, how to avoid skin damage, obtain highly accurate measurement results, and improve the comfort of testing personnel has become the focus of current research. Summary of the Invention

[0008] The purpose of this invention is to overcome the shortcomings of existing blood glucose testing technologies, such as causing skin irritation and damage, and inaccurate detection, and to provide a non-invasive blood glucose testing method that can obtain highly accurate measurement results without causing skin damage; significantly improving the comfort and testing effect of the test subjects.

[0009] To achieve the above objectives, the present invention provides a non-invasive blood glucose detection method, comprising: attaching and fixing a blood glucose detection device to the subject's skin to be tested, and then sequentially performing reverse ion electroosmosis extraction and electrochemical detection;

[0010] The extraction conditions include: extraction current of 0.1-0.5mA, extraction voltage of 5-12V, extraction time of 5-30min, extraction current frequency of 1-4kHz, and extraction current duty cycle of 10-100%.

[0011] In some preferred embodiments, the extraction conditions include: extraction current of 0.1-0.3mA, extraction voltage of 5-12V, extraction time of 17-30min, extraction current frequency of 1-4kHz, and extraction current duty cycle of 10-100%.

[0012] In some preferred embodiments, the non-invasive blood glucose detection method further includes:

[0013] In the reverse ion electroosmosis extraction, the surface water content of the extraction / detection electrode used in the blood glucose detection device is measured in real time to obtain the relative extraction amount.

[0014] If the relative extraction amount exceeds a preset threshold, the extract is subjected to electrochemical detection, and the resulting response current value is used as the basis for judging blood glucose changes. If the relative extraction amount does not exceed the threshold, the response current value obtained from the electrochemical detection is discarded and is not used as the basis for judging blood glucose changes.

[0015] In some preferred embodiments, the blood glucose detection device includes: an adhesive substrate, and a first electrode assembly and a second electrode assembly respectively disposed on the adhesive substrate;

[0016] The first electrode assembly includes an extraction / detection electrode layer, which includes dual electrodes for use as a working electrode and a counter electrode, respectively, to perform the electrochemical detection;

[0017] The second electrode assembly includes an extraction electrode positive electrode, which is used to cooperate with one of the electrodes in the dual electrode assembly, serving as the positive electrode and the negative electrode respectively, to perform the reverse ion electroosmosis extraction;

[0018] Furthermore, the positive electrode of the extraction electrode covers the extraction / detection electrode layer, and the positive electrode of the extraction electrode extends along the edge covered by the extraction / detection electrode layer.

[0019] In some preferred embodiments, with the direction closest to the skin as the top, the extraction / detection electrode layer consists of, from bottom to top, fiber paper, a carbon layer, a potassium ferricyanide layer, and a glucose oxidase layer.

[0020] In some preferred embodiments, the blood glucose detection device further includes a gel layer disposed on the skin-contacting side of the extraction / detection electrode layer.

[0021] In some preferred embodiments, the non-invasive blood glucose detection method further includes:

[0022] In the reverse ion electroosmosis extraction, the water content of the gel layer is measured;

[0023] Based on the water content of the gel layer, the surface water content of the extraction / detection electrode layer is used to further obtain the relative extraction amount;

[0024] If the relative extraction amount exceeds a preset threshold, the extract is subjected to electrochemical detection, and the resulting response current value is used as the basis for judging blood glucose changes. If the relative extraction amount does not exceed the threshold, the response current value obtained from the electrochemical detection is discarded and is not used as the basis for judging blood glucose changes.

[0025] In some preferred embodiments, the non-invasive blood glucose detection method further includes: obtaining the relative extraction amount after excluding environmental evaporation factors.

[0026] In some preferred embodiments, the method for obtaining the relative extraction amount by excluding environmental evaporation factors includes:

[0027] The weight and water content of the gel layer during the evaporation process over time were measured in advance when the extraction was not performed, and the corresponding relationship between the weight x and water content y of the gel layer was obtained.

[0028] The water content y1 of the gel layer after extraction is tested over a certain period of time, and x1 is obtained based on y1 and the corresponding relationship.

