A sensor integrating sweat induction and substance detection and a method of making the same

Abstract

This invention discloses a sensor integrating sweat induction and substance detection, and its preparation method. The sensor includes an electrically heated sweat induction layer and a sweat detection layer. The sweat induction layer is woven from conductive and hydrophobic yarns, and the sweat detection layer is a screen-printed electrode. This invention's sweat sensor achieves controllable sweat generation through electroheating technology, exhibiting rapid, sensitive, and stable characteristics. It can be flexibly integrated with conductive and hydrophobic fabric substrates and can also achieve real-time monitoring of glucose, uric acid, and dopamine in sweat, demonstrating promising market application prospects.

Description

Technical Field

[0001] This invention relates to the field of flexible biosensing technology, specifically to a sensor that integrates sweat induction and substance detection, and its preparation method. Background Technology

[0002] Clinical studies have confirmed that diabetes is a major risk factor for severe pneumonia and infectious sepsis, with approximately 20% of pneumonia patients having diabetes. Hyperuricemia can induce gout and kidney damage and is closely related to cardiovascular disease. Dopamine, as a key neurotransmitter, is directly associated with abnormal levels in body fluids and diseases such as Parkinson's disease and depression. Human sweat contains various chemical substances related to metabolism and nerve function, such as glucose, uric acid, and dopamine, and the concentrations of each component show a good correlation with corresponding blood indicators. Compared to traditional invasive blood collection and interstitial fluid testing methods, sweat testing has significant advantages such as being completely non-invasive, painless, having no risk of cross-infection, and allowing for continuous in-situ sampling, making it highly suitable for the application scenarios of flexible wearable health monitoring devices.

[0003] Single-walled carbon nanotubes, as typical one-dimensional carbon nanomaterials, possess ultra-high specific surface area, excellent electronic conductivity, and good mechanical flexibility. They can provide abundant loading sites for catalytically active substances and biorecognition elements, accelerate electron transfer at the electrode interface, and adapt to the repeated deformation requirements of flexible substrates. They are ideal electrode substrates for constructing high-performance flexible multi-target sensors. At the same time, the unique tube wall structure and defects in carbon nanotubes can serve as electrochemical active sites, catalyzing the redox of uric acid (UA) and dopamine (DPA) in solution by adsorbing a large amount of dopamine and uric acid, thus achieving highly selective detection of dopamine and uric acid.

[0004] Prussian blue, a classic ferricyanide coordination compound, can efficiently catalyze the reduction of hydrogen peroxide at low potentials. After glucose oxidase (GOx) catalyzes the decomposition of glucose into hydrogen peroxide, Prussian blue acts as an intermediate mediator for the sensor by detecting hydrogen peroxide, enabling highly selective detection of glucose and effectively reducing signal cross-interference between multiple components.

[0005] Currently, mainstream sweat sensors rely heavily on the human body's sweating patterns during exercise. They can only collect and detect biochemical signals of sweat during exercise, and cannot effectively collect and accurately detect sweat when the human body is at rest. This greatly limits the all-weather, all-scenario application capabilities of wearable health monitoring devices. Summary of the Invention

[0006] The purpose of this invention is to provide a sensor that integrates sweat induction and substance detection, and its preparation method. It effectively solves the problems of low electron transfer efficiency, insufficient stability, and limited detection range and accuracy of traditional glucose sensors, and realizes the simultaneous detection of glucose, uric acid, and dopamine.

[0007] In one aspect of the invention, a sensor integrating sweat induction and substance detection is proposed. According to an embodiment of the invention, the sensor includes an electrically heated sweat induction layer and a sweat detection layer, the sweat induction layer being woven from conductive hydrophobic yarns, and the sweat detection layer being a screen-printed electrode.

[0008] In addition, a sensor integrating sweat induction and substance detection according to the above embodiments of the present invention may also have the following additional technical features:

[0009] In some embodiments of the present invention, the conductive hydrophobic yarn comprises, from the inside out, a conductive inner core and a hydrophobic polymer nanofiber sheath layer.

