A 3D printed bionic wristband for sweat collection and multiplexed health monitoring

Abstract

The application belongs to the field of sensing, and particularly relates to a 3D-printed bionic wristband for sweat collection and multiple health monitoring. The transmission and detection of sweat are realized through a sensing layer, which comprises a super-hydrophilic region, a super-hydrophobic region and a detection region. The super-hydrophilic region has a conical structure similar to a cactus spine, the root of the conical structure is in communication with the detection region, and the tip is in communication with a liquid inlet hole. The super-hydrophilic region, the detection region and the liquid inlet hole are surrounded by the super-hydrophobic region, so that the sensing layer has a bionic structure similar to the alternating hydrophilic and hydrophobic regions of a desert beetle elytra and the conical structure of a cactus spine, realizing the directional transmission of sweat. The directional detection of lactic acid, vitamin C and pH value in sweat is realized in the detection region.

Description

Technical Field

[0001] This invention belongs to the field of sensing, specifically relating to a 3D-printed bionic wristband for sweat collection and multiple health monitoring. Background Technology

[0002] Sweat can enable early disease screening and real-time health monitoring. Sweat contains abundant biochemical markers, including lactic acid, vitamin C, and pH levels, which reflect human metabolism and physiological responses. For example, lactic acid levels in sweat are related to energy metabolism and are an important metabolite for assessing fatigue and stress-induced ischemia. Vitamin C deficiency can lead to a range of diseases, including skin conditions, gastrointestinal complications, and even mental illness. Furthermore, sweat pH is an important indicator for diagnosing disease states such as cystic fibrosis. Currently, many technologies have been developed for detecting human sweat, such as colorimetric sensing, electrochemical sensing, and surface plasmon resonance biosensors.

[0003] Current sweat detection methods suffer from the following drawbacks: sweat itself has a low secretion rate, and the concentrations of many ions and metabolites in sweat are quite low. Furthermore, continuous sweating leads to the accumulation of salt, biomolecules, and bacteria on the sensor surface, which is detrimental to sensor performance. Therefore, these challenges necessitate sweat sensors with efficient sweat collection capabilities, high sensitivity, and long-term stability. Traditional methods use absorbent materials such as paper and thread / fabric to collect sweat samples. This transport is non-directional, making it impossible to guarantee the freshness of the sweat in the sensing area, which may hinder immediate feedback during collection. Summary of the Invention

[0004] To address the aforementioned problems, the purpose of this invention is to provide a 3D-printed bionic wristband capable of ultra-rapid sweat collection and multiple health monitoring functions. The technical solution of this invention is based on the wettable back of a desert beetle (the alternating hydrophilic and hydrophobic structures create surface energy differences) and the wedge-shaped structure of cactus spines (facilitating liquid transport), to design and fabricate a 3D-printed bionic superhydrophilic / superhydrophobic sweat-sensing wristband.

[0005] The hydrophilic protrusions and hydrophobic grooves on the wettable dorsal surface of the desert beetle create a surface energy difference, resulting in a "hydrophobic-hydrophobic" biphasic structure in the beetle's elytra. The Laplace pressure induced by the surface gradient provides an effective water collection and transport system across the entire surface. This invention's biomimetic transformation of desert beetle characteristics is primarily reflected in the use of a multi-material 3D printing strategy to construct alternating hydrophilic and hydrophobic regions. This achieves superhydrophilicity of the transport channels and superhydrophobicity around the channels, providing a structural basis for directional liquid transport.

[0006] Cactus spines have a wedge-shaped structure with a cone angle of approximately 10°. Water droplets at the narrow end form a small radius of curvature, generating a large Laplace pressure. As the droplet flows towards the wide end, the radius of curvature gradually increases, continuously pulling the liquid towards the wide end and promoting the directional movement of the droplet. This invention's biomimetic transformation of this feature is mainly reflected in the use of 3D printing technology to fabricate a cactus-like cone-shaped structure as a channel for the directional transport of sweat. The surface of a beetle is coupled to the 3D-printed cone-shaped structure to achieve the directional transport of sweat.

