Self-driven humidity sensor and application

Abstract

The invention discloses a self-driven humidity sensor and application, the self-driven humidity sensor comprises a sensor monomer, and the sensor monomer comprises a substrate; the functional layer is arranged on the surface of the substrate and comprises dispersed and stacked nano silicon particles and nano pore channels arranged among the nano silicon particles, and the nano silicon particles are matched to form a conductive path; the electrodes are arranged at the two ends of the functional layer respectively. The self-driven humidity sensor can carry out rapid voltage response on humidity, has excellent repeatability and stability, can be applied to a flexible wearable scene, can be attached to any bent surface and can deform along with attachments, and normal work is not affected; the self-driven humidity sensor takes the silicon substrate with wide source as the raw material, is extremely low in cost, can be applied to humidity monitoring in disposable products such as masks and diapers, and greatly improves the application prospect of the self-driven humidity sensor.

Description

Technical Field

[0001] The present application belongs to the technical field of self-generated humidity sensors, and in particular relates to a self-driven humidity sensor and its application. Background Art

[0002] Ambient humidity is a physical quantity closely related to production and life. Humidity not only affects industrial production and agricultural activities, but also has an important impact on human health and living comfort. Conventional humidity sensors mainly include capacitive sensors and resistive sensors, both of which require power modules to measure humidity. They do not have the characteristics of flexibility, portability, and continuous detection, and are difficult to apply to humidity detection in wearable fields and special local environments, such as breathing detection. In recent years, wearable humidity sensors that rely on the interaction between flexible humidity-sensitive materials and water to generate electrical signals have received widespread attention, but these sensors still need to rely on power modules when in use, which not only increases the complexity and cost of the sensor system, but also brings challenges to the portability and long-term use of the sensor, which greatly limits the application of sensors in the wearable field.

[0003] In order to avoid the negative impact of external power modules, self-driven humidity sensors have begun to be reported in the prior art, which generate electricity through the interaction between hydrovoltaic materials and water molecules. However, current self-driven humidity sensors generally use modified nanomaterials, graphene, polyaniline / TiO 2 The preparation of materials such as composite materials is high in cost, has poor environmental friendliness and biocompatibility, and has poor flexibility and strength, making it difficult to apply in the wearable field. Summary of the invention

[0004] The purpose of this application is to provide a self-driven humidity sensor and its application to solve the technical problems in the prior art that conventional humidity sensors require an external power module, the self-driven humidity sensor has a high cost, poor environmental friendliness and biocompatibility, poor flexibility and strength, and is difficult to apply in the wearable field.

[0005] In order to achieve the above-mentioned object, the first aspect of the present application provides a self-driven humidity sensor, including a sensor unit, wherein the sensor unit includes:

[0006] substrate;

[0007] A functional layer is arranged on the surface of the substrate, the functional layer comprises dispersed and stacked nano-silicon particles and nano-channels arranged between the nano-silicon particles, and the nano-silicon particles cooperate to form a conductive path;

[0008] A pair of electrodes are disposed at two ends of the functional layer.

[0009] In one or more embodiments, the functional layer further includes a binder, and the binder is dispersed between the nano-silicon particles to bind the nano-silicon particles.

[0010] In one or more embodiments, the binder is one or more combinations of polyvinyl alcohol, polyvinyl pyrrolidone, sodium carboxymethyl cellulose and polyacrylic acid.

[0011] In one or more embodiments, the mass ratio of the nano-silicon particles to the binder is (60-75):(25-40).

[0012] In one or more embodiments, the distance between the pair of electrodes is greater than 0.6 cm.

[0013] In one or more embodiments, a plurality of sensor cells are connected in series.

[0014] In one or more embodiments, the substrate is filter paper, cellulose membrane, nonwoven fabric or sponge.

[0015] In one or more embodiments, the electrode is made of conductive carbon paste, conductive silver paste or liquid metal.

[0016] In one or more embodiments, a packaging layer is further included, and the packaging layer is arranged on the electrode on one side.

[0017] In one or more embodiments, the particle size of the nano-silicon particles is 50 nm to 2 μm.

[0018] In order to achieve the above-mentioned purpose, the second aspect of the present application provides an application of the self-driven humidity sensor described in any of the above-mentioned embodiments as a flexible wearable humidity sensor.

[0019] In order to achieve the above-mentioned object, the third aspect of the present application provides a respiratory monitoring device, comprising:

[0020] Face mask;

[0021] The self-driven humidity sensor described in any of the above embodiments is arranged on the mask, and the self-driven humidity sensor is used to monitor the breathing intensity and frequency and output a voltage response signal;

[0022] The communication module is used to receive and forward the voltage response signal.

[0023] In one or more embodiments, the self-driven humidity sensor is arranged in the interlayer of the mask.

[0024] In order to achieve the above-mentioned purpose, the fourth aspect of the present application provides a smart diaper monitoring device, characterized in that it includes:

[0025] The diaper body includes a water-absorbing layer arranged on one side;

[0026] The self-driven humidity sensor described in any of the above embodiments is arranged in the water absorption layer, and the self-driven humidity sensor is used to monitor the humidity of the water absorption layer and output a voltage response signal;

[0027] The communication module is used to receive and forward the voltage response signal.