[0010] In some embodiments of the present invention, the conductive core yarn is carbon fiber, with a single filament diameter ranging from 6.5 to 7 μm. Compared to other conductive yarns, such as copper-plated nylon yarn and silver-plated nylon yarn, it has better conductivity and oxidation resistance. The hydrophobic polymer nanofiber sheath is polyvinylidene fluoride (PVDF) yarn. Due to the large number of low surface energy CF bonds in the PVDF molecular structure, the nanofiber sheath has inherent hydrophobicity. At the same time, the high porosity of the nanoscale porous structure further reduces the surface energy of the nanofiber sheath, which facilitates sweat evaporation and maintains breathability at the wearing area in the conductive hydrophobic yarn of the present invention.

[0011] In another aspect of the present invention, a method for preparing the integrated sweat induction and substance detection sensor is provided. According to an embodiment of the present invention, the method includes the following steps: bonding the sweat induction layer and the sweat detection layer with medical adhesive (b-7000) and connecting them to an integrated chip and a lithium battery. Specifically, the yarn electrode is connected to the integrated chip, transmitting electrical signals related to the concentrations of glucose, uric acid, and dopamine in the sweat after the user sweats. Even in a resting state, the sweat induction layer can still stimulate the skin to produce sweat, obtaining a stable electrical signal.

[0012] Furthermore, the method for preparing a sensor integrating sweat induction and substance detection according to the above embodiments of the present invention may also have the following additional technical features:

[0013] In some embodiments of the present invention, the method for preparing the conductive hydrophobic yarn includes the following steps:

[0014] (1) Prepare polyvinylidene fluoride spinning solution; the concentration of polyvinylidene fluoride spinning solution is 15-16wt%, and the solvent is N,N-dimethylformamide (DMF) and acetone, with a volume ratio of (3-3.1):1.

[0015] (2) A hydrophobic nanofiber sheath is coated on the outside of the conductive core by electrospinning to obtain conductive hydrophobic yarn. The electrospinning process parameters are as follows: spinning voltage ±5.75kV, needle spacing 14.5-15.5cm, flow rate 0.7-0.8mL / h, winding speed 0.2-0.3m / min, and metal disc rotation speed 330-360r / min.

[0016] Hydrophobic and conductive fabrics, namely sweat-inducing layers, are obtained by weaving conductive and conductive yarns using a braiding machine.

[0017] In some embodiments of the present invention, the method for preparing the screen-printed electrode includes the following steps: constructing a three-electrode system by screen printing, comprising a carbon counter electrode, an Ag / AgCl reference electrode, and a sensing material functionalized working electrode; the sensing material includes glucose sensing material, uric acid sensing material, and dopamine sensing material.

[0018] In some embodiments of the present invention, the glucose sensing material is glucose oxidase (GOx), and the uric acid sensing material and dopamine sensing material are single-walled carbon nanotube materials.

[0019] In some embodiments of the present invention, the method for preparing a functionalized working electrode of a sensing material includes the following steps:

[0020] a. In-situ growth of Prussian blue on single-walled carbon nanotubes;

[0021] b. Mix the in-situ grown Prussian blue single-walled carbon nanotubes with a chitosan solution to obtain Prussian blue@carbon nanotubes / chitosan solution;

[0022] c. Mix glucose oxidase solution with Prussian blue@carbon nanotubes / chitosan (PB-CNTs / chitosan) solution, and then drop-cast it onto the surface of the working electrode to obtain a sensor material functionalized working electrode.

[0023] In some embodiments of the present invention, step a specifically includes the following steps: mixing 10 mM FeCl3 solution, 10 mM K3Fe(CN)6 solution, 1 mg / mL single-walled carbon nanotube aqueous dispersion, and solvent, then adding H2O2 dropwise and stirring the reaction to grow Prussian blue in situ on single-walled carbon nanotubes. Specifically, the solvent is deionized water, the volume ratio of FeCl3 solution, K3Fe(CN)6 solution, and single-walled carbon nanotube aqueous dispersion is (1.98-2.02):(1.98-2.02):1, the stirring speed is 900-1000 r / min, and the reaction time is 29.5-30.5 min.

[0024] In another aspect of the invention, the invention proposes an application of the sensor integrating sweat induction and substance detection in sweat monitoring.

