A wearable sensor for liquid rate detection and method of manufacture

Abstract

The present application relates to a kind of wearable sensor for liquid rate detection and preparation method, wearable sensor includes: sensor layer, including substrate, flow rate sensor and electrolyte sensor being arranged on the side surface of the substrate, the flow rate sensor has cantilever structure, cantilever structure protrudes from the surface of one side of the sensor layer;Flow channel layer, flow channel layer is closely combined with one side of the sensor layer, the cantilever structure of the flow rate sensor is inside the flow channel of the flow channel layer;Adhesion layer, adhesion layer is closely combined with the other side of the flow channel layer.The present application is a kind of wearable sensor for liquid rate detection and preparation method this can effectively avoid the interference caused by electrolyte concentration to sweat rate detection, and can be universally integrated embedded in the sensor based on micro-flow channel design, realize the real-time detection of liquid rate in micro-flow channel, solve the detection accuracy problem existing in prior art.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of sensors, in particular to a wearable sensor for liquid rate detection and a preparation method. BACKGROUND

[0002] When people work and do sports in high-temperature environments, a large amount of body fluid will be lost (dehydration) due to thermoregulatory sweating, and if reasonable hydration is not supplemented in time, the endurance of work and sports will be impaired, accompanied by changes in various physiological functions, and in severe cases or long-term dehydration state, it will pose a threat to people's life and health. With the intensification of global warming, heat waves (temperature rise) make vulnerable populations at high risk of heat-related diseases, especially patients, children, the elderly, outdoor workers (construction workers, traffic police), firefighters, soldiers, athletes and people participating in sports. Sweat rate and electrolyte concentration can be used as effective indicators of hydration status and heat stress-related illness conditions. Developing wearable sweat rate and electrolyte concentration sensors has important research and application significance in the fields of sports health, health management and medical diagnosis.

[0003] Most of the currently reported sweat rate sensors are based on the design of flexible microfluidic devices with microfluidic channels. Sweat flows into the microfluidic channel through the contact between the device and the skin for sweat rate detection. The design of flexible microfluidic devices based on microfluidic channels faces several key problems: first, the impedance / conductance value of the sweat entering the microfluidic channel is affected by both the electrolyte concentration and the volume of the sweat, which will affect the accuracy of sweat rate detection; second, the current long microfluidic channel design will cause inconvenience in sweat discharge and fluid resistance when used multiple times. Therefore, accurate detection of sweat rate is one of the key challenges faced by current wearable sensors. SUMMARY

[0004] The present application provides a wearable sensor with fish lateral line-like biological structure and function for liquid rate detection in a microfluidic channel.

[0005] The specific technical solution is as follows: a wearable sensor for liquid rate detection, comprising: a sensor layer, including a substrate, a flow rate sensor and an electrolyte sensor disposed on one side surface of the substrate, the flow rate sensor having a cantilever beam structure protruding from the surface of one side of the sensor layer; a flow channel layer tightly attached to one side of the sensor layer, the cantilever beam structure of the flow rate sensor being inside the flow channel of the flow channel layer; an adhesive layer tightly attached to the other side of the flow channel layer.

[0006] In some embodiments, the electrolyte sensor is exposed to the flow channel, and the flow channel layer is provided with a liquid inlet and a liquid outlet, the liquid inlet being in communication with the flow channel of the flow channel layer.

[0007] In some embodiments, the adhesion layer has a liquid collection cavity, and a central axis of the liquid collection cavity coincides with a central axis of the liquid inlet.

[0008] In some embodiments, the flow rate sensor is a bending strain sensor with a table nerve ganglion cantilever structure simulating a fish lateral line, and the liquid flows through the flow rate sensor, i.e. causes the cantilever structure of the flow rate sensor to have different deflections of bending strain, and the size of the bending strain is positively correlated with the size of the flow rate, and the electrolyte sensor is a interdigitated electrode.

[0009] In some embodiments, the surface area of the interdigitated electrode of the flow rate sensor is coated with a nano-sensitive material.