[0028] In one or more embodiments, the self-driven humidity sensor includes a plurality of sensor units arranged at different positions in the water absorption layer, and the plurality of sensor units are sequentially connected in series.

[0029] Different from the prior art, the beneficial effects of this application are:

[0030] The self-driven humidity sensor of the present application can respond to humidity with a fast voltage, and has excellent repeatability and stability. It can maintain the stability of the voltage response signal under repeated wetting-drying cycles and repeated bending-reset cycles. It can be applied to flexible wearable scenarios and can be attached to any curved surface and deform with the attached object without affecting normal operation.

[0031] The self-driven humidity sensor of the present application uses widely available silicon as raw material, has extremely low cost, is green, safe and environmentally friendly, and harmless to the human body. It can be used in disposable products such as masks and diapers for humidity monitoring, greatly improving the application prospects of self-driven humidity sensors.

[0032] The respiratory monitoring device of the present application integrates a self-generated humidity sensor driven by moisture adsorption into the field of human health monitoring, which can directly convert the respiratory frequency and intensity into electrical signals, and is expected to be used for respiratory monitoring and assist in the diagnosis of related diseases.

[0033] The smart monitoring diaper of the present application can realize segmented monitoring of the urine volume of the diaper. During the application process, as the urine volume increases, the urine gradually spreads in the water absorbent layer, causing the sensor units at different positions to respond. The voltage response signals of different sensor units will be superimposed and presented, thereby providing a reference and reminder for whether to change the diaper, without the need to frequently check the diaper. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0035] Figure 1 It is a structural schematic diagram of a sensor unit of the self-driven humidity sensor of the present application;

[0036] Figure 2 This is a graph of the Zeta potential measurement data of the nano-silicon particles of the present application;

[0037] Figure 3 It is a schematic diagram of the double electric layer of the water / nano silicon particle interface of the present application;

[0038] Figure 4 is a schematic diagram of the charge flow of the present application;

[0039] Figure 5 is a device morphology diagram of the three-electrode experiment of this application;

[0040] Figure 6 It is a voltage response signal diagram of the three-electrode experiment of this application;

[0041] Figure 7 It is a schematic flow chart of an implementation method of a method for preparing a self-driven humidity sensor of the present application;

[0042] Figure 8 It is a structural schematic diagram of an embodiment of a respiratory monitoring device of the present application;

[0043] Fig. 9 is a schematic structural diagram of another embodiment of the respiratory monitoring device of the present application;

[0044] Fig.10 This is a structural diagram of an implementation method of the intelligent diaper monitoring method of the present application;

[0045] Fig.11 This is a characterization analysis diagram of effect example 1 of the present application;

[0046] Fig.12 is a SEM image of the interface between the functional layer and the electrode of Example 1 of the present application;

[0047] Fig.13 This is a conductive performance analysis data diagram of Effect Example 1 of the present application;

[0048] Fig.14 is a voltage response signal diagram of effect example 1 of the present application;

[0049] Fig.15 This is a voltage response signal diagram under the condition of water evaporation in effect example 1 of the present application;

[0050] Fig.16 is a voltage response signal diagram of a repeatability experiment of effect example 2 of the present application;

[0051] Fig.17 is a voltage response signal diagram of stability analysis of effect example 2 of the present application;

[0052] Fig.18 is a voltage response signal diagram of effect example 3 of the present application;

[0053] Fig.19 is a voltage response signal diagram of effect example 4 of the present application;

[0054] Fig. 20 is a voltage response signal diagram of the respiratory monitoring device of Example 14;

[0055] Fig.21 This is a voltage response signal diagram of the intelligent diaper monitoring system of Example 15. DETAILED DESCRIPTION

[0056] In order to enable those skilled in the art to better understand the technical solutions in the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without creative work should fall within the scope of protection of the present application.

[0057] The hydrovoltaic devices reported since 2014 can generate electricity through the interaction between hydrovoltaic materials and water molecules. Their voltage output can change with the change of ambient humidity, so they are suitable for use as self-driven humidity sensors. For example, the literature reports that AgInZnS modified nano-TiO 2 Composite materials, graphene, polyaniline / TiO 2 The hydrovoltaic self-driven humidity sensor is prepared using composite materials and other materials, achieving highly sensitive self-driven humidity monitoring.

[0058] Although relevant research has made some progress, self-driven humidity sensor devices for wearable scenarios are still moving towards low cost, environmental friendliness, and high biocompatibility. Silicon materials have attracted widespread attention due to their abundant reserves, low cost, environmental and biological friendliness, mature processing technology, and ability to be integrated with existing silicon-based circuits. They are ideal materials for preparing hydrovoltaic self-driven humidity sensors. However, current silicon-based hydrovoltaic devices are all rigid devices prepared based on silicon nanowire arrays, which are difficult to apply to wearable applications.

[0059] In order to solve the above problems, the applicant has developed a new type of self-driven humidity sensor, which is made of silicon-based materials and has excellent flexibility, portability, stability and repeatability. It can be used for continuous humidity detection in wearable scenarios.