[0007] This invention discloses a 3D-printed biomimetic wristband for sweat collection and multiple health monitoring. It achieves sweat transmission and detection through a sensing layer comprising a superhydrophilic region, a superhydrophobic region, and a detection region. The superhydrophilic region has a cone-shaped structure resembling cactus spines. The root of the cone-shaped structure is connected to the detection region, and the tip is connected to the liquid inlet. The superhydrophilic region, detection region, and liquid inlet are surrounded by the superhydrophobic region, giving the sensing layer a biomimetic structure that mimics the alternating hydrophilic and hydrophobic regions of a desert beetle elytra and the cone-shaped structure resembling cactus spines, thus enabling directional sweat transmission and detection.

[0008] There are three superhydrophilic regions, each with a corresponding liquid inlet and detection area, separated by superhydrophobic regions, which are used for detecting lactic acid, vitamin C, and pH value in sweat, respectively.

[0009] Below the sensing layer is a resin substrate with pores that match the liquid inlet vents, allowing sweat to pass through the pores and vents into the superhydrophilic region. The sweat is then transported from the tip of the conical structure to the detection area at the base for detection. The angle of the conical tip is approximately 10°.

[0010] Both the sensing layer and the resin substrate are prepared by 3D printing. First, the resin substrate is printed, and then a superhydrophilic region and a superhydrophobic region are printed on the resin substrate. Liquid inlet holes and detection area holes are reserved in the superhydrophobic region. Then, the printed detection area is embedded in the detection area hole, so that the superhydrophobic region surrounds the superhydrophilic region, the detection area and the liquid inlet hole, forming alternating hydrophilic and hydrophobic regions.

[0011] The material composition and mass content used in the superhydrophilic region are as follows: 100 parts polyethylene glycol diacrylate, 1 part diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide, 10 parts acrylic acid, and 6 parts hydrophilic fumed silica nanoparticles.

[0012] The material composition and mass content used in the superhydrophobic region are as follows: 30 parts hydrophobic butyl acrylate, 20 parts ethylene glycol dimethacrylate, 50 parts n-decyl alcohol, and 1 part diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide.

[0013] The detection area is prepared as follows: diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide, sodium alginate, and triethylamine are dissolved in polyethylene glycol diacrylate, organic ligands are added and mixed, and 3D printing is performed. After printing, the metal-organic framework is immersed in an ionic solution for in-situ growth and assembly to obtain the detection area.

[0014] The mass fractions of each material in the testing area are as follows: 1 part diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide, 1.5 parts sodium alginate, 1 part triethylamine, 100 parts polyethylene glycol diacrylate, 1 part organic ligand, and the concentration of the ion solution is 0.5M.

[0015] For different analytes, specific organic ligands and ionic solutions are used to give each detection zone different functions, so that lactic acid, vitamin C and pH in sweat can be detected independently in different detection zones, thereby achieving targeted detection of different components in sweat.

[0016] When the detection zone is used to detect lactic acid, the organic ligand is 1,4-naphthalenedicarboxylic acid, 1 part, and the ionic solution is 0.5M Eu. 3+ Solution;

[0017] When the detection zone is used to detect vitamin C, the organic ligand is 2,5-dihydroxyterephthalic acid, 1 part, and the ionic solution is 0.5M Fe. 3+ Solution;

[0018] When the detection zone is used to detect pH value, the organic ligand is 2,2-biphenyldicarboxylic acid, 1 part, and the ionic solution is 0.5M Tb. 3+ Solution.

[0019] A bionic wristband is obtained by assembling a resin substrate, a sensing layer, a 254nm ultraviolet filter, an ultraviolet lamp, a battery, a ring, and a shell. The resin substrate is the bottom layer that is in direct contact with the skin. The sensing layer is located on the resin substrate. The ultraviolet light emitted by the ultraviolet lamp passes through the filter and completely illuminates the detection area. A window is provided on the shell at the location corresponding to the detection area for observation and image acquisition.

[0020] Ultraviolet light is transmitted through a filter to irradiate the detection area, producing a color change. Images of the detection area before and after the sweat reaches the area are collected and analyzed to determine the levels of lactic acid, vitamin C, and pH in the sweat.

