CN114931378A

CN114931378A - Noninvasive blood glucose detection method

Info

Publication number: CN114931378A
Application number: CN202210460998.8A
Authority: CN
Inventors: 刘仁材; 陈靖容; 周玉龙
Original assignee: Beijing Weiqiao Guoke New Energy Technology Research Institute Co ltd; University of Chinese Academy of Sciences
Current assignee: Beijing Weiqiao Guoke New Energy Technology Research Institute Co ltd; University of Chinese Academy of Sciences
Priority date: 2022-04-28
Filing date: 2022-04-28
Publication date: 2022-08-23

Abstract

The invention belongs to the technical field of non-invasive blood glucose detection, and particularly relates to a non-invasive blood glucose detection method, which comprises the following steps: attaching and fixing a blood sugar detection device on the skin to be detected of a subject, and then sequentially carrying out reverse iontophoresis extraction and electrochemical detection; wherein the extraction conditions include: the extraction current is 0.1-0.5mA, the extraction voltage is 5-12V, the extraction time is 5-30min, the extraction current frequency is 1-4kHz, and the duty ratio of the extraction current is 10-100%. According to the invention, by optimizing the extraction current, the extraction voltage, the extraction time, the extraction current frequency and the extraction current duty ratio, on one hand, the extraction efficiency can be promoted, and the detection accuracy is improved, on the other hand, the skin pricking or damage phenomenon can be avoided, the stability of the extraction process at different times is improved, and the high-accuracy measurement result is obtained.

Description

Noninvasive blood glucose detection method

Technical Field

The invention belongs to the technical field of non-invasive blood glucose detection, and particularly relates to a non-invasive blood glucose detection method.

Background

Non-invasive blood glucose detection refers to the detection of subcutaneous interstitial fluid without causing damage to human tissue. The existing methods for non-invasive blood glucose detection are divided into three major blood glucose detection methods based on optical, thermal and electrical principles. For the detection of interstitial fluid of diabetic patients, besides glucose in human blood, there is also a considerable amount of glucose in other body fluids, wherein the glucose concentration in ISF (interstitial fluid of skin tissue) is closest to the blood glucose concentration. The electrical principle method mainly utilizes the coherence relationship between other body fluids of human body and blood sugar value, such as the glucose content in body fluids of saliva, tears, sweat, ISF and the like can be measured, and a data model is established after the glucose content is calibrated with the standard blood sugar value, so as to obtain a measured value; the measurement of interstitial fluid glucose concentration is mainly performed by extraction detection using a reverse iontophoresis method (RI), and the measurement of other body fluids is generally performed by directly using a glucose sensor to perform electrochemical property detection.

Sweat noninvasive glucose sensors are also a type that has been studied more recently. The sweat noninvasive glucose sensor has the advantages that sampling can be conveniently carried out, most of devices are highly integrated and wearable, continuous measurement can be achieved, and the comfort degree of a human body is high. However, sweat can only be detected and analyzed when it is discharged to the surface of the skin, and how to properly collect sweat at any time becomes a unique limitation. At present, most schemes extract and collect sweat by adopting ways of long-time sports, heating, pressure, ionization energy stimulation and the like, but all schemes have the disadvantages (for example, a diabetic is not suitable for long-time sports to perspire, and the heating and ionization stimulation can bring pain and discomfort). Sensitivity is low due to a low sugar content in sweat, and a certain hysteresis with respect to blood glucose concentration is also a factor that restricts the use thereof.

Glucose concentration in subcutaneous interstitial fluid is measured, i.e., blood glucose changes are monitored. Subcutaneous tissue interstitial fluid is a body fluid containing glucose. The subcutaneous tissue interstitial fluid is extracted through the reverse iontophoresis extraction technology for detection, so that a blood sugar change curve can be obtained, and great reference significance is provided for the administration of patients. Currently, a number of research teams have established large-scale wearable medical device research projects at home and abroad, such as the smart shirt project of the american college of georgia, the MIThril project of the american college of labor and technology, the IST FP5 and FP6 projects of the european union, and the "sentry" and health shirt project of the chinese university of hong kong, china. Relevant wearable medical equipment research trials are actively established and some research progress is made at various key universities in China, such as Qinghua university, Zhejiang university, Shanghai transportation university and the like.