[0010] In some embodiments, the nano-sensitive material is coated with an insulating waterproof material.

[0011] In some embodiments, the three-edge edge of the interdigitated electrode area of the flow rate sensor is cut and one end is raised to form a cantilever structure.

[0012] In some embodiments, the flow channel layer and the sensor side of the sensor layer are tightly attached by a chemical covalent cross-linking method.

[0013] A preparation method of a wearable sensor, comprising preparing a sensor layer, the preparation of the sensor layer comprising: S1: preparing an interdigitated electrode structure and an electrode connecting line with a flow channel size on a flexible substrate; S2: coating a layer of nano-sensitive material on the surface area of the interdigitated electrode of the flow rate sensor, and then coating a thin layer of insulating waterproof material on the nano-sensitive material to form a bending strain deflection sensor; S3: covering a layer of insulating layer on the surface of the electrode conductor in the area other than the interdigitated area of the flow rate sensor and the electrolyte sensor, and the electrode connecting line area; S4: cutting the interdigitated electrode area of the flow rate sensor and prying up the interdigitated electrode to form a cantilever structure.

[0014] In some embodiments, the flow channel layer and the sensor side of the sensor layer are tightly attached by a chemical covalent cross-linking method, and the chemical covalent cross-linking method comprises: preparing a 3-aminopropyl triethoxysilane aqueous solution for standby, cleaning the sensor side of the sensor layer 1 and then soaking it in the above-mentioned aqueous solution, and then blowing it dry after taking it out; aligning and attaching the flow channel layer and the above-mentioned treated sensor layer together and heating.

[0015] The technical effect of the present application: the wearable sensor and preparation method for liquid rate detection can effectively avoid the interference of electrolyte concentration on sweat rate detection, and can be universally integrated into the sensor based on micro-flow channel design, realizing real-time detection of the liquid rate flowing into the micro-flow channel, and solving the detection accuracy problem existing in the prior art. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 This is a schematic diagram of the structure of a wearable sensor according to an embodiment of the present invention.

[0017] Figure 2 This is a schematic diagram of the lateral line of a fish according to an embodiment of the present invention.

[0018] Figure 3 This is a front view of the sensor layer according to an embodiment of the present invention.

[0019] Figure 4 This is a reverse schematic diagram of the sensor layer according to an embodiment of the present invention.

[0020] Figure 5 This is a three-dimensional schematic diagram of the sensor layer according to an embodiment of the present invention.

[0021] Figure 6 This is a schematic diagram of the working state of a wearable sensor placed on the surface of human skin according to an embodiment of the present invention.

[0022] Figure 7 This is a schematic diagram of the flow rate sensor test curve according to an embodiment of the present invention. Detailed Implementation

[0023] The substantive features and advantages of the present invention will be further described below with reference to examples, but the present invention is not limited to the listed embodiments.

[0024] like Figures 1 to 7 As shown, a wearable sensor for liquid rate detection according to this embodiment includes a sensor layer 1, a flow channel layer 21, and an adhesive layer 31. The sensor layer 1 includes a substrate 11, a flow velocity sensor 13 disposed on one surface of the substrate 11, and an electrolyte sensor 12. The flow velocity sensor 13 has a cantilever beam structure 2, which protrudes beyond the surface of one side of the sensor layer 1. The flow channel layer 21 is tightly attached to one side of the sensor layer 1, and the cantilever beam structure 2 of the flow velocity sensor 13 is inside the flow channel 24 of the flow channel layer 21. The adhesive layer 31 is tightly attached to the other side of the flow channel layer 21. In the above technical solution, the flow velocity sensor 13 has a biomimetic structure and function of natural organisms (including but not limited to the lateral line of fish, the auditory hair of spiders or scorpions). The flow velocity sensor in this embodiment has a cantilever beam structure of the epineurium thalamus that imitates the lateral line of fish. The liquid 5 will first flow through the electrolyte sensor 12, and the electrolyte sensor 12 can obtain the electrolyte concentration change curve of the liquid 5 in real time and continuously. The liquid 5 then flows through the flow velocity sensor 13, which causes the cantilever beam structure of the flow velocity sensor 13 to undergo bending strain with different deflections. The magnitude of the bending strain is positively correlated with the magnitude of the flow velocity, and the flow velocity sensor 13 can obtain the rate information of the liquid 5 flowing through in real time and continuously.

