A sweat sensor with shunt dike structure

Abstract

The present application relates to a kind of sweat sensor with shunt dike structure.Sweat sensor includes detection layer and sealing layer arranged on detection layer;Sample collection hole is arranged on the detection layer, sample flow channel is communicated with the sample collection hole and extends to the outside of detection layer, a plurality of detection chambers are arranged on one side of the sample flow channel;One end of the detection chamber is connected to the sample flow channel by first flow channel, and the other end is connected to the sample flow channel by second flow channel;Shunt dike is formed between the sample flow channel, first flow channel, detection chamber, second flow channel, and part of the sample flows to the detection chamber along the first flow channel after shunting through the shunt dike after entering the sample flow channel from the sample collection hole;A plurality of water stop grooves are opened in the side wall of the sample flow channel away from the shunt dike;Sample detection chip is arranged in the detection chamber.The sweat sensor designed in the present application has smaller sweat evaporation loss and more accurate sweat detection result.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of sweat detection, in particular to a sweat sensor with a shunt dike structure. BACKGROUND

[0002] Sweat is a non-invasive biofluid, and due to its ease of collection and rich information content, sweat detection has great potential in non-invasive wearable sensing. The pH value of sweat can reflect the changes in electrolyte concentration, thereby indicating diseases and metabolic activities. Therefore, reliable monitoring of the pH value of sweat is crucial for health monitoring and applications. In addition, biomarkers such as electrolytes, small molecules and proteins in sweat can also be used to assess overall health status, such as hydration status, cystic fibrosis, physical stress and bone mineral loss. Traditional sweat sampling methods, such as whole-body flushing techniques, patches and polymer bags / membranes, are non-invasive but require cumbersome procedures and professional personnel. Challenges include sweat evaporation and pre-analytical biomarker degradation. These factors greatly impair the reliability and sensitivity of the detection results. Therefore, based on these challenges, the integration of sampling and analysis in wearable sweat sensors through material functionalization and device miniaturization has become a popular trend.

[0003] The existing multi-sweat detection chamber sensor has two structural design schemes. One scheme is to draw N flow channels from the sweat collection area, and each flow channel is connected to a detection chamber. The disadvantage of this scheme is that there are many flow channels, the residual amount of sweat in the flow channels is large, the utilization rate of sweat collection is low, the device has N openings connected to the outside, and the loss of sweat evaporation is large. Another scheme is to draw one flow channel from the sweat collection area, and the detection chambers are connected to one side of the flow channel. Each detection chamber is provided with an additional opening for gas to flow out. The device has at least N openings (such as the structure disclosed in patent CN115969426A) in this structural design, and still has the problem of large loss of sweat evaporation. In this scheme, if the opening at the connection between the detection chamber and the flow channel is too small, the sweat will flow directly into the rear detection chamber after not entering the front detection chamber, causing the detection result to be inaccurate or even undetectable due to insufficient sweat flow into some detection chambers. If the opening at the connection between the detection chamber and the flow channel is too large, the sweat will flow out of the chamber after entering the chamber, causing the sweat to cross-flow in different detection chambers, which will affect the accuracy of sweat index detection.

[0004] The existing multi-chamber sweat sensor needs to set up multiple external connection ports (channel ports or gas outlets), which has the problems of large loss of sweat evaporation, poor sample preservation, easy pollution by external environment, redundant device structure, etc. Therefore, it is an urgent problem to design a new type of sweat sensor with simple structure, small loss of sweat evaporation and high utilization rate of sweat. SUMMARY

[0005] The present application aims to solve the problems of the existing sweat sensor structure, such as multiple air outlets, large sweat evaporation loss, and easy pollution by external environment.

[0006] In a first aspect, the present application provides a sweat sensor with a Dujiangyan diversion structure, comprising a detection layer and a sealing layer arranged on the detection layer.

[0007] The detection layer is provided with a sample collection hole, a sample flow channel communicating with the sample collection hole and extending to the outside of the detection layer, and a plurality of detection chambers arranged on one side of the sample flow channel.

