CN114216937B - Flexible humidity sensing material, sensor and preparation method thereof - Google Patents
Flexible humidity sensing material, sensor and preparation method thereof Download PDFInfo
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- CN114216937B CN114216937B CN202111595406.5A CN202111595406A CN114216937B CN 114216937 B CN114216937 B CN 114216937B CN 202111595406 A CN202111595406 A CN 202111595406A CN 114216937 B CN114216937 B CN 114216937B
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Classifications
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
- G01N27/02—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance
- G01N27/04—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating resistance
- G01N27/12—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating resistance of a solid body in dependence upon absorption of a fluid; of a solid body in dependence upon reaction with a fluid, for detecting components in the fluid
- G01N27/125—Composition of the body, e.g. the composition of its sensitive layer
- G01N27/127—Composition of the body, e.g. the composition of its sensitive layer comprising nanoparticles
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- Chemical & Material Sciences (AREA)
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- Nanotechnology (AREA)
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- Investigating Or Analyzing Materials By The Use Of Electric Means (AREA)
- Investigating Or Analyzing Materials By The Use Of Fluid Adsorption Or Reactions (AREA)
Abstract
The application discloses a flexible humidity sensing material, a sensor and a preparation method thereof. The flexible humidity sensing material includes: an electrospun membrane and polydopamine and silver nanoparticles attached thereto. The surface of the electrostatic spinning film has a convex structure. The flexible humidity sensor includes: the electrode and the flexible humidity sensing layer prepared from the flexible humidity sensing material. The preparation method of the flexible humidity sensing material comprises the following steps: mixing a polymeric material, a silver ion displacer, dopamine and water to obtain a precursor solution; preparing an electrostatic spinning film by adopting a precursor solution; and sequentially placing the electrostatic spinning film in dopamine monomer solution according to sequence to perform in-situ polymerization, placing the electrostatic spinning film in silver ion salt solution to perform silver ion replacement reaction, and placing the electrostatic spinning film in weak oxidant and protective agent supplementing solution to oxidize silver nano particles to finally obtain the flexible humidity sensing material. The humidity sensor provided by the application can be comfortably worn on a human body, and can be used for detecting the perspiration of the human body.
Description
Technical Field
The application relates to a flexible humidity sensing material, a sensor and a preparation method thereof.
Background
As an important component of the treatment of local tumors, the role and role of radiation therapy in tumor therapy is increasingly prominent. However, accidents are easy to occur in the radiotherapy process, and some patient bodies cannot bear larger radiation doses in the radiotherapy process, so that obvious body reactions, such as a large amount of sweating, can occur. In order to better monitor the condition of the patient's body, it is important to know the change of the patient's body during radiotherapy. It is important to find a humidity sensor that can effectively monitor the amount of perspiration of the human skin.
Disclosure of Invention
The application aims to provide a flexible humidity sensing material capable of detecting sweat of human skin, a flexible humidity sensor and a preparation method thereof.
In order to achieve the above object, the present application provides the following solutions:
a flexible humidity sensing material comprising: the electrostatic spinning membrane comprises an electrostatic spinning membrane and polydopamine and silver nano particles attached to the electrostatic spinning membrane.
Optionally, the surface of the electrostatic spinning film is provided with a convex structure.
Optionally, the convex structure is a micro-cone structure.
The application also provides a flexible humidity sensor comprising: the flexible humidity sensing device comprises an electrode and a flexible humidity sensing layer, wherein the electrode is attached to the surface of the flexible humidity sensing layer, and the flexible humidity sensing layer is made of the flexible humidity sensing material.
Optionally, one surface of the flexible humidity sensing layer has a protruding structure, and the electrode is attached to the surface of the flexible humidity sensing layer having the protruding structure.
Optionally, the flexible humidity sensing device further comprises an encapsulation layer, wherein the encapsulation layer is attached to the side, with the electrode, of the flexible humidity sensing layer.