[0029] The water content y0 of the gel layer before extraction was tested at the corresponding time, and x0 was obtained based on y0 and the corresponding relationship.

[0030] Based on x1 and x0, the relative extraction amount Δx is obtained, where Δx = x1 - x0.

[0031] More preferably, the correspondence is obtained by fitting the gel layer weight x and water content y at each time point.

[0032] More preferably, the correspondence is as follows:

[0033] y = -0.19*x 2 +10.11*x-44.28.

[0034] In some preferred embodiments, the blood glucose detection device further includes a waterproof layer disposed on the side of the extraction / detection electrode layer away from the skin.

[0035] This invention optimizes the extraction current, extraction voltage, extraction time, extraction current frequency, and extraction current duty cycle. On the one hand, it can improve extraction efficiency and detection sensitivity. On the other hand, it can avoid skin irritation or damage, improve the stability of the extraction process at different times, and obtain highly accurate measurement results.

[0036] In a preferred embodiment of the present invention, the weight of the gel layer is adjusted to exclude environmental evaporation factors. More preferably, a fitting relationship is constructed between the weight and water content of the gel layer, which can further obtain more accurate blood glucose measurement results and more stable test results. Attached Figure Description

[0037] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0038] Explanation of reference numerals in the attached figures

[0039] Figure 1 This is a schematic diagram of one embodiment of the blood glucose detection device of the present invention.

[0040] Figure 2 yes Figure 1 A schematic diagram of one embodiment of the first electrode assembly.

[0041] Figure 3 This refers to the single extraction amount obtained under different extraction conditions in Example 1 of the present invention.

[0042] Figure 4 This is a fitted curve showing the correspondence between the weight x of the gel layer and the water content y of the gel layer obtained in Example 1 of this invention.

[0043] Figure 5 This is a graph showing the change in water content of the gel layer under different extraction conditions as a function of monitoring time, according to an embodiment of the present invention.

[0044] Figure 6The curves show the response current of the non-invasive blood glucose detection in Embodiment 1 of the present invention and the blood glucose concentration results of the invasive blood glucose detection in the prior art.

[0045] Figure 7 The curves show the response current obtained from the detection of Comparative Example 1 and the blood glucose concentration values ​​from invasive blood glucose detection using existing technologies.

[0046] Figure 8 These are skin images of the subjects after testing in Embodiment 1 of the present invention.

[0047] Figure 9 These are skin images of the subjects tested in Comparative Example 1 of this invention.

[0048] Explanation of reference numerals in the attached figures

[0049] 1-Extraction electrode positive electrode, 2-Adhesive substrate, 3-Extraction / detection electrode layer, 4-Modification coating, 5-Dual electrode. Detailed Implementation

[0050] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0051] In this invention, extraction time refers to the duration of time the extraction current is applied to the skin during a single extraction process.

[0052] In this invention, the extraction / detection electrode layer 3 refers to a layer that can be used as both an extraction electrode layer and a detection electrode layer.

[0053] This invention provides a non-invasive blood glucose detection method, comprising: attaching and fixing a blood glucose detection device to the subject's skin to be tested, and then sequentially performing reverse ion electroosmosis extraction and electrochemical detection; wherein the extraction conditions include: extraction current of 0.1-0.5mA, extraction voltage of 5-12V, extraction time of 5-30min, extraction current frequency of 1-4kHz, and extraction current duty cycle of 10-100%.

[0054] Existing extraction methods generally employ a single DC extraction condition: an extraction current of 0.3-0.5 mA and a fixed extraction time of 3, 5, or 12 minutes. Existing experiments have shown that continuous extraction under this current can cause skin redness and damage. The inventors of this invention have discovered that by modularizing the extraction process and setting appropriate extraction current frequencies and duty cycles for pulsed extraction, skin damage caused by prolonged current stimulation can be effectively avoided.