[0008] One end of the detection chamber is connected to the sample flow channel through a first flow channel, and the other end is connected to the sample flow channel through a second flow channel; a diversion dike is formed between the sample flow channel, the first flow channel, the detection chamber, and the second flow channel, and the first flow channel and the sample flow channel form an acute angle towards the sample collection hole; the sample enters the sample flow channel from the sample collection hole, and part of the sample flows to the detection chamber along the first flow channel after being diverted by the diversion dike.

[0009] The side wall of the sample flow channel away from the diversion dike is provided with a plurality of water stopping grooves.

[0010] The detection chamber is provided with a sample detection chip.

[0011] Further specifically, the water stopping grooves are located between the connection between the first flow channel and the sample flow channel and the connection between the second flow channel and the sample flow channel.

[0012] Further specifically, the plurality of water stopping grooves are unevenly distributed.

[0013] Further specifically, the water stopping grooves have four.

[0014] Further specifically, the cross-sectional dimension of the sample flow channel in the sample flow direction is 300x300μm, and the size of the water stopping groove is 500x300x300μm.

[0015] Further specifically, the acute angle is 30°.

[0016] Further specifically, the sample detection chip is selected from any one of a chloride ion detection chip, a pH detection chip, a glucose detection chip, and a calcium ion detection chip.

[0017] Further specifically, the sample detection chip in at least one of the detection chambers is different from the sample detection chip of the other detection chambers.

[0018] Further specifically, the detection layer and the sealing layer are both made of flexible materials.

[0019] Further specifically, the surface of the detection layer away from the sealing layer is provided with a adhesion layer, and the adhesion layer has a sample collection port corresponding to the sample collection hole.

[0020] In a second aspect, the application provides a preparation method of a sweat sensor, comprising the following steps:

[0021] S1, preparing a detection layer mold and a sealing layer mold in the shape of a sweat sensor;

[0022] S2, uniformly mixing a resin prepolymer and a curing agent to remove bubbles to obtain a resin mixture, and placing the resin mixture into the detection layer mold and the sealing layer mold respectively, and obtaining a detection layer and a sealing layer after the resin mixture is cured and demolded;

[0023] S3, performing surface plasmon treatment on the detection layer, and then performing surface hydrophilic modification treatment;

[0024] S4, placing a sample detection chip into the detection chamber subjected to the surface hydrophilic modification treatment, and bonding the detection layer and the sealing layer to obtain a sweat sensor.

[0025] The working principle of the application is as follows:

[0026] The sweat in the sample flow channel (main flow channel) is shunted to the detection chamber through the diversion dike of Dujiangyan, and the sweat in the main flow channel is temporarily slowed down due to the pinning effect of the side wall dam, thereby providing sufficient time for the discharge of the gas in the detection chamber. The dam filled with sweat and having flowed through will not affect the flow of the sweat, and the sweat will not enter the detection chamber filled with sweat due to the design of the second flow channel. The discharge of the internal air and the transportation of the sweat are both through the sample flow channel, so that the device only needs to open one external connection port to complete the sweat detection work of multiple chambers and multiple indexes.

[0027] The application has the following beneficial effects:

[0028] The transmission path of the sweat on the detection layer is regulated through the diversion dike and the dam structure, so that the sweat sensor designed in the application only needs to be provided with one external connection port to complete the detection work of multiple indexes, and the single opening can greatly reduce the amount of sweat evaporation loss. In the application, the sweat fills the detection chambers in sequence, and the sweat will not enter the detection chambers filled with sweat, thereby avoiding the situation that the detection results are affected due to the mixing of new and old sweat in the traditional multi-chamber sweat sensor. The sweat sensor designed in the application has a smaller amount of sweat evaporation loss and a more accurate sweat detection result. BRIEF DESCRIPTION OF DRAWINGS

[0029] Figure 1 is an exploded schematic view of the sweat sensor in the application;

[0030] Figure 2 is a top view of the adhesion layer in the application;