[0025] In this embodiment, the electrolyte sensor 12 is exposed to the flow channel 24, the flow channel layer 21 is provided with a liquid inlet 22 and a liquid outlet 23, and the liquid inlet 22 is in communication with the flow channel 24 of the flow channel layer 21. The adhesive layer 31 has a liquid collection cavity 32, and the central axis of the liquid collection cavity 32 coincides with the central axis of the liquid inlet 22.

[0026] The wearable sensor of this embodiment is applied to the scene of human sweat detection.

[0027] When detecting sweat, the wearable sensor is closely attached to the skin 4 through the adhesive layer 31. In the motion state, sweat is collected from the liquid collection cavity 32, flows into the flow channel 24 in the flow channel layer 21 through the liquid inlet 22, and first flows through the electrolyte sensor 12, so that the electrolyte sensor 12 can continuously obtain the electrolyte concentration change curve of the flowing sweat 5 in real time. The sweat 5 then flows through the flow rate sensor 13, which causes the cantilever beam structure of the flow rate sensor 13 to bend with different degrees of bending strain. The size of the bending strain is positively correlated with the size of the flow rate, and the flow rate sensor 13 can continuously obtain the rate information of the flowing sweat in real time. Finally, the sweat flows out from the liquid outlet 23.

[0028] From the above, it can be seen that when the cantilever beam structure of the flow rate sensor 13 bends with different degrees of bending strain, the distance between the nano-sensitive material particles increases, and the resistance / capacitance value increases or changes. In this embodiment, the flow rate sensor with the bionic structure and function of the fish lateral line can convert the flow rate information of the sweat in the micro-flow channel into the resistance / capacitance signal of the bending strain deflection sensor. The surface of the flow rate sensor is covered with an insulating layer, which can completely avoid the interference of the electrolyte concentration on the sweat rate detection, and can be universally integrated into the sensor based on the micro-flow channel design to realize real-time detection of the liquid rate flowing into the micro-flow channel, and solve the problems existing in the prior art. Figure 7

[0029] ​A wearable sensor preparation method, including sensor layer preparation, sensor layer preparation including: S1: on a flexible substrate, by screen printing, or flexible circuit board preparation process, or micro-machining process, prepare a flow channel size interdigital electrode structure and electrode connecting line; S2: a layer of nano-sensitive material is coated on the surface area of the interdigital electrode of the flow rate sensor, including but not limited to metal nanoparticles, carbon nanoparticles and other bending strain sensitive materials; then a thin layer of insulating waterproof material is coated on the nano-sensitive material, including but not limited to polydimethylsiloxane, polyester, polyimide and the like, and then a bending strain deflection sensor is formed; S3: except for the interdigital area of the flow rate sensor and the electrolyte sensor, and the electrode connecting line area, the electrode conductor surface of other areas is covered with an insulating layer, including but not limited to polydimethylsiloxane, polyester, polyimide and the like; S4: the interdigital electrode area of the flow rate sensor is cut open by laser cutting, and the interdigital electrode is pried up using a tool to form a cantilever beam structure simulating fish lateral line and the like.