[0060] Specifically, the self-driven humidity sensor of the present application is composed of a sensor monomer, see Figure 1, Figure 1 It is a structural schematic diagram of a sensor unit of the self-driven humidity sensor of the present application.

[0061] like Figure 1 As shown, the sensor unit includes a substrate 100 , a functional layer 200 and a pair of electrodes 300 .

[0062] The functional layer 200 is arranged on the surface of the substrate 100, and the functional layer 200 includes dispersed and stacked nano-silicon particles, nano-channels are formed between the nano-silicon particles, and the nano-silicon particles (hereinafter referred to as SiNPs) cooperate to form a conductive path. A pair of electrodes 300 are respectively arranged at both ends of the functional layer 200.

[0063] In this embodiment, the substrate 100 is only used as a carrier of the functional layer, and therefore, the material and thickness of the substrate are not limited; in one embodiment, since the self-driven humidity sensor is mainly used in humidity measurement environments, in order to improve its service life, the substrate can be a waterproof material or a water-permeable material. For example, the substrate can be filter paper, cellulose film, non-woven fabric or sponge.

[0064] The electrode 300 in this embodiment can be made of any conductive material commonly used in the art. For example, in one embodiment, the material of the electrode can be conductive carbon paste, conductive silver paste or liquid metal.

[0065] In one embodiment, in order to ensure the hydrostatic effect, the particle size of the nano silicon particles may be 50 nm to 2 μm.

[0066] In order to ensure the unidirectional movement of water in the functional layer 200, Figure 1 As shown, the self-driven humidity sensor in this embodiment further includes a packaging layer 400, which is arranged on the electrode 300 on one side to package the electrode 300 on one side. The packaging layer 400 can be made of polymer materials such as silicone rubber, PMDS, Ecoflex, etc., which can achieve the effect of this embodiment.

[0067] In addition, in order to prevent water from overflowing the functional layer 200, in this embodiment, a circle of waterproof glue 500 is also attached to the outer edge of the functional layer 200. It can be understood that in other embodiments, the waterproof glue 500 can also be omitted, and the water-hiding effect of the sensor in this embodiment can also be achieved.

[0068] Based on the sensor monomer with the above structure, when water contacts the functional layer 200, it will enter the coating and gradually accumulate. We measured the Zeta potential of SiNP and obtained Figure 2 , see Figure 2 , Figure 2 This is a graph showing the Zeta potential measurement data of the nano-silicon particles of the present application. Figure 2As shown, the Zeta potential of the nano-silicon particles is -31.5 mV, proving that their surface carries a large amount of negative charge.

[0069] When water infiltrates SiNPs, the negatively charged surface of SiNPs naturally adsorbs positive ions in water, thereby establishing an electrical double layer (EDL) at the water / SiNP interface. Figure 3 , Figure 3 Schematic diagram of the double electrical layer of the water / SiNP interface of the present application.

[0070] According to streaming potential theory, when water flows through a charged narrow capillary channel with micro-nano size characteristics, due to the superposition of diffusion layers inside the channel, counterions with charges opposite to those on the solid surface are selectively transported downstream, resulting in the formation of a charge flow, see Figure 4 , Figure 4 It is a schematic diagram of the charge flow of this application. With the accumulation of counterions, a streaming potential, that is, a potential difference, will be formed between the upstream and downstream, which is the source of the hydrovoltaic potential.

[0071] In the sensor monomer of this embodiment, on the one hand, the large specific surface area of ​​SiNP provides more hydrophilic sites, which promotes the interaction between water molecules and solid surfaces. On the other hand, the high density of nanopores between particles promotes the capillary flow of water and the overlap of space charge regions. Finally, the high surface potential of SiNP helps to increase the charge in the space charge region and better achieve the selective passage of counterions. Therefore, the device prepared using SiNP coating has a significant hydrovoltaic effect. It is based on this mechanism that when the silicon nanoparticle self-driven environmental humidity sensor is wetted by water, it will output a voltage signal, thereby realizing the sensing of humidity.

[0072] In order to verify the above reaction mechanism, we designed a three-electrode device experiment to further confirm that water coverage on the device is a necessary condition for generating electrical signals. Specifically, the morphology of the three-electrode device is as follows: Figure 5 As shown, Figure 5 This is the device morphology diagram of the three-electrode experiment in this application, such as Figure 5 As shown, in Figure 1 A third electrode is also led out from the middle of the functional layer of the sensor monomer shown. The three electrodes can be named as electrodes 1, 2, and 3 from left to right.

[0073] During the test, a small amount of water was dripped near electrode 3, and the amount of water was controlled so that it did not flow through electrode 2. Different electrodes were connected using an electrochemical workstation. Initially, electrode 1 and electrode 3 were connected. After 200s, electrode 2 and electrode 3 were connected. After another 200s, electrode 1 and electrode 2 were connected. Figure 6 See Figure 6 , Figure 6 This is the voltage response signal diagram of the three-electrode experiment of this application. Figure 6 As shown, after dripping water, the response voltage between electrodes 1 and 3 can reach 100mV, and the signal remains stable at around 100mV after replacing electrodes 2-3. When electrodes 1 and 2 with no water vapor in between are connected, the voltage response immediately returns to zero. The above results show that whether the device can respond is closely related to whether there is water between the electrodes, that is, the device generates electricity by utilizing the hydrovoltaic effect.