[0021] The beneficial effects of this invention are as follows:

[0022] This invention relates to a biomimetic wristband that draws inspiration from the unique wettability of a desert beetle's back and the structure and function of cactus spines. A biomimetic structure composed of superhydrophilic / superhydrophobic layers was designed. Superhydrophilic / superhydrophobic inks were self-made to obtain printing layers with varying wettability, and precursor inks for in-situ growth and assembly of different MOFs were prepared. The various parts were printed and assembled using 3D printing. The structure of the detection area was immersed in different metal ion solutions to achieve in-situ growth of different MOFs and for the detection of physiological substances in sweat. Due to the differences in geometry and the wettability between the superhydrophobic / superhydrophilic layers, the biomimetic channel exhibits higher sweat collection efficiency than traditional microfluidic channels, reducing the time sweat remains in the transport area and the volume required to reach the detection area.

[0023] This invention employs an in-situ growth strategy of "first printing a detection area structure containing ligands and sodium alginate, then immersing the entire structure in a metal ion solution." This allows MOFs to grow directionally from within and on the surface of the 3D-printed structure, forming chemical bonds and physical interpenetration with the substrate, fundamentally solving the problem of MOF detachment. The porosity of the 3D-printed structure provides space for the directional growth of MOFs, forming a root-like interpenetrating network, further enhancing long-term stability. Sodium alginate is specifically introduced into the formulation, utilizing its abundant carboxyl groups to efficiently complex metal ions, forming uniformly distributed metal ion anchors within the substrate, inducing MOF nucleation and growth, resulting in more uniform MOF distribution and stronger bonding.

[0024] The bionic wristband with sweat indicator of the present invention has the following advantages:

[0025] 1. This invention achieves highly sensitive detection of multiple substances in sweat. The detection limit for lactic acid in sweat is as low as 0.6 mM, and the detection limit for vitamin C in sweat is as low as 0.3 μM.

[0026] 2. Compared with conventional microfluidic channels, the biomimetic structure requires less time and less sweat to transport sweat, realizing active, directional and rapid sweat transport, and inhibiting scale buildup in principle.

[0027] 3. MOFs assembled using in-situ growth exhibit high selectivity and long-term storage stability.

[0028] 4. By integrating with smartphone imaging technology, this wristband can conveniently and quickly capture minute signals generated by sweat during human exercise. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the biomimetic structure in the sensing layer.

[0030] Figure 2 Flowchart for the fabrication of a bionic wristband.

[0031] Figure 3 This is a schematic diagram of the 3D printing process for a bionic wristband.

[0032] Figure 4 This is a schematic diagram showing the structure and dimensions of the liquid inlet, the superhydrophilic region, and the sensing region.

[0033] Figure 5 This is a schematic diagram showing the assembly and internal layout of the bionic wristband.

[0034] Figure 6 Pearson correlation plot for sweat detection; where (a) represents lactic acid, (b) represents vitamin C, and (c) represents pH value.

[0035] Figure 7 Brand-Altmann plot for sweat testing; where (a) represents lactic acid, (b) represents vitamin C, and (c) represents pH value. Detailed Implementation

[0036] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments and accompanying drawings. It should be noted that the embodiments described in this invention are only for further explanation and illustration, and not for limiting their application scope. Based on this invention, all other embodiments obtained by those skilled in the art without inventive effort are within the protection scope of this invention.

[0037] Example 1

[0038] Constructing a biomimetic wristband. Biomimetic structures such as... Figure 1 As shown, the production process is as follows: Figure 2 As shown.

[0039] (1) Preparation of superhydrophilic ink based on polyethylene glycol diacrylate. Diphenyl (2,4,6-trimethylbenzoyl)phosphine oxide (1 wt%) was dissolved in 10 mL of polyethylene glycol diacrylate, and acrylic acid (10 wt%) and hydrophilic fumed nano silica (6 wt%) were added. The mixture was stirred at room temperature until the solution was homogeneous.

[0040] (2) Prepare a superhydrophobic ink composed of a pore-forming agent and a hydrophobic acrylate monomer. Mix hydrophobic butyl acrylate (30 wt%), ethylene glycol dimethacrylate (20 wt%), n-decyl alcohol (pore-forming agent, 50 wt%) and diphenyl (2,4,6-trimethylbenzoyl)phosphine oxide (1 wt%) evenly.