[0030] Specifically, in step S1, the flexible substrate 11 is a polyimide film with a thickness of 0.05-0.2 millimeters, and the interdigital electrode 12 of the electrolyte sensor is prepared by a traditional micro-machining process with a diameter of 0.5-2 millimeters; the interdigital electrode of the flow rate sensor 13 is prepared with a length of 1 millimeter and a width of 0.1-0.2 millimeters; and the electrode connecting line 14 is prepared with a size matching a commercially sold flexible printed circuit board FPC flat push-pull connector. In step S2, a layer of nano-sensitive material is coated on the surface area of the interdigital electrode of the flow rate sensor 13, including but not limited to metal nanoparticles, carbon nanoparticles and other bending strain sensitive materials; then a thin layer of insulating waterproof material is coated on the nano-sensitive material, including but not limited to polydimethylsiloxane, polyester, polyimide and the like, and then a bending strain sensor is formed; in some embodiments, the nano-sensitive material is a layer of gold nanoparticle film prepared by a magnetron sputtering method, and the thin layer of insulating waterproof material coated on the surface of the nano-sensitive material is polydimethylsiloxane, and the sensor generates cracks during bending, thereby causing resistance / capacitance and other signal changes. In step S3, the area of the flow rate sensor 13 and the electrolyte sensor 12, and the area of the electrode connecting line 14 are reserved, and the electrode conductor surface of other areas is covered with an insulating layer 15, including but not limited to polydimethylsiloxane, polyester, polyimide and the like; in one example, the insulating layer 15 is a polyimide film with a thickness of 0.01-0.05 millimeters. In step S4, the three edges of the interdigital electrode area of the flow rate sensor 13 are cut open by laser cutting, and the flow rate sensor 13 is pried up using tweezers, so that the flow rate sensor 13 forms a cantilever beam structure simulating fish lateral line and the like, i.e. the flow rate sensor 13 protrudes out of the surface of the substrate 11 on one side of the sensor layer 1.

[0031] The preparation method of the flow channel layer 21 is as follows:

[0032] L1: Process a mold with a flow channel structure, the preparation of the mold includes but is not limited to machining, 3D printing and other methods, the size of the flow channel is: 10-20 millimeters long, 0.5-1 millimeter wide, 0.5-1 millimeter high;

[0033] L2: Prepare a polydimethylsiloxane prepolymer solution, pour it into the flow channel structure mold, and after curing at 60-80 degrees Celsius, a flow channel layer 21 is formed, the overall thickness of the flow channel layer 21 is 1-2 millimeters.

[0034] In some embodiments, the flow channel layer 21 and the sensor side of the sensor layer 1 are tightly attached by a method of chemical covalent crosslinking, which ensures that the flow rate sensor 13 and the electrolyte sensor 12 are exposed to the flow channel 24, and the cantilever beam structure of the flow rate sensor 13 is inside the flow channel 24 of the flow channel layer 21, and the electrolyte sensor 12 is directly opposite the liquid inlet 22. The method of chemical covalent crosslinking is as follows:

[0035] H1: Prepare a 3-aminopropyltriethoxysilane aqueous solution, place the sensor side of the sensor layer 1 face up in a plasma cleaner for 0.5-5 minutes, then immediately place it in the above-mentioned aqueous solution, soak for 10-30 minutes, and then blow dry the surface with nitrogen;

[0036] H2: Align and attach the flow channel layer 21 and the sensor layer 1 treated as above together, and place them in a 60-80 degree Celsius oven for 30 minutes.

[0037] In some embodiments, the adhesive layer 31 is tightly attached to the other side of the flow channel layer 21, and the central axis of the liquid collection cavity 32 coincides with the central axis of the liquid inlet 22. The adhesive layer is double-sided tape with a thickness of 0.05-0.1 millimeters, and the liquid collection cavity 32 has a diameter of 5-10 millimeters.

[0038] The wearable sensor for liquid rate detection and the preparation method of the embodiment are inspired by the function and structure of fish lateral line and other organisms: in nature, the lateral line on the body of fish can have precise sensing ability to flow field (flow rate, pressure difference / acceleration). Some animals including spider and scorpion hearing hair also have the function of sensing wind speed. The present invention first proposes a new method of applying a sensor simulating fish lateral line and its surface neural crest structure and function to liquid rate detection. The flow rate sensor is a cantilever beam structure bending strain deflection sensor with a biomimetic structure and function of a biomimetic structure including but not limited to fish lateral line, spider or scorpion hearing hair, and the cantilever beam structure protrudes from the surface of the sensor layer on one side of the sensor layer.

