A flexible wearable dual-channel sweat sensing device and a preparation method thereof

Abstract

The present application relates to a kind of flexible wearable dual-channel sweat sensor device and its preparation method, comprising: detection module and sweat sensor patch, the detection module is connected with the sweat sensor patch by plug-in interface or ejector pin type ejector pin, to collect the conductance signal in the sweat sensor patch, and the conductance signal is converted into electrolyte concentration information and sweat information / sweat rate information.The flexible wearable sweat sensor device provided by the present application, by setting a certain length of sweat channel, and sweat volume and electrolyte concentration are detected in sweat channel, the preparation process of the device is simple, only needs simple adhesion to complete the manufacture of a sensor patch.The flexible wearable sweat sensor device provided by the present application, detection is based on the principle of conductance, so sensor can realize real-time continuous detection of sweat volume and sweat electrolyte concentration through conductance curve, and sensor can be reused after sweat discharge flow channel, not disposable consumables.

Description

Technical Field

[0001] This invention relates to the field of wearable devices and sensor technology, specifically to a flexible wearable dual-channel sweat sensing device and its preparation method. Background Technology

[0002] Monitoring the body's physical and chemical signals is crucial for disease prevention, especially chronic diseases. However, efficient, continuous, real-time, and non-invasive monitoring of the human body remains a challenge. Substances carried by sweat are closely related to human physiological states; therefore, one important approach to achieving accurate, real-time detection and analysis of these biomarkers is to develop non-invasive, wearable sweat sensors.

[0003] Sweat, as an important biofluid for real-time health monitoring, carries a large number of substances that transmit physiological information, such as metabolites (glucose, lactic acid), electrolytes (Na+, Cl-, K+), and hormones (cortisol, dopamine (DA)). Various physiological parameters in sweat can effectively reflect an individual's health status. For example, sodium ion detection can provide timely warnings of hyponatremia (serum sodium <135 mmol / L); cortisol can reflect stress levels. Compared to other human biofluids (blood, tissue fluid, tears, urine, saliva, etc.), sweat is easily obtained and non-invasive to monitor, playing a vital physiological role in thermoregulation, immune defense, electrolyte and pH balance, and is thus recognized as an important indicator for human health monitoring. To maintain the body's hydration balance during continuous sweating, personalized rehydration strategies need to be tailored to individual circumstances, and sweating rate detection can provide crucial information for developing such strategies.

[0004] Colorimetric, hydrogel swelling, capacitive, and impedance methods have been used to detect sweating rates. These methods can all perform in-situ detection, but they also have some limitations.

[0005] 1. Colorimetric and hydrogel swelling methods require continuous acquisition of optical images and analysis of these images to obtain information on the rate of sweating, which is not convenient for automated detection. Measurement methods based on electrical signals can achieve real-time automated monitoring.

[0006] 2. Among these, the impedance measurement method converts the volume of sweat within the microfluidic channel into the impedance of the sensing electrode. A continuous impedance sweat rate sensor can provide real-time sweat rate information based on electrode impedance; however, changes in electrolyte concentration can significantly affect the electrode impedance, thus requiring correction of the results.

[0007] Wearable flexible sweat sensors can detect sweating speed and electrolyte concentration in real time, greatly facilitating people's lives. However, the current preparation methods for sweat sensors are relatively cumbersome and complex, which undoubtedly increases the cost of the sensors and narrows the target audience. Summary of the Invention

[0008] The technical problem solved by this invention is to provide a flexible wearable dual-channel sweat sensing device that is simple to manufacture and reusable.

[0009] The technical solution adopted by this invention to solve its technical problem is:

[0010] A flexible wearable dual-channel sweat sensing device includes: a detection module and a sweat sensor patch. The detection module is regularly electrically connected to the sweat sensor patch via a plug-in interface or a pin-type spring to collect the electrical conductivity signal in the sweat sensor patch and convert the electrical conductivity signal into electrolyte concentration information and sweat volume / sweating rate information.

[0011] The detection module integrates a reference voltage generation unit, a voltage conversion unit, an AFE small signal acquisition unit, and a wireless communication unit.

[0012] The sweat sensor patch includes a hydrophobic film layer, a channel layer, an electrode layer, and a bottom layer arranged regularly from top to bottom;

[0013] The bottom layer includes a skin adhesive layer for adhering to human skin and is disposed on the lower surface of the flexible substrate of the electrode layer. The bottom layer has regularly arranged openings and forms a sweat-retaining chamber between itself and the flexible substrate of the electrode layer.