[0025] Compared with the prior art, the beneficial effects of the present invention are:

[0026] 1) This invention, based on a carbon fiber electrothermal-induced sweating strategy, develops a multifunctional sweat sensor that can actively induce sweat secretion in the human body at rest, possessing extremely high application value. This sensor precisely stimulates the skin through electrothermal heating, inducing the body to passively produce sweat, eliminating dependence on exercise-induced sweating, while simultaneously meeting the need for simultaneous detection of three target substances: glucose, uric acid, and dopamine. By optimizing the sensor's functional modification layer structure, the overall detection efficiency and component detection specificity are further improved, ultimately achieving multi-indicator, highly sensitive, and highly selective simultaneous detection of electrothermal-induced sweat in a resting state. This invention effectively overcomes the limitations and shortcomings of traditional sweat detection methods, providing reliable technical support for all-weather, non-invasive physiological signal monitoring, and is of great significance for promoting the practical application and popularization of wearable multi-indicator health monitoring technology.

[0027] (2) This invention achieves the stimulation of sweat production by controlling the yarn structure and properties without any additional movement. It is fast and stable, and the fabric base has good breathability, which can ensure comfort in real-time monitoring of human sweat. It has good market application prospects.

[0028] (3) This invention integrates the detection of three target substances into one working electrode, realizing highly sensitive and selective multiple detection of glucose, uric acid and dopamine in sweat, which is of great significance for promoting the commercialization of wearable multi-index health monitoring technology. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the sensor integrating sweat induction and substance detection in Embodiment 1 of the present invention;

[0030] Figure 2 SEM image of the cross section of the conductive hydrophobic yarn prepared in Example 1 of the present invention;

[0031] Figure 3 SEM image of the nanofiber sheath of the conductive hydrophobic yarn prepared in Example 1 of this invention;

[0032] Figure 4 The hydrophobic angles of the sweat-inducing layer prepared in Example 1 of the present invention are: (a) 0s, (a) 15s, and (a) 30s.

[0033] Figure 5 The diagram shows the electroheating performance of the sweat-inducing layer prepared in Example 1 of this invention.

[0034] Figure 6 In the text, 'a' represents four bottles containing the same mass of water, but with the bottle openings being polyester, empty, the sweat-inducing layer in Example 1, and the sweat-inducing layer in Comparative Example 1, respectively; and 'b' represents the water evaporation rate under the four different conditions after 168 hours.

[0035] Figure 7 SEM image of in-situ grown carbon nanotubes prepared in Example 1 of this invention;

[0036] Figure 8 In the diagram, a is an impedance comparison diagram of the sweat detection layer prepared in Example 1 of the present invention and Comparative Examples 2-5, and b is a transfer resistance comparison diagram of the sweat detection layer prepared in Example 1 of the present invention and Comparative Examples 2-5.

[0037] Figure 9 This is a performance comparison diagram of the sweat detection layers prepared in Example 1 and Comparative Examples 2-5 of the present invention for glucose detection;

[0038] Figure 10 In the figure, a is a graph showing the performance of the sweat detection layer prepared in Example 1 of the present invention for the detection of uric acid (UA) and dopamine (DPA), and b is a linear fitting graph showing the sweat detection layer prepared in Example 1 for the detection of uric acid (UA) and dopamine (DPA). Detailed Implementation

[0039] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0040] Example 1

[0041] A sensor integrating sweat induction and substance detection, its structure is as follows: Figure 1 As shown, it includes an electrically heated sweat induction layer and a sweat detection layer. The sweat induction layer is woven from conductive hydrophobic yarn, and the sweat detection layer is a screen-printed electrode.

[0042] A method for preparing a sensor integrating sweat induction and substance detection includes the following steps:

[0043] (1) Method for preparing sweat-inducing layer

[0044] S1. Prepare polyvinylidene fluoride spinning solution, i.e. PVDF spinning solution, with a concentration of 16wt%, using DMF and acetone as solvents in a volume ratio of 3:1.

