Flexible wearable dual-channel sweat sensing device and preparation method therefor

Abstract

The present invention relates to a flexible wearable dual-channel sweat sensing device and a preparation method therefor. The device comprises: a detection module and a sweat sensor patch. The detecti

Description

FLEXIBLE WEARABLE DUAL-CHANNEL SWEAT SENSING DEVICE AND PREPARATION METHOD THEREFOR TECHNICAL FIELD

[0001] The present invention relates to the technical field of wearable devices and sensors, and in particular to a flexible wearable dual-channel sweat sensing device and a preparation method therefor. BACKGROUND

[0002] Monitoring the physical and chemical signals of the human body is crucial for preventing diseases, especially chronic diseases. However, it is still a challenge currently to conduct efficient, continuous, real-time, and non-invasive monitoring of the human body. The substances carried by sweat are closely related to the physiological state of the human body. Therefore, one of the important ways to achieve accurate and real-time detection and analysis of these biomarkers is to develop a non-invasive and wearable sweat sensor.

[0003] Sweat, as an important biological fluid for real-time health monitoring, carries a large number of substances that transmit physiological information in the human body, such as metabolites (glucose, lactic acid), electrolytes (Na+, Cl-, K+), hormones (cortisol, dopamine (DA)), etc. The parameters of various physiological indicators in sweat can effectively reflect an individual’s physical health status. For example, sodium ion detection can promptly warn of hyponatremia (serum sodium <135 mmol / L); cortisol can reflect stress status, and the like. Compared with other biological fluids (blood, tissue fluid, tears, urine, saliva, etc.) in the human body, sweat, due to its easy accessibility and non-invasive monitoring, plays an important physiological role in thermoregulation, immune defense, electrolyte and pH balance and has been recognized as an important indicator for human health detection. In order to maintain the hydration balance state of the body during continuous sweating, it is necessary to customize personalized fluid replenishment strategies according to individual conditions, and the detection of sweating rate can provide a key basis for the formulation of fluid replenishment strategies.

[0004] Colorimetric, hydrogel swelling, capacitive and impedance-based methods have been used for the detection of sweating rate. These methods can all be used for in-situ detection, but there are also some deficiencies.

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

[0006] 2. Among them, the impedance-based measurement method converts the sweating volume in the microfluidic channel into the impedance of the sensing electrode. A continuous impedance-based sweating rate sensor can provide real-time sweating rate information based on the impedance of the electrode. However, changes in electrolyte concentration will have a significant impact on the impedance of the electrode, so the results need to be corrected.

[0007] Wearable flexible sweat sensors can enable real-time and in-situ detection of the sweating rate and electrolyte concentration, which greatly facilitates 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 reduces the target audience. SUMMARY OF THE INVENTION

[0008] The technical problem solved by the present invention is to provide a flexible wearable dual-channel sweat sensing device with a simple preparation process and reusability.

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

[0010] A flexible wearable dual-channel sweat sensing device, which includes: a detection module and a sweat sensor patch, the detection module is electrically connected to the sweat sensor patch regularly via a plug-in interface or a spring-loaded pogo pin and is configured to acquire a conductance signal in the sweat sensor patch and convert the conductance signal into electrolyte concentration information and sweating volume / sweating rate information;

[0011] the detection module internally 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 flow channel layer, an electrode layer, and an underlying layer sequentially arranged from top to bottom;

[0013] the underlying layer includes a skin adhesive layer for adhesion to human skin and is arranged on a lower surface of a flexible substrate of the electrode layer, an opening is provided in the underlying layer regularly to form a sweat-holding chamber between the underlying layer and the flexible substrate of the electrode layer;

[0014] the electrode layer includes the flexible substrate and a plurality of detection interdigitated electrodes regularly arranged on the upper surface of the flexible substrate for testing, a liquid inlet is provided in the flexible substrate, and the plurality of interdigitated electrodes are regularly arranged in front of the liquid inlet, and are led out through leads disposed on the flexible substrate and are regularly connected to a plurality of electrode contacts to form detection electrode contacts;

[0015] a flow channel is regularly arranged in the flow channel layer, and the flow channel is configured in accordance with the shape of the plurality of detection interdigitated electrodes and is positioned directly above the plurality of finger electrodes between the plurality of detection interdigitated electrodes so as to position the plurality of finger electrodes between the plurality of detection interdigitated electrodes in the flow channel; a front end and a rear 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 is communicated with the sweat-holding chamber through the liquid inlet, and the flow channel outlet extends from the flow channel layer to communicate with the external environment;

[0016] the hydrophobic film layer is attached to an upper surface of the flow channel layer to encapsulate the flow channel within the flow channel layer.