[0055] In this invention, by adjusting extraction conditions, including extraction current, extraction voltage, extraction time, extraction current frequency, and extraction current duty cycle, the extraction efficiency can be adjusted to ensure that the extraction and detection process does not cause any signs of irritation, pain, or damage to the skin surface; simultaneously, it increases the stability of extraction at different times, thereby improving detection accuracy. Specifically, this invention fully considers extraction voltage intensity, extraction time, extraction current frequency, extraction current duty cycle, and a relatively low extraction current as influencing factors, and uses the damage to the extracted skin area (preferably combined with the water content of the extraction / detection electrode layer surface) as an evaluation criterion to find the optimal extraction conditions, verify these conditions, achieve optimal extraction of tissue fluid, and finally use these conditions for continuous, non-invasive blood glucose monitoring.

[0056] In some preferred embodiments, the extraction conditions include: extraction current of 0.1-0.3mA, extraction voltage of 5-12V, extraction time of 17-30min, extraction current frequency of 1-4kHz, and extraction current duty cycle of 10-100%.

[0057] In some preferred embodiments, the extraction conditions include: an extraction current of 0.1-0.3 mA, an extraction voltage of 8.5-12 V, an extraction time of 20-30 min, an extraction current frequency of 1-2 kHz, and an extraction current duty cycle of 10-40%. This preferred embodiment is more conducive to improving extraction efficiency and obtaining more accurate measurement results.

[0058] According to the present invention, in the electrochemical detection, based on the extract obtained by the reverse ion electroosmosis extraction, the glucose content in the extract is detected electrochemically to obtain a response current value, thereby reflecting the blood glucose value. This is well known to those skilled in the art and is prior art. For example, the following calculation formula can be used:

[0059]

[0060] Where i(t) is the limiting current, and the response current value obtained at a specific moment;

[0061] n is the number of electrons transferred in the electrode reaction;

[0062] F is Faraday's constant;

[0063] A represents the electrode area;

[0064] This represents the initial molar concentration of the active ingredient in the solution, i.e., the glucose content.

[0065] D0 is the diffusion coefficient of the active ingredient glucose;

[0066] t is the electrolysis time.

[0067] In some preferred embodiments, the non-invasive blood glucose detection method further includes:

[0068] In the reverse ion electroosmosis extraction, the surface water content of the extraction / detection electrode used in the blood glucose detection device is measured in real time to obtain the relative extraction amount.

[0069] If the relative extraction amount exceeds a preset threshold, the extract is subjected to electrochemical detection, and the resulting response current value is used as the basis for judging blood glucose changes. If the relative extraction amount does not exceed the threshold, the response current value obtained from the electrochemical detection is discarded and is not used as the basis for judging blood glucose changes.

[0070] Studies have shown that excessively small amounts of subcutaneous tissue fluid extracted can severely affect the accuracy of measurement results. Furthermore, the relative amount of subcutaneous tissue fluid extracted can be calculated by measuring the water content on the surface of the extraction electrode. Therefore, the detection method of this invention includes a step of real-time measurement of the water content on the surface of the extraction / detection electrode layer to obtain the relative amount of subcutaneous tissue fluid obtained during the extraction process. During the detection process, it is necessary to determine whether the relative amount of extraction exceeds a preset threshold. If it exceeds the preset threshold, electrochemical detection is performed on the extract, and the resulting response current value is used as the basis for judging blood glucose changes, accurately reflecting the glucose content in human subcutaneous tissue fluid. If it does not exceed the preset threshold, it cannot accurately reflect the glucose content in human subcutaneous tissue fluid, and the response current value obtained from the electrochemical detection is discarded and not used as the basis for judging blood glucose changes.

[0071] In this invention, the preset threshold can be adjusted according to the required detection accuracy; generally, the preset threshold can be set to 0.1 mg or higher, and preferably, the threshold can be set to 0.8 mg or higher.

[0072] The present invention provides a wide range of possible structures for the blood glucose detection device, as long as it can perform subcutaneous tissue fluid extraction and detection.

[0073] In some embodiments, the blood glucose detection device includes: an adhesive substrate 2, and a first electrode assembly and a second electrode assembly respectively disposed on the adhesive substrate 2. Those skilled in the art can select the first electrode assembly and the second electrode assembly to be connected according to extraction and electrochemical detection requirements.