[0031] Figure 3 is the top view of the detection layer in the present application;

[0032] Figure 4 is the schematic diagram of sweat flow in the present application;

[0033] Figure 5 is the schematic diagram of sweat flow in the present application;

[0034] Figure 6 is the schematic diagram of structure comparison between the present application and traditional double-opening sweat sensor;

[0035] Figure 7 is the schematic diagram of performance detection between the present application and traditional double-opening sweat sensor;

[0036] Figure 8 is the corresponding diagram of pH and RGB index of the pH detection chip in the present application;

[0037] Figure 9 is the schematic diagram of preparation process of the sweat sensor in the present application.

[0038] In the figure: 1, the adhesion layer; 2, the detection layer; 3, the sealing layer; 11, the sample collection port; 21, the sample collection hole; 22, the sample flow channel; 23, the detection chamber; 24, the shunt dike; 25, the first flow channel; 26, the second flow channel; 27, the water stop groove. DETAILED DESCRIPTION

[0039] In order to make the purpose, technical scheme and advantages of the present application more clear, the specific embodiments of the present application are described clearly and completely below. Obviously, the described embodiments are part of the embodiments of the present application, not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0040] In the description of the present application, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer" and the like indicate the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, therefore it cannot be understood as a limitation of the present application. In addition, the terms "first", "second", "third" are only for the purpose of description, and cannot be understood as indicating or implying relative importance.

[0041] In the description of the present application, it should be noted that unless otherwise expressly specified and limited, the terms "mounting", "connection", "connecting" should be understood in a broad sense, for example, it can be fixed connection, or detachable connection, or integrally connected; it can be mechanical connection, or electrical connection; it can be directly connected, or indirectly connected through an intermediate medium, or the internal communication of two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances. In addition, the technical features involved in the different embodiments of the present application described below can be combined with each other as long as they do not conflict with each other.

[0042] As shown in Figure 1 , the present application provides a sweat sensor with a shunt dike structure, the sensor sequentially includes a fitting layer 1, a detection layer 2 and a sealing layer 3 from bottom to top. As shown in Figure 2 , the fitting layer 1 is used to fit the skin surface of the human body, and a sample collection port 11 is formed on the fitting layer 1. Sweat enters the detection layer 2 from the sample collection port 11, and the detection of various biomarkers in the detection layer 2 is completed. The overall structure of the sweat sensor designed by the present application can be rectangular, circular or semicircular, etc.

[0043] As shown in Figure 3 , the detection layer 2 is provided with a sample collection hole 21, a sample flow channel 22, and a plurality of detection chambers 23 arranged on one side of the sample flow channel 22. The sample collection hole 21 corresponds to the sample collection port 11 of the fitting layer 1, which is a through hole for collecting sweat and entering the detection layer 2. Each detection chamber 23 has a shunt structure similar to Dujiangyan and a corresponding speed reduction structure arranged in the sample flow channel 22. The shunt structure similar to Dujiangyan is used to introduce part of the sweat in the sample flow channel 22 into the detection chamber 23, and the speed reduction structure with pinning effect on microfluids is used to temporarily slow down the flow rate in the sample flow channel 22 to allow the gas in the detection chamber 23 to be discharged in time. The sweat sensor has only one sample collection port 11 in contact with the skin surface and one sample flow channel in communication with the external environment.

[0044] Specifically, after the sweat is collected from the sweat collection hole 21, it further flows into the sample flow channel 22 due to capillary action and fills the plurality of detection chambers 23 in turn. The inlet of the detection chamber 23 is connected to the sample flow channel 22 through the first flow channel 25, and the outlet is connected to the sample flow channel 22 through the second flow channel 26. The sample flow channel 22, the first flow channel 25, the detection chamber 23 and the second flow channel 26 form a shunt dike 24. Among them, the side of the shunt dike 24 close to the sample collection hole 21 is an acute angle structure, that is, an acute angle is formed between the first flow channel 25 and the sample flow channel 22, which points to the sample collection hole 21. When the sweat sample flow channel 22 flows, due to the acute angle structure of the shunt dike 24 similar to Dujiangyan opposite to the flow direction, the sweat will partially flow into the detection chamber 23.