[0017] Furthermore, the substrate of the flow channel layer is made of a hydrophobic material, and rounded comers are arranged at bending sections of the flow channel to form a hydrophobic flow channel.

[0018] Furthermore, the plurality of detection interdigitated electrodes include first interdigitated electrodes for electrolyte concentration testing and second interdigitated electrodes for sweating volume / sweating rate testing; the first interdigitated electrodes and the second interdigitated electrodes are regularly arranged in front of the liquid inlet; the second interdigitated electrodes are designed in an S-shaped pattern and configured to cover the flexible substrate as much as possible, and are regularly arranged along both the left and right sides of the liquid inlet.

[0019] Furthermore, the second interdigitated electrodes on the left and right sides of the liquid inlet are arranged vertically with equal spacing and equal length on both 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, the flow channel layer and the hydrophobic film layer are provided with electrode via holes directly above the plurality of electrode contacts regularly for facilitating electrical connection between the detection module and the electrode layer.

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

[0022] Furthermore, the double-sided adhesive layer is also provided with electrode via holes directly above the plurality of electrode contacts regularly.

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

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

[0025] A method for preparing a flexible wearable dual-channel sweat sensor device, including the following steps:

[0026] step SI: preparation of an electrode layer by etching copper or nickel-gold on a flexible substrate to obtain a plurality of detection interdigitated electrodes, a plurality of electrode contacts, and electrode leads for connecting the plurality of detection interdigitated electrodes to the plurality of electrode contacts regularly, and laser-cutting a liquid inlet in the electrode layer;

[0027] step S2: preparation of a flow channel layer by laser-cutting along the shape of the plurality of detection interdigitated electrodes to form the shape of a flow channel, cutting along the shape of the plurality of electrode contacts to form electrode via holes, designing a flow channel inlet communicating with the liquid inlet at a front end of the flow channel, and leading an outlet at the end of the flow channel out from the flow channel layer; rounded corners are arranged at bending sections of the flow channel, and upper and lower surfaces of the flow channel are adhered to an upper surface of the electrode layer through adhesive backing treatment or with double-sided adhesive;

[0028] step S3: preparation of a hydrophobic film layer by laser-cutting into a main shape of a sweat sensor patch, then adhering the hydrophobic film layer to an upper surface of the flow channel layer through backing, adhesive or double-sided adhesive, and laser-cutting the hydrophobic film layer along the shape of the plurality of electrode contacts to form the electrode via holes;

[0029] step S4: preparation of a double-sided adhesive layer by laser-cutting along the shape of the detection module to form the double-sided adhesive layer, and further cutting the electrode via holes along the plurality of electrode contacts, and adhering the double-sided adhesive layer to an upper surface of the hydrophobic film layer;

[0030] step S5: preparation of an underlying layer by laser-cutting a hypoallergenic skin adhesive into the main shape to form a skin adhesive layer, and further cutting a chamber through-hole in the skin adhesive layer for storage of sweat, adhering the skin adhesive layer to a lower surface of the electrode layer, and adhering a release film to a lower surface of the skin adhesive layer;

[0031] step S6: connection between the detection module and the electrode layer by electrically connecting the detection module to the electrode layer via a plug-in interface or a spring-loaded pogo pin interface and adhering the detection module to an upper surface of the hydrophobic film layer through the double-sided adhesive layer.

[0032] The present invention has the following beneficial effects:

[0033] 1. In the flexible wearable sweat sensor device provided by the present invention, a sweat channel with a certain length is arranged, so that the sweating volume and electrolyte concentration are detected in the sweat channel. Therefore, the device has a simple fabrication process, requiring only simple lamination to complete the construction of a sensor patch.

[0034] 2. The flexible wearable sweat sensor device provided by the present invention is based on the principle of electrical conductance for detection. Therefore, the sensor can realize realtime continuous detection of the sweating volume and sweat electrolyte concentration through the electrical conductance curve. Meanwhile, the sensor can be reused after the sweat is discharged from the flow channel, so it is not a disposable consumable.