[0045] S2. A conjugate electrospinning machine is used, and the electrospinning process parameters are adjusted as follows: spinning voltage ±5.75kV, needle spacing 15cm, flow rate 0.8mL / h, winding speed 0.2m / min, and metal disc rotation speed 360r / min. A hydrophobic nanofiber sheath layer is wrapped around the outside of the conductive inner core to obtain a conductive hydrophobic yarn; wherein, the conductive core yarn is a carbon fiber bundle.

[0046] Figure 2 The image shows a cross-sectional SEM image of the conductive hydrophobic yarn, with a nanofiber sheath thickness of approximately 60 μm. Figure 3 This is a SEM image of the nanofiber sheath of a conductive hydrophobic yarn. The nanofiber size is mainly distributed between 0.4 and 1.2 μm.

[0047] S3. Using conductive and hydrophobic yarn as raw material, the fabric is woven by warp and weft through a braiding machine to obtain a hydrophobic and conductive fabric, namely an electrically heated sweat-inducing layer, with a thickness of 0.98mm.

[0048] (2) Preparation of sweat detection layer

[0049] S1. Place 10 mg of single-walled carbon nanotubes in a beaker, add 10 mL of deionized water, and sonicate for 10 min to obtain a dispersion. Prepare 20 mL of 5 mM FeCl3 solution and 20 mL of 5 mM K3Fe(CN)6 solution in deionized water. Mix the above solutions, add 10 μL of 30% H2O2 solution dropwise, stir at 1000 r / min, react for 30 min, filter and wash 5 times, and redisperse the filtered product in 10 mL of deionized water to obtain an aqueous dispersion of carbon nanotubes with in-situ Prussian blue growth. Figure 7 This is a SEM image of Prussian blue grown in situ on carbon nanotubes.

[0050] S2. Take 1 mL of the prepared aqueous dispersion, add 0.01 g chitosan and 0.02 g acetic acid to it, stir thoroughly to dissolve, and then add 2.5 μL of the solution to the working electrode area of ​​the screen-printed electrode.

[0051] S3. Take 10 mg of glucose oxidase and prepare a 10 mg / mL glucose oxidase aqueous solution. Add 2.5 μL to the working electrode and air dry at room temperature for 2 h to obtain the functionalized working electrode of the sensing material.

[0052] (3) Preparation of a sensor integrating sweat induction and substance detection

[0053] The sweat induction layer and the sweat detection layer are bonded together with b-7000 adhesive. The thickness after bonding is 1.36mm and the size is 5×4cm. The sweat detection layer and the sweat induction layer are connected to the integrated chip and the 400mAh lithium battery respectively by wires. The integrated chip and the lithium battery are attached to the other side of the sweat induction layer.

[0054] Figure 4 The graph shows the change in water contact angle of the sweat-inducing layer. Due to the CF bonds in the polyvinylidene fluoride structure and the nanoscale porous structure, the nanofiber sheath exhibits hydrophobicity. The water contact angle does not change significantly within 0-30s, remaining at 137°.

[0055] Figure 5 The graph shows the electrothermal performance at 4.6V. A stable voltage of 4.6V was applied to the sweat-inducing layer using a 400mAh lithium battery, and the temperature was recorded using an infrared thermometer. After 30 seconds, the temperature of the sweat-inducing layer stabilized at 48℃.

[0056] Example 2

[0057] A method for preparing a sensor integrating sweat induction and substance detection, which differs from Example 1 in that the spinning solution concentration is different, includes the following steps:

[0058] (1) Method for preparing sweat-inducing layer

[0059] S1. Prepare polyvinylidene fluoride spinning solution, i.e. PVDF spinning solution, with a concentration of 15wt%, using DMF and acetone as solvents in a volume ratio of 3:1.

[0060] S2. A conjugate electrospinning machine is used, and the electrospinning process parameters are adjusted as follows: spinning voltage ±5.75kV, needle spacing 15cm, flow rate 0.8mL / h, winding speed 0.2m / min, and metal disc rotation speed 360r / min. A hydrophobic nanofiber sheath layer is wrapped around the outside of the conductive inner core to obtain a conductive hydrophobic yarn; wherein, the conductive core yarn is a carbon fiber bundle.