[0074] In some embodiments, the first electrode assembly of the blood glucose detection device is an extraction electrode, and the second electrode assembly is a detection electrode, wherein the detection electrode can be a three-electrode structure (including a working electrode, a reference electrode, and a counter electrode) or a two-electrode structure (including a working electrode and a counter electrode).

[0075] In some implementations, such as Figure 1 As shown, the first electrode assembly includes an extraction / detection electrode layer 3, which includes dual electrodes 5, used as a working electrode and a counter electrode, respectively, for the electrochemical detection. The second electrode assembly includes an extraction electrode positive electrode 1, which cooperates with one of the electrodes in the dual electrodes 5, serving as a positive and negative electrode, respectively, for the counterion electroosmosis extraction. The extraction electrode positive electrode 1 covers the extraction / detection electrode layer 3 and extends along the edge of the covered extraction / detection electrode layer 3. Studies have shown that the above electrode structure can achieve a more uniform electric field and can efficiently promote permeation at a low voltage of 0.1 mA.

[0076] The adhesive substrate 2 can be a flexible polymer tape, such as PET or other plastic or resin materials, as long as it can fix the first electrode assembly and the second electrode assembly to the skin surface, such as the exposed epidermis of the arm or the back of the hand.

[0077] It should be understood that, when the detection device is used, both the first electrode assembly and the second electrode assembly are fixedly attached to the skin to be tested on the human body surface through the adhesive substrate 2. Those skilled in the art can wipe the skin with a cotton swab before measurement, and after it dries, perform the fixing and attachment.

[0078] In this invention, those skilled in the art can also select and use some accessories in the detection device according to requirements such as fixation, reverse iontophoresis, electrochemical detection, and increased comfort. For example, the detection device also includes a clamping and fixing part, electrode wires, a current source, and an electrochemical detection device to realize reverse iontophoresis and electrochemical detection. During reverse iontophoresis, the positive electrode wire of the extraction electrode is connected to the positive electrode of the current source, and either of the two electrode wires is connected to the negative electrode of the current source to perform extraction. Glucose molecules in the tissue fluid are concentrated in the extraction / detection electrode layer 3 region of the first electrode assembly along with the ion flow. During electrochemical detection, the current source is disconnected, and the two electrode wires are connected to an external electrochemical analysis instrument.

[0079] In some implementations, such as Figure 1 and Figure 2 As shown, the extraction / detection electrode layer 3 includes a modified coating 4 containing electron transfer and molecular recognition, which corresponds to glucose in the subcutaneous tissue fluid for electrochemical detection of blood glucose.

[0080] In some more preferred embodiments, such as Figure 2As shown, with the direction closest to the skin as the top, the extraction / detection electrode layer 3 consists of, from bottom to top, a fiber paper, a carbon layer (containing dual electrodes 5), a potassium ferricyanide layer, and a glucose oxidase layer. In this preferred embodiment, the extraction / detection electrode layer 3 has excellent electron transfer capabilities and can more sensitively identify glucose.

[0081] The present invention does not limit the preparation method of the extraction / detection electrode layer 3, as long as the above-mentioned layers can be prepared and their electrochemical performance can be improved. In some specific embodiments, a carbon electrode is printed on a fiber paper substrate by screen printing to form a carbon layer, and then potassium ferricyanide and glucose oxidase are fixed in the working area of ​​the carbon electrode by liquid spraying using a dispensing machine.

[0082] In the above preferred embodiment, the detection device formed by the extraction / detection electrode layer 3 with a specific structure, in conjunction with specific extraction conditions, can achieve faster extraction efficiency, higher response current, and higher sensitivity in non-invasive blood glucose detection, without causing skin damage under prolonged reverse ion electroosmosis, and obtain more accurate measurement results.

[0083] In some preferred embodiments, the blood glucose detection device further includes a gel layer disposed on the skin-contacting side of the extraction / detection electrode layer 3, such as... Figure 2 As shown. In this embodiment, the gel layer is used to collect subcutaneous tissue fluid and improves the comfort of extraction.