[0035] 3. In the present invention, two channels are designed to detect the electrolyte concentration in sweat and the sweating volume, respectively. That is to say, two variables can be detected simultaneously through one sensor, thus achieving dual-channel detection and making the detection results more accurate and reliable. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] FIG. 1 is an exploded view of the structure of the present invention;

[0037] FIG. 2 is a structural diagram of the electrode layer in FIG. 1;

[0038] FIG. 3 is a structural diagram of the flow channel layer in FIG. 1;

[0039] FIG. 4 is a schematic diagram showing an electrical connection mode between the detection module and the sweat sensor patch according to the present invention;

[0040] FIG. 5 is a schematic diagram showing another electrical connection mode between the detection module and the sweat sensor patch according to the present invention;

[0041] FIG. 6 shows the change in conductance over time at an electrolyte concentration of 100 mM under different sweat flow rates in Embodiment 1;

[0042] FIG. 7 shows the change in conductance over time at an electrolyte concentration of 100 mM under different sweat flow rates in Embodiment 2;

[0043] FIG. 8 shows the change in conductance over time at an electrolyte concentration of 100 mM under different sweat flow rates in Embodiment 3;

[0044] FIG. 9 is a schematic diagram showing the sweat sensor device of the present invention attached to human skin surface;

[0045] where:

[0046] 1. detection module, 2. hydrophobic film layer, 3. flow channel layer, 4. electrode layer, 5. underlying layer, 6. release film layer, 11. double-sided adhesive layer;

[0047] 101. pogo pin;

[0048] 301. flow channel, 302. flow channel inlet, 303. flow channel outlet, 3011. rounded corner, 304. electrode via hole;

[0049] 401. flexible substrate, 4011. liquid inlet, 402. detection interdigitated electrode, 4021. first interdigitated electrode, 4022, second interdigitated electrode, 403. electrode contact;

[0050] 501. sweat-holding chamber;

[0051] 701. male terminal, 702. female terminal. DETAILED DESCRIPTION

[0052] To make the above objects, features, and advantages of the present invention more obvious and understandable, the specific embodiments of the present invention are described in detail below in conjunction with the accompanying drawings. Many specific details are set forth in the following description to facilitate a full understanding of the present invention. However, the present invention can be implemented in many other ways different from those described herein, and similar improvements can be made by those skilled in the art without departing from the connotation of the present invention. Therefore, the present invention is not limited by the specific examples disclosed below.

[0053] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which the present invention belongs. The terms used in the description of the present invention herein are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more of the related listed items.

[0054] As shown in FIGs. 1-5, the present invention provides a flexible wearable dual-channel sweat sensing device, which includes a detection module 1 and a sweat sensor patch. The sweat sensor patch is configured as a flexible structure, and the detection module 1 is configured as a rigid structure. The detection module is electrically connected to the sweat sensor patch via a plug-in terminal or a spring-loaded pogo pin, and the detection module is configured to acquire a conductance signal in the sweat sensor patch and convert the conductance signal into electrolyte concentration information and sweating volume information or sweating rate information.

[0055] The detection module internally 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 the present invention performs wireless transmission of signals via the wireless communication unit and communicates with a circuit processing module via a wireless communication module to transmit electrical output signals to the circuit processing module. The received electrical output signals (analog signals) are processed, such as waveform shaping, amplification, filtering, and A / D conversion, by a signal processing circuit within the circuit processing module to obtain the output electrical signals (digital signals) of the sensor. The output electrical signals are then converted into digitized sweat monitoring parameters by algorithms integrated within the circuit processing module.

[0056] As shown in FIG. 1, the detection module 1 is adhered to an upper surface of the sweat sensor patch through a double-sided adhesive layer 11.

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

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

[0059] Among them, the underlying layer 5 is a skin adhesive layer for adhering to human skin. An opening is provided in the underlying layer 5 regularly to form a sweat-holding chamber 501 between the underlying layer and the substrate of the electrode layer.

[0060] Furthermore, the lower surface of the underlying layer 5 is also attached with a protective release film layer 6.

[0061] During use, the release film layer 6 is torn off to attach the underlying layer 5 to the surface of human skin, thereby adhering the sweat sensor device of the present invention to the surface of human skin. During exercising, sweat will continuously be produced on the surface of human skin, and the sweat on the surface of human skin enters the sweat-holding chamber 501 between the underlying layer 5 and the substrate of the electrode layer.

[0062] Preferably, the underlying layer 5 is made of a hypoallergenic skin adhesive film to avoid or minimize allergic reactions to human skin as much as possible.

[0063] As shown in FIG. 2, it is a structural diagram of the electrode layer 4. The electrode layer 4 includes a flexible substrate 401 and a plurality of detection interdigitated electrodes 402 arranged on the upper surface of the flexible substrate. The flexible substrate 401 is provided with a liquid inlet 4011, which is preferably arranged at the middle position of the substrate and communicates with the sweat-holding chamber 501. The plurality of detection interdigitated electrodes are regularly arranged in front of the liquid inlet 4011.