[0074] In the self-driven humidity sensors of the above-mentioned embodiments, the functional layer of the sensor monomer is composed only of dispersed and stacked SiNPs, which are stacked together by van der Waals forces and have weak connection. When the device is prepared or the substrate is bent, the coating is still prone to cracking, resulting in device failure. In addition, the pure SiNP structure is loose, and there may be a problem of not being able to achieve a good conductive path.

[0075] In order to improve the flexibility and strength of the sensor and avoid cracking of the coating, in another embodiment, the functional layer may further include a binder, and the binder is dispersed between the nano-silicon particles to bond the nano-silicon particles.

[0076] Specifically, in one embodiment, the binder can be made of materials such as polyvinyl alcohol (PVA), polyvinyl pyrrolidone (PVP), sodium carboxymethyl cellulose (CMC), polyacrylic acid (PAA), etc. Preferably, the binder can be made of PVA material. As a high molecular polymer, PVA has the characteristics of good hydrophilicity, good film-forming property, non-toxicity and non-irritation to human skin, and is very suitable for use as a binder for SiNP. In other embodiments, the binder can also be made of other polymers with similar properties, all of which can achieve the effect of this embodiment.

[0077] It should be noted that the amount of adhesive added in the functional layer needs to be limited. When the amount of adhesive added is too small, it cannot play an effective bonding role, which will lead to insufficient bonding between SiNPs in most areas and affect the construction of the conductive path. When the amount of adhesive added is too large, the SiNPs will be too aggregated or even completely wrapped by PVA, which will reduce the conductive path between SiNPs and almost block the nanopores, which is not conducive to the passage of water or water vapor.

[0078] Specifically, in one embodiment, when the binder is PVA, the mass ratio of nano silicon particles to the binder in the functional layer can be (60-75): (25-40). After adding an appropriate amount of PVA, the SiNPs on the surface of the coating can form an effective conductive path, and nanopores are also retained between the particles to facilitate the passage of water or water vapor. The presence of these nanopores enables water or water vapor to pass through them to produce a hydrovoltaic effect, thereby performing self-driven humidity sensing.

[0079] In the above-mentioned embodiments, the functional layer is a rectangular structure. It is foreseeable that in other embodiments, the size and shape of the functional layer can be adjusted based on actual needs, and the effect of the present embodiment can be achieved.

[0080] In addition, in order to avoid the device being too short, which may affect the length of the micro-nano channels in the functional layer and prevent the water droplets from fully interacting with the material in the channel, the distance between a pair of electrodes can be set to be greater than 0.6 cm, thereby ensuring the strength of the voltage response signal.

[0081] In a preferred embodiment, under the premise of ensuring that the sensor has a strong output signal, taking into account the amount of material used and the miniaturization of the device, the length of the functional layer can be 1 cm and the width can be 0.2 cm.

[0082] The structure of the sensor unit is introduced in the above-mentioned embodiments. It can be expected that the self-driven humidity sensor of the present application can be composed of one sensor unit or multiple sensor units connected in series in sequence; when the self-driven humidity sensor is composed of multiple sensors connected in series, the voltage response signal output by it can be the superposition of the voltage response signals of multiple sensor units.

[0083] The present application also provides a method for preparing a self-driven humidity sensor according to any of the above embodiments. Figure 7 , Figure 7 It is a schematic flow chart of an implementation method of a method for preparing a self-driven humidity sensor of the present application.

[0084] like Figure 7 As shown, the preparation method comprises:

[0085] S100, coating a nano-silicon particle dispersion on the surface of a substrate, and obtaining a functional layer after the nano-silicon particle dispersion is dried.

[0086] The nano silicon particle dispersion comprises a solvent and nano silicon particles dispersed in the solvent.

[0087] In one embodiment, the nano silicon particle dispersion further includes a binder, thereby preparing a functional layer containing a binder.

[0088] In one embodiment, the coating amount of the nano silicon particle dispersion can be 80 to 120 μL / cm 2 .

[0089] S200, preparing electrodes at both ends of the functional layer and encapsulating one side of the electrode.

[0090] After the functional layer is prepared, electrodes can be prepared at both ends of the functional layer respectively, and one side of the electrode can be encapsulated at the same time to obtain a sensor monomer of the self-driven humidity sensor.

[0091] When the self-driven humidity sensor includes a plurality of sensor units, the electrodes of the plurality of sensor units may be sequentially connected in series through electrode lines.

[0092] The present application also provides a respiratory monitoring device using a self-driven humidity sensor of any of the above embodiments, see Figure 8 , Figure 8 It is a structural schematic diagram of an embodiment of a respiratory monitoring device of the present application.

[0093] like Figure 8 As shown, the respiratory monitoring device includes a mask 20 and a self-driven humidity sensor 10 arranged on the mask 20. The self-driven humidity sensor 10 is used to monitor the respiratory intensity and frequency and output a voltage response signal.