[0045] A plurality of stop grooves 27 are formed on the side wall of the sample flow channel 22 away from the flow divider 24. In the micro-nano flow channel, the stop groove 27 has a significant pinning effect on the flow of the fluid, which can greatly slow down the flow rate of the fluid flowing through the stop groove 27. When the stop groove 27 is filled with fluid, the rear stop groove 27 will no longer affect the flow rate of the fluid in the front. The size and number of stop grooves 27 will affect the time of sweat passing through the flow divider 24, and the size and number of stop grooves need to be adjusted according to the size of the detection chamber 23. The position of the stop groove 27 will affect the position where the flow rate of the sweat in the sample flow channel 22 begins to slow down. Preferably, the first stop groove 27 is arranged on the other side wall opposite to the connection between the sample flow channel 22 and the first flow channel 25. The distribution of the stop groove 27 will also affect the overall slowing effect on the flow of sweat. The stop groove 27 can be uniformly distributed or not uniformly distributed. The size, number, position and distribution interval of the stop groove 27 need to be adjusted according to the sweat filling condition of the detection chamber 23, and at least meet the requirement that the front end sweat position in the sample flow channel 22 cannot exceed the connection between the second flow channel 26 and the sample flow channel 22 before storing enough sweat for detection in the detection chamber 23.

[0046] In some embodiments, the sweat sensor is a cuboid with a length of 2.2 cm, a width of 0.5 cm, and a height of 0.8 mm. The sealing layer is 0.2 mm high, and the detection layer 2 is 0.6 mm high. The sweat collection port 11 and the sweat collection hole 21 are both circular with a diameter of 0.3 mm.

[0047] In further embodiments: the cross section of the sample flow channel 22 in the sample flow direction in the detection layer 2 is a square with a side length of 300 μm. The first flow channel 25 is arranged at an angle of 30° with the sample flow channel 22, and the connection has a width of 1000 μm. The second flow channel 26 is arranged perpendicularly to the sample flow channel 22, and the connection has a width of 300 μm. The detection chamber 23 is a circular groove with a diameter of 3000 μm and a depth of 300 μm. The length of the flow divider 24 is 3100 μm. The size of the stop groove 27 is 5000 μm x 30 μm x 300 μm, the number of stop grooves 27 is 4, and the stop grooves 27 are uniformly distributed at an interval of 500 μm. The first stop groove 27 is arranged on the other side wall opposite to the connection between the sample flow channel 22 and the first flow channel 25. The sweat sensor is provided with three detection chambers 23, and each detection chamber 23 has a corresponding flow divider 24 and four stop grooves 27.

[0048] As shown in Figure 4 , the flow rate of the sweat in this distance is slowed down by the stop groove 27 on the opposite side of the flow divider 24, and the sweat flows from the first flow channel 25 to the detection chamber 23 at a faster speed. As shown in Figure 5As shown, when the sweat fills the detection chamber 23 and is about to flow out from the second flow channel 26, the sweat in the sample flow channel 22 is just close to the connection between the second flow channel 26 and the sample flow channel 22, at this time, the two streams of sweat will converge and continue to flow to the next detection chamber 23. In the device structure designed in the present application, it is not necessary to additionally provide an air outlet for each detection chamber 23, when the sweat flows in from the first flow channel 25, the internal air will flow out from the second flow channel 26 due to extrusion and finally be discharged to the external environment through the sample flow channel 22. Since the detection chambers 23 in the present application are sequentially filled, the device can also provide effective timing sampling capability.

[0049] The sweat sensor designed in the present application can work when pasted on the skin surface, the natural sweat excretion positive pressure of the skin and the capillary negative pressure in the hydrophilic channel drive the sweat to flow into the detection layer 2 through the sweat collection hole 21. In order to further improve the adhesion, the adhesion layer 1 is provided on the surface of the detection layer 2 away from the sealing layer 3. The adhesion layer 1 can be selected from commercially available adhesion film IV3000 or other medical sterile adhesives. The device can be made of flexible resin and pasted on the skin surface of the human body (such as forehead, forearm and back, etc.), which is almost not deformed or strained.