[0064] Furthermore, the plurality of detection interdigitated electrodes 402 include first interdigitated electrodes for electrolyte concentration testing / detection and second interdigitated electrodes for sweating volume / sweating rate testing / detection. Among them, the second interdigitated electrodes are designed in an S-shaped or serpentine pattern and are regularly arranged in front of the first interdigitated electrodes.

[0065] Furthermore, the second interdigitated electrodes designed in an S-shaped pattern cover the upper surface of the flexible substrate 401 as much as possible, thereby making the best use of the area of the upper surface of the flexible substrate 401. As shown in FIG. 2, in an embodiment, the second interdigitated electrodes designed in an S-shaped pattern are regularly arranged along both the left and right sides of the liquid inlet, and the finger electrodes of the second interdigitated electrodes on the left and right sides are arranged vertically with equal spacing and equal length on both the left and right sides of the liquid inlet. Therefore, on a flexible substrate of the same area, a longer overall length of the second interdigitated electrodes and a longer flow channel can be arranged. In other words, for the second interdigitated electrodes and the flow channel of the same length, the sweat sensor patch of the present invention can be made smaller.

[0066] Furthermore, the flexible substrate 401 is also provided with a plurality of electrode contacts 403 regularly. A plurality of detection interdigitated electrodes 402 are electrically connected to corresponding electrode contacts 403 regularly via leads. In an embodiment, there are six electrode contacts, the first interdigitated electrodes and the second interdigitated electrodes are respectively connected to four of the electrode contacts via leads to form detection electrode contacts. The remaining two electrode contacts are used as the power supply electrode contacts.

[0067] Furthermore, a thin-film electrode is employed as the flexible substrate, and the film material may be selected from polyimide, polydimethylsiloxane or polyethylene terephthalate. The detection interdigitated electrodes are conductance electrodes, and the material of the conductance electrodes may be selected from carbon nanotubes, graphene, carbon black, or carbon fibers.

[0068] As shown in FIG. 3, it is a structural diagram of the flow channel layer 3. The flow channel layer 3 is provided with a flow channel 301 regularly, and a front end and a rear end of the flow channel 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 arranged directly above the liquid inlet and is communicated therewith. The flow channel outlet 303 extends from the flow channel layer 3 and is arranged at the side of the flow channel layer 3, thereby leading the flow channel out of the flow channel layer.

[0069] Furthermore, the flow channel inlet 302 in the flow channel layer 3, the liquid inlet 4011 in the electrode layer 4, and the sweat-holding chamber 501 in the underlying layer 5 are vertically arranged and communicate with each other, thereby allowing the sweat secreted by the human body to be first stored in the sweat-holding chamber 501, and then to flow through the liquid inlet 4011 in the electrode layer and the flow channel inlet 302 into the flow channel 301 within the flow channel layer.

[0070] Furthermore, the flow channel 301 is configured in accordance with the shape of the second interdigitated electrodes 4022, and is arranged directly above these electrodes, thereby guiding sweat across the plurality of finger electrodes of the second interdigitated electrodes to generate corresponding conductance signals for enabling the measurement of sweating volume. Therefore, in an embodiment, the flow channel 301 is arranged along the S-shaped second interdigitated electrodes, and S-shaped flow channels of equal length and equal distance are formed on both the left and right sides of the flow channel inlet.

[0071] Furthermore, the plurality of finger electrodes of the first interdigitated electrodes and the second interdigitated electrodes are all arranged within the flow channel 301.

[0072] Furthermore, rounded corners 3011 are designed at the bending sections of the flow channel 301, and the substrate of the entire flow channel layer is made of a hydrophobic material, thereby forming a hydrophobic flow channel to reduce the flow resistance of sweat within the flow channel.

[0073] As shown in FIG. 1, the hydrophobic film layer 2 covers the upper surface of the flow channel layer 3, thereby covering and sealing the flow channel formed in the flow channel layer 3 to ensure that the sweat liquid can flow along the flow channel within the flow channel layer 3.

