CN114917771B - 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 a high-efficiency preparation method thereof. And (3) preparing a large number of hollow fiber membranes into a filter assembly by utilizing the characteristic of the hollow fiber membranes for intercepting large-size substances, uniformly filtering a conductive material to the outer wall of the hollow fiber membranes under the driving of pressure, and subsequently soaking polyelectrolyte viscous humidity sensitive materials 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 operation and the like.
Description
Technical Field
The invention relates to a hollow fiber membrane flexible humidity sensor and a high-efficiency preparation method thereof, and application of the flexible humidity sensor in the field of wearable intelligent sensing, belonging to the technical field of flexible humidity sensing.
Background
With the improvement of living standard, people's attention to medical care continues to increase, and the demand for intelligent devices capable of realizing early diagnosis and prevention of diseases is also 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 into readable data for health assessment or human-computer interaction to enable early detection or prevention of various diseases. The humidity sensor is used for on-line detection of environmental humidity change caused by the gas exhaled by a human body, and can identify breathing abnormality in real time, so that early diagnosis of breathing related diseases is realized. The skin condition of the human body can also be evaluated by monitoring the humidity change of the surface layer of the skin in real time through a humidity sensor. In addition, the application of the humidity sensor in the field of man-machine interaction can be realized by utilizing the quick and sensitive response of the humidity sensor to humidity, and the non-contact control of the intelligent device is realized, so that the virus transmission is reduced, and the epidemic is prevented. Therefore, the humidity sensor with excellent research and development performance and quick and efficient preparation method is significant. Particularly, the flexible humidity sensor has wide application prospect in the fields of wearable intelligent clothing, portable medical equipment, electronic skin and the like, and is in particular attention of scientific researchers in recent years.
Polyelectrolyte is used as a long-chain polymer with ionizable groups, and can be prepared into a resistance type humidity sensor by utilizing the characteristic that the polyelectrolyte is ionized in the interaction process of the polyelectrolyte and water molecules to generate ions capable of freely migrating. The polyelectrolyte humidity-sensitive material has the advantages of simple preparation, high sensitivity and the like, and becomes one of the humidity-sensitive materials most studied at present. Nevertheless, they still have the disadvantages of slow response, excessively high resistance in low humidity environments, large wet hysteresis, etc.
Most of traditional polyelectrolyte humidity sensors are ceramic substrates, have no flexibility and bending property, and limit application of the polyelectrolyte humidity sensors in wearable intelligent equipment. Based on this, the choice of flexible substrate has become an important research direction for the preparation of flexible humidity sensors. Suitable flexible substrates not only provide support, but also have an impact on the performance and manufacturing process options of the flexible sensor. 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 purposes of improving response sensitivity and response speed are achieved. The preparation of flexible humidity sensors such as a suction filtration method based on a porous substrate and a spin coating method based on a dense substrate is reported in the literature by utilizing the characteristics of the substrate. 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 further explored.
Disclosure of Invention
Aiming at the defects of the prior art, the invention aims to provide a hollow fiber membrane flexible humidity sensor and a high-efficiency 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 polymer hollow fiber membrane port by using a glue material, cutting a part of the polymer hollow fiber membrane port at the fixing position after the polymer hollow fiber membrane port is completely solidified, and exposing the inner pore canal of the hollow fiber membrane to form a hollow fiber membrane filter assembly; the polymer hollow fiber membrane is hollow and cylindrical, and porous structures are distributed on the wall;
2) Inserting the hollow fiber membrane filter assembly prepared in the step 1) into a peristaltic pump, configuring an aqueous dispersion of a conductive material, starting the peristaltic pump, setting a flow rate, filtering the aqueous dispersion of the conductive material from the outer wall of the hollow fiber membrane to the inner wall under the driving of pressure, intercepting a large-size conductive material outside the wall of the hollow fiber membrane, filtering for a period of time, taking down the hollow fiber membrane assembly, and drying to obtain a hollow fiber membrane modified by the conductive material;
3) Preparing a polyelectrolyte solution, soaking the conductive material modified hollow fiber membrane prepared in the step 2) into the polyelectrolyte solution, taking out and drying to obtain the polyelectrolyte and conductive material modified hollow fiber membrane, cutting the polyelectrolyte and conductive material modified hollow fiber membrane into proper sizes, 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 is 5-20 cm; the concentration of the aqueous dispersion of the conductive material in the step 2) is 0.01-10 mg/ml, and the flow rate of the peristaltic pump is 60-500 [ mu ] L.min -1 The filtering time is 0.1-12h, performing H; the concentration of the polyelectrolyte solution in step 3) is 5-50 mg/ml and the soaking time is 0.1-10 h.