[0094] The respiratory monitoring device further includes a communication module 40 , which is used to receive the voltage response signal and forward it to a display terminal 50 .

[0095] The communication module 40 may be any type of communication element commonly used in the art, such as a Bluetooth communication module, a wireless communication module, etc., as long as it can output a voltage response signal. The display terminal 50 may be a mobile phone, a computer, etc.

[0096] Since the human body exhales water vapor when breathing, the humidity inside the mask 20 changes. The intensity of breathing is related to the degree of humidity change. The humidity change can be captured by the self-driven humidity sensor 10 and output a voltage response signal, thereby realizing the monitoring of the frequency and intensity of breathing.

[0097] In order to prevent the self-driven humidity sensor 10 from being affected by the external environment, please refer to Fig. 9 , Fig. 9 It is a structural schematic diagram of another embodiment of the respiratory monitoring device of the present application.

[0098] like Fig. 9 As shown, the mask 20 may include an outer layer 201 located on both sides and an inner layer 202 , and the self-driven humidity sensor 10 may be arranged in the inner layer 202 .

[0099] For example, the outer layer 201 may be made of a spunbond nonwoven fabric, and the interlayer 202 may be made of a meltblown nonwoven fabric.

[0100] With the rapid growth in the number of patients with respiratory diseases (such as sleep apnea, rhinitis and dyspnea), real-time monitoring of human breathing has attracted attention and is crucial for the early prevention, auxiliary diagnosis and rehabilitation treatment of respiratory diseases. However, due to the limitations of cost and diagnostic instruments and locations, the demand for real-time monitoring at home is still challenging. Based on the above-mentioned respiratory monitoring device, it is a key step to integrate the self-generating humidity sensor driven by moisture adsorption into the field of human health monitoring. Based on this sensing method, the respiratory frequency and intensity will be directly converted into electrical signals, which is expected to be used for respiratory monitoring and assist in the diagnosis of related diseases.

[0101] The present application also provides an intelligent diaper monitoring system using a self-driven humidity sensor in any of the above embodiments. Fig.10 , Fig.10 It is a structural schematic diagram of an implementation method of the intelligent diaper monitoring method of the present application.

[0102] like Fig.10 As shown, the smart monitoring diaper 30 includes a diaper 30 body and a self-driven humidity sensor 10. The diaper 30 includes a water absorbing layer 301 arranged on one side; the self-driven humidity sensor 10 is arranged in the water absorbing layer 301, and the self-driven humidity sensor 10 is used to monitor the humidity of the water absorbing layer 301 and output a voltage response signal.

[0103] The intelligent diaper monitoring system further includes a communication module 40 , which is used to receive a voltage response signal and forward it to a display terminal 50 .

[0104] The communication module 40 may be any type of communication element commonly used in the art, such as a Bluetooth communication module, a wireless communication module, etc., as long as it can output a voltage response signal. The display terminal 50 may be a mobile phone, a computer, etc.

[0105] In actual applications, when the amount of urine is small, the diaper 30 may be replaced after being wetted multiple times, so a segmented response of the sensor is required. In order to achieve segmented response, in this embodiment, the self-driven humidity sensor 10 includes three sensor units arranged at different positions of the water absorption layer 301, and the three sensor units are sequentially connected in series to achieve multi-point humidity monitoring of the diaper 30.

[0106] In other implementations, the number and arrangement positions of the sensor units may also be adjusted based on actual needs, and the effects of this implementation can be achieved.

[0107] It is understandable that diapers are currently a necessity for infant care. Whenever they are over-soaked with urine, they need to be replaced in time, otherwise they will cause skin redness, allergies and other discomforts. If the wetting state of diapers can be monitored, they can be replaced in time when they are over-soaked, ensuring the comfort of infants and avoiding the occurrence of skin discomfort symptoms. As a consumable, the humidity sensor used for diapers must be cheap and easy to prepare, and the self-driven humidity sensor of the present application just meets this requirement.

[0108] The intelligent diaper monitoring based on the above-mentioned embodiments can realize segmented monitoring of the urine volume of the diaper. During application, as the urine volume increases, the urine gradually spreads in the water absorbent layer, causing the sensor units at different positions to respond. The voltage response signals of different sensor units will be superimposed and presented, thereby providing a reference and reminder for whether to change the diapers, without the need to frequently check the diapers.

[0109] The effects of the technical solution of the present application are further elaborated in detail below in conjunction with specific embodiments.

[0110] Embodiment 1:

[0111] A self-driven environmental humidity sensor includes a sensor unit, and the preparation process of the sensor unit includes: firstly, a rectangular shape for coating is framed on the surface of a substrate with waterproof glue, and the size of the rectangular shape is 1 cm×1 cm;

[0112] According to 100μL / cm 2 The prepared SiNP / PVA dispersion is uniformly added dropwise in a rectangular shape, wherein the solvent of the dispersion is water, the particle size of SiNP is 100 nm, and the mass ratio of SiNP to PVA is 67:33;

[0113] After the water evaporates naturally and dries, the functional layer is obtained. Carbon conductive glue is used to prepare "L"-shaped electrodes at both ends of the functional layer in the length direction. Finally, copper wires are used to lead out the electrodes at both ends, and one side of the electrode is encapsulated to obtain a sensor monomer.