[0074] Furthermore, the hydrophobic film layer is primarily laser-cut into a main shape, and six through-holes need to be laser-cut in the surface to facilitate the connection between the electrodes and the external environment. The diameter of the through-holes is 1.4 mm, and the distance between the six through-holes is the same as 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] As shown in FIGs. 4 and 5, the present invention provides two ways of electrically connecting the detection module to the electrode contacts on the surface of the electrode layer:

[0076] The first way, as shown in FIG. 4, adopts a plug-in terminal to achieve the electrical connection between the detection module and the electrode layer. The plurality of electrode contacts 403 on electrode layer 4 are led out through wires and the wires are gathered through terminals regularly to form a plug terminal (male terminal 701). Correspondingly, the detection module is provided with an extended plug-in interface (female terminal 702). The plug terminal led out from the electrode layer is inserted into the plug-in interface led out from the detection module, thereby achieving the electrical connection between the detection module and the electrode layer, that is, the electrical connection between the detection module and the sweat sensor patch. The detection module is adhered to the designated position on the upper surface of the sweat sensor patch through a double-sided adhesive layer 11.

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

[0078] Furthermore, the plug-in interface can also be integrated on the detection module and positioned on the front, rear, left, right sides, or the top surface of the detection module.

[0079] Furthermore, the wires extending from the electrode layer pass through the flow channel layer and the hydrophobic film layer, respectively. Therefore, electrode via holes 304 are regularly arranged in the flow channel layer and the hydrophobic film layer directly above the plurality of electrode contacts.

[0080] The second way, as shown in FIG. 5, adopts a spring-loaded pogo pin interface to achieve the electrical connection between the detection module and the electrode contacts on the surface of the electrode layer. A plurality of pogo pins 101 for electrical connection, equal in number to the plurality of electrode contacts, are regularly arranged along the electrode contacts on the detection module 1 and extend from the lower surface of the detection module. Electrode via holes 304 are regularly arranged in the hydrophobic film layer 2 and the flow channel layer 3 along the plurality of electrode contacts. The plurality of pogo pins 101 pass through the electrode via holes in the hydrophobic film layer and the flow channel layer and are electrically connected to the plurality of electrode contacts on the surface of the electrode layer.

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

[0082] In order to improve the reliability between the detection module and the sweat sensor patch, the double-sided adhesive layer covers the lower surface of the detection module as much as possible. Therefore, in an embodiment, electrode via holes for facilitating the passing of the pogo pins are also regularly arranged in the double-sided adhesive layer 11.

[0083] The electrode via holes 304 may be through-holes equal in number to the electrode contacts 403, or slot holes avoiding the electrode contact area.

[0084] The present invention also provides a method for preparing a flexible wearable dualchannel sweat sensor device, which includes the following steps:

[0085] step SI: preparation of an electrode layer 4 by etching copper (nickel-gold) electrodes on a polyimide film. The electrode layer has a thickness of 12-100 pm. A sweat inlet is lasercut in the electrode layer, which is a circular through-hole with a diameter of 1 mm. Multiple circular electrode contacts are simultaneously fabricated on the electrode layer, preferably 6 electrode contacts, with a diameter of 0.12-2 mm, preferably 0.9 mm, and the distance between each circle is 0.5-5 mm, preferably 2.5 mm.

[0086] step S2: preparation of a flow channel layer 3 by laser-cutting into a desired shape of flow channel and then adhering the flow channel layer to the upper surface of the electrode layer 4. A through-hole with a diameter of 1 mm (flow channel inlet) needs to be designed at the inlet of the flow channel layer as the sweat inlet. Meanwhile, the material of the flow channel layer can be selected from polyethylene, biaxially oriented polypropylene, polytetrafluoroethylene and other double-sided adhesive film materials, with a thickness of 50-500 pm. The middle part of the flow channel is made of a hydrophobic material, which can reduce the flow resistance of sweat in the flow channel.

[0087] step S3: preparation of a hydrophobic film layer 2 by laser-cutting a main shape and then adhering the hydrophobic film layer to an upper surface of the flow channel layer 3. Meanwhile, six through-holes need to be laser-cut in the surface to facilitate the connection between the electrode contacts and the external environment. The diameter of the through-holes is 1.4 mm, and the distance between the six through-holes is the same as that on the electrode layer. The material of the hydrophobic film can be selected from polyethylene terephthalate (PET), ethylene-vinyl acetate copolymer (EVA), etc. The hydrophobic film layer primarily serves to encapsulate the flow channel layer, covering the flow channel layer to ensure that the liquid can flow along the flow channel.

[0088] step S4: preparation of a double-sided adhesive layer 11 by laser-cutting a 3M VHB strong double-sided adhesive into a 3*3 cm square structure, and laser-cutting six through-holes in the surface to facilitate the connection between the circular electrode contacts on the surface of the electrode layer and the external environment, then adhering the double-sided adhesive layer to the upper surface of the hydrophobic film layer 2. Double-sided adhesive is used to securely adhere the detection module 1 to the hydrophobic film layer 2, ensuring that the device does not fall off during use.