The inventor of the invention earlier applies CN105954331B to disclose a paper-based electrode detection platform for biochemical analysis and a preparation method thereof, the paper-based electrode detection platform for biochemical analysis takes degradable paper as a substrate material, a carbon electrode is printed on the substrate material, and an electron transfer medium and a recognition molecular layer are fixed on the surface of the carbon electrode to obtain a completely degradable brand new paper-based electrode detection platform. Electrochemical tests show that the prepared degradable paper-based electrode detection platform has the same good electrochemical performance as the plastic substrate electrode. The completely degradable paper-based electrode detection platform is used for detecting glucose, and has the advantages of high sensitivity, short detection time, small difference, good stability and the like. CN1973768A discloses a noninvasive blood glucose meter for closed-loop insulin injection, embeds wireless communication module, and it combines electrochemical electrode to draw human subcutaneous tissue liquid, realizes noninvasive blood glucose detection to through radio frequency wireless communication and insulin pump coupling, guide insulin injection. The constant current source sampling circuit of the glucometer can be combined with an electrochemical biosensor to continuously and non-invasively extract subcutaneous tissue fluid through human skin, detect the concentration of glucose contained in the subcutaneous tissue fluid by an electrochemical method, further obtain the concentration of the blood glucose, send the blood glucose information and the time information to an insulin pump through a radio frequency wireless communication module, guide the injection of insulin, realize the closed-loop control of the blood glucose level of a diabetic patient, greatly relieve the pain of the diabetic patient and improve the life quality of the diabetic patient.

However, in the existing counter-ion permeation process, since the ISF glucose extraction rate has a correlation with the current intensity, and the improvement of the ISF glucose extraction rate can effectively improve the detection accuracy of the sensor, the current intensity is generally increased at present, but the long-time monitoring can cause irritation and damage to the skin. In addition, the blood glucose level used for calibration in noninvasive blood glucose measurement is generally referred to as blood or venous blood. When the blood sugar of a human body is changed rapidly, the blood sugar change in the skin dermis (namely, the sugar concentration in the interstitial fluid of the skin tissue) lags behind the blood sugar change in the peripheral blood or the venous blood, and the testing instrument can correct the lag according to the metabolic rate of the human body. However, the existing detection method inevitably causes certain stimulation and damage to the skin, which causes uncontrollable simultaneous detection of blood glucose and ISF (blood glucose threshold) during measurement, affects the correction result, and further affects the detection accuracy. For patients with hyperglycemia or hypoglycemia, such inaccuracy of the test results is very dangerous.

Therefore, how to avoid skin damage and obtain a high-accuracy measurement result has become a key point of current exploration.

Disclosure of Invention

The invention aims to overcome the defects that the existing blood sugar detection in the prior art can cause skin irritation and damage and inaccurate detection, and provides a non-invasive blood sugar detection method which can obtain a high-accuracy measurement result on the premise of not causing skin damage; the comfort level and the test effect of the crowd to be tested are obviously improved.

In order to achieve the above object, the present invention provides a non-invasive blood glucose detecting method, comprising: attaching and fixing a blood sugar detection device on the skin to be detected of a subject, and then sequentially carrying out reverse iontophoresis extraction and electrochemical detection;

wherein the extraction conditions include: the extraction current is 0.1-0.5mA, the extraction voltage is 5-12V, the extraction time is 5-30min, the extraction current frequency is 1-4kHz, and the extraction current duty ratio is 10-100%.

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

In some preferred embodiments, the non-invasive blood glucose detection method further comprises:

in the reverse iontophoresis extraction, the surface water content of an extraction/detection electrode adopted in the blood sugar detection device is measured in real time at the same time, so that the relative extraction amount is obtained;

and judging whether the relative extraction amount exceeds a preset threshold value, if so, carrying out electrochemical detection on the extracting solution, taking the obtained response current value as a judgment basis of blood sugar change, and if not, discarding the response current value obtained by the electrochemical detection, and not taking the response current value as the judgment basis of the blood sugar change.

In some preferred embodiments, the blood glucose detecting device comprises: an adherable substrate, and a first electrode assembly and a second electrode assembly respectively disposed on the adherable substrate;

the first electrode assembly comprises an extraction/detection electrode layer comprising a double electrode for respectively serving as a working electrode and a counter electrode for the electrochemical detection;

the second electrode assembly comprises an extraction electrode anode, which is used for matching with one electrode in the double electrodes and respectively used as an anode and a cathode to perform the reverse iontophoresis extraction;

and the extraction electrode anode covers the extraction/detection electrode layer, and the extraction electrode anode is arranged along the covered edge of the extraction/detection electrode layer in an extending manner.