[0114] Embodiments 2 to 4:

[0115] A self-driven environmental humidity sensor, which is basically the same as Example 1, except that:

[0116] The content of PVA in the dispersion was different.

[0117] Examples 5 to 11:

[0118] A self-driven environmental humidity sensor, which is basically the same as Example 1, except that:

[0119] The functional layers vary in size.

[0120] Embodiment 12, 13:

[0121] A self-driven environmental humidity sensor, which is basically the same as Example 8, except that:

[0122] Example 12 includes 5 sensor cells connected in series, and Example 13 includes 10 sensor cells connected in series.

[0123] For the parameters of the above embodiments, please refer to the data in the table below.

[0124]

[0125] Effect Example 1: Analysis of the influence of PVA mass fraction

[0126] The functional layers of Examples 1 to 4 were characterized by macroscopic optical microscope and scanning electron microscope, and the results were as follows: Fig.11 , Fig.11 It is a characterization analysis diagram of the effect example 1 of the present application. Among them, Figures a, b, c, and d are macroscopic optical characterization diagrams of the functional layers of Examples 2, 3, 1, and 4, respectively, Figures e and e-1 are SEM diagrams of the functional layer of Example 2, Figures f and f-1 are SEM diagrams of the functional layer of Example 3, Figures g and g-1 are SEM diagrams of the functional layer of Example 1, and Figures h and h-1 are SEM diagrams of the functional layer of Example 4.

[0127] First, from a macroscopic point of view, as shown in Figures a, b, c, and d, the surface flatness of the functional layers of Examples 2 and 4 is poor, which is not conducive to later flexible applications; the functional layer of Example 3 has obvious cracks, which is mainly caused by too little PVA addition, which is also not conducive to later flexible applications; the surface of the functional layer of Example 1 is flat and has no obvious cracks.

[0128] Next, from a microscopic analysis, as shown in Figures e and e-1, PVA is not added to the functional layer of Example 2, and the structure between the SiNP particles is loose, which may affect the construction of the conductive path. This also confirms the problem of uneven surface in the macroscopic morphology.

[0129] As shown in Figures f and f-1, in the functional layer of Example 3, SiNPs can be effectively stacked in local areas to form conductive paths, but most areas still have pits left by SiNP peeling, indicating that the adhesion between SiNPs is insufficient, which is manifested in the macroscopic optical microscope image as many cracks.

[0130] As shown in Figures h and h-1, the SiNPs in the functional layer of Example 4 are too aggregated and even completely wrapped by PVA, which reduces the conductive paths between the SiNPs and almost blocks the nanopores, making it difficult for water or water vapor to pass through.

[0131] As shown in Figures g and g-1, the SiNPs in the functional layer of Example 1 can form an effective conductive path, and nanopores are also retained between the particles to facilitate the passage of water or water vapor. The presence of these nanopores can allow water or water vapor to pass through them to generate a hydrovoltaic effect, thereby performing self-driven humidity sensing.

[0132] The interface between the functional layer and the electrode of Example 1 was characterized and analyzed to obtain Fig.12 , Fig.12 This is a SEM image of the interface between the functional layer and the electrode in Example 1 of the present application.

[0133] like Fig.12 As shown, the left side of the dotted line is the spherical SiNP, and the right side is the cured flaky carbon conductive adhesive, forming a clear interface between the two.

[0134] Furthermore, the conductivity performance analysis and hydrovoltaic performance analysis of the sensors of Examples 1 to 4 were performed, wherein the hydrovoltaic performance analysis specifically involves dripping the same amount of water on the functional layer of each example and recording the voltage response signal output by the sensor to obtain Fig.13 and Fig.14 , Fig.13 This is a diagram showing the conductivity analysis data of Example 1 of the present application. Fig.14 This is a voltage response signal diagram of effect example 1 of the present application.

[0135] like Fig.13 and Fig.14 As shown, the conductivity of the sensor of Example 1 is the best, and it can generate the maximum current under the same voltage. At the same time, the hydrovoltaic voltage generated by the sensor of Example 1 is the largest, which is about 100mV. This is consistent with the previous characterization results of the macroscopic and microscopic morphologies. The other embodiments have defects to varying degrees, resulting in poor conductivity and hydrovoltaic performance, but still have certain hydrovoltaic performance.

[0136] The sensor of Example 1 was placed on a heating platform, and the voltage response signal of the sensor was detected after water was added dropwise. The hydrovoltaic performance of the sensor under the condition of water evaporation was tested, and the results were obtained. Fig.15 , Fig.15 This is a voltage response signal diagram when water evaporates in Effect Example 1 of the present application.

[0137] like Fig.15 As shown, under the condition of water evaporation, the sensor of Example 1 can also generate a voltage close to 100 mV, and also has good hydrovoltaic performance.

[0138] Therefore, the sensor of Example 1 with the best performance was selected for subsequent experiments.