The polymer hollow fiber membrane comprises polyvinylidene fluoride, polypropylene or polyethersulfone.
The glue material comprises hot melt glue, epoxy resin or paraffin.
The conductive material comprises redox graphene, silver nanowires, metal carbide and metal nitride with two-dimensional lamellar structures, carbon nanotubes, carbon black or conductive high polymer materials.
The polyelectrolyte comprises polydimethyl diallyl ammonium chloride, polystyrene sulfonic acid, sodium polystyrene sulfonate and polydimethyl diallyl ammonium chloride: polystyrene sulfonic acid blends, polyacrylic acid or polymaleic acid.
A polyelectrolyte and conductive material composite hollow fiber membrane obtained according to the method.
A flexible humidity sensor prepared by 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 as follows:
the invention selects a hollow fiber membrane with a flexible porous structure as a substrate. By utilizing the characteristic of the high-size material interception, a large number of hollow fiber membranes are prepared into a filter assembly, under the drive of pressure, conductive materials are uniformly filtered to the outer wall of the hollow fiber membranes, and then the hollow fiber membrane flexible humidity sensor taking polyelectrolyte as a humidity sensitive component is obtained in batches by soaking polyelectrolyte viscous materials.
The hollow fiber membrane is used as a flexible substrate, the contact area between water molecules and polyelectrolyte sensitive materials is increased through the hollow pore canal and pore wall porous structure, migration and diffusion of the water molecules on the surface of the sensor are promoted, the response sensitivity of the humidity sensor is improved, the response speed is accelerated, and the response wet stagnation is reduced. Meanwhile, the hollow fiber membrane flexible humidity sensor prepared in batches 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 of the hollow fiber membrane that the large-size substances are trapped by filtration. 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 conductive material is piled up on the outer wall of the hollow fiber membrane to increase the specific surface area of the polyelectrolyte humidity-sensitive membrane, thereby accelerating the response speed and reducing the wet stagnation.
The hollow fiber membrane flexible humidity sensor prepared by the pressurized filtration auxiliary soaking method has the advantages of high speed, high efficiency, good product consistency, strong controllability, good repeatability and simple operation. When used as a humidity sensor, the sensor has the advantages of high response sensitivity, high response speed, small wet hysteresis 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 preparing 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 a scanning electron microscope image of the outer surface of the flexible humidity sensor of the polydimethyldiallyl ammonium chloride (PDDA), metal carbide and metal nitride (MXene) composite PVDF hollow fiber membrane having a two-dimensional layered structure obtained in example 1 of the present invention.
Fig. 5 is a scanning electron microscope image of the outer surface of the hollow fiber membrane flexible humidity sensor of polyacrylic acid (PAA) and conductive polymer polyaniline nanofiber (PANI) composite Polyethersulfone (PES) obtained in example 3 of the present invention.
Fig. 6 is a scanning electron microscope image of the outer surface of the flexible humidity sensor of the sodium polystyrene sulfonate (PSSNa) and silver nanowire (Ag) composite PVDF hollow fiber membrane obtained in example 5 of the invention.
FIG. 7 is a scanning electron microscope image of the outer surface of the PDDA/poly (styrene sulfonate) (PSS) and conductive polymer polypyrrole nanoparticle (PPy) composite PES hollow fiber membrane flexible humidity sensor prepared in example 10 of the invention.
Fig. 8 is a response chart of the flexible humidity sensor of the PDDA and MXene composite PVDF hollow fiber membrane prepared in the embodiment 1 of the invention for detecting the breathing process of a human body in real time.
Fig. 9 is a graph showing the response of the PAA and PANI composite PES hollow fiber membrane flexible humidity sensor prepared in example 3 of the present invention to the change of finger distance.
Fig. 10 is a sample consistency test result of different batches of PSSNa and Ag composite PVDF hollow fiber membrane flexible humidity sensors prepared in example 5.
Detailed Description
The invention is further illustrated in the following figures and examples.
