CN114917771A - Hollow fiber membrane flexible humidity sensor and efficient preparation method thereof - Google Patents
Hollow fiber membrane flexible humidity sensor and efficient preparation method thereof Download PDFInfo
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D71/00—Semi-permeable membranes for separation processes or apparatus characterised by the material; Manufacturing processes specially adapted therefor
- B01D71/06—Organic material
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D61/00—Processes of separation using semi-permeable membranes, e.g. dialysis, osmosis or ultrafiltration; Apparatus, accessories or auxiliary operations specially adapted therefor
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D67/00—Processes specially adapted for manufacturing semi-permeable membranes for separation processes or apparatus
- B01D67/0002—Organic membrane manufacture
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D67/00—Processes specially adapted for manufacturing semi-permeable membranes for separation processes or apparatus
- B01D67/0079—Manufacture of membranes comprising organic and inorganic components
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D69/00—Semi-permeable membranes for separation processes or apparatus characterised by their form, structure or properties; Manufacturing processes specially adapted therefor
- B01D69/02—Semi-permeable membranes for separation processes or apparatus characterised by their form, structure or properties; Manufacturing processes specially adapted therefor characterised by their properties
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D69/00—Semi-permeable membranes for separation processes or apparatus characterised by their form, structure or properties; Manufacturing processes specially adapted therefor
- B01D69/08—Hollow fibre membranes
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D71/00—Semi-permeable membranes for separation processes or apparatus characterised by the material; Manufacturing processes specially adapted therefor
- B01D71/02—Inorganic material
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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
Abstract
The invention discloses a hollow fiber membrane flexible humidity sensor and an efficient preparation method thereof. The method comprises the steps of utilizing the characteristic that a hollow fiber membrane intercepts large-size substances, preparing a large number of hollow fiber membranes into a filtering assembly, uniformly filtering a conductive material to the outer wall of the hollow fiber membrane under the driving of pressure, and then soaking a polyelectrolyte viscous humidity sensitive material to obtain the hollow fiber membrane flexible humidity sensor in batches. The preparation method of the hollow fiber membrane flexible humidity sensor has the advantages of good product consistency, strong controllability, good repeatability, simple and convenient operation and the like.
Description
Technical Field
The invention relates to a hollow fiber membrane flexible humidity sensor, an efficient preparation method thereof and application of the flexible humidity sensor in the field of wearable intelligent sensing, and belongs to the technical field of flexible humidity sensing.
Background
With the improvement of living standards, people continuously pay more attention to medical care, and the demand for intelligent devices capable of realizing early diagnosis and prevention of diseases is increasing. As a core component of such smart devices, sensors are widely used to identify characteristics related to human physiological activities, such as pressure, humidity, temperature, etc., and convert the characteristics into readable data for health assessment or human-computer interaction to achieve early detection or prevention of various diseases. The humidity sensor is used for online detection of environmental humidity change caused by human body exhaled air, can identify breathing abnormity in real time, and achieves early diagnosis of breathing related diseases. The skin condition of the human body can be evaluated by monitoring the change of the skin surface humidity in real time through the humidity sensor. In addition, the application of the humidity sensor in the field of human-computer interaction can be realized by utilizing the quick and sensitive response of the humidity sensor to the humidity, and the non-contact control of intelligent equipment is realized, so that the virus propagation is reduced, and the epidemic disease is prevented. Therefore, the humidity sensor which is excellent in research and development performance and rapid and efficient in preparation method has great significance. Especially, the flexible humidity sensor has wide application prospect in the fields of wearable intelligent clothes, portable medical equipment, electronic skin and the like, and is concerned by scientific research personnel in recent years.
The polyelectrolyte is taken as a long-chain polymer with an ionizable group, and can be prepared into a resistance type humidity sensor by utilizing the characteristic that the polyelectrolyte is ionized in the interaction process with water molecules to generate ions capable of freely moving. The polyelectrolyte humidity-sensitive material has the advantages of simple preparation, high sensitivity and the like, so that the polyelectrolyte humidity-sensitive material becomes one of the most researched humidity-sensitive materials at present. Nevertheless, they still have the defects of slow response, excessively high resistance value in a low humidity environment, large wet retardation and the like.