[0061] S3. Using conductive and hydrophobic yarn as raw material, the fabric is woven by warp and weft through a braiding machine to obtain a hydrophobic and conductive fabric, namely an electrically heated sweat-inducing layer, with a thickness of 0.94-0.98mm.

[0062] (2) Preparation of sweat detection layer

[0063] S1. Place 10 mg of single-walled carbon nanotubes in a beaker, add 10 mL of deionized water, and sonicate for 10 min to obtain a dispersion. Prepare 20 mL of 5 mM FeCl3 solution and 20 mL of 5 mM K3Fe(CN)6 solution in deionized water. Mix the above solutions, add 10 μL of 30% H2O2 solution dropwise, stir at 1000 r / min, react for 30 min, filter and wash 5 times, and redisperse the filtered product in 10 mL of deionized water to obtain an aqueous dispersion of Prussian blue carbon nanotubes grown in situ.

[0064] S2. Take 1 mL of the prepared aqueous dispersion, add 0.01 g chitosan and 0.02 g acetic acid to it, stir thoroughly to dissolve, and then add 2.5 μL of the solution to the working electrode area of ​​the screen-printed electrode.

[0065] S3. Take 10 mg of glucose oxidase and prepare a 10 mg / mL glucose oxidase aqueous solution. Add 2.5 μL to the working electrode and air dry at room temperature for 2 h to obtain the functionalized working electrode of the sensing material.

[0066] (3) Preparation of a sensor integrating sweat induction and substance detection

[0067] The sweat induction layer and the sweat detection layer are bonded together with b-7000 adhesive. After bonding, the thickness is 1.32mm-1.36mm and the size is 5×4cm. The sweat detection layer and the sweat induction layer are connected to the integrated chip and the 400mAh lithium battery through wires. The integrated chip and the lithium battery are attached to the other side of the sweat induction layer.

[0068] Example 3

[0069] A sensor integrating sweat induction and substance detection, differing from Example 1 in that the metal disk rotates at a different speed, includes the following steps:

[0070] (1) Method for preparing sweat-inducing layer

[0071] S1. Prepare polyvinylidene fluoride spinning solution, i.e. PVDF spinning solution, with a concentration of 14wt%, using DMF and acetone as solvents in a volume ratio of 3:1.

[0072] S2. A conjugate electrospinning machine is used, and the electrospinning process parameters are adjusted as follows: spinning voltage ±5.75kV, needle spacing 15cm, flow rate 0.8mL / h, winding speed 0.2m / min, and metal disc rotation speed 330r / min. A hydrophobic nanofiber sheath layer is wrapped around the outside of the conductive inner core to obtain a conductive hydrophobic yarn; wherein, the conductive core yarn is a carbon fiber bundle.

[0073] S3. Using conductive and hydrophobic yarn as raw material, the fabric is woven by warp and weft through a braiding machine to obtain a hydrophobic and conductive fabric, namely an electrically heated sweat-inducing layer, with a thickness of 0.94-0.98mm.

[0074] (2) Preparation of sweat detection layer

[0075] S1. Place 10 mg of single-walled carbon nanotubes in a beaker, add 10 mL of deionized water, and sonicate for 10 min to obtain a dispersion. Prepare 20 mL of 5 mM FeCl3 solution and 20 mL of 5 mM K3Fe(CN)6 solution in deionized water. Mix the above solutions, add 10 μL of 30% H2O2 solution dropwise, stir at 1000 r / min, react for 30 min, filter and wash 5 times, and redisperse the filtered product in 10 mL of deionized water to obtain an aqueous dispersion of Prussian blue carbon nanotubes grown in situ.

[0076] S2. Take 1 mL of the prepared aqueous dispersion, add 0.01 g chitosan and 0.02 g acetic acid to it, stir thoroughly to dissolve, and then add 2.5 μL of the solution to the working electrode area of ​​the screen-printed electrode.

[0077] S3. Take 10 mg of glucose oxidase and prepare a 10 mg / mL glucose oxidase aqueous solution. Add 2.5 μL to the working electrode and air dry at room temperature for 2 h to obtain the functionalized working electrode of the sensing material.