The application also provides a preparation method of the flexible humidity sensing material, which comprises the following steps:
mixing a polymeric material, a silver ion displacer, dopamine and water to obtain a precursor solution;
preparing an electrostatic spinning film by adopting the precursor solution;
placing the electrostatic spinning membrane in a dopamine monomer solution for in-situ polymerization to obtain a first electrostatic spinning membrane;
placing the first electrostatic spinning film in silver ion salt solution to perform silver ion replacement reaction to obtain a second electrostatic spinning film;
and placing the second electrostatic spinning film in a weak reducing agent solution, and reducing silver nano particles on the second electrostatic spinning film to obtain the flexible humidity sensing material.
Optionally, the precursor solution is used for preparing the electrostatic spinning film, which specifically comprises the following steps:
and spinning the precursor solution on one surface of the template with the convex structure, and collecting to obtain the electrostatic spinning film with the convex structure.
The application also provides a preparation method of the flexible humidity sensor, which comprises the following steps:
the flexible humidity sensing material prepared by the preparation method is prepared to obtain a flexible humidity sensing layer;
and attaching an electrode on the flexible humidity sensing layer.
Optionally, the method further comprises:
and packaging one surface of the flexible humidity sensing layer with the electrode by adopting a packaging film.
According to the specific embodiment provided by the application, the following technical effects are disclosed: the flexible humidity sensing material provided by the embodiment of the application comprises an electrostatic spinning film and polydopamine and silver nano particles attached to the electrostatic spinning film. The silver nano particles are used for forming conductive paths, and polydopamine can provide different numbers of proton jump sites according to different humidity, so that the conductive performance of the flexible humidity sensing material is different under different humidity. Meanwhile, the electrostatic spinning film can be comfortably worn on the skin and attached to the skin. Therefore, the flexible humidity sensor (comprising the flexible humidity sensing layer and the electrodes attached to the flexible humidity sensing layer) can be prepared from the flexible humidity sensing material, and the humidity can be detected based on the conductive characteristic of the flexible humidity sensing material, so that the flexible humidity sensor can be applied to the detection scene of the sweat of the skin of a human body.
Drawings
In order to more clearly illustrate the embodiments of the present application or the technical solutions of the prior art, the drawings that are needed in the embodiments will be briefly described below, it being obvious that the drawings in the following description are only some embodiments of the present application, and that other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
FIG. 1 is a schematic diagram of proton jump sites on the surface of a flexible humidity sensing material under low humidity conditions in example 1 of the present application;
FIG. 2 is a schematic diagram of proton jump sites on the surface of a flexible humidity sensing material under high humidity conditions in example 1 of the present application;
FIG. 3 is a schematic view showing the whole device of the flexible humidity sensor in example 2 of the present application;
fig. 4 is a schematic diagram of an external bluetooth wireless low energy flexible detection system according to embodiment 2 of the present application;
FIG. 5 is a flow chart showing a method for preparing a flexible humidity sensing material in example 3 of the present application;
FIG. 6 is a graph showing the response recovery time to humidity of the flexible humidity sensing material of example 3 of the present application;
FIG. 7 is a Field Emission Scanning Electron Microscope (FESEM) image of a Cu template in example 3 of the present application;
FIG. 8 is a flowchart of a method for manufacturing a flexible humidity sensor in example 4 of the present application;
FIG. 9 is a flowchart showing a method for manufacturing a flexible humidity sensor according to embodiment 4 of the present application;
FIG. 10 is a Field Emission Scanning Electron Microscope (FESEM) image of nanofibers after in situ polymerization in example 4 of the present application;
FIG. 11 is a specific data graph of current values, current changes, and relative current changes of a flexible humidity sensor according to an embodiment of the present application under different relative humidities;
FIG. 12 is a graph showing the relative current change of a flexible humidity sensor according to an embodiment of the present application.
Reference numerals: 1. PVP/SA/DA composite nanofiber; 2. silver nanoparticles; 3. polydopamine; 4. water molecules; 5. an electrode; 6. externally connecting a wire; 7. a flexible humidity sensing layer; 8. and an encapsulation layer.
Detailed Description
The following description of the embodiments of the present application will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present application, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the application without making any inventive effort, are intended to be within the scope of the application.