[0089] step S5: electrical connection between the detection module 1 and the electrode layer 4 by means of a plug-in interface or a spring-loaded pogo pin interface. The detection module 1 is then adhered to the upper surface of the hydrophobic film layer 2 through the above doublesided adhesive layer 11.

[0090] step S6: preparation of an underlying layer 5 by first laser-cutting a hypoallergenic skin adhesive into the main shape and a chamber through-hole with a diameter of 6 mm for storage of sweat, with the through-hole serving as the sweat inlet at the same time, then adhering the skin adhesive layer to the lower surface of the electrode layer 4, and adhering a release film to the lower surface of the skin adhesive layer. During use, one only needs to remove the release film and directly adhere the overall structure to the human skin surface.

[0091] Furthermore, in an embodiment, the overall length and width of the sweat sensor patch (including the underlying layer, the electrode layer, the flow channel layer, and the hydrophobic film layer) are greater than or equal to 6 cm * 3 cm, the size of the detection module is smaller than or equal to the overall size of the sweat sensor patch, the sweat sensor patch is configured as a flexible structure, and the detection module is configured as a rigid structure. The sweatholding chamber has a diameter of 6-10 mm and a height of 100-200 pm. The sweat-holding chamber is a chamber formed by a layer of hypoallergenic skin adhesive via holes and the electrode underlying layer. The diameter of the sweat inlet in the electrode layer is 0.3 mm to 10 mm, and the diameter of the sweat inlet in the surface of the flow channel layer is comparable to that of the electrode layer and is between 0.3 mm and 10 mm. Rounded corners are designed at bending sections of the entire sweat flow channel, and the inner wall is a hydrophobic flow channel with a width of 0.5 to 4 mm and a thickness of 0.1 to 0.6 mm. Among them, when the width is 1 to 2 mm and the thickness is 0.15 to 0.3 mm, the circulation of sweat can be better ensured, and at the same time, a single sweat patch can accommodate a liquid filling duration of one hour, which is in line with the detection mode of outdoor sports. The flow channel also includes a sweat outlet, which is located at the outlet of the sweat flow channel, that is, at the edge of the sweat sensor patch for liquid discharge.

[0092] Embodiment 1:

[0093] As shown in FIG. 1 and FIG. 5, this embodiment provides a wearable sweat sensor device for real-time continuous detection of electrolyte concentration, which includes an underlying layer and an electrode layer, a silicone rubber flow channel layer, a hydrophobic film layer and a detection module sequentially arranged on the underlying layer.

[0094] The underlying layer 5 is provided with a first sweat inlet, with the opening at one end positioned close to the skin surface for the continuous input of the sweat generated on the skin surface. A second sweat inlet is arranged in the surface of the electrode layer 4, which, together with the first sweat inlet, enables the sweat to reach the surface of the electrode layer and then enter the flow channel layer 3.

[0095] The underlying layer connects the skin to the electrode layer and provides a sweatholding chamber 501. The electrode layer is used to detect the volume of sweat flowing through the sweat flow channel and / or detect the electrolyte concentration by analyzing electrical signals.

[0096] The underlying layer is set as a hypoallergenic skin adhesive film and a release film 6. The release film needs to be removed before adhering the overall structure to the skin surface during use.

[0097] The flow channel layer 3 is made of silicone rubber, on the surface of which is provided a sweat flow channel. A third sweat inlet in the sweat flow channel communicates with the first and second sweat inlets in the vertical direction. The surfaces of the electrolyte concentration detection interdigitated electrodes and the sweating volume detection interdigitated electrodes of the electrode layer are located at the bottom surface of the sweat flow channel layer, and are used to detect the sweat flowing through the sweat channel to obtain the electrolyte concentration and sweating volume information in the sweat.

[0098] The flow channel layer is provided with a sweat outlet for guiding the input sweat out of the flow channel layer.