In some preferred embodiments, the extraction/detection electrode layer is a fibrous paper, a carbon layer, a potassium ferricyanide layer, and a glucose oxidase layer in this order from the bottom to the top, in the direction toward the skin.

In some preferred embodiments, the blood glucose test device further comprises: and a gel layer disposed on the skin-contacting side of the extraction/detection electrode layer.

measuring the water content of the gel layer in the reverse iontophoresis extraction;

further obtaining a relative extraction amount based on the water content of the gel layer as an extraction/detection electrode layer surface water content;

In some preferred embodiments, the non-invasive blood glucose detection method further comprises: the relative extraction was obtained excluding ambient evaporation factors.

In some preferred embodiments, the method of obtaining relative extraction excluding environmental evaporation factors comprises:

pre-measuring the weight and the water content of the gel layer in the process of evaporating along with time when the extraction is not carried out, and obtaining the corresponding relation between the weight x and the water content y of the gel layer;

testing the water content y of the gel layer after the extraction for a certain time ₁ Based on y ₁ And obtaining x from the corresponding relation ₁ ；

Testing the water content y of the gel layer without the extraction under the corresponding time ₀ Based on y ₀ And obtaining x from the corresponding relation ₀ ；

Based on x ₁ And x ₀ Obtaining a relative extraction quantity delta x, wherein delta x is x ₁ -x ₀ 。

More preferably, the correspondence is obtained by fitting the gel layer weight x and the water content y for each time.

Further preferably, the corresponding relationship is:

y＝-0.19*x ² +10.11*x-44.28。

in some preferred embodiments, the blood glucose test device further comprises: and the waterproof layer is arranged on the side, far away from the skin, of the extraction/detection electrode layer.

According to the invention, by optimizing the extraction current, the extraction voltage, the extraction time, the extraction current frequency and the extraction current duty ratio, on one hand, the extraction efficiency can be promoted, the detection sensitivity can be improved, on the other hand, the skin can be prevented from being stabbed or damaged, the stability of the extraction process at different times can be improved, and the high-accuracy measurement result can be obtained.

In the preferred scheme of the invention, environmental evaporation factors are eliminated from the weight of the gel layer, and more preferably, a fitting corresponding relation is constructed by the weight and the water content of the gel layer, so that a more accurate blood sugar determination result can be further obtained, and the detection result is more stable.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required in the embodiments will be briefly described below, it should be understood that the following drawings only illustrate some embodiments of the present invention and therefore should not be considered as limiting the scope, and those skilled in the art can also obtain other related drawings based on the drawings without inventive efforts.

Description of the reference numerals

FIG. 1 is a schematic configuration diagram of one embodiment of a blood glucose measuring device according to the present invention.

FIG. 2 is a schematic diagram of one embodiment of the first electrode assembly of FIG. 1.

FIG. 3 is a graph showing the single extraction yields obtained under different extraction conditions in example 1 of the present invention.

FIG. 4 is a curve fitted to the correspondence between the weight x of the gel layer and the water content y of the gel layer obtained in example 1 of the present invention.

FIG. 5 is a graph of the moisture content of a gel layer as a function of monitored time for various extraction conditions in accordance with an embodiment of the present invention.

FIG. 6 is a graph of the response current of the non-invasive blood glucose test of example 1 of the present invention versus the blood glucose concentration results of the prior art invasive blood glucose test.

FIG. 7 is a graph of the response current obtained from the test of comparative example 1 versus the blood glucose concentration value of a prior art invasive blood glucose test.

FIG. 8 is a photograph of the skin of the subject of example 1 of the present invention after examination.

Fig. 9 is a photograph of the skin of the subject of comparative example 1 of the present invention after examination.

Description of the reference numerals

1-extraction electrode positive electrode, 2-adhesive substrate, 3-extraction/detection electrode layer, 4-modified coating and 5-double electrode.

Detailed Description

The endpoints of the ranges and any values disclosed herein are not limited to the precise range or value, and these ranges or values should be understood to encompass values close to these ranges or values. For ranges of values, between the endpoints of each of the ranges and the individual points, and between the individual points may be combined with each other to give one or more new ranges of values, and these ranges of values should be considered as specifically disclosed herein.

In the present invention, the extraction time refers to the length of time that the extraction current is applied to the skin in a single extraction process.

In the present invention, the extraction/detection electrode layer 3 is used as both an extraction electrode layer and a detection electrode layer.