Most of traditional polyelectrolyte humidity sensors are ceramic substrates, and have no flexibility and bendability, so that the application of the traditional polyelectrolyte humidity sensors in wearable intelligent equipment is limited. Based on this, the selection of flexible substrates has become an important research direction for the fabrication of flexible humidity sensors. Suitable flexible substrates not only provide support, but also can have an impact on the performance of the flexible sensor and the choice of manufacturing process. If a porous structure is introduced into the flexible substrate, the specific surface area of the system is increased while the weight of the sensor is reduced, more transmission channels are provided for water molecules, and the aims of improving the response sensitivity and the response speed are fulfilled. By utilizing the characteristics of the substrate, the preparation of flexible humidity sensors such as a suction filtration method based on a porous substrate, a spin coating method based on a dense substrate and the like is reported in the literature. Although a large number of research works on polyelectrolyte type flexible humidity sensors are reported, technologies or products meeting the requirements of excellent performance, simple processing method, low cost, good product consistency, convenience for mass production and the like are still under further exploration.
Disclosure of Invention
Aiming at the defects of the prior art, the invention aims to provide a hollow fiber membrane flexible humidity sensor and an efficient preparation method thereof.
The invention adopts the following technical scheme:
a high-efficiency preparation method of a hollow fiber membrane flexible humidity sensor comprises the following steps:
1) sealing and fixing the end opening of the polymer hollow fiber membrane by using a glue material, cutting off a part of the end opening at the fixing position after the end opening is completely cured, and exposing the pore passage in the hollow fiber membrane to form a hollow fiber membrane filtering component; the polymer hollow fiber membrane is in a hollow cylinder shape, and a porous structure is distributed on the wall of the polymer hollow fiber membrane;
2) inserting the hollow fiber membrane filtration assembly prepared in the step 1) into a peristaltic pump, preparing a conductive material aqueous dispersion, starting the peristaltic pump, setting the flow rate, filtering the conductive material aqueous dispersion from the outer wall to the inner wall of the hollow fiber membrane under the driving of pressure, intercepting large-size conductive materials to the outer side of the wall of the hollow fiber membrane, taking down the hollow fiber membrane assembly after filtering for a period of time, and drying to obtain a conductive material modified hollow fiber membrane;
3) preparing a polyelectrolyte solution, soaking the hollow fiber membrane modified by the conductive material prepared in the step 2) into the polyelectrolyte solution, taking out and drying to obtain the hollow fiber membrane modified by the polyelectrolyte and the conductive material, cutting the hollow fiber membrane into a proper size, and connecting a lead into an external circuit to prepare the polyelectrolyte and conductive material composite hollow fiber membrane flexible humidity sensor.
The inner diameter of the polymer hollow fiber membrane in the step 1) is 0.4-1 mm, the outer diameter is 0.7-2 mm, the diameter of the hollow fiber membrane component is 1-10 cm, and the length of the hollow fiber membrane component is 5-20 cm; the concentration of the conductive material water dispersion liquid in the step 2) is 0.01-10 mg/ml, and the flow rate of the peristaltic pump is 60-500 muL-min -1 The filtration time is 0.1-12 h; the concentration of the polyelectrolyte solution in the step 3) is 5-50 mg/ml, and the soaking time is 0.1-10 h.
The polymeric hollow fiber membrane comprises polyvinylidene fluoride, polypropylene, or polyethersulfone.
The glue material comprises hot melt adhesive, epoxy resin or paraffin.
The conductive material comprises redox graphene, silver nanowires, metal carbide and metal nitride with a two-dimensional layered structure, carbon nanotubes, carbon black or a conductive high polymer material.
The polyelectrolyte comprises polydimethyldiallyl ammonium chloride, polystyrene sulfonic acid, sodium polystyrene sulfonate and polydimethyldiallyl ammonium chloride: polystyrene sulfonic acid blends, polyacrylic acid or polymaleic acid.
The polyelectrolyte and conductive material composite hollow fiber membrane obtained by the method.
A flexible humidity sensor prepared according to the polyelectrolyte and conductive material composite hollow fiber membrane is used in the field of wearable intelligent sensing.