[0014] The electrode layer includes the flexible substrate and a plurality of interdigitated electrodes for testing, which are regularly arranged on the upper surface of the flexible substrate. A liquid inlet is provided on the flexible substrate. The plurality of interdigitated electrodes are regularly arranged in front of the liquid inlet and are regularly connected to a plurality of electrode contacts by leads provided on the flexible substrate to form detection electrode contacts.

[0015] The flow channel layer is regularly arranged with flow channels that are regularly arranged along the shape of the plurality of interdigital electrodes and positioned directly above the plurality of finger electrodes between the plurality of interdigital electrodes, so as to place the plurality of finger electrodes between the plurality of interdigital electrodes in the flow channel; the front end and the end end of the flow channel are respectively provided with a flow channel inlet for sweat to flow in and a flow channel outlet for sweat to flow out, the flow channel inlet communicating with the sweat containing chamber through the liquid inlet, and the flow channel outlet leading out of the flow channel layer to communicate with the outside;

[0016] The hydrophobic film layer is attached to the upper surface of the flow channel layer to encapsulate the flow channels in the flow channel layer.

[0017] Furthermore, the substrate of the flow channel layer is made of a hydrophobic material, and the bends of the flow channel are rounded to form a hydrophobic flow channel.

[0018] Furthermore, the plurality of interdigital electrodes includes a first interdigital electrode for electrolyte concentration testing and a second interdigital electrode for sweat volume / sweating rate testing. The first interdigital electrode and the second interdigital electrode are regularly arranged in front of the liquid inlet. The second interdigital electrode has an S-shaped design and covers the flexible substrate as much as possible. The second interdigital electrode is regularly arranged along the left and right sides of the liquid inlet.

[0019] Furthermore, the second interdigital electrodes on the left and right sides of the liquid inlet are arranged at equal intervals and of equal length on the left and right sides of the liquid inlet, so as to cover the left and right sides of the flexible substrate as much as possible.

[0020] Furthermore, electrode vias are regularly arranged on the flow channel layer and the hydrophobic film layer along the top of the plurality of electrode contacts to facilitate electrical connection between the detection module and the electrode layer.

[0021] Furthermore, the detection module is attached to the upper surface of the hydrophobic film layer using a double-sided adhesive layer.

[0022] Furthermore, electrode vias are also regularly arranged on the double-sided adhesive layer directly above the plurality of electrode contacts.

[0023] Furthermore, the sweat sensor patch is a flexible structure, while the detection module is a rigid structure.

[0024] Furthermore, the flexible substrate of the electrode layer is a thin-film electrode, and the plurality of detection interdigitated electrodes are conductivity electrodes.

[0025] A method for fabricating a flexible wearable dual-channel sweat sensor device includes the following steps:

[0026] Step S1: Prepare an electrode layer by etching copper or nickel-gold on a flexible substrate to prepare a number of detection interdigital electrodes, a number of electrode contacts, and electrode leads that regularly connect the number of detection interdigital electrodes and the number of electrode contacts, and laser-cut a liquid inlet on the electrode layer.

[0027] Step S2: Prepare the flow channel layer by cutting along the shape of the interdigitated electrodes with a laser to form the flow channel shape, and cutting along the shape of the electrode contacts to form electrode through holes. Design a flow channel inlet that communicates with the liquid inlet at the front end of the flow channel, and lead the outlet of the flow channel out of the flow channel layer. Set rounded corners at the bends of the flow channel. Adhesive backing is applied to both the top and bottom sides of the flow channel to stick it to the upper surface of the electrode layer, or it can be stuck to the upper surface of the electrode layer with double-sided adhesive.

[0028] Step S3: Prepare a hydrophobic film layer, cut it into the main body shape of the sweat sensor patch by laser cutting, and then attach it to the upper surface of the channel layer by the backing adhesive, adhesive or double-sided adhesive. The hydrophobic film layer is also cut along the shape of the several electrode contacts by laser cutting to form the electrode through holes.

[0029] Step S4: Prepare a double-sided adhesive layer by cutting the double-sided adhesive layer along the shape of the detection module with a laser, and further cut the electrode through holes along the several electrode contacts, and then stick the double-sided adhesive layer to the upper surface of the hydrophobic film layer.

[0030] Step S5: Prepare the base layer. Cut the low-sensitivity skin adhesive into the shape of the main body by laser cutting to form a skin adhesive layer. Further cut the cavity through-hole for sweat storage on the skin adhesive layer. Attach the skin adhesive layer to the lower surface of the electrode layer and attach a release film to the lower surface of the skin adhesive layer.

[0031] Step S6: Connect the detection module and the electrode layer. Electrically connect the detection module and the electrode layer through a plug-in interface or a pin-type spring-loaded interface, and attach the detection module to the upper surface of the hydrophobic film layer through the double-sided adhesive layer.