[0041] (3) The detection area is made using the following method:

[0042] Diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide (1 wt%) was dissolved in 10 mL of polyethylene glycol diacrylate, followed by the addition of sodium alginate (1.5 wt% final concentration) and triethylamine (1 wt% final concentration) and stirred until the ink was uniform.

[0043] (3-1) When used for lactic acid detection: Add 2wt% of the organic ligand 1,4-naphthalenedicarboxylic acid (1,4-H2NDC) to the ink. After preparation, 3D print the corresponding detection area structure and immerse it in 0.5M Eu. 3+ In ionic solution, in situ growth and assembly of metal-organic frameworks (MOFs) (ISG-Eu-NDC) were achieved for the detection of lactic acid in sweat.

[0044] (3-2) When used for vitamin C detection: Add 2wt% of the organic ligand 2,5-dihydroxyterephthalic acid (DOBDC) to the ink. After preparation, 3D print the corresponding detection area structure and immerse it in 0.5M Fe. 3+ In ionic solution, in situ growth and assembly of metal-organic frameworks (MOFs) (ISG-Fe-DOBDC) were achieved for the detection of vitamin C in sweat.

[0045] (3-3) When used for pH detection: Add 2wt% of the organic ligand 2,2'-biphenyl dicarboxylic acid (DPA) to the ink. After preparation, 3D print the corresponding detection area structure and immerse it in 0.5M Tb. 3+ In ionic solution, in situ growth and assembly of metal-organic frameworks (MOFs) (ISG-Fe-DOBDC) is achieved for the detection of pH values ​​in sweat.

[0046] (4) 3D printing functional layer. The printing process is as follows: Figure 3 As shown, the structure and dimensions of each region of the sensing layer are as follows: Figure 4As shown, the corresponding printing structure was designed using Solidworks software, and the design drawings were imported into the 3D printer. This sweat sensor consists of multiple functional layers: First, a resin substrate is printed using commercial resin, located at the bottom layer of the sensor and in direct contact with the skin. The resin substrate has three holes. Then, superhydrophilic ink is used to print cactus-spine-shaped superhydrophilic regions on top of the resin substrate. Three separate superhydrophilic cone structures are printed, each cone's tip connected to a corresponding hole, and the root of each cone connected to a detection area. Superhydrophobic areas are printed using superhydrophobic ink, with inlet holes pre-drilled at the tips of the superhydrophobic areas of each conical structure and detection area holes pre-drilled at the base. The prepared detection areas are then embedded into these holes, ensuring the conical tips are connected to the inlet holes and the base to the detection area. This allows the superhydrophobic areas to surround the inlet holes, superhydrophilic areas, and detection areas. The sensing layer features a biomimetic structure with alternating hydrophilic and hydrophobic regions reminiscent of desert beetle elytra and coupled with cactus spine conical structures. A Laplace pressure gradient derived from cactus spines and a surface energy gradient derived from the hydrophilic and hydrophobic interface of desert beetles are constructed, allowing sweat to enter the sensing layer through the pores in the resin substrate and be directionally transported from the tips of the superhydrophilic conical structures to the detection area at the base, thus achieving directional sweat transport and micro-volume detection. Finally, medical tape is used as the top of the patch to encapsulate the sensor. Figure 2 The dimensions of the sweat sensor and the bionic channel are as follows: Figure 3 As shown.

[0047] (5) Assemble the bionic wristband. The internal layout is as follows: Figure 5 As shown in the diagram, the bionic wristband is assembled by combining components such as a resin substrate, sensing layer, LED UV lamp (254nm), filter, battery, ring, and custom shell. The specific arrangement is as follows: Figure 4 The wristband measures 74mm in length, 50mm in width, and 24mm in height. The resin substrate is the bottom layer, directly contacting the skin. Above the resin substrate is the sensing layer, allowing ultraviolet light to pass through a filter and fully illuminate the detection area.

[0048] Experimental Example 2

[0049] Sweat testing. Five healthy volunteers, aged 20-26, were selected and their consent was obtained. During the experiment, volunteers sequentially performed 15 minutes of aerobic exercise, 15 minutes of rest, 15 minutes of anaerobic exercise, and 15 minutes of rest. Changes in the substances detected in the volunteers' sweat were recorded every 15 minutes.