The application aims to provide a flexible humidity sensing material capable of detecting sweat of human skin, a flexible humidity sensor and a preparation method thereof.
In order that the above-recited objects, features and advantages of the present application will become more readily apparent, a more particular description of the application will be rendered by reference to the appended drawings and appended detailed description.
The flexible humidity sensor can be applied to the medical field, such as a radioactive tumor treatment scene: during radiotherapy, a patient may not bear the dosage of rays or other reasons, and some uncomfortable manifestations such as a large amount of sweating appear on the body, and at this time, the patient can realize real-time detection of the sweat amount by wearing the flexible humidity sensor provided by the application.
Referring to fig. 4, the flexible humidity sensor includes: the electrode 5 is attached to the surface of the flexible humidity sensing layer 7, and the flexible humidity sensing layer 7 is made of a flexible humidity sensing material.
In addition, the flexible humidity sensor can be integrated with a wireless communication module to form a wireless communication system, referring to fig. 1, the wireless communication module can exemplarily adopt a bluetooth communication module, taking a radiation treatment scene as an example, the bluetooth communication module is arranged in a radiation machine room, the bluetooth communication module comprises a bluetooth communication module at a sensor end and a bluetooth communication module at an industrial control end, and the bluetooth module at the industrial control computer end and the industrial control computer complete information transmission through cables. Thus, the information collected by the flexible humidity sensor can be transmitted to the industrial computer terminal through Bluetooth in a wireless mode, and the industrial computer is used for analyzing, processing and displaying the information.
As will be described in more detail below.
Example 1
The present embodiment describes a flexible humidity sensing material used for the flexible humidity sensing layer.
Referring to fig. 2, the flexible humidity sensing material includes: the electrostatic spinning membrane comprises an electrostatic spinning membrane, and polydopamine 3 and silver nano particles 2 attached to the electrostatic spinning membrane.
The silver nano-particles 2 are used for forming conductive paths, and the polydopamine 3 can provide different numbers of proton jump sites according to different humidities, so that the conductive performance of the flexible humidity sensing material is different under different humidities. Meanwhile, the electrostatic spinning film can be comfortably worn on the skin and attached to the skin. Therefore, the flexible humidity sensor can be prepared by using the flexible humidity sensing material, and humidity is detected based on the conductive characteristic and the humidity sensitive characteristic of the flexible humidity sensing material, so that the flexible humidity sensor can be applied to a detection scene of sweat of human skin.
In one example, to increase the moisture volatility of the humidity sensing material to increase the detection recovery time and detection frequency of the humidity sensing material, the electrospun film has a protrusion structure on at least one side, which may be a micro cone structure, which may increase the contact area to achieve timely volatilization of moisture.
Specifically, the electrostatic spinning film comprises a plurality of PVP/SA/DA composite nanofibers 1, and polydopamine 3 and silver nanoparticles 2 are attached to the PVP/SA/DA composite nanofibers 1.
Referring to fig. 2 and 3, a part of pvp/SA/DA composite nanofiber 1 is coated with polydopamine 3 for detecting different humidity, and the rest is coated with silver nanoparticles 2 for forming a conductive path.
The principle of different conductivity under different humidity is as follows:
when the relative humidity is low, protons transfer charge between polydopamine 3 molecules through a transition mechanism: PDA polymers (polymers formed by DA) have more hydroxyl and amino groups and can be used as proton donors and acceptors. An increase in relative humidity can provide more sites for proton hopping, increasing conductivity.
While protons are transported under high humidity conditions by the grotthus mechanism: the polydopamine 3 captures a large amount of water molecules to form hydrogen bond chains or a hydrogen bond network to transfer protons, the hydrogen bond chains become long due to the increase of humidity, and the hydrogen bond network is more complete, so that the conductivity of the sensor is higher. Therefore, the flexible humidity sensing material has different conductive properties under different humidity conditions, and the humidity detection is realized based on the conductive properties.
Example 2
The present embodiment provides a flexible humidity sensor having a micro-cone structure, referring to fig. 4, the flexible humidity sensor includes: the electrode 5 and the flexible humidity sensing layer 7, the electrode 5 is attached to the surface of the flexible humidity sensing layer 7, and the material of the flexible humidity sensing layer 7 is the flexible humidity sensing material provided in embodiment 1. The flexible humidity sensing layer 7 has a convex structure on one side.