[0139] Effect Example 2: Repeatability and Stability Analysis

[0140] In the practical application of humidity sensors, stability and repeatability are also very important indicators. We studied the repeatability of the device during the wetting-drying cycle test and the stability during mechanical bending. In order to verify the repeatability of the SiNP self-driven environmental humidity sensor under the wetting-drying cycle, we used a hot plate to accelerate water evaporation to achieve the wetting-drying cycle.

[0141] The sensor of Example 1 was placed on a hot plate at 60°C, and water was dripped to moisten the sensor. After the water on the hot plate was completely evaporated, water was dripped again, and the above operation was repeated to obtain Fig.16 . Fig.16 This is a voltage response signal diagram of the repeatability experiment of Effect Example 2 of the present application.

[0142] like Fig.16 As shown, when the water droplet contacts the sensor, the sensor quickly generates a voltage response. In the final stage of the gradual evaporation of water, the output signal gradually decreases with the drying intensity of the functional layer. Finally, after the water is completely evaporated, the voltage response signal of the sensor disappears and returns to the open circuit voltage state of 0V. It can be seen from the responses of different cycles that the humidity sensor has relatively stable repeatability, and the size of the response signal generated by each dripping is between 150-200mV. The reason why the response signal exceeds the 100mV response signal of the previous standard sensor test is that at higher temperatures, the evaporation rate of water is accelerated, the speed of induced water flow microcirculation is accelerated, and the hydrovoltaic effect is enhanced. The fluctuation of the voltage response signal is caused by the difficulty of precise control of needle dripping and fluctuations in environmental temperature, humidity, wind, etc.

[0143] The above results show that the self-driven humidity sensor of Example 1 has good reversibility and reproducibility, and can work reliably in practical sensing applications.

[0144] Next, in the dripping response signal test, the sensor of Example 1 was repeatedly bent and restored, and each state change was maintained for 50 seconds to observe the change of the voltage response signal of the sensor, and the result was Fig.17 , Fig.17 This is a voltage response signal diagram of the stability analysis of Effect Example 2 of the present application.

[0145] like Fig.17 As shown, the voltage response signal of the self-driven humidity sensor of Example 1 can remain relatively stable, and the output voltage remains at about 100mV in both the bending and recovery states without being affected by bending, which indicates that it has good mechanical stability. This is of great significance for the practical application of sensors in flexible wearable scenarios, which means that the device can be attached to any curved surface and deform with the attached object without affecting the normal operation of the device.

[0146] Effect Example 3: Analysis of the Impact of Functional Layer Size

[0147] In order to study the effect of the size of the functional layer on its voltage output signal, the sensors of Examples 1, 5 to 11 were subjected to hydrovoltaic performance analysis and obtained: Fig.18 , Fig.18 It is a voltage response signal diagram of effect example 3 of the present application, wherein Figure a is a voltage response signal diagram of embodiments 1, 5 to 8, and Figure b is a voltage response signal diagram of embodiments 1, 9 to 11.

[0148] like Fig.18 As shown in a, when water drops are added to the functional layers of different widths, the sensors of Examples 1, 5 to 8 all quickly generate voltage response signals of about 100 mV, and the response signals remain basically stable during the presence of the water droplets. The above results show that the width of the functional layer has no significant effect on the size of the voltage response signal.

[0149] like Fig.18 As shown in b, when water droplets are added to the functional layer, the sensors of Examples 1, 9 to 11 all respond quickly, with a response time of less than 0.5 s. The voltage responses of the three devices (Examples 1, 10, and 11) with lengths of 1, 1.5, and 2 cm are basically the same, and can be stabilized at around 100 mV, while the device with too short a length (Example 9) will cause the response signal of the device to be significantly reduced, only about 30 mV, because the length is too short, which also affects the length of the micro-nano channel in the functional layer, and the water droplets fail to fully interact with the material in the channel.

[0150] According to the above results, taking into account miniaturization and integration, Example 8 with a length of 1 cm and a width of 0.2 cm is preferred as the preferred embodiment, which is beneficial to reducing the amount of material used.

[0151] Effect example 4:

[0152] The hydrostatic performance of the multi-sensor self-driven environmental humidity sensor of Examples 12 and 13 was analyzed and compared with that of Example 8. Fig.19 , Fig.19 This is a voltage response signal diagram of Effect Example 4 of the present application.

[0153] like Fig.19 As shown, the sensors of Example 12 and Example 13 can generate voltage response signals up to 0.5V and 1V, respectively, which are 5 times and 10 times that of Example 8.

[0154] The above data show that the voltage response signal of the sensor monomers in the self-driven humidity sensor of the present application after being connected in series presents a linear additive relationship. The self-driven humidity sensor of the present application can improve the device output voltage through multi-monomer integration, can realize device signal amplification and is expected to expand the application of the device in more scenarios requiring high voltage.