[0078] (3) Preparation of a sensor integrating sweat induction and substance detection

[0079] The sweat induction layer and the sweat detection layer are bonded together with b-7000 adhesive. After bonding, the thickness is 1.32mm-1.36mm and the size is 5×4cm. The sweat detection layer and the sweat induction layer are connected to the integrated chip and the 400mAh lithium battery through wires. The integrated chip and the lithium battery are attached to the other side of the sweat induction layer.

[0080] Comparative Example 1

[0081] A method for preparing a sweat-inducing layer, which differs from Example 1 in that it uses flat electrospinning and directly uses carbon cloth for collecting electrospun fibers, including the following steps:

[0082] S1. Prepare polyvinylidene fluoride spinning solution, i.e. PVDF spinning solution, with a concentration of 12wt%, using DMF and acetone as solvents in a volume ratio of 3:1.

[0083] S2. The carbon cloth is attached to the flat plate collector. The electrospinning process parameters of the flat plate are adjusted as follows: the spinning voltage is 13kV, the distance between the needle and the spinning plate is 30cm, and the spinning time is 10h. The PVDF fiber is collected on the carbon cloth to obtain the sweat-inducing layer prepared by the flat plate electrospinning. The size is 5×4cm and the thickness is 0.29mm.

[0084] Four glass bottles were filled with room temperature deionized water of the same initial mass. The bottle openings were covered with polyester, empty (i.e., open), the sweat-inducing layer in Example 1, and the sweat-inducing layer in Comparative Example 1, respectively. After being sealed, the bottles were left to stand at 25°C for 168 h. The mass of the remaining water phase in the bottles after standing was measured and compared with the initial mass. The water evaporation rate was evaluated by calculating the water evaporation loss. Figure 6 In the figure, a is a physical image of the test of the water vapor permeability of the sweat-inducing layer, in four bottles containing the same mass of water, but with the bottle openings being polyester, empty, the sweat-inducing layer in Example 1, and the sweat-inducing layer in Comparative Example 1, respectively. b is the water evaporation rate under the four different conditions after 168 hours. Example 1 is superior to the commercially available 240T polyester and the sweat-inducing layer of Comparative Example 1, and is close to the breathability under the empty condition.

[0085] Comparative Example 2

[0086] A method for preparing a sweat detection layer, which differs from Example 1 in that it contains a different amount of Prussian blue, includes the following steps:

[0087] S1. Place 10 mg of single-walled carbon nanotubes in a beaker, add 10 mL of deionized water, and sonicate for 10 min to obtain a dispersion. Prepare 10 mL of 2.5 mM FeCl3 solution and 10 mL of 2.5 mM K3Fe(CN)6 solution, with deionized water as the solvent. Mix the above solutions, add 10 μL of 30% H2O2 solution dropwise, stir at 1000 r / min, react for 30 min, filter and wash 5 times, and redisperse the filtered product in 10 mL of deionized water to obtain an aqueous dispersion of carbon nanotubes with in-situ Prussian blue growth.

[0088] S2. Take 1 mL of the aqueous dispersion prepared in S1, add 0.01 g of chitosan and 0.02 g of acetic acid to it, stir thoroughly to dissolve, and then add 2.5 μL of the solution to the working electrode area of ​​the screen-printed electrode.

[0089] S3. Take 10 mg of glucose oxidase and prepare a 10 mg / mL glucose oxidase aqueous solution. Add 2.5 μL to the working electrode and air dry at room temperature for 2 h to obtain the functionalized working electrode of the sensing material.

[0090] Comparative Example 3

[0091] A method for preparing a sweat detection layer, which differs from Example 1 in that it contains a different amount of Prussian blue, includes the following steps:

[0092] S1. Place 10 mg of single-walled carbon nanotubes in a beaker, add 10 mL of deionized water, and sonicate for 10 min to obtain a dispersion. Prepare 10 mL of 7.5 mM FeCl3 solution and 10 mL of 7.5 mM K3Fe(CN)6 solution, with deionized water as the solvent. Mix the above solutions, add 5 μL of 30% H2O2 solution dropwise, stir at 1000 r / min, react for 30 min, filter and wash 5 times, and redisperse the filtered product in 10 mL of deionized water to obtain an aqueous dispersion of carbon nanotubes with in-situ Prussian blue growth.