The beneficial effects of the invention are:
the invention selects a hollow fiber membrane with a flexible porous structure as a substrate. By utilizing the characteristic of the sensor for intercepting large-size substances, a large number of hollow fiber membranes are prepared into a filtering component, a conductive material is uniformly filtered to the outer wall of the hollow fiber membrane under the drive of pressure, and then the hollow fiber membrane flexible humidity sensor taking polyelectrolyte as a humidity sensitive component is obtained in batches by soaking the polyelectrolyte viscous material.
The hollow fiber membrane is used as a flexible substrate, and the hollow pore canal and pore wall porous structure of the hollow fiber membrane increase the contact area between water molecules and polyelectrolyte sensitive materials, promote the migration and diffusion of the water molecules on the surface of the sensor, and are beneficial to improving the response sensitivity of the humidity sensor, accelerating the response speed and reducing the response hysteresis. Meanwhile, the hollow fiber membrane flexible humidity sensor prepared in batch in the form of the filter assembly has the advantages of good product consistency, strong controllability, good repeatability, simplicity and convenience in operation and the like.
The conductive material is uniformly filtered to the outer wall of the hollow fiber membrane by utilizing the characteristic that the hollow fiber membrane filters and intercepts large-size substances. The introduction of the conductive material can effectively reduce the impedance value of the system, improve the problem of overhigh impedance value of the polyelectrolyte humidity sensitive material in a low-humidity environment and enlarge the humidity detection range of the humidity sensor. In addition, the accumulation of the conductive material on the outer wall of the hollow fiber membrane also has the purposes of increasing the specific surface area of the polyelectrolyte humidity-sensitive membrane, accelerating the response speed and reducing the wet hysteresis.
The invention relates to a method for preparing a hollow fiber membrane flexible humidity sensor by a pressure filtration auxiliary soaking method, which has the advantages of high speed and efficiency, good product consistency, strong controllability, good repeatability and simple operation. When the sensor is used as a humidity sensor, the sensor has the advantages of high response sensitivity, high response speed, small wet retardation and wide detection range.
Drawings
FIG. 1 is a schematic view of a polymer hollow fiber membrane module prepared in the present invention.
FIG. 2 is a schematic diagram of a process for manufacturing a hollow fiber membrane flexible humidity sensor according to the present invention.
FIG. 3 is a scanning electron microscope image of the outer surface, inner surface and cross section of a polyvinylidene fluoride (PVDF) hollow fiber membrane used in example 1 of the present invention.
Fig. 4 is an external surface scanning electron microscope image of the flexible humidity sensor with the composite PVDF hollow fiber membrane of poly dimethyl diallyl ammonium chloride (PDDA), metal carbide and metal nitride (MXene) with a two-dimensional layered structure obtained in example 1 of the present invention.
Fig. 5 is an external surface scanning electron microscope image of the flexible humidity sensor of a polyacrylic acid (PAA) and conductive polymer polyaniline nanofiber (PANI) composite Polyethersulfone (PES) hollow fiber membrane obtained in example 3 of the present invention.
Fig. 6 is an external surface scanning electron microscope image of the flexible humidity sensor made of sodium polystyrene sulfonate (PSSNa) and silver nanowire (Ag) composite PVDF hollow fiber membrane obtained in example 5 of the present invention.
FIG. 7 is a scanning electron microscope image of the outer surface of a PDDA/PS/PES composite hollow fiber membrane flexible humidity sensor prepared in example 10 of the present invention.
Fig. 8 is a response diagram of the PDDA and MXene composite PVDF hollow fiber membrane flexible humidity sensor prepared in embodiment 1 of the invention for detecting the human breathing process in real time.
FIG. 9 is a response graph of the change of the distance of the tested finger of the PAA and PANI composite PES hollow fiber membrane flexible humidity sensor prepared in example 3 of the present invention.
Fig. 10 shows the results of the consistency test of different batches of samples of the PSSNa and Ag composite PVDF hollow fiber membrane flexible humidity sensor prepared in example 5.
Detailed Description
The invention is further illustrated below with reference to the figures and examples.