The thickness range of the flexible humidity sensor layer 7 is illustratively 85 micrometers.
The shape of the flexible humidity sensing layer 7 may be square, circular, etc., and those skilled in the art can flexibly design the shape according to needs, which will not be described herein.
In one example, the electrode 5 is attached to a side of the flexible humidity sensing layer 7 having a convex structure (e.g., a micro cone structure). When flexible humidity transducer wears on the human body, flexible humidity transducer layer 7 has protruding structure's one side towards outside, protruding structure's setting is favorable to the timely volatilization of moisture in the flexible humidity transducer to outside, and then shortens flexible humidity transducer's recovery time, improves flexible humidity transducer's detection frequency.
In one example, the flexible humidity sensor further comprises an encapsulation layer 8, said encapsulation layer 8 being attached to the side of said flexible humidity sensor layer 7 having the electrodes 5. The encapsulation layer 8 not only plays a role in fixing and protecting the electrode 5, but also can effectively prevent the interference of the outside on detection. The material of the encapsulation layer 8 is preferably a hydrophobic material.
The encapsulation layer 8 may encapsulate only the electrode 5, or may cover the side of the flexible humidity sensing layer 7 having the electrode 5 entirely.
The electrode material can be conductive adhesive tape, aluminum electrode, copper electrode.
The electrode comprises a positive electrode and a negative electrode. Each electrode is connected with a wire to output current.
Example 3
Referring to fig. 5, the present embodiment provides a method for preparing the flexible humidity sensing material of embodiment 1, which includes the following steps:
step 11: mixing a polymeric material, a silver ion displacer, dopamine and water to obtain a precursor solution;
step 12: preparing an electrostatic spinning film by adopting the precursor solution;
step 13: placing the electrostatic spinning membrane in a dopamine monomer solution for in-situ polymerization to obtain a first electrostatic spinning membrane;
step 14: placing the first electrostatic spinning film in silver ion salt solution to perform silver ion replacement reaction to obtain a second electrostatic spinning film;
step 15: and placing the second electrostatic spinning film in a weak reducing agent, and oxidizing silver nano particles on the second electrostatic spinning film to obtain the flexible humidity sensing material.
In order to accelerate evaporation and absorption of moisture, the corresponding recovery time and detection frequency of the sensor can be significantly improved, and a convex structure (such as a micro cone structure) can be arranged on the surface of the humidity sensing material, wherein the convex structure is at least arranged on one side surface which is not contacted with the surface to be measured.
The setting of protruding structure has increased the area of contact of humidity sensing material and outside, makes the moisture on the humidity sensing material volatilize in time, and then can carry out the continuation detection of humidity again fast. Curve of response recovery time of flexible humidity sensor to humidityThe line is shown in FIG. 6, I 0 Indicating the measured current at 15% relative humidity; i represents the variation of Δi=i-I with humidity 0 。
The preparation of the raised structures (e.g., microcone structures) may be accomplished in the following manner:
a template of raised structures (such as micro-cone structures) is prepared using a laser marking machine, which may be composed of copper plates. And replacing part of the collecting paper used in the electrostatic spinning process with the template, and collecting the electrostatic spinning film on the template. And stripping to obtain the electrostatic spinning film with the convex structure. Therein, a Field Emission Scanning Electron Microscope (FESEM) image of the Cu template is shown in fig. 7.
In one example, to increase the strength of the humidity sensing material, this may be accomplished by increasing the thickness of the electrospun film. Specifically, the electrostatic spinning film is attached to new collecting paper, and further spinning is performed on the back surface of the fiber with the convex structure, so that the thickness of the electrostatic spinning film is increased.
In step 13, the ratio of polydopamine covered on the surface of the electrospun membrane may be controlled by controlling the time of in-situ polymerization.
After the first electrospun film is obtained in step 13, it is dried, and then immersed in a silver ion salt solution to perform a silver ion substitution reaction.