Example 1
(1) Firstly, preparing 0.01 mg/ml of two-dimensional lamellar structure metal carbide and metal nitride (MXene) aqueous dispersion, filtering MXene on the surface of polyvinylidene fluoride (PVDF) hollow fiber membrane, wherein the PVDF hollow fiber membrane has an inner diameter of 0.4 mm, an outer diameter of 0.7 mm, a hollow fiber membrane component diameter of 10 cm and a length of 10 cm, and a peristaltic pump flow rate of 500 [ mu ] L.min -1 The filtration time was 5 h, and after drying treatment, an MXene-modified PVDF hollow fiber membrane was obtained.
(2) And (2) immersing the MXene modified PVDF hollow fiber membrane prepared in the step (1) into 5 mg/ml polydimethyldiallyl ammonium chloride (PDDA) solution, fully immersing for 10 h, and drying to obtain the PDDA and MXene composite PVDF hollow fiber membrane. And cutting the flexible film to serve as a sensing element of the sensor, and connecting the sensing element to an external circuit to prepare the wearable flexible humidity sensor. Such applications are relatively straightforward for a person skilled in the art, and can be implemented using existing technical 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 preparing a hollow fiber membrane flexible humidity sensor according to the present invention. Firstly, preparing a polymer hollow fiber membrane modified by a conductive material by a pressure filtration method, soaking the polymer hollow fiber membrane in a polyelectrolyte solution, and preparing 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 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, MXene composite PVDF hollow fiber membrane flexible humidity sensor obtained in example 1 of the present invention. The large-size MXene conductive nano-sheets are trapped on the outer wall of the PVDF hollow fiber membrane, and after PDDA solution is soaked in the PVDF hollow fiber membrane, the MXene is fixed on the outer wall of the PVDF hollow fiber membrane by the PDDA.
Fig. 8 is a response chart of the flexible humidity sensor of the PDDA and MXene composite PVDF hollow fiber membrane prepared in the embodiment 1 of the invention for detecting the breathing process of a human body in real time. By detecting the high-humidity gas exhaled by the human body, the effective identification of the static breath and the rapid breath of the human body is realized, and the method is expected to be used for early diagnosis of respiratory diseases.
Example 2
(1) Firstly, preparing 3 mg/ml MXene aqueous dispersion, filtering MXene on the surface of a PVDF hollow fiber membrane, wherein the inner diameter of the PVDF hollow fiber membrane is 1 mm, the outer diameter of the PVDF hollow fiber membrane is 2 mm, the diameter of a hollow fiber membrane assembly is 6 cm, the length of the hollow fiber membrane assembly is 20 cm, and the flow rate of a peristaltic pump is 200 mu L.min -1 The filtration time was 12 h, and after drying treatment, an MXene-modified PVDF hollow fiber membrane was obtained.
(2) And (2) soaking the MXene modified PVDF hollow fiber membrane prepared in the step (1) into 25 mg/ml PDDA solution, fully soaking for 5 h, and drying to obtain the PDDA and MXene composite PVDF hollow fiber membrane flexible humidity sensor.
Example 3
(1) Firstly, preparing 5 mg/ml polyaniline conductive polymer nanofiber aqueous dispersion liquid (PANI), filtering the PANI on the surface of a polyether sulfone (PES) hollow fiber membrane, wherein the PES hollow fiber membrane has an inner diameter of 0.7 mm and an outer diameter of 1.5 mm, the hollow fiber membrane component has a diameter of 1 cm and a length of 15 cm, and a peristaltic pump flow rate of 90 [ mu ] L.min is arranged -1 The filtration time is 5 h, and the PANI modified PES hollow fiber membrane is obtained after drying treatment.
(2) And (2) 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 a scanning electron microscope image of the outer surface of the PAA and PANI composite PES hollow fiber membrane flexible humidity sensor obtained in example 3 of the present invention. The PANI conductive nano-fiber with large size is trapped on the outer wall of the PES hollow fiber membrane, and PANI is fixed on the outer wall of the PES hollow fiber membrane by PAA after the PAA solution is soaked in the PAA solution.
Fig. 9 is a graph showing the response of the PAA and PANI composite PES hollow fiber membrane flexible humidity sensor prepared in example 3 of the present invention to the change of finger distance. The surface humidity of the finger is higher than the humidity in the air, so that the obvious change of the electrical signal of the PAA and PANI composite PES hollow fiber membrane flexible humidity sensor can be caused in the process of approaching and keeping away the finger, and the application of the PAA and PANI composite PES hollow fiber membrane flexible humidity sensor in the field of man-machine interaction is expected to be realized.