[0084] Those skilled in the art can select the volume and composition of the gel layer based on the detection requirements. Preferably, the gel layer is a hydrogel. This invention does not require a specific initial water content for the hydrogel; instead, it utilizes a hydrogel water content change curve to obtain the relative value of the water content change, and uses this to obtain the relative extraction yield.

[0085] In some preferred embodiments, the non-invasive blood glucose detection method further includes: measuring the water content of the gel layer during the reverse ion electroosmosis extraction; using the water content of the gel layer as the surface water content of the extraction / detection electrode layer 3 to further obtain the relative extraction amount; determining whether the relative extraction amount exceeds a preset threshold; if it exceeds, performing electrochemical detection on the extract, and using the obtained response current value as the basis for judging blood glucose changes; if it does not exceed, discarding the response current value obtained from the electrochemical detection and not using it as the basis for judging blood glucose changes.

[0086] In this invention, the preset threshold can be adjusted according to the required detection accuracy; generally, the preset threshold can be set to 0.1 mg or higher, and preferably, the threshold can be set to 0.8 mg or higher.

[0087] In the above preferred embodiment, when the tissue fluid is extracted using reverse ion electroosmosis by utilizing the set gel layer, the weight and water content of the gel layer will inevitably increase as the tissue fluid permeates through the skin. This can more accurately reflect the amount of subcutaneous tissue fluid extracted, and is more conducive to obtaining highly accurate blood glucose measurement results.

[0088] Non-invasive subcutaneous fluid detection is more susceptible to environmental influences than invasive detection. Correcting for environmental factors is an effective way to improve the accuracy of non-invasive blood glucose testing. During the entire extraction process for non-invasive blood glucose testing, the skin area being tested undergoes both extraction and evaporation. Evaporation affects the weight change of the gel layer, thus impacting the accuracy of measuring the extraction amount. To address this, in some preferred embodiments of the present invention, a method is provided to obtain the relative extraction amount based on the water content of the gel layer as the surface water content of the extraction / detection electrode layer 3, while excluding environmental evaporation factors.

[0089] Specifically, the method for obtaining the relative extraction amount after excluding environmental evaporation factors includes:

[0090] S1 pre-determines the weight and water content of the gel layer during the evaporation process over time when the extraction is not performed (e.g., ...). Figure 4 As shown in the figure, the relationship between the weight x of the gel layer and the water content y is obtained.

[0091] Those skilled in the art can select the appropriate equipment to determine the weight x and water content y of the gel layer as needed. For example, a high-precision balance and a moisture meter can be used to test the weight x and water content y of the gel layer, respectively.

[0092] In some preferred embodiments, the correspondence is obtained by fitting the gel layer weight x and water content y at each time point.

[0093] In some preferred embodiments, the correspondence obtained after fitting is as follows:

[0094] y = -0.19*x 2 +10.11*x-44.28

[0095] Where x is the weight of the hydrogel layer and y is the water content of the hydrogel layer.

[0096] S2 tests the water content y1 of the gel layer after extraction for a certain period of time, and obtains x1 based on y1 and the corresponding relationship.

[0097] S3 tests the water content y0 of the gel layer before extraction at the corresponding time, and obtains x0 based on y0 and the corresponding relationship;

[0098] S4 obtains the relative extraction amount Δx based on x1 and x0, where Δx = x1 - x0.

[0099] It is understood that x1 and x0 refer to the weight of the gel layer after the same amount of time, with or without the extraction performed. When the correspondence between the gel layer weight x and the water content y is determined in advance, the water content y1 of the gel layer after extraction is measured simultaneously after the same extraction time, and the water content y0 of the gel layer before extraction is measured. These values ​​are then substituted into the fitted relationship to obtain x1 and x0. In the above preferred embodiment of the present invention, by pre-determining x and y when the extraction is not performed during the measurement time period, it can serve as a control group for correction and also obtain the correspondence between x and y. Subsequently, the relative extraction amount can be obtained using this correspondence. This indirectly measures the extraction amount based on humidity (water content) and can use environmental humidity (or other measurable environmental factors) to correct the detection results, thereby obtaining a more accurate extraction amount and guiding the blood glucose measurement results.