It will be appreciated that after the flexible humidity sensing material is obtained in step 15, the flexible humidity sensing material is washed and dried in a nitrogen atmosphere for more than six hours to obtain the final flexible humidity sensing material.
In this embodiment, the method of in-situ polymerization, ion replacement and reduction is used, so that the whole nanofiber is simply filled with silver nano particles and polydopamine, and the sensing active sites are greatly increased. The silver nanoparticles constitute the conductive path. The polydopamine and the silver nano particles are alternately distributed, so that the humidity sensing material has a conductive network, and the conductivity of the humidity sensing material can be changed along with the change of humidity.
Example 4
This embodiment provides a method for preparing a flexible humidity sensor according to embodiment 2, referring to fig. 8, which further includes the following steps on the basis of the method for preparing a flexible humidity sensor material according to embodiment 3:
step 21: and preparing the flexible humidity sensing layer by using a flexible humidity sensing material.
The structure and preparation method of the flexible humidity sensing material can be referred to the description of the previous embodiments.
Step 22: and attaching an electrode on the flexible humidity sensing layer.
In one example, electrodes are attached to both ends of the flexible humidity sensing layer on the side with the micro cone structure, and the encapsulation layer is attached to the flexible humidity sensing layer on the side with the electrodes. The encapsulation layer needs to be made of a hydrophobic material, such as a PDMS film.
Referring to fig. 9, in one example, the method of manufacturing the flexible sensor is specifically as follows:
1) And preparing the Cu template with the micro-cone structure by using a cold light laser marking machine, wherein the diameter of the bottom of the micro-cone structure is 15-20 mu m, and the height of the bottom of the micro-cone structure is 30-40 mu m.
2) Polyvinylpyrrolidone (PVP) was dissolved in deionized water and stirred at room temperature for 2 hours to obtain a 3wt% PVP solution. This aims at increasing the solution viscosity and facilitating the electrospinning.
3) Sodium Alginate (SA) powder and Dopamine (DA) powder are added into PVP solution, and the mixture is fully stirred and dissolved at room temperature, and the concentration of the obtained solution is 3wt% PVP,1.5wt% SA and 0.5wt% DA solution. Electrospinning was carried out at a voltage of 19kV for one hour. The distance between the electrode and the collecting paper is 15cm, the flow rate of the needle tube is 0.8mL/h, and the rotating speed of the collecting cylinder is 200r/min. The nanofibers obtained by comparing the concentration ratio are more uniform and have smaller average diameter.
4) And reversely attaching the electrostatic spinning film to new collecting paper, and further carrying out electrostatic spinning on the back surface with the microstructure fiber for 4 hours so as to increase the thickness of the electrostatic spinning film, enlarge the sensing volume, greatly enlarge the surface area of the microstructure of the outer layer of the electrostatic spinning film, accelerate the outward diffusion speed of moisture and increase the air permeability.
5) DA buffer was prepared by adding 20mg DA powder to 10ml tris-HCl buffer (ph=8.5) and stirring for two hours until fully dissolved. The electrospun film obtained in 4) was immersed in a DA buffer solution and stirred at 30℃for 6 hours. PDA coatings were formed on the PVP/SA/DA composite nanofiber portion surface by in situ self-polymerization of DA. The in-situ self-polymerization time can be long or short, but in order to control that the PDA coating is formed on only part of the fiber surface, other operations are carried out on the rest of the fiber surface, and the in-situ self-polymerization time is not suitable to be too long. After experiments, the time of 6 hours is found to be optimal; a Field Emission Scanning Electron Microscope (FESEM) image of the nanofibers after in situ polymerization is shown in fig. 10.
6) The nanofibers of 5) were immersed in 30wt% aqueous silver nitrate solution, and then the obtained nanofibers were taken out and washed with deionized water. Since the carboxyl groups in the alginate are easily combined with silver ions, the sodium alginate and silver nitrate on the surface of the fiber at the uncovered part undergo a displacement reaction to generate silver alginate. Because the nanofiber is immersed into the silver nitrate aqueous solution to react, sodium alginate in the fiber is replaced by silver alginate, and the area of the sensing layer is greatly increased. Silver alginate is insoluble in water and will not be washed away by deionized water.