The invention provides a non-invasive blood sugar detection method, which comprises the following steps: attaching and fixing a blood sugar detection device on the skin to be detected of a subject, and then sequentially carrying out reverse iontophoresis extraction and electrochemical detection; wherein the extraction conditions include: the extraction current is 0.1-0.5mA, the extraction voltage is 5-12V, the extraction time is 5-30min, the extraction current frequency is 1-4kHz, and the extraction current duty ratio is 10-100%.

In the existing extraction method, a single direct current extraction condition is generally adopted: the extraction current is 0.3-0.5mA, the extraction time is 3 min, 5min and 12min for a fixed time, and the existing experiments show that the skin is red, swollen and damaged when the extraction is continuously carried out under the current. The inventor of the invention finds that the skin damage condition under long-time current stimulation can be effectively avoided by modularizing the extraction process, setting proper extraction current frequency and current duty ratio and carrying out pulse type extraction.

In the scheme of the invention, the extraction efficiency can be adjusted by adjusting the extraction conditions including the extraction current, the extraction voltage, the extraction time, the extraction current frequency and the extraction current duty ratio, so that the extraction and detection processes can ensure that no signs of irritation, pain or injury appear on the surface of the skin; meanwhile, the stability of extraction at different time is improved; thereby improving the detection accuracy. Specifically, the invention takes the extraction voltage intensity, the extraction time length, the extraction current frequency and the extraction current duty ratio into full consideration, and the extraction current with lower duty ratio is used as an influence factor, the damage condition of the extracted skin area (preferably the water content of the surface of the extraction/detection electrode layer) is used as an evaluation standard, the optimal extraction condition is found, the condition is verified, the optimal extraction of the interstitial fluid is realized, and finally the condition is used for continuous and noninvasive blood glucose monitoring.

In some preferred embodiments, the conditions of the extraction include: the extraction current is 0.1-0.3mA, the extraction voltage is 8.5-12V, the extraction time is 20-30min, the extraction current frequency is 1-2kHz, and the extraction current duty ratio is 10-40%. The preferred embodiment is more beneficial to improving the extraction efficiency and obtaining a measurement result with higher accuracy.

According to the present invention, it is known to those skilled in the art that the electrochemical detection is a technique for obtaining a response current value by electrochemically detecting the glucose content in the extract solution obtained by the reverse iontophoresis extraction, thereby reflecting the blood glucose level. Illustratively, the following calculation formula may be employed:

wherein i (t) is a limiting current, a response current value obtained at a specific time thereof;

n is the electron transfer number of the electrode reaction;

f is a Faraday constant;

a is the electrode area;

is the initial molar concentration of the active in solution, i.e. the glucose content;

D ₀ the diffusion coefficient for glucose as the active;

t is the electrolysis time.

in the reverse iontophoresis extraction, the surface water content of an extraction/detection electrode adopted in the blood sugar detection device is measured in real time, so that the relative extraction amount is obtained;

Research shows that when the extraction amount of subcutaneous tissue fluid is too small, the accuracy of the measurement result is seriously influenced, and meanwhile, the relative extraction amount of the subcutaneous tissue fluid can be calculated through extracting the water content of the surface of the electrode. Therefore, the detection method of the invention comprises the step of measuring the water content of the surface of the extraction/detection electrode layer in real time to obtain the liquid-phase relative extraction amount of the subcutaneous tissue obtained in the extraction process. In the detection process, whether the relative extraction amount exceeds a preset threshold value or not needs to be judged, if the relative extraction amount exceeds the preset threshold value, the extracting solution is subjected to electrochemical detection, and the obtained response current value is used as a judgment basis for blood sugar change, so that the content of glucose in human subcutaneous tissue fluid can be accurately reflected; if the blood glucose content does not exceed the preset threshold, the content of the glucose in the subcutaneous tissue fluid of the human body cannot be accurately reflected, and the response current value obtained by electrochemical detection of the blood glucose content is abandoned and is not used as a judgment basis for blood glucose change.

In the invention, the preset threshold value can be adjusted according to the detection precision requirement; generally, the preset threshold may be set to 0.1mg or more, and preferably, the threshold may be set to 0.8mg or more.

The blood sugar detection device has a wide range of optional structures as long as subcutaneous tissue fluid extraction and detection can be performed.

In some embodiments, the blood glucose test device comprises: an adherable substrate 2, and a first electrode assembly and a second electrode assembly respectively disposed on the adherable substrate 2. The first electrode assembly and the second electrode assembly can be selected by those skilled in the art according to the extraction and electrochemical detection requirements.