[0100] In the above embodiments, the present invention establishes a model correspondence between the gel layer weight x and the water content y, which facilitates the measurement of the extraction amount under different extraction conditions and is more conducive to obtaining high-accuracy blood glucose measurement.

[0101] In this invention, during the extraction and electrochemical detection, those skilled in the art can monitor parameters such as extraction current and extraction voltage, as well as changes in the water content of the gel layer, to ensure that the extraction process operates within a safe range and to save the detection data.

[0102] In some preferred embodiments, the blood glucose detection device further includes a waterproof layer disposed on the skin-away side of the extraction / detection electrode layer 3 to cover the extraction / detection electrode layer 3, such as... Figure 2 As shown in the diagram. This preferred solution avoids the interference of temperature and humidity on the skin, further improving the accuracy of the detection.

[0103] The present invention will now be described in detail with reference to specific embodiments.

[0104] Example 1

[0105] The blood glucose detection device used in this embodiment is as follows: Figure 1 As shown, the device includes an adhesive substrate 2, a first electrode assembly, a second electrode assembly, a current source (not shown), and an electrochemical detection and analysis device (not shown). The second electrode assembly includes an extraction electrode positive electrode 1 and an extraction electrode positive electrode wire (not shown). The first electrode assembly includes... Figure 2 The paper-based flexible bioelectrode shown consists of a waterproof layer, a fiber paper, a carbon layer, a potassium ferricyanide layer, a glucose oxidase layer, and a hydrogel layer, arranged from the point away from the skin to the point close to the skin. In the carbon layer, the dual electrodes 5 have a comb-like interdigitated structure, and there are a first electrode wire (not shown in the figure) and a second electrode wire (not shown in the figure).

[0106] Non-invasive blood glucose testing methods include:

[0107] S1: The weight and water content of the gel layer were measured in real time using a high-precision balance and a moisture meter.

[0108] First, the relative extraction yield for a single extraction was obtained by measuring the weight of the gel layer under different extraction conditions. The experimental results are as follows: Figure 3 As shown, the achievable single-shot extraction amount varies considerably under different measurement conditions:

[0109] Under extraction conditions of 5V / 5min / 1kHz / 10%, 5V / 5min / 4kHz / 100%, and 12V / 5min / 4kHz / 10%, the single extraction yield was less than 0.4mg; while under the extraction condition of 12V / 5min / 1kHz / 100%, the single extraction yield was 0.69mg.

[0110] Under the conditions of extraction current of 0.1-0.3mA, extraction voltage of 5-12V, extraction time of 17-30min, extraction current frequency of 1-4kHz, and extraction current duty cycle of 10-100%, the single extraction yield is above 0.8mg. Furthermore, the extraction yield is consistent under the same extraction conditions, ensuring the effectiveness and repeatability of the extraction methods.

[0111] Subsequently, the weight and water content (e.g., ) of the gel layer during the evaporation process over time were measured. Figure 4 As shown in the figure, the fitted relationship between the gel layer weight x and the water content y is: y = -0.19003*x 2 +10.10528*x-44.28187.

[0112] With the detection area of ​​the blood glucose testing device facing the subject's skin, the first electrode assembly and the second electrode assembly are attached to the skin area on the inside of the subject's forearm through the adhesive substrate 2.

[0113] Without setting extraction conditions, the water content of the gel layer at different times was measured as a control group.

[0114] The positive electrode wire of the extraction electrode is connected to the positive electrode of the current source, and one electrode of the dual electrode 5 is connected to the negative electrode of the current source for reverse ion electroosmosis extraction. This allows subcutaneous tissue fluid to be extracted to the skin surface and enriched in the region of the extraction / detection electrode layer 3. During this process, the water content y1 of the gel layer is measured using a moisture meter. Based on y1, the above fitting relationship is used to obtain x1. Based on the control group, y0 at the same extraction time is selected, and the corresponding x0 is obtained after substituting it into the above fitting relationship curve. The relative extraction amount Δx at each time is obtained, where the formula for calculating the relative extraction amount Δx is Δx = x1 - x0. Under the same measurement time, extraction is performed using different extraction currents, extraction voltages, extraction times, extraction current frequencies, and extraction current duty cycles. The water content change curve of the gel layer is measured as follows: Figure 5 As shown.