[0050] Sweat droplets enter the sensing layer's inlet pores through the pores in the resin substrate and move along a superhydrophilic track surrounded by superhydrophobic regions. When the droplet deposits at the narrower tip of the superhydrophilic track, the Laplace pressure difference between the leading and trailing edges propels the droplet towards the root along the superhydrophilic wedge structure, allowing sweat to spontaneously and rapidly flow from the inlet pores towards the detection area. During detection, an LED ultraviolet lamp is turned on, and ultraviolet light passes through a filter to illuminate the surface of the sensing area. The MOF material grown in situ in the sensing area is excited by 254nm ultraviolet light, exhibiting a visible color change. Images are captured using a smartphone through the detection window. The collected images are imported into a computer, and the color (RGB) values ​​are extracted using ImageJ software. The changes in RGB values ​​before and after the sweat reaches the detection area are analyzed.

[0051] The results showed that all volunteers produced higher levels of lactic acid, lower levels of vitamin C, and lower pH values ​​during anaerobic exercise compared to aerobic exercise. This is completely consistent with normal human metabolism in biology, indicating that the bionic wristband of this invention has reliable test results.

[0052] The results of the bionic wristband were compared with those obtained using laboratory methods. The laboratory methods for lactic acid and vitamin C involved dispersing MOF powder synthesized using conventional methods in a solution, adding 10mM-30mM lactic acid or 1μM-30μM vitamin C, and detecting the results using a fluorescence spectrometer. pH values ​​(5.5-7) were measured using a pH meter. Comparison of the Pearson correlation and Brand-Altman plots for lactic acid, vitamin C, and pH sensing revealed a strong correlation between the results of the bionic wristband and the laboratory methods.

[0053] Pearson correlation analysis results are as follows Figure 6 As shown. Figure 6 As shown in (a), the lactic acid concentration measured by the bionic wristband showed a significant linear correlation with the results of the laboratory method (P < 0.01), indicating that the bionic wristband has a high degree of consistency with the standard method in lactic acid detection. Figure 6 As shown in (b), the vitamin C concentration measured by the bionic wristband also showed an excellent correlation with the results of laboratory methods (P < 0.01), indicating that the bionic wristband can accurately reflect the true level of vitamin C in sweat. Figure 6 As shown in (c), a strong correlation (P < 0.05) was also observed between the pH value measured by the bionic wristband and the pH meter measurement, confirming its reliability in pH detection. This verified the detection accuracy of in-situ grown MOFs as sensing elements.

[0054] The results of the Brand-Altmann consistency analysis are as follows: Figure 7 As shown. Figure 7As shown in (a), the mean deviation of lactic acid detection is (-0.4 mM to +0.4 mM), with a narrow 95% agreement limit. The vast majority of data points fall within this limit, indicating good consistency between the bionic wristband and the laboratory method, and no significant systematic bias. Figure 7 As shown in (b), the mean deviation of vitamin C detection is close to zero (e.g., (-2.51 μM to +2.51 μM)), and the 95% agreement limit is also narrow, indicating that the results of vitamin C determination by the two methods are highly consistent, with very few outliers. Figure 7 The mean deviation of the values ​​detected in (c) is close to zero (e.g., (-0.45 to +0.45)), and the data points within the 95% consistency limit are evenly and centrally distributed, further confirming the high consistency and stability of the bionic wristband in repeated tests.

[0055] The Brand-Altmann analysis results and Pearson correlation analysis corroborate each other, indicating that the bionic wristband's detection performance has a high degree of consistency and correlation with standard laboratory methods, with errors within clinically acceptable ranges. This comprehensively confirms the accuracy and practicality of the bionic wristband for in-situ detection of human sweat. Therefore, the bionic wristband has certain practical applications for in-situ detection of human sweat.

Claims

1. A 3D-printed bionic wristband for sweat collection and multiple health monitoring, characterized in that, The bionic wristband achieves sweat transmission and detection through a sensing layer, which includes a superhydrophilic region, a superhydrophobic region, and a detection region. The superhydrophilic region has a cone-shaped structure that mimics cactus spines, with the root of the cone structure connected to the detection region and the tip connected to the liquid inlet. The superhydrophilic region, the detection region, and the liquid inlet are surrounded by the superhydrophobic region, giving the sensing layer a bionic structure that mimics the alternating hydrophilic and hydrophobic regions of the elytra of a desert beetle and the cone-shaped structure that mimics cactus spines.