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

In some embodiments, as shown in fig. 1, the first electrode assembly comprises an extraction/detection electrode layer 3, the extraction/detection electrode layer 3 comprising a double electrode 5 for acting as a working electrode and a counter electrode, respectively, for performing the electrochemical detection; the second electrode assembly comprises an extraction electrode anode 1, which is used for matching with one electrode in the double electrodes 5 and respectively used as an anode and a cathode to perform the reverse iontophoresis extraction; and the extraction electrode anode 1 covers the extraction/detection electrode layer 3, and the extraction electrode anode 1 is extended along the covered edge of the extraction/detection electrode layer 3. Research shows that the electrode structure can obtain a more uniform electric field and can promote the permeation efficiently at the low temperature of 0.1 mA.

The adherable substrate 2 may be a flexible polymer tape, such as PET or other plastic or resin material, as long as the first electrode assembly and the second electrode assembly can be fixedly attached to the skin surface, such as the exposed epidermis of the arm, the back of the hand, etc.

It should be understood that, when the detection device is used, the first electrode assembly and the second electrode assembly are both fixedly attached to the skin to be detected on the surface of the human body through the adhesive substrate 2. One skilled in the art can wipe the skin with a cotton swab before measurement and perform the fixation after drying.

In the invention, a person skilled in the art can also choose to use some accessories in the detection device according to the fixing requirements, the requirements of reverse iontophoresis technology, the requirements of electrochemical detection, the requirements of comfort enhancement and the like. For example, the detection device further comprises a clamping fixing part, an electrode lead, a current source and an electrochemical detection device, so as to realize the reverse iontophoresis and the electrochemical detection. During the reverse iontophoresis, the positive electrode lead of the extraction electrode is connected with the positive electrode of the current source, any one of the double electrode leads is connected with the negative electrode of the current source, so as to perform extraction, and glucose molecules in the tissue fluid are concentrated in the area of the extraction/detection electrode layer 3 of the first electrode assembly along with ion flow. When electrochemical detection is carried out, the current source is disconnected, and the double-electrode lead is respectively externally connected with an electrochemical analysis instrument.

In some embodiments, as shown in fig. 1 and 2, the extraction/detection electrode layer 3 includes a modified coating 4 containing electron transfer and molecular recognition corresponding to glucose in subcutaneous interstitial fluid for electrochemical detection of blood glucose.

In some more preferred embodiments, as shown in fig. 2, the extraction/detection electrode layer 3 is a fibrous paper, a carbon layer (which contains the double electrode 5), a potassium ferricyanide layer, and a glucose oxidase layer in this order from the bottom to the top, in the direction near the skin. In this preferred embodiment, the extraction/detection electrode layer 3 has excellent electron transfer capability, while enabling more sensitive recognition of glucose.

The preparation method of the extraction/detection electrode layer 3 is not limited in the present invention, as long as the above layers can be prepared and the electrochemical performance thereof can be improved. In some embodiments, a carbon electrode is printed on a substrate of the fiber paper by a screen printing method to form a carbon layer, and then potassium ferricyanide and glucose oxidase are fixed on a working area of the carbon electrode by a liquid jet printing method of a dispenser.

In the above preferred embodiment, the detection device formed by the extraction/detection electrode layer 3 having a specific structure, in combination with specific extraction conditions, can achieve faster extraction efficiency, higher response current, and higher sensitivity in noninvasive blood glucose measurement, and can obtain more accurate measurement results without injuring the skin under long-term anti-iontophoresis.

In some preferred embodiments, the blood glucose test device further comprises: and a gel layer provided on the skin-contacting side of the extraction/detection electrode layer 3, as shown in fig. 2. In this embodiment, the gel layer serves to collect subcutaneous tissue fluid and enhance the comfort of extraction.

The volume and composition of the gel layer can be selected by one skilled in the art based on the detection requirements. Preferably, the gel layer is a hydrogel. The invention has no requirement on the initial water content of the hydrogel, and the invention utilizes the water content change curve of the hydrogel to obtain the relative value of the water content change of the hydrogel and obtain the relative extraction amount.

In some preferred embodiments, the non-invasive blood glucose detection method further comprises: measuring the water content of the gel layer in the reverse iontophoresis extraction; further obtaining a relative extraction amount based on the water content of the gel layer as the surface water content of the extraction/detection electrode layer 3; and judging whether the relative extraction amount exceeds a preset threshold value, if so, carrying out electrochemical detection on the extracting solution, taking the obtained response current value as a judgment basis of blood sugar change, and if not, discarding the response current value obtained by the electrochemical detection, and not taking the response current value as the judgment basis of the blood sugar change.