[0032] The beneficial effects of this invention are:

[0033] 1. The flexible wearable sweat sensor device provided by the present invention detects the amount of sweat and electrolyte concentration within a sweat channel by setting a certain length of sweat channel. The device has a simple manufacturing process and only requires simple bonding to complete the fabrication of a sensor patch.

[0034] 2. The flexible wearable sweat sensor device provided by the present invention is based on the principle of electrical conductivity. Therefore, the sensor can realize real-time continuous detection of sweat volume and sweat electrolyte concentration through the conductivity curve. At the same time, the sensor can be reused after the sweat is discharged from the channel, and is not a disposable consumable.

[0035] 3. This invention designs a dual-channel system to detect electrolyte concentration and sweat volume in sweat, allowing for simultaneous detection of both variables using a single sensor, thus achieving dual-channel detection and making the detection results more accurate and reliable. Attached Figure Description

[0036] Figure 1 This is an exploded view of the structure of the present invention;

[0037] Figure 2 for Figure 1 Structural diagram of the middle electrode layer;

[0038] Figure 3 for Figure 1 Structural diagram of the mid-channel layer;

[0039] Figure 4 This is a schematic diagram of an electrical connection method between the detection module and the sweat sensor patch of the present invention;

[0040] Figure 5 This is a schematic diagram illustrating another electrical connection method between the detection module and the sweat sensor patch of the present invention;

[0041] Figure 6 This shows the relationship between conductivity and time under different sweat flow rates at an electrolyte concentration of 100 mM in Example 1.

[0042] Figure 7 This is the relationship between conductivity and time under different sweat flow rates at an electrolyte concentration of 100 mM in Example 2;

[0043] Figure 8 This is the relationship between conductivity and time under different sweat flow rates at an electrolyte concentration of 100 mM in Example 3;

[0044] Figure 9 This is a schematic diagram of the sweat sensor device of the present invention being attached to the surface of human skin;

[0045] in:

[0046] 1. Detection module; 2. Hydrophobic film layer; 3. Flow channel layer; 4. Electrode layer; 5. Bottom layer; 6. Release film layer; 11. Double-sided adhesive layer.

[0047] 101. Spring pin;

[0048] 301, Flow channel; 302, Flow channel inlet; 303, Flow channel outlet; 3011, Fillet; 304, Electrode via.

[0049] 401, Flexible substrate; 4011, Liquid inlet; 402, Detection interdigital electrode; 4021, First interdigital electrode; 4022, Second interdigital electrode; 403, Electrode contact.

[0050] 501. Sweat storage chamber;

[0051] 701, male end; 702, female end. Detailed Implementation

[0052] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a thorough understanding of the present invention. However, the present invention can be practiced in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0053] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0054] like Figure 1-5 As shown, this invention provides a flexible wearable dual-channel sweat sensing device, including a detection module 1 and a sweat sensor patch. The sweat sensor patch is a flexible structure, while the detection module 1 is a rigid structure. The detection module is electrically connected to the sweat sensor patch via pluggable terminals or spring-loaded pins. The detection module collects the electrical conductivity signal from the sweat sensor patch and converts it into information such as electrolyte concentration, sweat volume, or sweat rate.

[0055] The detection module integrates a DAC reference voltage generation unit, a voltage conversion unit, an AFE small signal acquisition unit, and a wireless communication unit. The sweat sensor device of this invention transmits signals wirelessly via the wireless communication unit. It communicates with the circuit processing module via the wireless communication module, transmitting the electrical output signal to the circuit processing module. The signal processing circuit in the circuit processing module shapes, amplifies, filters, and performs A / D conversion on the received electrical output signal (analog signal) to obtain the sensor's output electrical signal (digital signal). Then, the algorithm integrated in the circuit processing module converts the output electrical signal into digitized sweat monitoring parameters.

[0056] like Figure 1 As shown, the detection module 1 is attached to the upper surface of the sweat sensor patch using double-sided adhesive tape 11.

[0057] Furthermore, the size of the detection module is less than or equal to the overall size of the sweat sensor patch.

[0058] like Figure 1 As shown, the sweat sensor patch includes a hydrophobic film layer 2, a flow channel layer 3, an electrode layer 4, and a bottom layer 5 arranged regularly from top to bottom.

[0059] The bottom layer 5 is a skin adhesive layer used for adhesion to human skin. Regularly spaced openings are provided on the bottom layer 5, forming a sweat-retaining chamber 501 between it and the electrode layer substrate.

[0060] Furthermore, a release film layer 6 for protection is also attached to the lower surface of the bottom layer 5.