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

[0100] The underlying layer, the electrode layer, the flow channel layer, and the hydrophobic film layer are collectively referred to as the sweat sensor patch. The overall length and width of the sweat sensor patch is greater than or equal to 6 cm 3 cm, the size of the detection module is smaller than or equal to the overall size of the sweat sensor patch, the sweat sensor patch is configured as a flexible structure, and the detection module is configured as a rigid structure. The sweat-holding chamber has a diameter of 6 to 10 mm and a height of 100 to 200 pm. The sweat-holding chamber is a chamber formed by a layer of hypoallergenic skin adhesive via holes and the electrode underlying layer. The diameter of the sweat inlet in the electrode layer is 0.3 mm to 10 mm, and the diameter of the sweat inlet in the surface of the flow channel layer is comparable to that of the electrode layer and is between 0.3 mm and 10 mm. Rounded corners are designed at bending sections of the entire sweat flow channel, and the inner wall is a hydrophobic flow channel with a width of 0.5 to 4 mm and a thickness of 0.1 to 0.6 mm. Among them, when the width is 1 to 2 mm and the thickness is 0.15 to 0.3 mm, the circulation of sweat can be better ensured, and at the same time, a single sweat patch can accommodate a liquid filling duration of one hour, which is in line with the detection mode of outdoor sports. The flow channel also includes a sweat outlet, which is located at the outlet of the sweat flow channel, that is, at the edge of the sweat sensor patch for liquid discharge.

[0101] In actual use, the wearable sweat sensor device in this embodiment is attached to the skin surface. As shown in FIG. 9, sweat has a certain pressure when it is secreted from sweat glands, with a maximum of 70,000 Nm-2, which is sufficient to pump the sweat into the first sweat inlet at the underlying layer. When sweat passes through the first sweat inlet and flows upward, it will successively contact the interdigitated electrodes exposed on the surface of the electrode layer and is connected to the detection module via a plug-in interface or a pogo pin to obtain the conductance signal of the wearable sweat sensor device in real time. The continuous conductance values of sweat are recorded in real time using a conductance detection instrument. The conductance curve is positively correlated with the real-time total electrolyte concentration of the sweat. Among them, the time interval between the stepwise signal changes in the conductance curve is directly proportional to the sweating rate, and the conductance signal measured by the first interdigitated electrode is positively correlated with the real-time electrolyte concentration.

[0102] Therefore, the real-time continuous changes in both the sweat electrolyte concentration and the sweating volume can be obtained through a real-time continuous conductance curve. Some test results when the flow channel layer is made of silicone rubber are shown in FIG. 6, where the upper curve corresponds to a flow rate of 4 pL / min, and the lower curve corresponds to a flow rate of 3 pL / min.

[0103] Embodiment 2:

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

[0105] Some test results when the flow channel layer is made of biaxially oriented polypropylene film are shown in FIG. 7, where the upper curve corresponds to a flow rate of 4 pL / min, and the lower curve corresponds to a flow rate of 3 pL / min.

[0106] Embodiment 3:

[0107] The specific structure of this embodiment refers to Embodiment 1, in which the flow channel layer is made of polytetrafluoroethylene film.

[0108] Some test results when the flow channel layer is made of polytetrafluoroethylene film are shown in FIG. 8, where the upper curve corresponds to a flow rate of 4 pL / min, and the lower curve corresponds to a flow rate of 3 pL / min.

[0109] In FIGs. 6-8, the abscissa represents the time, and the ordinate represents the conductance. The coordinates in FIGs. 6-8 represent the change in conductance over time at an electrolyte concentration of 100 mM under different sweat flow rates.

[0110] For the selection of different materials for the flow channel layer, the resistance brought by the material on the inner side of the flow channel and the cutting precision of the inner side to the liquid is different. The resistance of silicone material is relatively high, leading to longer durations for individual step signals, followed by biaxially oriented polypropylene film, and polytetrafluoroethylene shows the best performance, with high consistency of step signals.

[0111] The specific embodiments described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. 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 shall be included within the scope of protection of the present invention.

Claims

1. A flexible wearable dual-channel sweat sensing device, comprising a detection module and a sweat sensor patch, characterized in that the detection module is electrically connected to the sweat sensor patch regularly via a plug-in interface or a spring-loaded pogo pin and is configured to acquire a conductance signal in the sweat sensor patch and convert the conductance signal into electrolyte concentration information and sweating volume / sweating rate information;the detection module internally 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 comprises a hydrophobic film layer, a flow channel layer, an electrode layer, and an underlying layer sequentially arranged from top to bottom;the underlying layer comprises a skin adhesive layer for adhesion to human skin and is arranged on a lower surface of a flexible substrate of the electrode layer, an opening is provided in the underlying layer regularly to form a sweat-holding chamber between the underlying layer and the flexible substrate of the electrode layer;the electrode layer comprises the flexible substrate and a plurality of detection interdigitated electrodes regularly arranged on the upper surface of the flexible substrate for testing, a liquid inlet is provided in the flexible substrate, and the plurality of interdigitated electrodes are regularly arranged in front of the liquid inlet, and are led out through leads disposed on the flexible substrate and are regularly connected to a plurality of electrode contacts to form detection electrode contacts;a flow channel is regularly arranged in the flow channel layer, and the flow channel is configured in accordance with the shape of the plurality of detection interdigitated electrodes and is positioned directly above the plurality of finger electrodes between the plurality of detection interdigitated electrodes so as to position the plurality of finger electrodes between the plurality of detection interdigitated electrodes in the flow channel; a front end and a rear 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 is communicated with the sweat-holding chamber through the liquid inlet, and the flow channel outlet extends from the flow channel layer to communicate with the external environment;the hydrophobic film layer is attached to an upper surface of the flow channel layer to encapsulate the flow channel within the flow channel layer.