[0039] It should be noted that the above preferred embodiments are only used to illustrate the technical concepts and characteristics of the present application, and the purpose is to enable those skilled in the art to understand the content of the present application and implement it, and cannot limit the protection scope of the present application. Any equivalent changes or modifications made in accordance with the spirit and essence of the present application should be covered within the protection scope of the present application.

Claims

1. A wearable sensor for liquid rate detection, characterized by, The application relates to a sensor layer, a flow channel layer and an adhesive layer. The sensor layer comprises a substrate, a flow rate sensor provided on one side surface of the substrate and an electrolyte sensor, wherein the flow rate sensor has a cantilever structure which protrudes from the surface of one side of the sensor layer. The flow channel layer is tightly attached to one side of the sensor layer, and the cantilever structure of the flow rate sensor is inside the flow channel of the flow channel layer. The adhesive layer is tightly attached to the other side of the flow channel layer. The electrolyte sensor is exposed to the flow channel, and the flow channel layer is provided with a liquid inlet and a liquid outlet, wherein the liquid inlet is communicated with the flow channel of the flow channel layer.

2. The wearable sensor for liquid rate detection of claim 1, wherein, The liquid first flows through the electrolyte sensor, and the electrolyte sensor can continuously obtain the electrolyte concentration change curve of the flowing liquid in real time.

3. The wearable sensor for liquid rate detection of claim 1, wherein, The liquid then flows through the flow rate sensor.

4. The wearable sensor for liquid rate detection of claim 3, wherein, The flow rate sensor is a curved strain sensor with a surface neural crest cantilever structure simulating a fish lateral line.

5. The wearable sensor for liquid rate detection of claim 4, wherein, The liquid flowing through the flow rate sensor causes the cantilever structure of the flow rate sensor to have different deflection curved strains, and the size of the curved strain is positively correlated with the size of the flow rate.

6. The wearable sensor for liquid rate detection of claim 5, wherein, The surface of the flow rate sensor is covered with an insulating layer to avoid the interference of the electrolyte concentration on the sweat rate detection.

7. The wearable sensor for liquid rate detection of claim 6, wherein, The adhesive layer has a liquid collection cavity, and the central axis of the liquid collection cavity is coincident with the central axis of the liquid inlet.

8. A method of manufacturing a wearable sensor, the wearable sensor being the wearable sensor for liquid rate detection according to any one of claims 1 to 7, characterized in that, The electrolyte sensor is a interdigital electrode. The surface area of the interdigital electrode of the flow rate sensor is coated with a nano-sensitive material. The nano-sensitive material is coated with an insulating waterproof material. The three edges of the interdigital electrode area of the flow rate sensor are cut and one end is raised to form a cantilever structure. The flow channel layer and the sensor side of the sensor layer are tightly attached through a chemical covalent crosslinking method.

9. The method of claim 8, wherein the wearable sensor is prepared by, The sensor layer is prepared, and the preparation of the sensor layer comprises the following steps: S1: preparing an interdigital electrode structure and an electrode connecting line with a flow channel size on a flexible substrate; S2: coating a layer of nano-sensitive material on the surface area of the interdigital electrode of the flow rate sensor, and then coating a thin layer of insulating waterproof material on the nano-sensitive material to form a curved strain deflection sensor; S3: covering a layer of insulating layer on the surface of the electrode conductor in other areas except the interdigital area of the flow rate sensor and the electrolyte sensor and the electrode connecting line area; S4: cutting the interdigital electrode area of the flow rate sensor and prying up the interdigital electrode to form a cantilever structure. The flow channel layer and the sensor side of the sensor layer are tightly attached through a chemical covalent crosslinking method. An aqueous solution of 3-aminopropyltriethoxysilane is prepared for use, and the sensor side of the sensor layer is cleaned and then soaked in the aqueous solution. The flow channel layer and the treated sensor layer are aligned and attached together, and then heated.

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