[0061] In use, the release film 6 is peeled off, and the bottom layer 5 is attached to the surface of human skin, thereby attaching the sweat sensor device of the present invention to the surface of human skin. During exercise, sweat is continuously produced on the surface of human skin, and the sweat on the surface of human skin enters the sweat receiving chamber 501 between the bottom layer 5 and the electrode layer substrate.

[0062] Preferably, the bottom layer 5 uses a hypoallergenic skin film to minimize or avoid allergic reactions on human skin.

[0063] like Figure 2 The diagram shows the structure of electrode layer 4. Electrode layer 4 includes a flexible substrate 401 and a plurality of interdigital electrodes 402 disposed on the upper surface of the flexible substrate. A liquid inlet 4011 is disposed on the flexible substrate 401, preferably located in the middle of the substrate and communicating with the sweat containing chamber 501. The plurality of interdigital electrodes are regularly arranged in front of the liquid inlet 4011.

[0064] Furthermore, the plurality of interdigital electrodes 402 include a first interdigital electrode for testing / detecting electrolyte concentration and a second interdigital electrode for testing / detecting sweat volume or sweat rate. The second interdigital electrode is S-shaped or serpentine in design and is regularly positioned in front of the first interdigital electrode.

[0065] Furthermore, the S-shaped second interdigital electrode covers as much of the upper surface of the flexible substrate 401 as possible, thereby maximizing the utilization of the area of ​​the upper surface of the flexible substrate 401. For example... Figure 2 As shown, in one embodiment, the S-shaped second interdigital electrodes are regularly arranged along the left and right sides of the liquid inlet. The finger-shaped electrodes of the second interdigital electrodes on the left and right sides are arranged equidistantly and of equal length on both sides of the liquid inlet. Therefore, a longer second interdigital electrode and flow channel can be provided on a flexible substrate of the same area. That is, with the same length of second interdigital electrode and flow channel, the sweat sensor patch of the present invention can be made smaller.

[0066] Furthermore, a plurality of electrode contacts 403 are regularly arranged on the flexible substrate 401, and a plurality of detection interdigital electrodes 402 are regularly electrically connected to the corresponding electrode contacts 403 via leads. In one embodiment, six electrode contacts are provided, and the first interdigital electrode and the second interdigital electrode are respectively connected to four of the electrode contacts via leads to form detection electrode contacts. The other two electrode contacts serve as power supply electrode contacts.

[0067] Furthermore, the flexible substrate employs thin-film electrodes, and the thin-film material can be polyimide, polydimethylsiloxane, or polyethylene terephthalate. The detection interdigitated electrodes are conductive electrodes, and the conductive electrode material can be carbon nanotubes, graphene, carbon black, or carbon fiber, etc.

[0068] like Figure 3 The diagram shows the structure of the flow channel layer 3. Flow channels 301 are regularly arranged on the flow channel layer 3. The front and rear ends of the flow channels 301 are respectively provided with a flow channel inlet 302 for sweat to flow in and a flow channel outlet 303 for sweat to flow out. The flow channel inlet 302 is located directly above and connected to the liquid inlet, while the flow channel outlet 303 extends out of the flow channel layer 3 and is located on the side of the flow channel layer 3, thus leading the flow channels out of the flow channel layer.

[0069] Furthermore, the flow channel inlet 302 on the flow channel layer 3, the liquid inlet 4011 on the electrode layer 4, and the sweat containing chamber 501 on the bottom layer 5 are vertically arranged and interconnected, so that the sweat secreted by the human body is first stored in the sweat containing chamber 501, and then flows from the liquid inlet 4011 and the flow channel inlet 302 on the electrode layer into the flow channel 301 in the flow channel layer.

[0070] Furthermore, the flow channel 301 is arranged along the shape of the second interdigital electrode 4022 and positioned directly above it, thereby guiding sweat to flow onto the finger-shaped electrodes of the second interdigital electrode to generate corresponding electrical conductivity signals and realize the measurement of sweat volume. Therefore, in one embodiment, the flow channel 301 is arranged along the S-shaped second interdigital electrode, forming S-shaped flow channels of equal length and distance on both the left and right sides of the flow channel inlet.

[0071] Furthermore, several finger electrodes of the first interdigital electrode and the second interdigital electrode are disposed within the flow channel 301.

[0072] Furthermore, the flow channel 301 is designed with rounded corners 3011 at the bends, and the base of the entire flow channel layer is made of hydrophobic material, thereby forming a hydrophobic flow channel to reduce the flow resistance of sweat in the flow channel.

[0073] like Figure 1 As shown, the hydrophobic film layer 2 covers the upper surface of the channel layer 3, thereby sealing and encapsulating the channels in the channel layer 3 to ensure that sweat liquid can flow along the channels in the channel layer 3.