7) The nanofibers in 6) were immersed in a 0.08% dmab (dimethylamine borane) solution and reacted for 30 minutes. The reduction time can be long or short, so that the silver nano particles can be covered on the surface of the fiber as much as possible to form a conductive path, the quantity and the size of the silver nano particles can be increased by properly increasing the reduction time, and the conductivity is improved.
8) And taking out the composite nanofiber, washing and drying the composite nanofiber in a nitrogen atmosphere for 6 hours to obtain the final PVP/PDA/Ag nano particles nanofiber. And narrow silver electrodes are attached to the two ends of the fiber on the side with the microstructure.
9) PDMS (polydimethylsiloxane) was mixed with a curing agent at 10:1 are fully stirred for 20-60min, are placed in a vacuum drying oven for foam removal treatment for 30-60min, and are cured for 1-3h at 80-120 ℃.
Then cutting into a fiber surface with a proper size and attaching the fiber surface with the electrode as a flexible packaging layer, thereby protecting the electrode and preventing the detection interference of the outside.
The material of the electrostatic spinning film in the embodiment of the application is not limited to PVP material, but can be the following materials: acrylonitrile-butadiene-styrene copolymer (ABS), polyurethane (PU), poly (vinylidene fluoride-trifluoroethylene) (P (VDF-TrFE)), polytetrafluoroethylene (PTFE), poly (vinylidene fluoride-hexafluoropropylene) (P (VDF-HFP)), polyacrylonitrile (PAN), polyketone (PK), polylactic acid (PLA), silk fibroin (silk fibrin), l-polylactic acid (PLLA), polyvinyl butyral ester (PVB), polycaprolactone (PCL).
The material of the flexible packaging layer in the embodiment of the application is not limited to PDMS material, but can be the following materials: polyvinylidene fluoride (PVDF), poly (vinylidene fluoride-trifluoroethylene) (P (VDF-TrFE)), poly (vinylidene fluoride-trifluoroethylene-chlorotrifluoroethylene) (P (VDF-TrFE-CTFE)), polyurethane (PU), thermoplastic polyurethane elastomer rubber (TPU), acrylonitrile-butadiene-styrene copolymer (ABS), polyethylene terephthalate (PET), polyimide (PI), polytetrafluoroethylene (PTFE), polyvinylchloride (PVC), polyvinylpyrrolidone (PVP), polymethyl methacrylate (PMMA), and polyethylene naphthalate (PEN).
The material of the electrode in the embodiment of the application is not limited to silver, but can be the following materials: conductive adhesive tape, aluminum electrode, copper electrode.
Taking the following sensor as an example, the humidity sensing effect is verified.
The humidity sensing layer is 1cm by 1.5cm in size; silver paste is dripped on two ends of the sensing film, and the conductive adhesive tape is attached to the silver paste to form an electrode; the electrodes at the two ends are loaded with 1V voltage to form a loop. The current in the loop was measured and the experimental results are shown in fig. 11 and 12.
Fig. 11 shows the current value, current variation and relative current variation in the loop at different relative humidities, it being seen that as humidity increases, the current value also increases. FIG. 12 shows the change of the relative current with different humidity, and as can be seen from FIG. 12, the change of the relative current increases linearly with the increase of humidity (I in FIG. 12 0 Indicating the measured current at 15% relative humidity; i represents the variation of Δi=i-I with humidity 0 ). Based onThe calibration between the current value and the humidity can be realized, and the detected humidity is determined by the magnitude of the current value or the relative current change.
It should be noted that most of the conventional humidity sensors are non-flexible non-contact humidity sensors, which cannot be well attached to the skin, and thus cannot accurately detect the perspiration amount of the skin.