Example 1
Firstly, preparing 0.01 mg/ml metal carbide and metal nitride (MXene) aqueous dispersion with a two-dimensional layered structure, filtering the MXene to the surface of a polyvinylidene fluoride (PVDF) hollow fiber membrane, wherein the inner diameter of the PVDF hollow fiber membrane is 0.4 mm, the outer diameter of the PVDF hollow fiber membrane is 0.7 mm, the diameter of the hollow fiber membrane component is 10 cm, the length of the PVDF hollow fiber membrane component is 10 cm, and the flow rate of a peristaltic pump is set to be 500 mu L min -1 And the filtering time is 5 h, and the MXene modified PVDF hollow fiber membrane is obtained after drying treatment.
Soaking the MXene modified PVDF hollow fiber membrane prepared in the step 1) into 5 mg/ml poly dimethyl diallyl ammonium chloride (PDDA) solution, fully soaking for 10 hours, and drying to obtain the PDDA and MXene composite PVDF hollow fiber membrane. The flexible film is cut to serve as a sensing element of the sensor, and after the flexible film is connected to an external circuit, the wearable flexible humidity sensor is prepared. Such an application is straightforward for the skilled person and can be implemented using existing solutions.
FIG. 1 is a schematic view of a polymer hollow fiber membrane module prepared in the present invention.
FIG. 2 is a schematic diagram of a process for manufacturing the hollow fiber membrane flexible humidity sensor according to the present invention. Firstly, preparing a polymer hollow fiber membrane modified by a conductive material through a pressure filtration method, and soaking the polymer hollow fiber membrane in a polyelectrolyte solution to prepare the polyelectrolyte and conductive material composite polymer hollow fiber membrane flexible humidity sensor.
FIG. 3 is a scanning electron microscope image of the outer surface, inner surface and cross section of the PVDF hollow fiber membrane used in example 1 of the present invention.
Fig. 4 is a scanning electron microscope image of the outer surface of the PDDA and MXene composite PVDF hollow fiber membrane flexible humidity sensor obtained in example 1 of the present invention. The large-size MXene conductive nanosheet is retained on the outer wall of the PVDF hollow fiber membrane, and after the MXene conductive nanosheet is subsequently soaked in a PDDA solution, the MXene is fixed on the outer wall of the PVDF hollow fiber membrane through PDDA.
Fig. 8 is a response diagram of a PDDA and MXene composite PVDF hollow fiber membrane flexible humidity sensor prepared in embodiment 1 of the present invention for detecting the human respiration process in real time. The method realizes effective recognition of static respiration and tachypnea of the human body by detecting the high-humidity gas exhaled by the human body, and is expected to be used for early diagnosis of respiratory diseases.
Example 2
Firstly, preparing 3 mg/ml MXene aqueous dispersion, filtering MXene to the surface of a PVDF hollow fiber membrane, setting the inner diameter of the PVDF hollow fiber membrane to be 1 mm, the outer diameter to be 2 mm, the diameter and the length of the hollow fiber membrane to be 6 cm and 20 cm, and setting the flow rate of a peristaltic pump to be 200 muL/min -1 The filtering time is 12 h, and MXene modified PVDF hollow fiber membrane is obtained after drying treatment。
Soaking the MXene modified PVDF hollow fiber membrane prepared in the step 1) into 25 mg/ml PDDA solution, fully soaking for 5 hours, and drying to obtain the PDDA and MXene composite PVDF hollow fiber membrane flexible humidity sensor.
Example 3
Firstly, preparing 5 mg/ml polyaniline conductive polymer nanofiber aqueous dispersion (PANI), filtering the PANI to the surface of a polyether sulfone (PES) hollow fiber membrane, wherein the inner diameter of the PES hollow fiber membrane is 0.7 mm, the outer diameter of the PES hollow fiber membrane is 1.5 mm, the diameter of the hollow fiber membrane component is 1 cm, the length of the hollow fiber membrane component is 15 cm, and the flow rate of a peristaltic pump is set to be 90 muL.min -1 And the filtration time is 5 h, and the PANI modified PES hollow fiber membrane is obtained after drying treatment.
Soaking the PANI modified PES hollow fiber membrane prepared in the step 1) into 50 mg/ml polyacrylic acid (PAA) solution, fully soaking for 0.1 h, and drying to obtain the PAA and PANI composite PES hollow fiber membrane flexible humidity sensor.