[0074] Furthermore, the hydrophobic film layer is mainly formed into the main shape by laser cutting, and six through holes need to be laser-cut on the surface to facilitate the connection of the electrode with the outside world. The diameter of the through holes is 1.4 mm, and the distance between the six through holes is consistent with that on the electrode layer. The material of the hydrophobic film can be selected from polyethylene terephthalate (PET), ethylene-vinyl acetate copolymer (EVA), etc.

[0075] like Figure 4 and Figure 5 As shown, this invention provides two methods for electrically connecting the detection module to the electrode contacts on the surface of the electrode layer:

[0076] The first method, such as Figure 4 As shown, a plug-in terminal is used to achieve electrical connection between the detection module and the electrode layer. Several electrode contacts 403 on the electrode layer 4 are led out through wires and regularly converged through terminals to form a plug terminal (male end 701). Correspondingly, the detection module is provided with a protruding plug-in interface (female end 702). The plug terminal from the electrode layer is inserted into the plug-in interface from the detection module, thereby achieving electrical connection between the detection module and the electrode layer, i.e., electrical connection between the detection module and the sweat sensor patch. The detection module is then attached to a designated position on the upper surface of the sweat sensor patch using a double-sided adhesive layer 11.

[0077] Of course, the male and female terminals mentioned above can also be set in reverse.

[0078] Furthermore, pluggable interfaces can also be integrated into the detection module, located on the front, back, left, right sides, or top of the detection module.

[0079] Furthermore, the lead wires leading out of the electrode layer pass through the flow channel layer and the hydrophobic film layer, respectively. Therefore, electrode vias 304 are regularly arranged on the flow channel layer and the hydrophobic film layer directly above the plurality of electrode contacts.

[0080] The second method, such as Figure 5 As shown, a pin-type spring-loaded interface is used to achieve electrical connection between the detection module and the electrode contacts on the surface of the electrode layer. A number of spring-loaded pins 101 for electrical connection are regularly arranged along several electrode contacts on the detection module 1, extending out from the lower surface of the detection module. Electrode vias 304 are regularly arranged along several electrode contacts on the hydrophobic film layer 2 and the flow channel layer 3. The spring-loaded pins 101 pass through the electrode vias on the hydrophobic film layer and the flow channel layer to electrically connect with several electrode contacts on the surface of the electrode layer.

[0081] Furthermore, the detection module 1 is attached to the upper surface of the hydrophobic film layer 2 via a double-sided adhesive layer 11.

[0082] To improve the adhesion between the detection module and the sweat sensor patch, the double-sided adhesive layer is applied to cover as much of the lower surface of the detection module as possible. Therefore, in one embodiment, electrode vias are regularly arranged on the double-sided adhesive layer 11 to facilitate the passage of the spring needle.

[0083] Among them, the electrode via 304 can be the same number of through holes as the electrode contacts 403, or it can be a strip hole that avoids the electrode contact area.

[0084] The present invention also provides a method for fabricating a flexible wearable dual-channel sweat sensor device, comprising the following steps:

[0085] Step S1: Prepare electrode layer 4, obtained by etching copper (nickel-gold) electrodes onto a polyimide film, with a thickness of 12-100 μm. Cut a 1 mm diameter circular through-hole for sweat inlet on the electrode layer using a laser. Simultaneously prepare multiple circular electrode contacts on the electrode layer, preferably six, with a diameter of 0.12-2 mm, preferably 0.9 mm, and a distance of 0.5-5 mm, preferably 2.5 mm, between each circle.

[0086] Step S2: Prepare the channel layer 3 by laser cutting it into the desired channel shape and then attaching it to the upper surface of the electrode layer 4. A 1mm diameter through-hole (channel inlet) needs to be designed at the inlet of the channel layer as a sweat inlet. The channel layer material can be selected from double-sided adhesive film materials such as polyethylene, biaxially oriented polypropylene, and polytetrafluoroethylene, with a thickness of 50-500µm. A hydrophobic material in the middle of the channel can reduce the flow resistance of sweat within the channel.

[0087] Step S3: Prepare the hydrophobic film layer 2 by laser cutting it into its main shape and then attaching it to the upper surface of the channel layer 2. Simultaneously, six through-holes need to be laser-cut on the surface to facilitate connection between the electrode contacts and the outside world. The diameter of the through-holes is 1.4 mm, and the distance between the six through-holes is consistent with that on the electrode layer. The material of the hydrophobic film can be polyethylene terephthalate (PET), ethylene-vinyl acetate copolymer (EVA), etc. The hydrophobic film layer mainly encapsulates the channel layer, covering it to ensure that the liquid can flow along the channel.