[0155] In order to verify the performance of the respiratory monitoring device and the intelligent monitoring diaper of the present application, the present application also conducted relevant embodiment tests, as follows:

[0156] Example 14: Respiration Monitoring Device

[0157] like Fig. 9 As shown, the self-driven environmental humidity sensor of Example 8 is arranged in the interlayer of the mask. After the test person wears the mask, the voltage response signal of the self-driven environmental humidity sensor is monitored under different breathing conditions, and the voltage response signal of the self-driven environmental humidity sensor is obtained. Fig. 20 , Fig. 20 : is a voltage response signal diagram of the respiratory monitoring device of Example 14, wherein a is the voltage response signal under normal breathing, b is the voltage response signal under deep breathing, and c is the voltage response signal under rapid breathing after exercise.

[0158] like Fig. 20 As shown in the figure, the voltage response signal of the sensor can clearly distinguish the three breathing patterns. In normal breathing, the voltage signal reflects the periodic regularity of fluctuations with breathing; in deep breathing, due to the increase in breathing intensity, the peak value of the response voltage also increases accordingly. Compared with normal breathing, the peak signal intensity brought by deep breathing is almost twice that of normal breathing; the frequency of the response signal under rapid breathing after exercise is significantly increased, which is consistent with the increase in breathing frequency.

[0159] Example 15: Intelligent Diaper Monitoring

[0160] like Fig.10 As shown, three self-driven environmental humidity sensors of Example 8 are arranged in series on the water absorption layer of the diaper, and the same volume of "urine" is poured into the diaper three times, and the voltage response signal of the device is observed to obtain Fig.21 , Fig.21 This is a voltage response signal diagram of the intelligent diaper monitoring system of Example 15.

[0161] like Fig.21 As shown in the figure, each time a liquid is poured in, a sensor will respond. After multiple wetting, the voltage response signals of different sensors will be summed up. After adding water three times, the device output signals are about 100, 200, and 300 mV respectively. This shows that the series segmented environmental humidity sensor can monitor the wetting state and urine content of diapers, providing reference and reminder for taking reasonable treatment methods.

[0162] It is obvious to those skilled in the art that the present application is not limited to the details of the exemplary embodiments described above, and that the present application can be implemented in other specific forms without departing from the spirit or essential features of the present application. Therefore, the embodiments should be regarded as exemplary and non-limiting in all respects, and the scope of the present application is defined by the appended claims rather than the above description, and it is intended that all changes falling within the meaning and scope of the equivalent elements of the claims be included in the present application. Any reference numeral in a claim should not be regarded as limiting the claim to which it relates.

[0163] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. A self-driven humidity sensor, characterized in that: The invention comprises a sensor unit, wherein the sensor unit comprises: substrate; A functional layer is arranged on the surface of the substrate, the functional layer comprises dispersed and stacked nano-silicon particles and nano-channels arranged between the nano-silicon particles, and the nano-silicon particles cooperate to form a conductive path; A pair of electrodes are disposed at two ends of the functional layer.

2. The self-driven humidity sensor according to claim 1, characterized in that: The functional layer further includes a binder dispersed between the nano-silicon particles to bind the nano-silicon particles.

3. The self-driven humidity sensor according to claim 2, characterized in that: The binder is one or more combinations of polyvinyl alcohol, polyvinyl pyrrolidone, sodium carboxymethyl cellulose and polyacrylic acid; and / or, The mass ratio of the nano silicon particles to the binder is (60-75):(25-40).

4. The self-driven humidity sensor according to claim 1, characterized in that: The distance between the pair of electrodes is greater than 0.6 cm.

5. The self-driven humidity sensor according to claim 1, characterized in that: It comprises a plurality of sensor monomers connected in series.

6. The self-driven humidity sensor according to claim 1, characterized in that: The substrate is filter paper, cellulose membrane, non-woven fabric or sponge; and / or, The material of the electrode is conductive carbon paste, conductive silver paste or liquid metal.

7. The self-driven humidity sensor according to claim 1, characterized in that: The invention also includes a packaging layer, wherein the packaging layer is arranged on the electrode on one side.

8. The self-driven humidity sensor according to claim 1, characterized in that: The particle size of the nano silicon particles is 50nm-2μm.

9. Use of the self-driven humidity sensor according to any one of claims 1 to 8 as a flexible wearable humidity sensor.

10. A respiratory monitoring device, characterized in that: include: Face mask; The self-driven humidity sensor according to any one of claims 1 to 8, arranged on the mask, the self-driven humidity sensor is used to monitor the breathing intensity and frequency and output a voltage response signal; The communication module is used to receive and forward the voltage response signal.

11. The respiratory monitoring device according to claim 10, characterized in that: The self-driven humidity sensor is arranged in the interlayer of the mask.

12. An intelligent diaper monitoring device, characterized in that: include: The diaper body includes a water-absorbing layer arranged on one side; The self-driven humidity sensor according to any one of claims 1 to 8, arranged in the water absorbing layer, the self-driven humidity sensor is used to monitor the humidity of the water absorbing layer and output a voltage response signal; The communication module is used to receive and forward the voltage response signal.

13. The smart monitoring diaper according to claim 12, characterized in that: The self-driven humidity sensor comprises a plurality of sensor units arranged at different positions in the water absorption layer, and the plurality of sensor units are sequentially connected in series.

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