In the above preferred embodiment, the gel layer is disposed, when interstitial fluid is extracted by reverse iontophoresis, the weight and water content of the gel layer tend to increase as interstitial fluid permeates through the skin, which can reflect the subcutaneous interstitial fluid extraction amount more accurately, and is more beneficial to obtaining a high-accuracy blood glucose measurement result.

The subcutaneous tissue fluid noninvasive detection process is greatly influenced by the environment compared with invasive detection, and the correction of environmental factors is an effective means for improving the accuracy of noninvasive blood glucose detection. In the whole extraction process of noninvasive blood glucose detection, the skin area to be detected has not only extraction effect, but also evaporation effect, and the evaporation effect can influence the weight change of the gel layer, thereby influencing the accuracy of measuring the extraction amount. In this regard, the present invention provides, in some preferred embodiments, a method of obtaining a relative extraction amount based on the water content of the gel layer as the surface water content of the extraction/detection electrode layer 3, and excluding the environmental evaporation factor.

Specifically, the method for obtaining the relative extraction amount by excluding the environmental evaporation factor comprises the following steps:

s1, determining in advance the weight and water content of the gel layer during evaporation of the gel layer over time without the extraction (as shown in fig. 4), and obtaining a correspondence between the weight x and water content y of the gel layer.

The skilled person can select the equipment for measuring the weight x and the water content y of the gel layer according to the requirements, for example, the weight x and the water content y of the gel layer can be measured by using a high-precision balance and a water content meter.

In some preferred embodiments, the correspondence is obtained by fitting the gel layer weight x and the water content y for each time.

In some preferred embodiments, the corresponding relationship obtained after the fitting is:

y＝-0.19*x ² +10.11*x-44.28

wherein x is the weight of the hydrogel layer and y is the water content of the gel layer.

S2 testing the water content y of the gel layer after the extraction for a certain time ₁ Based on y ₁ And obtaining x from the corresponding relation ₁ ；

S3 testing the water content y of the gel layer without the extraction at the corresponding time ₀ Based on y ₀ And obtaining x from the corresponding relation ₀ ；

S4 is based on x ₁ And x ₀ Obtaining a relative extraction quantity delta x, wherein delta x is x ₁ -x ₀ 。

It will be understood that x ₁ And x ₀ Respectively mean to carry outWeight of gel layer over the same time with or without extraction. When the correspondence between the weight x of the gel layer and the water content y is determined in advance, the water content y of the gel layer after extraction is measured simultaneously after the same extraction time ₁ And measuring the water content y of the gel layer without said extraction ₀ Respectively substituting into fitting relational expression to obtain x ₁ ，x ₀ . In the above preferred embodiment of the present invention, by measuring x and y in advance when the extraction is not performed during the measurement time period, the x and y can be used as a control group for calibration, and the corresponding relationship between x and y can be obtained, and then the relative extraction amount can be obtained by using the corresponding relationship, which indirectly measures the extraction amount with respect to humidity (water content), and the detection result can be calibrated by using the environmental humidity (or other measurable environmental factors), so as to obtain a more accurate extraction amount, thereby guiding the blood glucose measurement result.

In the above embodiment, the model corresponding relationship between the gel layer weight x and the water content y is established, which is convenient for measuring the extraction amount in the extraction process under different extraction conditions, and is more beneficial to obtaining high-accuracy blood sugar measurement.

In the extraction and the electrochemical detection, the technical personnel in the field can monitor parameters such as extraction current, extraction voltage and the like in the extraction and the change of the water content of the gel layer, ensure that the extraction process operates in a safe range, and store detection data.

In some preferred embodiments, the blood glucose detecting device further comprises: a water-proof layer disposed on the skin-away side of the extraction/detection electrode layer 3 to cover the extraction/detection electrode layer 3, as shown in fig. 2. Under this preferred scheme, can avoid the interference of humiture to skin, further promote the accuracy that detects.

The present invention will be described in detail with reference to specific examples.

Example 1

The blood sugar detecting device adopted in the present embodiment is shown in fig. 1, and comprises an adhesive substrate 2, a first electrode assembly, a second electrode assembly, a current source (not shown in the figure), and an electrochemical detection and analysis device (not shown in the figure), wherein the second electrode assembly comprises an extraction electrode anode 1 and an extraction electrode anode lead (not shown in the figure), the first electrode assembly comprises a paper-based flexible bioelectrode (a waterproof layer, a fiber paper, a carbon layer, a potassium ferricyanide layer, a glucose oxidase layer, and a hydrogel layer in sequence from a position far away from the skin to a position close to the skin) as shown in fig. 2, and in the carbon layer, the double electrode 5 is a comb-shaped interdigital structure, and the first electrode lead (not shown in the figure) and the second electrode lead (not shown in the figure).