2. The flexible wearable dual-channel sweat sensing device according to claim 1, characterized in that the substrate of the flow channel layer is made of a hydrophobic material, and rounded corners are arranged at bending sections of the flow channel to form a hydrophobic flow channel.

3. The flexible wearable dual-channel sweat sensing device according to claim 1, characterized in that the plurality of detection interdigitated electrodes comprise first interdigitated electrodes for electrolyte concentration testing and second interdigitated electrodes for sweating volume / sweating rate testing; the first interdigitated electrodes and the second interdigitated electrodes are regularly arranged in front of the liquid inlet; the second interdigitated electrodes are designed in an S-shaped pattern and configured to cover the flexible substrate as much as possible, and are regularly arranged along both the left and right sides of the liquid inlet.

4. The flexible wearable dual-channel sweat sensing device according to claim 3, characterized in that the second interdigitated electrodes on the left and right sides of the liquid inlet are arranged vertically with equal spacing and equal length on both 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. The flexible wearable dual-channel sweat sensing device according to any one of claims 1-4, characterized in that the flow channel layer and the hydrophobic film layer are provided with electrode via holes directly above the plurality of electrode contacts regularly for facilitating electrical connection between the detection module and the electrode layer.

6. The flexible wearable dual-channel sweat sensing device according to claim 5, characterized in that the detection module is adhered to an upper surface of the hydrophobic film layer through a double-sided adhesive layer.

7. The flexible wearable dual-channel sweat sensing device according to claim 6, characterized in that the double-sided adhesive layer is also provided with electrode via holes regularly directly above the plurality of electrode contacts.

8. The flexible wearable dual-channel sweat sensing device according to claim 1,characterized in that the sweat sensor patch is configured as a flexible structure, and the detection module is configured as a rigid structure.

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

10. A method for preparing a flexible wearable dual-channel sweat sensor device, characterized in that the method comprises the following steps:step SI: preparation of an electrode layer by etching copper or nickel-gold on a flexible substrate to obtain a plurality of detection interdigitated electrodes, a plurality of electrode contacts, and electrode leads for connecting the plurality of detection interdigitated electrodes to the plurality of electrode contacts regularly, and laser-cutting a liquid inlet in the electrode layer;step S2: preparation of a flow channel layer by laser-cutting along the shape of the plurality of detection interdigitated electrodes to form the shape of a flow channel, cutting along the shape of the plurality of electrode contacts to form electrode via holes, designing a flow channel inlet communicating with the liquid inlet at a front end of the flow channel, and leading an outlet at the end of the flow channel out from the flow channel layer; rounded comers are arranged at bending sections of the flow channel, and upper and lower surfaces of the flow channel are adhered to an upper surface of the electrode layer through adhesive backing treatment or with double-sided adhesive;step S3: preparation of a hydrophobic film layer by laser-cutting into a main shape of a sweat sensor patch, then adhering the hydrophobic film layer to an upper surface of the flow channel layer through backing, adhesive or double-sided adhesive, and laser-cutting the hydrophobic film layer along the shape of the plurality of electrode contacts to form the electrode via holes;step S4: preparation of a double-sided adhesive layer by laser-cutting along the shape of the detection module to form the double-sided adhesive layer, and further cutting the electrode via holes along the plurality of electrode contacts, and adhering the double-sided adhesive layer to an upper surface of the hydrophobic film layer;step S5: preparation of an underlying layer by laser-cutting a hypoallergenic skin adhesiveinto the main shape to form a skin adhesive layer, and further cutting a chamber through-hole in the skin adhesive layer for storage of sweat, adhering the skin adhesive layer to a lower surface of the electrode layer, and adhering a release film to a lower surface of the skin adhesive layer;step S6: connection between the detection module and the electrode layer by electrically connecting the detection module to the electrode layer via a plug-in interface or a spring-loaded pogo pin interface and adhering the detection module to an upper surface of the hydrophobic film layer through the double-sided adhesive layer.

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