FIG. 5 is an external scanning electron microscope image of the PAA and PANI composite PES hollow fiber membrane flexible humidity sensor obtained in example 3 of the present invention. The large-size PANI conductive nano-fibers are retained on the outer wall of the PES hollow fiber membrane, and after the PES hollow fiber membrane is subsequently soaked in a PAA solution, the PANI is fixed on the outer wall of the PES hollow fiber membrane by using the PAA.
FIG. 9 is a response graph of the change of the distance of the tested finger of the PAA and PANI composite PES hollow fiber membrane flexible humidity sensor prepared in example 3 of the present invention. The surface humidity of the finger is higher than the humidity in the air, so that the electric signals of the PAA and PANI composite PES hollow fiber membrane flexible humidity sensor can be obviously changed in the process of approaching and departing the finger, and the application of the sensor in the field of human-computer interaction is expected to be realized.
Example 4
Firstly, preparing 2 mg/ml Carbon Nano Tube (CNTs) aqueous dispersion, filtering the CNTs to the surface of a PES hollow fiber membrane, wherein the inner diameter of the PES hollow fiber membrane is 0.4 mm, the outer diameter of the PES hollow fiber membrane is 0.7 mm, the diameter of the hollow fiber membrane module is 7 cm, the length of the hollow fiber membrane module is 5 cm, and the flow rate of a peristaltic pump is set to be 80 muL/min -1 Filtering for 8 h, and drying to obtain modified CNTsPES hollow fiber membrane.
Soaking the CNTs modified PES hollow fiber membrane prepared in the step 1) into 30 mg/ml sodium polystyrene sulfonate (PSSNa) solution, fully soaking for 0.5 h, and drying to obtain the PSSNa and CNTs composite PES hollow fiber membrane flexible humidity sensor.
Example 5
Firstly, preparing 1 mg/ml silver nanowire (Ag) water dispersion, filtering Ag nanowires to the surface of a PVDF hollow fiber membrane, wherein the inner diameter of the PVDF hollow fiber membrane is 0.6 mm, the outer diameter of the PVDF hollow fiber membrane is 1.4 mm, the diameter of the hollow fiber membrane component is 8 cm, the length of the PVDF hollow fiber membrane component is 10 cm, and the flow rate of a peristaltic pump is set to be 60 mu L.min -1 And the filtering time is 4 h, and the Ag nanowire modified PVDF hollow fiber membrane is obtained after drying treatment.
Soaking the Ag modified PVDF hollow fiber membrane prepared in the step 1) into a PSSNa solution of 40 mg/ml, fully soaking for 5 hours, and drying to obtain the PSSNa and Ag composite PVDF hollow fiber membrane flexible humidity sensor.
FIG. 6 is an external scanning electron microscope image of the PSSNa and Ag composite PVDF hollow fiber membrane flexible humidity sensor obtained in example 5 of the invention. The large-size Ag nanowires are retained on the outer wall of the PVDF hollow fiber membrane, and are fixed on the outer wall of the PVDF hollow fiber membrane by utilizing PSSNa after being subsequently soaked in PSSNa solution.
Fig. 10 shows the results of the consistency test of different batches of samples of the PSSNa and Ag composite PVDF hollow fiber membrane flexible humidity sensor prepared in example 5. The flexible humidity sensors of the PSSNa and Ag composite PVDF hollow fiber membranes at different batches and different positions are randomly selected to test the impedance values of the flexible humidity sensors in the same humidity environment and draw pictures, and the results show that the flexible humidity sensors prepared by the preparation method have better consistency.
Example 6
Firstly, preparing 0.5 mg/ml Ag nanowire aqueous dispersion, filtering Ag nanowires to the surface of a PES (polyether sulfone) hollow fiber membrane, setting the inner diameter and the outer diameter of the PES hollow fiber membrane to be 0.8 mm and 1.3 mm, setting the diameter and the length of the hollow fiber membrane to be 5 cm and 8 cm, and setting the flow rate of a peristaltic pump to be 300 mu L/min -1 The filtering time is 1 hour,and drying to obtain the Ag nanowire modified PES hollow fiber membrane.
Soaking the Ag modified PES hollow fiber membrane prepared in the step 1) into a polymaleic acid (PMA) solution of 15 mg/ml, fully soaking for 4 hours, and drying to obtain the PMA and Ag composite PES hollow fiber membrane flexible humidity sensor.