[0088] Step S4: Prepare the double-sided adhesive layer 11. 3M VHB strong double-sided adhesive is used, laser-cut into a 3*3cm square structure, with six through holes laser-cut on the surface to facilitate connection between the circular electrode contacts on the electrode layer surface and the outside environment. Then, it is attached to the upper surface of the hydrophobic film layer 2. The double-sided adhesive ensures a tight connection between the detection module 1 and the hydrophobic film layer 2, preventing it from falling off during wear.

[0089] Step S5: Connect the detection module 1 and the electrode layer 4. Electrically connect the detection module 1 and the electrode layer 4 using a plug-in interface or a spring-loaded connector. Then, attach the detection module 1 to the upper surface of the hydrophobic film layer 2 using the double-sided adhesive layer 11.

[0090] Step S6: Prepare the bottom layer 5. First, use laser cutting to cut the low-sensitivity skin adhesive into its main shape and a 6mm diameter sweat storage chamber. This chamber also serves as a sweat inlet. Then, attach it to the lower surface of the electrode layer 4, and attach a release film layer to the lower surface of the skin adhesive layer. In use, simply peel off the release film and apply it to the surface of human skin.

[0091] Furthermore, in one embodiment, the overall length and width of the sweat sensor patch (including a bottom layer, an electrode layer, a channel layer, and a hydrophobic film layer) are greater than or equal to 6cm × 3cm, and the size of the detection module is less than or equal to the overall size of the sweat sensor patch. The sweat sensor patch is a flexible structure, while the detection module is a rigid structure. The sweat storage chamber has a diameter of 6-10mm and a height of 100-200μm, and is formed by a low-sensitivity skin adhesive through-hole and the electrode bottom layer. The diameter of the sweat inlet on the electrode layer is 0.3mm to 10mm, and the diameter of the sweat inlet on the surface of the channel layer is similar to that of the electrode layer, between 0.3mm and 10mm. The entire sweat channel is designed with rounded corners at bends, and the inner wall is a hydrophobic channel with a width of 0.5-4mm and a thickness of 0.1-0.6mm. The sweat distribution system features a width of 1–2 mm and a thickness of 0.15–0.3 mm, which better ensures sweat circulation and allows a single sweat patch to fill for one hour, meeting the requirements for outdoor sports monitoring. The system also includes a sweat outlet located at the exit of the sweat circulation channel, specifically at the edge of the sweat sensor patch.

[0092] Example 1:

[0093] like Figure 1 and Figure 5 As shown in the figure, this embodiment provides a wearable sweat sensor device for real-time continuous detection of electrolyte concentration, including: a bottom layer and an electrode layer, a silicone rubber channel layer, a hydrophobic film layer and a detection module sequentially disposed on the base layer.

[0094] The first sweat inlet is provided on the bottom layer 5, with one end open close to the skin surface to allow continuous input of sweat generated on the skin surface. A second sweat inlet is provided on the surface of the electrode layer 4. The first and second sweat inlets allow sweat to reach the surface of the electrode layer and then enter the flow channel layer 3.

[0095] The bottom layer connects the skin and the electrode layer, and provides a sweat-retaining chamber 501. The electrode layer analyzes electrical signals to detect the amount of sweat flowing through the sweat channels and / or to detect electrolyte concentration.

[0096] The bottom layer is set with a hypoallergenic skin adhesive film and a release film 6. When using it, you need to remove the release film first and then apply it to the skin surface.

[0097] The material used for the flow channel layer 3 is silicone rubber, and sweat channels are provided on its surface. The third sweat inlet of the sweat channel is vertically connected to the first sweat inlet and the second sweat inlet. The surfaces of the electrolyte concentration detection interdigital electrode and the sweat volume detection interdigital electrode of the electrode layer are located on the bottom surface of the sweat channel layer, and are used to detect the sweat flowing through the sweat channel to obtain information on the electrolyte concentration and sweat volume in the sweat.

[0098] The channel layer is equipped with a sweat outlet to remove incoming sweat from the channel layer.

[0099] A hydrophobic film layer is placed above the flow channel layer to seal the liquid in the flow channel and prevent it from overflowing during use.