[0093] S2. Take 1 mL of the aqueous dispersion prepared in S1, add 0.01 g of chitosan and 0.02 g of acetic acid to it, stir thoroughly to dissolve, and then add 2.5 μL of the solution to the working electrode area of ​​the screen-printed electrode.

[0094] S3. Take 10 mg of glucose oxidase and prepare a 10 mg / mL glucose oxidase aqueous solution. Add 2.5 μL to the working electrode and air dry at room temperature for 2 h to obtain the functionalized working electrode of the sensing material.

[0095] Comparative Example 4

[0096] A method for preparing a sweat detection layer, which differs from Example 1 in that it contains a different amount of Prussian blue, includes the following steps:

[0097] S1. Place 10 mg of single-walled carbon nanotubes in a beaker, add 10 mL of deionized water, and sonicate for 10 min to obtain a dispersion. Prepare 10 mL of 2.5 mM FeCl3 solution and 10 mL of 2.5 mM K3Fe(CN)6 solution, with deionized water as the solvent. Mix the above solutions, add 5 μL of 30% H2O2 solution dropwise, stir at 1000 r / min, react for 30 min, filter and wash 5 times, and redisperse the filtered product in 10 mL of deionized water to obtain an aqueous dispersion of carbon nanotubes with in-situ Prussian blue growth.

[0098] S2. Take 1 mL of the aqueous dispersion prepared in S1, add 0.01 g of chitosan and 0.02 g of acetic acid to it, stir thoroughly to dissolve, and then add 2.5 μL of the solution to the working electrode area of ​​the screen-printed electrode.

[0099] S3 and 10 mg of glucose oxidase were prepared into a 10 mg / mL glucose oxidase aqueous solution. 2.5 μL of the solution was added to the working electrode and air-dried at room temperature for 2 h to obtain the functionalized working electrode of the sensing material.

[0100] Comparative Example 5

[0101] A method for preparing a sweat detection layer, which differs from Example 1 in that it employs an electrochemical deposition process, including the following steps:

[0102] S1. Place 10 mg of single-walled carbon nanotubes in a beaker, add 10 mL of deionized water, and sonicate for 10 min to obtain a dispersion.

[0103] S2. Prepare 50 mL of electrodeposition solution with K3Fe(CN)6 and FeCl3 concentrations of 2.5 mM, HCl and KCl concentrations of 100 mM, and deionized water as the solvent. The electrodeposition potential range is -0.5 to 0.6 V, the scan rate is 0.05 V / s, and the number of cycles is 2.

[0104] S3, 10 mg glucose oxidase, prepare 1 mL of 10 mg / mL glucose oxidase aqueous solution;

[0105] S4. Take 1 mL of the aqueous dispersion prepared in S1, add 0.01 g of chitosan and 0.02 g of acetic acid, stir and dissolve thoroughly, then mix with the solution prepared in S3 at a ratio of 1:1. Add 5 μL of the solution to the working electrode area of ​​the screen-printed electrode, add 5 μL of the solution to the working electrode, and air dry at room temperature for 2 h to obtain the functionalized working electrode of the sensing material.

[0106] Figure 8 a represents the impedance spectrum of the sweat detection layer in Example 1 and Comparative Examples 2, 3, 4, and 5. Figure 8 b represents the charge transfer resistance. The sweat detection layer was connected to the CHI-760 electrochemical workstation via wires, and electrochemical impedance spectroscopy was performed in 50 ml of 0.1 M potassium chloride (KCl) solution. Prussian blue is a semiconductor; as the Prussian blue content increases, the sensor's impedance and charge transfer resistance increase, leading to a decrease in the sensor's electron transfer rate.