The non-invasive blood sugar detection method comprises the following steps:

s1: and respectively measuring the weight and the water content of the gel layer in real time by using a high-precision balance and a water content meter.

The relative extraction in a single extraction was first obtained by measuring the weight of the gel layer under different extraction conditions, and the results of the experiment are shown in fig. 3. It can be seen that the single extraction amounts obtainable under different measurement conditions vary greatly:

under the extraction conditions of 5V/5min/1 kHz/10%, 5V/5min/4 kHz/100%, 12V/5min/4 kHz/10%, the single extraction amount is below 0.4 mg; under the extraction condition of 12V/5min/1 kHz/100%, the single extraction amount is 0.69 mg;

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 ratio of 10-100%, the single extraction amount is above 0.8 mg. And the single repeated extraction amount is the same under the same extraction condition, and the effectiveness and the repeatability of the extraction condition are ensured.

Subsequently, the weight and water content of the gel layer during evaporation over time were measured (as shown in FIG. 4), and a fit between the weight x of the gel layer and the water content y was obtained as: y-0.19003 x ² +10.10528*x-44.28187。

The detection area of the blood glucose detecting device is faced to the skin of the subject, and the first electrode assembly and the second electrode assembly are attached to the skin area on the inner side of the forearm of the subject through the adhesive substrate 2.

The water content of the gel layer at different times was measured as a control without setting the extraction conditions.

Connecting the positive electrode lead of the extraction electrode with the positive electrode of a current source, connecting one electrode of the double electrodes 5 with the negative electrode of the current source, and carrying out reverse iontophoresis extraction to extract subcutaneous tissue fluid to the skin surface and enrich the subcutaneous tissue fluid in the extraction/detection electrode layer 3 area. During which the water content y of the gel layer was measured by means of a moisture meter ₁ Based on y ₁ Substituting the fitting relation to obtain x ₁ (ii) a Selecting y with same extraction time based on control group ₀ Substituting the fitting relation curve to obtain corresponding x ₀ Obtaining relative extraction amount delta x at each time, wherein the relative extraction amount delta x is calculated by the formula of delta x ═ x ₁ -x ₀ . Under the same measurement time, different extraction currents, extraction voltages, extraction times, extraction current frequencies and extraction current duty ratios are adopted for extraction, and the curve for measuring the water content change of the gel layer is shown in fig. 5.

As can be seen from FIG. 5, the change trends of the water content of the gel layer along with the monitoring time under different extraction conditions have certain differences, namely the stability of the extraction amount obtained in each period under different conditions is different, and researches show that under the test conditions of the invention, the water content of the gel layer on the surface of the carbon layer electrode is obviously more stable in the whole extraction process, the electrochemical detection values of the corresponding extracting solution in each time period are reliable values, the accuracy of the detection result can be improved, and skin damage caused by extraction can be prevented. Further, fig. 5 shows that, under the condition that the skin is not damaged, the water content change curve of the gel layer under the preferable extraction conditions can obtain relatively stable extraction conditions, and the preferable extraction conditions are 12V/30min/1 kHz/10%, 5V/30min/1 kHz/100%, and 8.5V/17.5min/2.5 kHz/55%, respectively.

As can be seen from FIGS. 3 and 5, the highest amount of the extract was obtained under the condition of 12V/30min/1 kHz/10%, and the stability of the extract was maintained at each time period, and the stability and accuracy of the blood glucose test could be ensured to the maximum extent by performing the blood glucose test under the condition.

S2: setting extraction conditions: the extraction current is 0.1mA, the extraction voltage is 12V, the extraction time is 30min, the extraction current frequency is 1kHz, the extraction current duty ratio is 10%, and extraction is carried out for subsequent electrochemical detection.

And after the extraction is finished, switching off the current source, taking the first electrode lead and the second electrode lead as a working electrode and a counter electrode respectively, connecting an electrochemical analysis instrument externally, and carrying out electrochemical detection on the extracting solution to obtain a response current value. And deducing the change trend of the blood sugar according to the change trend of the response current value.

During the extraction period, the changes of extraction current, extraction voltage and the water content of the gel layer in the extraction process are monitored, the extraction process is ensured to operate within a safety range, and detection data are stored.