Example 7
Firstly, preparing 10 mg/ml Redox Graphene (RGO) aqueous dispersion, filtering the RGO to the surface of a PES (polyether sulfone) hollow fiber membrane, wherein the inner diameter of the PES hollow fiber membrane is 0.9 mm, the outer diameter of the PES hollow fiber membrane is 1.8 mm, the diameter of the hollow fiber membrane module is 4 cm, the length of the hollow fiber membrane module is 15 cm, and the flow rate of a peristaltic pump is set to be 500 muL-min -1 And the filtration time is 0.1 h, and the RGO modified PES hollow fiber membrane is obtained after drying treatment.
Soaking the RGO modified PES hollow fiber membrane prepared in the step 1) into a 20 mg/ml PAA solution, fully soaking for 8 hours, and drying to obtain the PAA and RGO composite PES hollow fiber membrane flexible humidity sensor.
Example 8
Firstly, preparing an RGO aqueous solution with the concentration of 4 mg/ml, filtering the RGO to the surface of a PVDF hollow fiber membrane, wherein the inner diameter of the PVDF hollow fiber membrane is 0.7 mm, the outer diameter of the PVDF hollow fiber membrane is 1.6 mm, the diameter and the length of the PVDF hollow fiber membrane are 3 cm and 17 cm, and the flow rate of a peristaltic pump is set to be 70 mu L/min -1 And the filtration time is 3.5 h, and the RGO modified PVDF hollow fiber membrane is obtained after drying treatment.
Soaking the RGO modified PVDF hollow fiber membrane prepared in the step 1) in 50 mg/ml PDDA solution for 0.1 hour, and drying to obtain the PDDA and RGO composite PVDF hollow fiber membrane flexible humidity sensor.
Example 9
Firstly, preparing 2 mg/ml Carbon Black (CB) aqueous dispersion, filtering CB to the surface of a PES (polyether sulfone) hollow fiber membrane, setting the inner diameter of the PES hollow fiber membrane to be 0.5 mm, the outer diameter of the PES hollow fiber membrane to be 1.5 mm, setting the diameter and the length of the hollow fiber membrane to be 15 cm, and setting the flow rate of a peristaltic pump to be 90 mu L.min -1 And the filtering time is 6 h, and the PVDF hollow fiber membrane modified by CB is obtained after drying treatment.
Soaking the CB-modified PVDF hollow fiber membrane prepared in the step 1) into a PSSNa solution of 40 mg/ml, fully soaking for 4 hours, and drying to obtain the PSSNa and CB composite PVDF hollow fiber membrane flexible humidity sensor.
Example 10
Firstly, preparing 2 mg/ml conductive polymer polypyrrole (PPy) nanoparticle aqueous dispersion, filtering PPy nanoparticles to the surface of a PES (polyether sulfone) hollow fiber membrane, wherein the inner diameter of the PES hollow fiber membrane is 0.4 mm, the outer diameter of the PES hollow fiber membrane is 1.1 mm, the diameter of the hollow fiber membrane module is 5 cm, the length of the hollow fiber membrane module is 12 cm, and the flow rate of a peristaltic pump is set to be 110 muL.min -1 And the filtration time is 9 h, and the PES hollow fiber membrane modified by PPy nano particles is obtained after drying treatment.
Soaking the PPy modified PES hollow fiber membrane prepared in the step 1) into 35 mg/ml PDDA: and (3) fully soaking in a polystyrene sulfonic acid solution (PSS) for 7 h, and drying to obtain the PDDA (Poly methyl methacrylate) (PSS), PPy (poly propylene diene monomer) composite PES hollow fiber membrane flexible humidity sensor.
FIG. 7 is a scanning electron microscope image of the outer surface of the PDDA: PSS, PPy composite PES hollow fiber membrane flexible humidity sensor prepared in example 10 of the present invention. The large-size PPy conductive nanoparticles are intercepted on the outer wall of the PES hollow fiber membrane, and the PDDA is subsequently soaked: after PSS solution, PDDA: the PSS fixes the PPy nano particles on the outer wall of the PES hollow fiber membrane.