In contrast to the flexible humidity sensor prepared by the embodiment of the present application, the flexible humidity sensor material includes a structured nanofiber structure, and different materials are wrapped on the fiber surface at intervals: a portion of the fibers were coated with polydopamine for detection of different humidities, while the remaining portion was covered with silver nanoparticles for formation of conductive pathways. When the relative humidity is low, protons transfer charge through the mechanism of intermolecular transitions between polydopamine: PDA polymers have many hydroxyl and amino groups and can be used as proton donors and acceptors. An increase in relative humidity can provide more sites for proton hopping, increasing conductivity. While protons are transported under high humidity conditions by the grotthus mechanism: the polydopamine captures a large number of water molecules to form hydrogen bond chains or hydrogen bond networks to transfer protons, the relative humidity is increased, the hydrogen bond chains are longer, the hydrogen bond networks are more complete, and therefore the conductivity of the sensor is higher.
Meanwhile, the nanofiber of the flexible humidity sensing material is added with a multi-stage microstructure (micro cone structure), so that the contact area between the humidity sensor and the outside is increased, the evaporation and absorption of moisture are accelerated, the corresponding recovery time and detection frequency of the sensor can be remarkably improved, and the sensor has good application value in detecting the respiratory rate change and perspiration volume change of a tumor patient in the radiotherapy process.
In the present specification, each embodiment is described in a progressive manner, and each embodiment is mainly described in a different point from other embodiments, and identical and similar parts between the embodiments are all enough to refer to each other.
The principles and embodiments of the present application have been described herein with reference to specific examples, the description of which is intended only to assist in understanding the methods of the present application and the core ideas thereof; also, it is within the scope of the present application to be modified by those of ordinary skill in the art in light of the present teachings. In view of the foregoing, this description should not be construed as limiting the application.
Claims (8)
1. A flexible humidity sensing material comprising: an electrostatic spinning film and polydopamine and silver nano particles attached to the electrostatic spinning film;
the surface of the electrostatic spinning film is provided with a convex structure;
the convex structure is a micro-cone structure;
the electrostatic spinning film comprises a plurality of PVP/SA/DA composite nanofibers, and polydopamine and silver nanoparticles are attached to the PVP/SA/DA composite nanofibers; the flexible humidity sensing material comprises a structured nanofiber structure with different materials spaced around the fiber surface: a portion of the fibers were encapsulated with polydopamine and the remainder were covered with silver nanoparticles.
2. A flexible humidity sensor comprising: the flexible humidity sensing device comprises an electrode and a flexible humidity sensing layer, wherein the electrode is attached to the surface of the flexible humidity sensing layer, and the flexible humidity sensing layer is made of the flexible humidity sensing material as claimed in claim 1.
3. The flexible humidity sensor of claim 2 wherein one side of the flexible humidity sensing layer has a raised structure and the electrode is attached to the side of the flexible humidity sensing layer having the raised structure.
4. A flexible humidity sensor according to claim 3 further comprising an encapsulation layer attached to the side of the flexible humidity sensing layer having the electrodes.
5. A method of preparing a flexible humidity sensing material, comprising:
mixing a polymeric material, a silver ion displacer, dopamine and water to obtain a precursor solution;
preparing an electrostatic spinning film by adopting the precursor solution;
placing the electrostatic spinning membrane in a dopamine monomer solution for in-situ polymerization to obtain a first electrostatic spinning membrane;
placing the first electrostatic spinning film in silver ion salt solution to perform silver ion replacement reaction to obtain a second electrostatic spinning film;
and placing the second electrostatic spinning film in a weak reducing agent solution, and oxidizing silver nano particles on the second electrostatic spinning film to obtain the flexible humidity sensing material.
6. The method for preparing a flexible humidity sensing material according to claim 5, wherein the preparing an electrospun film using the precursor solution comprises:
and spinning the precursor solution on one surface of the template with the convex structure, and collecting to obtain the electrostatic spinning film with the convex structure.
7. A method of manufacturing a flexible humidity sensor, comprising:
a flexible humidity sensing layer prepared by using the flexible humidity sensing material prepared by the preparation method of any one of claims 5 or 6;
and attaching an electrode on the flexible humidity sensing layer.
8. The method of manufacturing a flexible humidity sensor of claim 7 further comprising: and packaging one surface of the flexible humidity sensing layer with the electrode by adopting a packaging film.
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