[0115] Depend on Figure 5 It can be seen that the change trend of gel layer water content with monitoring time varies under different extraction conditions, that is, the stability of the extraction yield obtained in each cycle is different under different conditions. The study shows that under the experimental conditions of this invention, the water content of the gel layer on the carbon electrode surface is significantly more stable throughout the extraction process, and the electrochemical detection values ​​of the extract at each time point are reliable values, which can improve the accuracy of the detection results and prevent skin damage caused by extraction. Furthermore, Figure 5 The results show that, under the premise that the skin is not damaged, the moisture content change curve of the gel layer under the preferred extraction conditions can obtain relatively stable extraction conditions. The preferred extraction conditions are 12V / 30min / 1kHz / 10%, 5V / 30min / 1kHz / 100%, and 8.5V / 17.5min / 2.5kHz / 55%.

[0116] Depend on Figure 3 and Figure 5 It can be seen that the highest amount of extract can be obtained under the conditions of 12V / 30min / 1kHz / 10%, and the extraction amount remains highly stable at each time period. Under these conditions, blood glucose detection can ensure the stability and accuracy of the detection to the greatest extent.

[0117] S2: Set the extraction conditions: extraction current is 0.1mA, extraction voltage is 12V, extraction time is 30min, extraction current frequency is 1kHz, and extraction current duty cycle is 10%. Perform extraction for subsequent electrochemical detection.

[0118] After extraction, the current source is disconnected, and the first and second electrode wires are used as the working electrode and counter electrode, respectively. An external electrochemical analysis instrument is connected to perform electrochemical detection on the extract to obtain the response current value. The trend of blood glucose change is inferred based on the trend of the response current value.

[0119] During the extraction process, the changes in extraction current, extraction voltage, and water content of the gel layer were monitored to ensure that the extraction process was conducted within a safe range, and the detection data were saved.

[0120] Figure 6 The diagram shows the response current value obtained in Embodiment 1 of the present invention and the blood glucose concentration result curve obtained using existing invasive blood glucose detection methods. Figure 6 It can be seen that the trend of the current response value obtained by this invention is highly consistent with the trend of blood glucose change measured by the Sinocare GA-3 blood glucose meter through finger-prick blood collection. The delay time between the ISF measurement result and the finger-prick blood measurement result is consistent with the diffusion time of intravascular substances to ISF, and the difference in delay time is small under long-term measurement results, and the accuracy is high after delay time correction.

[0121] Figure 8 The images show the skin of the subjects after testing according to an embodiment of the present invention. The subjects' skin showed no trauma or redness after the test. Furthermore, the subjects experienced no pain during the testing process.

[0122] Comparative Example 1

[0123] The procedure was carried out as in Example 1, except that the extraction time was 20 minutes and the extraction current frequency and extraction current duty cycle were not set.

[0124] Figure 7 The curves showing the response current obtained in Comparative Example 1 and the blood glucose concentration obtained using existing invasive blood glucose detection methods are displayed. Figure 7 It can be seen that the obtained blood glucose trend has a low degree of agreement with the blood glucose trend measured by the Sinocare GA-3 blood glucose meter using finger-prick blood. The delay time between the ISF measurement result and the finger-prick blood measurement result does not conform to the diffusion time of intravascular substances to ISF. The delay time difference is large under long-term measurement results, making it difficult to perform effective delay time calibration.

[0125] Figure 9 The test results showed the subject's skin after the test, with obvious wounds and large areas of redness and swelling. The subject also experienced significant stinging during the test.