Example 11
Firstly, preparing 4 mg/ml PPy nano particle aqueous dispersion, filtering PPy nano particles to the surface of a PP hollow fiber membrane, wherein the inner diameter of the PP hollow fiber membrane is 0.6 mm, the outer diameter of the PP hollow fiber membrane is 1.3 mm, the diameter of the hollow fiber membrane component is 3 cm, the length of the hollow fiber membrane component is 17 cm, and the flow rate of a peristaltic pump is set to be 280 muL.min -1 The filtering time is 4 h, and the PP hollow fiber membrane modified by PPy is obtained after drying treatment.
Soaking the PPy modified PP hollow fiber membrane prepared in the step 1) into 15 mg/ml PMA solution, fully soaking for 0.7 h, and drying to obtain the PMA and PPy composite PP hollow fiber membrane flexible humidity sensor.
The embodiments in the above description can be further combined or replaced, and the embodiments are only described as preferred embodiments of the present invention, and do not limit the concept and scope of the present invention, and various changes and modifications made to the technical solution of the present invention by those skilled in the art without departing from the design concept of the present invention belong to the protection scope of the present invention. The scope of the invention is given by the appended claims and any equivalents thereof.
Claims (8)
1. A high-efficiency preparation method of a hollow fiber membrane flexible humidity sensor is characterized by comprising the following steps: the method comprises the following steps:
1) sealing and fixing the end opening of the polymer hollow fiber membrane by using a glue material, cutting off a part of the end opening at the fixing position after the end opening is completely cured, and exposing the pore passage in the hollow fiber membrane to form a hollow fiber membrane filtering component; the polymer hollow fiber membrane is in a hollow cylinder shape, and a porous structure is distributed on the wall of the polymer hollow fiber membrane;
2) inserting the hollow fiber membrane filtration assembly prepared in the step 1) into a peristaltic pump, preparing a conductive material aqueous dispersion, starting the peristaltic pump, setting the flow rate, filtering the conductive material aqueous dispersion from the outer wall to the inner wall of the hollow fiber membrane under the driving of pressure, intercepting large-size conductive materials to the outer side of the wall of the hollow fiber membrane, taking down the hollow fiber membrane assembly after filtering for a period of time, and drying to obtain a conductive material modified hollow fiber membrane;
3) preparing a polyelectrolyte solution, soaking the hollow fiber membrane modified by the conductive material prepared in the step 2) into the polyelectrolyte solution, taking out and drying to obtain the hollow fiber membrane modified by the polyelectrolyte and the conductive material, cutting the hollow fiber membrane into a proper size, and connecting a lead into an external circuit to prepare the polyelectrolyte and conductive material composite hollow fiber membrane flexible humidity sensor.
2. The method of claim 1, wherein: the inner diameter of the polymer hollow fiber membrane in the step 1) is 0.4-1 mm, the outer diameter is 0.7-2 mm, the diameter of the hollow fiber membrane component is 1-10 cm, and the length is 5-20 cm; concentrating the conductive material aqueous dispersion in the step 2)The degree is 0.01-10 mg/ml, and the flow rate of the peristaltic pump is 60-500 muL-min -1 The filtration time is 0.1-12 h; the concentration of the polyelectrolyte solution in the step 3) is 5-50 mg/ml, and the soaking time is 0.1-10 h.
3. The method of claim 1, wherein: the polymeric hollow fiber membrane comprises polyvinylidene fluoride, polypropylene or polyethersulfone.
4. The method of claim 1, wherein: the glue material comprises hot melt glue, epoxy resin or paraffin.
5. The method of claim 1, wherein: the conductive material comprises redox graphene, silver nanowires, metal carbide and metal nitride with a two-dimensional layered structure, carbon nanotubes, carbon black or a conductive high polymer material.
6. The method of claim 1, wherein: the polyelectrolyte comprises polydimethyldiallyl ammonium chloride, polystyrene sulfonic acid, sodium polystyrene sulfonate and polydimethyldiallyl ammonium chloride: polystyrene sulfonic acid blend, polyacrylic acid, or polymaleic acid.
7. A polyelectrolyte, electrically conductive material composite hollow fiber membrane obtainable by the process according to any one of claims 1 to 6.
8. A flexible humidity sensor prepared from the polyelectrolyte, conductive material composite hollow fiber membrane according to claim 7, and used in the field of wearable intelligent sensing.
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