FIG. 6 is a graph showing the response current obtained in example 1 of the present invention versus the blood glucose concentration results obtained using the conventional invasive blood glucose test method. As can be seen from FIG. 6, the variation trend of the current response value obtained by the present invention is highly consistent with the variation trend of blood glucose measured by the Sanno GA-3 type blood glucose meter by collecting blood from fingertips. The delay time of the ISF measurement result and the fingertip blood measurement result accords with the diffusion time from the substance in the blood vessel to the ISF, the delay time difference under the long-time measurement result is small, and the accuracy is high after the delay time correction is carried out.

FIG. 8 shows the skin of the subjects after the test according to the example of the present invention, and the skin of the subjects after the test is non-traumatic and non-inflamed. In addition, the test subject has no pain during the detection process.

Comparative example 1

The procedure was as in example 1 except that the extraction time was 20min and the extraction current frequency and the extraction current duty cycle were not set.

FIG. 7 shows the response current obtained in comparative example 1 plotted against the blood glucose concentration results obtained using the current invasive blood glucose test procedure. As can be seen from fig. 7, the obtained blood glucose variation tendency is less consistent with the blood glucose variation tendency measured by the sanno GA-3 type blood glucose meter by collecting the blood from the fingertips. The delay time of the ISF measurement result and the finger blood measurement result does not accord with the diffusion time of the intravascular substances to the ISF, and the delay time difference under the long-time measurement result is large, so that the effective delay time calibration is difficult to carry out.

FIG. 9 shows the skin of the tested subject after the test, the skin shows obvious wound and large area red swelling after the test, and the tested subject has obvious stabbing pain during the test.

The preferred embodiments of the present invention have been described above in detail, but the present invention is not limited thereto. Within the scope of the technical idea of the invention, many simple modifications can be made to the technical solution of the invention, including various technical features being combined in any other suitable way, and these simple modifications and combinations should also be regarded as the disclosure of the invention, and all fall within the scope of the invention.

Claims

1. A non-invasive blood glucose detection method, comprising: attaching and fixing a blood sugar detection device on the skin to be detected of a subject, and then sequentially carrying out reverse iontophoresis extraction and electrochemical detection; it is characterized in that the preparation method is characterized in that,

the extraction conditions include: the extraction current is 0.1-0.5mA, the extraction voltage is 5-12V, the extraction time is 5-30min, the extraction current frequency is 1-4kHz, and the duty ratio of the extraction current is 10-100%.

2. The non-invasive blood glucose monitoring method according to claim 1, wherein the extracted conditions include: the extraction current is 0.1-0.3mA, the extraction voltage is 5-12V, the extraction time is 17-30min, the extraction current frequency is 1-4kHz, and the duty ratio of the extraction current is 10-100%.

3. The method of non-invasive blood glucose measurement according to claim 1, further comprising:

4. The non-invasive blood glucose detecting method according to claim 1,

the blood sugar detection device includes: an adherable substrate, and a first electrode assembly and a second electrode assembly respectively disposed on the adherable substrate;

5. The method of non-invasive blood glucose measurement according to claim 4, wherein the extraction/detection electrode layer comprises a fibrous paper layer, a carbon layer, a potassium ferricyanide layer and a glucose oxidase layer in this order from the bottom to the top, with the direction of the extraction/detection electrode layer being toward the skin.

6. The non-invasive blood glucose test method of claim 5, wherein the blood glucose test apparatus further comprises: a gel layer disposed on a skin-contacting side of the extraction/detection electrode layer.

7. The method of non-invasive blood glucose detection according to claim 6, further comprising:

further obtaining a relative extraction amount based on the water content of the gel layer as the water content of the surface of the extraction/detection electrode layer;

8. The non-invasive blood glucose monitoring method of claim 7, further comprising:

the relative extraction was obtained excluding ambient evaporation factors.

9. The method of noninvasive glucose sensing of claim 8, wherein the method of obtaining relative extraction excluding environmental evaporation factors comprises:

Based on x ₁ And x ₀ Obtaining a relative extraction amount Δ x, wherein Δ x ═ x ₁ -x ₀ 。

10. The method of non-invasive blood glucose measurement according to claim 9, wherein the correspondence is obtained by fitting the gel layer weight x and the water content y for each time.

11. The method of claim 10, wherein the correspondence relationship is:

y＝-0.19*x ² +10.11*x-44.28。

12. the non-invasive blood glucose test method of claim 6, wherein the blood glucose test apparatus further comprises: and the waterproof layer is arranged on the side, far away from the skin, of the extraction/detection electrode layer.