[0050] As shown in the Figure 6 The device was exposed to air at 26°C, the residual mass of the device was measured every 1 hour, the change amount of the mass compared with the initial mass was calculated, and the residual amount of sweat in the device was obtained. The specific test results are shown in the Figure 7 As shown, as the exposure time of the device in the air is prolonged, the sweat gradually evaporates, and finally the sweat is almost completely evaporated. From the test results, the sweat evaporation speed of the single opening device designed in the present application is slower than that of the traditional double opening device, and the sweat evaporation amount of the single opening structure is much smaller than that of the traditional double opening structure in the same time before 4h, and the residual amount (retention rate) of sweat in the single opening device is higher. The test object is the single chamber double opening, when the device has N chambers, the sweat evaporation speed of the traditional sweat sensor will be faster, and the sweat evaporation loss will be larger.

[0051] In some specific embodiments, in order to meet different detection needs, the sample detection chip placed in the detection chamber 23 can be any one of a chloride ion detection chip, a pH detection chip, a glucose detection chip or a calcium ion detection chip. Taking the device containing 3 detection chambers 23 as an example, one detection chip with different detection contents can be placed in each of the three chambers, or pH detection chips or glucose detection chips can be placed in all the chambers, and the average value of the detection results of the multiple detection chips can be taken as the final result in the subsequent detection results, or other number and other combination of sample detection chips can be placed.

[0052] The sample detection chip in the detection area can be composed of Whatman chromatographic filter paper with added pH indicator. Specifically, the Whatman chromatographic filter paper is cut into a circle with a diameter of 3 mm, 0.5 μL of a universal indicator is added to the circular filter paper to manufacture a pH detection area, and after volatilization, a pH detection chip is obtained. The sample detection chip can also be a chlorine ion detection chip, a glucose detection chip, or a calcium ion detection chip, etc. made in a similar manner.

[0053] The pH value of a healthy person is in the range of 4.5-6.5, but patients with cystic fibrosis have alkaline sweat (pH as high as 9) due to bicarbonate reabsorption (HCO3 + secretion) defects. The pH value in sweat is also an indicator of the intensity of human exercise and the degree of dehydration. During exercise, the ammonia concentration in sweat decreases due to conversion to NH4 + . Since NH4 + diffuses poorly on the cell membrane compared to ammonia, excess NH4 + will accumulate ions, causing the pH value of the sweat to rise. Considering these, it is important to reliably monitor the pH value of sweat for health monitoring and healthcare applications. When the detection chip uses a pH detection chip, the sweat secreted by the skin quickly flows into the detection chamber 23 with the pH detection chip, and the color change of the detection chip can be directly observed to obtain the pH value of the sweat. Electronic equipment can also be used to take pictures of the pH sample detection chip, and the detection result can be obtained by reading the RGB value in the area. The linear relationship between the pH value and the RGB value is shown in Figure 8 .

[0054] The preparation method of the sweat sensor with a shunt dike structure designed in the present application is shown in Figure 9 , and specifically includes the following steps:

[0055] S1, 3D printing mold, using modeling software (such as 3DS Max, Solid Works) to build mold models of the detection layer 2 and the sealing layer 3 patterns. Use a 3D printer nanoArch® P150 to print the mold. After printing, remove the mold printing piece from the printing platform, immerse it in isopropyl alcohol for 10 minutes, then rinse it with deionized water, and dry the mold in a vacuum drying oven for 20 minutes. Dry the mold after drying UV for 12 hours, and in a 120 degree Celsius oven for 3 hours. Finally, the mold of the detection layer 2 and the sealing layer 3 patterns is obtained.