2. The 3D-printed bionic wristband for sweat collection and multiple health monitoring according to claim 1, characterized in that, There are three superhydrophilic regions, each with a corresponding liquid inlet and detection area, separated by superhydrophobic regions, which are used for detecting lactic acid, vitamin C, and pH value in sweat, respectively.

3. The 3D-printed bionic wristband for sweat collection and multiple health monitoring according to claim 1, characterized in that, Below the sensing layer is a resin substrate with holes that match the liquid inlet holes, allowing sweat to enter the superhydrophilic region through the holes and liquid inlet holes, and be transmitted from the tip of the conical structure to the detection area at the root for detection.

4. The 3D-printed bionic wristband for sweat collection and multiple health monitoring according to claim 1, characterized in that, The material composition and mass content used in the superhydrophilic region are as follows: 100 parts of polyethylene glycol diacrylate, 1 part of diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide, 10 parts of acrylic acid, and 6 parts of hydrophilic fumed nano silica. The material composition and mass content used in the superhydrophobic region are as follows: 30 parts hydrophobic butyl acrylate, 20 parts ethylene glycol dimethacrylate, 50 parts n-decyl alcohol, and 1 part diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide.

5. A 3D-printed bionic wristband for sweat collection and multiple health monitoring according to claim 1, characterized in that, The detection area is prepared as follows: diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide, sodium alginate, and triethylamine are dissolved in polyethylene glycol diacrylate, organic ligands are added and mixed, and 3D printing is performed. After printing, the metal-organic framework is immersed in an ionic solution for in-situ growth and assembly to obtain the detection area.

6. A 3D-printed bionic wristband for sweat collection and multiple health monitoring according to claim 5, characterized in that, When the detection zone is used to detect lactic acid, the organic ligand is 1,4-naphthalenedicarboxylic acid, and the ionic solution is Eu. 3+ Solution; when the detection zone is used to detect vitamin C, the organic ligand is 2,5-dihydroxyterephthalic acid, and the ionic solution is Fe. 3+ Solution; when the detection zone is used to detect pH, the organic ligand is 2,2-biphenyldicarboxylic acid, and the ionic solution is Tb. 3+ Solution.

7. A 3D-printed bionic wristband for sweat collection and multiple health monitoring according to claim 5, characterized in that, The mass fractions of each material in the detection area are as follows: 1 part diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide, 1.5 parts sodium alginate, 1 part triethylamine, 100 parts polyethylene glycol diacrylate, 1 part organic ligand, and the concentration of the ion solution is 0.5M.

8. A 3D-printed bionic wristband for sweat collection and multiple health monitoring according to claim 1, characterized in that, Both the sensing layer and the resin substrate are prepared by 3D printing. First, the resin substrate is printed, and then a superhydrophilic region and a superhydrophobic region are printed on the resin substrate. Liquid inlet holes and detection area holes are reserved in the superhydrophobic region. Then, the printed detection area is embedded in the detection area hole, so that the superhydrophobic region surrounds the superhydrophilic region, the detection area and the liquid inlet hole, forming alternating hydrophilic and hydrophobic regions.

9. A 3D-printed bionic wristband for sweat collection and multiple health monitoring according to claim 1, characterized in that, The assembly method of the bionic wristband is as follows: the resin substrate, sensing layer, filter, ultraviolet lamp, battery, ring, and shell are assembled to obtain the bionic wristband; wherein, the resin substrate is the bottom layer and directly contacts the skin, the sensing layer is located on the resin substrate, the ultraviolet light emitted by the ultraviolet lamp passes through the filter to irradiate the detection area, and the shell is provided with a window at the part corresponding to the detection area for observation and image acquisition.

10. A 3D-printed bionic wristband for sweat collection and multiple health monitoring according to claim 9, characterized in that, Ultraviolet light is transmitted through a filter to irradiate the detection area, producing a color change. Images of the detection area before and after the sweat reaches the area are collected and analyzed to determine the levels of lactic acid, vitamin C, and pH in the sweat.

Images