[0126] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A non-invasive blood glucose detection method, comprising: The blood glucose testing device is attached and fixed to the subject's skin, and then reverse ion electroosmosis extraction and electrochemical detection are performed sequentially; its characteristic is that... The extraction conditions include: extraction current of 0.1-0.5mA, extraction voltage of 5-12V, extraction time of 5-30min, extraction current frequency of 1-4kHz, and extraction current duty cycle of 10-100%. The non-invasive blood glucose detection method also includes: In the reverse ion electroosmosis extraction, the surface water content of the extraction / detection electrode used in the blood glucose detection device is measured in real time to obtain the relative extraction amount. If the relative extraction amount exceeds a preset threshold, the extract is electrochemically detected, and the resulting response current value is used as the basis for judging blood glucose changes. If the relative extraction amount does not exceed the threshold, the response current value obtained from the electrochemical detection is discarded and is not used as the basis for judging blood glucose changes.

2. The non-invasive blood glucose detection method according to claim 1, characterized in that, The extraction conditions include: extraction current of 0.1-0.3mA, extraction voltage of 5-12V, extraction time of 17-30min, extraction current frequency of 1-4kHz, and extraction current duty cycle of 10-100%.

3. The non-invasive blood glucose detection method according to claim 1, characterized in that, The blood glucose detection device includes: an adhesive substrate, and a first electrode assembly and a second electrode assembly respectively disposed on the adhesive substrate; The first electrode assembly includes an extraction / detection electrode layer, which includes dual electrodes for use as a working electrode and a counter electrode, respectively, to perform the electrochemical detection; The second electrode assembly includes an extraction electrode positive electrode, which is used to cooperate with one of the electrodes in the dual electrode assembly, serving as the positive electrode and the negative electrode respectively, to perform the reverse ion electroosmosis extraction; Furthermore, the positive electrode of the extraction electrode covers the extraction / detection electrode layer, and the positive electrode of the extraction electrode extends along the edge covered by the extraction / detection electrode layer.

4. The non-invasive blood glucose detection method according to claim 3, characterized in that, With the direction closest to the skin as the top, the extraction / detection electrode layer consists of, from bottom to top, fiber paper, a carbon layer, a potassium ferricyanide layer, and a glucose oxidase layer.

5. The non-invasive blood glucose detection method according to claim 4, characterized in that, The blood glucose detection device further includes a gel layer disposed on the skin side of the extraction / detection electrode layer.

6. The non-invasive blood glucose detection method according to claim 5, characterized in that, The non-invasive blood glucose detection method also includes: In the reverse ion electroosmosis extraction, the water content of the gel layer is measured; Based on the water content of the gel layer, the surface water content of the extraction / detection electrode layer is used to further obtain the relative extraction amount; If the relative extraction amount exceeds a preset threshold, the extract is electrochemically detected, and the resulting response current value is used as the basis for judging blood glucose changes. If the relative extraction amount does not exceed the threshold, the response current value obtained from the electrochemical detection is discarded and is not used as the basis for judging blood glucose changes.

7. The non-invasive blood glucose detection method according to claim 6, characterized in that, The non-invasive blood glucose detection method also includes: The relative extraction amount was obtained by excluding environmental evaporation factors.

8. The non-invasive blood glucose detection method according to claim 7, characterized in that, The method for obtaining the relative extraction amount after excluding environmental evaporation factors includes: The weight and water content of the gel layer during the evaporation process over time were measured in advance when the extraction was not performed, and the corresponding relationship between the weight x and water content y of the gel layer was obtained. The water content y1 of the gel layer after extraction is tested over a certain period of time, and x1 is obtained based on y1 and the corresponding relationship. The water content y0 of the gel layer before extraction was tested at the corresponding time, and x0 was obtained based on y0 and the corresponding relationship. Based on x1 and x0, the relative extraction amount Δx is obtained, where Δx = x1 - x0.

9. The non-invasive blood glucose detection method according to claim 8, characterized in that, The correspondence was obtained by fitting the gel layer weight x and water content y at each time point.

10. The non-invasive blood glucose detection method according to claim 9, characterized in that, The correspondence is as follows: 。 11. The non-invasive blood glucose detection method according to claim 5, characterized in that, The blood glucose detection device further includes a waterproof layer disposed on the side of the extraction / detection electrode layer away from the skin.

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