[0056] S2, preparation of device parts, using SYLGARD® 184 material, the silicone elastomer (Aldrich 761036A) and the curing agent (Aldrich 761036B) in the material are mixed uniformly at a weight ratio of 10:1, after mixing, the mixture is uniformly filled into the collection layer mold, then placed in a vacuum dryer for 1 hour to remove bubbles, and cured at 60°C for 180 minutes, after demolding, a polydimethylsiloxane (PDMS) detection layer 2 is obtained. The sealing layer 3 is prepared in the same way.

[0057] S3, plasma treatment and hydrophilic treatment, the prepared detection layer 2 and sealing layer 3 are washed with ethanol and deionized water, dried and then treated with high-power air plasma for 3 minutes to activate the surface, then the collection layer and the detection layer are immersed in an 8% (w / v) polyvinylpyrrolidone solution for 3 minutes, washed with deionized water and vacuum dried to obtain the detection layer 2 and the sealing layer 3 with long-term hydrophilic surface.

[0058] S4, assembly of sweat sensor, place the sample detection chip in the detection chamber 23, align the side of the detection layer 2 containing the detection chamber 23 with the sealing layer 3 and adhere them together with an adhesive.

[0059] S5, adhere the layer 1 to the surface of the detection layer 2 away from the sealing layer 3 to obtain a sweat sensor with a shunt dike structure.

[0060] The embodiments of the present application are described in detail above, but the present application is not limited to the described embodiments. For those skilled in the art, various changes, modifications, replacements and variations of the embodiments can be made without departing from the principles and spirits of the present application, and still fall within the protection scope of the present application.

Claims

1. A sweat sensor having a shunt dike structure, characterized by, The detection layer and the sealing layer are arranged on the detection layer; The detection layer is provided with a sample collection hole, a sample flow channel communicating with the sample collection hole and extending to the outside of the detection layer, and a plurality of detection chambers arranged on one side of the sample flow channel; One end of the detection chamber is connected to the sample flow channel through a first flow channel, and the other end is connected to the sample flow channel through a second flow channel; a flow dividing dam is formed between the sample flow channel, the first flow channel, the detection chamber, and the second flow channel, and the first flow channel and the sample flow channel form an acute angle towards the sample collection hole; the sample enters the sample flow channel from the sample collection hole, and part of the sample flows along the first flow channel to the detection chamber after being divided by the flow dividing dam; A plurality of water stopping grooves are arranged on the side wall of the sample flow channel away from the flow dividing dam; the size, number, position, and distribution interval of the water stopping grooves need to be adjusted according to the sweat filling condition of the detection chamber, and at least the front end of the sweat in the sample flow channel should not exceed the connection between the second flow channel and the sample flow channel before enough sweat for detection is stored in the detection chamber; The detection chamber is provided with a sample detection chip.

2. The sweat sensor of claim 1, wherein, The water stopping grooves are located between the connection between the first flow channel and the sample flow channel and the connection between the second flow channel and the sample flow channel.

3. The sweat sensor of claim 2, wherein, The plurality of water stopping grooves are unevenly distributed.

4. The sweat sensor of claim 2, wherein, The water stopping grooves are four in number.

5. The sweat sensor of claim 4, wherein, The cross-sectional dimension of the sample flow channel in the sample flow direction is 300×300 μm, and the size of the water stopping groove is 500×300×300 μm.

6. The sweat sensor of claim 1, wherein, The acute angle is 30°.

7. The sweat sensor of claim 1, wherein, The sample detection chip is selected from any one of a chlorine ion detection chip, a pH detection chip, a glucose detection chip, and a calcium ion detection chip.

8. The sweat sensor of claim 7, wherein, The sample detection chip in at least one of the detection chambers is different from the sample detection chip in the other detection chambers.

9. The sweat sensor of claim 1, wherein, The detection layer and the sealing layer are both made of flexible materials.

10. The sweat sensor of claim 1, wherein, The surface of the detection layer away from the sealing layer is provided with a fitting layer, and the fitting layer has a sample collection port corresponding to the sample collection hole.

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