[0100] The bottom layer, electrode layer, channel layer, and hydrophobic film layer are collectively referred to as the sweat sensor patch. The overall length and width of the sweat sensor patch are greater than or equal to 6cm x 3cm, while the size of the detection module is less than or equal to the overall size of the sweat sensor patch. The sweat sensor patch is a flexible structure, while the detection module is a rigid structure. The sweat storage chamber has a diameter of 6-10mm and a height of 100-200μm. The sweat storage chamber is formed by a layer of low-sensitivity skin adhesive through-holes and the bottom electrode layer. The diameter of the sweat inlet on the electrode layer is 0.3mm to 10mm. The diameter of the sweat inlet on the surface of the channel layer is similar to that of the electrode layer, ranging from 0.3mm to 10mm. The entire sweat channel is designed with rounded corners at bends and a hydrophobic inner wall, with a width of 0.5–4 mm and a thickness of 0.1–0.6 mm. A width of 1–2 mm and a thickness of 0.15–0.3 mm better ensures sweat circulation and allows one sweat patch to refill for one hour, suitable for outdoor sports detection. The channel also includes a sweat outlet located at the exit of the sweat flow channel, i.e., at the edge of the sweat sensor patch for drainage.

[0101] In practical use, the wearable sweat sensor device in this embodiment is attached to the skin surface, such as... Figure 9As shown, sweat secreted from sweat glands has a certain pressure, reaching a maximum of 70,000 Nm⁻², sufficient to pump sweat into the first sweat inlet at the bottom layer. As sweat flows upward through the first sweat inlet, it successively contacts the interdigital electrodes exposed on the electrode layer surface. These electrodes connect to the detection module via a plug-in or pin-type connection to obtain the conductivity signal of the wearable sweat sensor device in real time. The continuous conductivity values ​​of the sweat are recorded in real time by a conductivity detection instrument. The conductivity curve is positively correlated with the real-time total electrolyte concentration of sweat and the amount of sweat. Specifically, the time interval of the step signal change in the conductivity curve is directly proportional to the sweating rate, while the conductivity signal measured by the first interdigital electrode is positively correlated with the real-time electrolyte concentration.

[0102] Therefore, a real-time, continuous conductivity curve can be used to obtain real-time, continuous changes in sweat electrolyte concentration and perspiration volume. When the flow channel layer is silicone rubber, some test results are as follows: Figure 6 As shown, the upper curve represents 4 μl / min, and the lower curve represents 3 μl / min.

[0103] Example 2:

[0104] The specific structure of this embodiment is referred to in Embodiment 1, wherein the material of the flow channel layer is biaxially oriented polypropylene film.

[0105] When the flow channel layer is a biaxially oriented polypropylene film, some test results are shown in Figure 7. The upper curve is 4 μl / min and the lower curve is 3 μl / min.

[0106] Example 3:

[0107] The specific structure of this embodiment is referred to in Embodiment 1, wherein the material of the flow channel layer is a polytetrafluoroethylene film.

[0108] When the flow channel layer is a biaxially oriented polypropylene film, some test results are shown in Figure 8. The upper curve is 4 μl / min and the lower curve is 3 μl / min.

[0109] Figure 6-8 The horizontal axis represents time, and the vertical axis represents conductivity. Figure 6-8 The coordinates represent the relationship between conductivity and time at different sweat flow rates under an electrolyte concentration of 100 mM.

[0110] For different materials chosen for the flow channel layer, the resistance to the liquid varies depending on the material on the inner side of the flow channel and the cutting precision on the inner side. Silicone has relatively high resistance, so the time of a single step signal is relatively long. Biaxially oriented polypropylene film is the next best, while polytetrafluoroethylene is the best, with high consistency of step signals.

[0111] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A flexible wearable dual-channel sweat sensing device, characterized in that: include: The detection module and the sweat sensor patch are provided. The detection module is regularly electrically connected to the sweat sensor patch through a plug-in interface or a pin-type spring to collect the electrical conductivity signal in the sweat sensor patch and convert the electrical conductivity signal into electrolyte concentration information and sweat volume / sweating rate information. The detection module integrates a reference voltage generation unit, a voltage conversion unit, an AFE small signal acquisition unit, and a wireless communication unit. The sweat sensor patch includes a hydrophobic film layer, a channel layer, an electrode layer, and a bottom layer arranged regularly from top to bottom; The bottom layer includes a skin adhesive layer for adhering to human skin and is disposed on the lower surface of the flexible substrate of the electrode layer. The bottom layer has regularly arranged openings and forms a sweat-retaining chamber between itself and the flexible substrate of the electrode layer. The electrode layer includes the flexible substrate and a plurality of interdigitated electrodes for testing, which are regularly arranged on the upper surface of the flexible substrate. A liquid inlet is provided on the flexible substrate. The plurality of interdigitated electrodes are regularly arranged in front of the liquid inlet and are regularly connected to a plurality of electrode contacts by leads provided on the flexible substrate to form detection electrode contacts. The flow channel layer is regularly arranged with flow channels that are regularly arranged along the shape of the plurality of interdigital electrodes and positioned directly above the plurality of finger electrodes between the plurality of interdigital electrodes, so as to place the plurality of finger electrodes between the plurality of interdigital electrodes in the flow channel; the front end and the end end of the flow channel are respectively provided with a flow channel inlet for sweat to flow in and a flow channel outlet for sweat to flow out, the flow channel inlet communicating with the sweat containing chamber through the liquid inlet, and the flow channel outlet leading out of the flow channel layer to communicate with the outside; The hydrophobic film layer is attached to the upper surface of the flow channel layer to encapsulate the flow channels in the flow channel layer.