[0107] Figure 9 The graphs show the performance of the sweat detection layers prepared in Example 1 and Comparative Examples 2, 3, 4, and 5 in detecting glucose. The sweat detection layers were connected to a CHI-760 electrochemical workstation via wires and placed in PBS buffer. A high concentration of glucose solution was added to the buffer every 25 seconds to increase the glucose concentration by 20 μmol / L. The change in glucose concentration was detected by the sweat detection layer. The thinning of the Prussian blue layer improved the sensitivity of the sweat detection layer in detecting glucose.

[0108] Figure 10 Figure a shows the performance of the sweat detection layer prepared in Example 1 in detecting uric acid and dopamine. The sweat detection layer was connected to a CHI-760 electrochemical workstation via wires and placed in PBS buffer. High concentrations of UA (uric acid) and DPA (dopamine) were added to the buffer, and changes in UA and DPA concentrations were detected through the sweat detection layer. Because the carbon nanotubes were not completely coated with Prussian blue, the exposed carbon nanotubes could still detect uric acid and dopamine. Figure 10b performed a linear fit on the detection of uric acid and dopamine, and the fit was good.

[0109] The above description is merely an example and illustration of the present invention. Those skilled in the art can make various modifications or additions to the specific embodiments described, or use similar methods to replace them, as long as they do not deviate from the structure of the present invention or exceed the scope defined in the claims, all of which should fall within the protection scope of the present invention.

Claims

1. A sensor integrating sweat induction and substance detection, characterized in that: It includes an electrically heated sweat induction layer and a sweat detection layer, wherein the sweat induction layer is woven from conductive hydrophobic yarn and the sweat detection layer is a screen-printed electrode.

2. The sensor integrating sweat induction and substance detection according to claim 1, characterized in that: The conductive hydrophobic yarn comprises, from the inside out, a conductive inner core and a hydrophobic polymer nanofiber sheath.

3. The sensor integrating sweat induction and substance detection according to claim 2, characterized in that: The conductive core yarn is carbon fiber, and the hydrophobic polymer nanofiber sheath is polyvinylidene fluoride yarn.

4. A method for preparing a sensor integrating sweat induction and substance detection as described in any one of claims 1-3, characterized in that, The process includes the following steps: bonding the sweat induction layer and the sweat detection layer together with adhesive and connecting them to an integrated chip and a lithium battery.

5. The method for preparing a sensor integrating sweat induction and substance detection according to claim 4, characterized in that, The method for preparing the conductive hydrophobic yarn includes the following steps: (1) Prepare polyvinylidene fluoride spinning solution; (2) A hydrophobic nanofiber sheath is coated on the outside of the conductive core by electrospinning.

6. The method for preparing a sensor integrating sweat induction and substance detection according to claim 4, characterized in that, The method for preparing the screen-printed electrode includes the following steps: A three-electrode system is constructed using a screen printing process, comprising a carbon counter electrode, an Ag / AgCl reference electrode, and a working electrode functionalized with sensing materials; the sensing materials include glucose sensing materials, uric acid sensing materials, and dopamine sensing materials.

7. The method for preparing a sensor integrating sweat induction and substance detection according to claim 6, characterized in that: The glucose sensing material is glucose oxidase, and the uric acid sensing material and dopamine sensing material are single-walled carbon nanotube materials.

8. The method for preparing a sensor integrating sweat induction and substance detection according to claim 6, characterized in that, The method for preparing a functionalized working electrode for sensing materials includes the following steps: a. In-situ growth of Prussian blue on single-walled carbon nanotubes; b. Mix the in-situ grown Prussian blue single-walled carbon nanotubes with a chitosan solution to obtain Prussian blue@carbon nanotubes / chitosan solution; c. Mix glucose oxidase solution with Prussian blue@carbon nanotube / chitosan solution, and then drop-cast it onto the surface of the working electrode to obtain a sensor material functionalized working electrode.

9. The method for preparing a sensor integrating sweat induction and substance detection according to claim 8, characterized in that: Step a specifically includes the following steps: After mixing FeCl3 solution, K3Fe(CN)6 solution, single-walled carbon nanotube aqueous dispersion and solvent, H2O2 is added dropwise and the reaction is stirred to grow Prussian blue in situ on single-walled carbon nanotubes.

10. The application of the sensor integrating sweat induction and substance detection as described in any one of claims 1-3 in sweat monitoring.

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