2. The flexible wearable dual-channel sweat sensing device as described in claim 1, characterized in that: The substrate of the flow channel layer is made of a hydrophobic material, and the bends of the flow channel are rounded to form a hydrophobic flow channel.

3. The flexible wearable dual-channel sweat sensing device as described in claim 1, characterized in that: The plurality of interdigital electrodes include a first interdigital electrode for electrolyte concentration testing and a second interdigital electrode for sweat volume / sweating rate testing, wherein the first interdigital electrode and the second interdigital electrode are regularly arranged in front of the liquid inlet; The second interdigital electrode is S-shaped and covers the flexible substrate as much as possible. The second interdigital electrode is arranged regularly on the left and right sides of the liquid inlet.

4. The flexible wearable dual-channel sweat sensing device as described in claim 3, characterized in that: The second interdigital electrodes on the left and right sides of the liquid inlet are arranged at equal intervals and of equal length on the left and right sides of the liquid inlet, so as to cover the left and right sides of the flexible substrate as much as possible.

5. A flexible wearable dual-channel sweat sensing device as described in any one of claims 1-4, characterized in that: Electrode vias are regularly arranged on the flow channel layer and the hydrophobic film layer above the plurality of electrode contacts to facilitate electrical connection between the detection module and the electrode layer.

6. The flexible wearable dual-channel sweat sensing device as described in claim 5, characterized in that: The detection module is attached to the upper surface of the hydrophobic film layer using double-sided adhesive.

7. The flexible wearable dual-channel sweat sensing device as described in claim 6, characterized in that: Electrode vias are also regularly arranged on the double-sided adhesive layer directly above the plurality of electrode contacts.

8. The flexible wearable dual-channel sweat sensing device as described in claim 1, characterized in that: The sweat sensor patch has a flexible structure, while the detection module has a rigid structure.

9. The flexible wearable dual-channel sweat sensing device as described in claim 1, characterized in that: The flexible substrate of the electrode layer is a thin-film electrode, and the plurality of detection interdigitated electrodes are conductivity electrodes.

10. A method for fabricating a flexible wearable dual-channel sweat sensor device, characterized in that: Includes the following steps: Step S1: Prepare an electrode layer by etching copper or nickel-gold on a flexible substrate to prepare a number of detection interdigital electrodes, a number of electrode contacts, and electrode leads that regularly connect the number of detection interdigital electrodes and the number of electrode contacts, and laser-cut a liquid inlet on the electrode layer. Step S2: Prepare the flow channel layer by cutting along the shape of the interdigitated electrodes with a laser to form the flow channel shape, and cutting along the shape of the electrode contacts to form electrode through holes. Design a flow channel inlet that communicates with the liquid inlet at the front end of the flow channel, and lead the outlet of the flow channel out of the flow channel layer. Set rounded corners at the bends of the flow channel. Adhesive backing is applied to both the top and bottom sides of the flow channel to stick it to the upper surface of the electrode layer, or it can be stuck to the upper surface of the electrode layer with double-sided adhesive. Step S3: Prepare a hydrophobic film layer, cut it into the main body shape of the sweat sensor patch by laser cutting, and then attach it to the upper surface of the channel layer by the backing adhesive, adhesive or double-sided adhesive. The hydrophobic film layer is also cut along the shape of the several electrode contacts by laser cutting to form the electrode through holes. Step S4: Prepare a double-sided adhesive layer by cutting the double-sided adhesive layer along the shape of the detection module with a laser, and further cut the electrode through holes along the several electrode contacts, and then stick the double-sided adhesive layer to the upper surface of the hydrophobic film layer. Step S5: Prepare the base layer. Cut the low-sensitivity skin adhesive into the shape of the main body by laser cutting to form a skin adhesive layer. Further cut the cavity through-hole for sweat storage on the skin adhesive layer. Attach the skin adhesive layer to the lower surface of the electrode layer and attach a release film to the lower surface of the skin adhesive layer. Step S6: Connect the detection module and the electrode layer. Electrically connect the detection module and the electrode layer through a plug-in interface or a pin-type spring-loaded interface, and attach the detection module to the upper surface of the hydrophobic film layer through the double-sided adhesive layer.

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