Example 4
(1) Firstly, preparing 2 mg/ml Carbon Nano Tube (CNTs) aqueous dispersion, filtering CNTs on 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 a hollow fiber membrane component is 7 cm, the length of the PES hollow fiber membrane component is 5 cm, and the flow rate of a peristaltic pump is 80 [ mu ] L.min -1 The filtration time is 8 h, and the PES hollow fiber membrane modified by CNTs is obtained after drying treatment.
(2) And (2) 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
(1) Firstly, preparing 1 mg/ml silver nanowire (Ag) aqueous dispersion, filtering the Ag nanowire on 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 a hollow fiber membrane component is 8 cm, the length of the hollow fiber membrane component is 10 cm, and the flow rate of a peristaltic pump is set to be 60 [ mu ] L.min -1 The filtration time is 4 h, and the PVDF hollow fiber membrane modified by the Ag nano wire is obtained after drying treatment.
(2) And (2) soaking the Ag modified PVDF hollow fiber membrane prepared in the step (1) into 40 mg/ml PSSNa solution, fully soaking for 5 h, and drying to obtain the PSSNa and Ag composite PVDF hollow fiber membrane flexible humidity sensor.
Fig. 6 is a scanning electron microscope image of the outer surface of the PSSNa and Ag composite PVDF hollow fiber membrane flexible humidity sensor obtained in example 5 of the present invention. The large-size Ag nanowires are trapped on the outer wall of the PVDF hollow fiber membrane, and after the PSSNa solution is soaked in the large-size Ag nanowires, the large-size Ag nanowires are fixed on the outer wall of the PVDF hollow fiber membrane by using the PSSNa.
Fig. 10 is a sample consistency test result of different batches of PSSNa and Ag composite PVDF hollow fiber membrane flexible humidity sensors prepared in example 5. The 50 PSSNa and Ag composite PVDF hollow fiber membrane flexible humidity sensors in different batches and different positions are randomly selected, impedance values of the sensor are tested under the same humidity environment, and pictures are drawn, so that the flexible humidity sensor prepared by the preparation method has good consistency.
Example 6
(1) Firstly, preparing 0.5 mg/ml Ag nanowire aqueous dispersion, filtering Ag nanowires on the surface of a PES hollow fiber membrane, wherein the inner diameter of the PES hollow fiber membrane is 0.8 mm, the outer diameter of the PES hollow fiber membrane is 1.3 mm, the diameter of a hollow fiber membrane component is 5 cm, the length of the PES hollow fiber membrane component is 8 cm, and the flow rate of a peristaltic pump is 300 [ mu ] L.min -1 Filtering time is 1 h, and drying to obtain the PES hollow fiber membrane modified by Ag nano wires.
(2) And (2) immersing the Ag modified PES hollow fiber membrane prepared in the step (1) into 15 mg/ml polymaleic acid (PMA) solution, fully immersing for 4 h, and drying to obtain the PMA and Ag composite PES hollow fiber membrane flexible humidity sensor.
Example 7
(1) Firstly, preparing 10 mg/ml of Redox Graphene (RGO) aqueous dispersion, filtering RGO on the surface of a PES 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 a hollow fiber membrane component is 4 cm, the length of the hollow fiber membrane component is 15 cm, and the peristaltic pump flow rate is 500 [ mu ] L.min -1 Filtering for 0.1-h, and drying to obtain RGO modified PES hollow fiber membrane.
(2) And (2) soaking the RGO modified PES hollow fiber membrane prepared in the step (1) into 20 mg/ml PAA solution, fully soaking for 8 h, and drying to obtain the PAA and RGO composite PES hollow fiber membrane flexible humidity sensor.
Example 8
(1) Firstly, preparing 4 mg/ml RGO aqueous solution, filtering RGO on 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 of a 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 70 mu L min -1 The filtration time is 3.5 and h, and the RGO modified PVDF hollow fiber membrane is obtained after drying treatment.
(2) And (2) soaking the RGO modified PVDF hollow fiber membrane prepared in the step (1) into 50 mg/ml PDDA solution, fully soaking for 0.1 h, and drying to obtain the PDDA and RGO composite PVDF hollow fiber membrane flexible humidity sensor.
Example 9
(1) Firstly, preparing 2 mg/ml Carbon Black (CB) aqueous dispersion, filtering CB on the surface of a PES hollow fiber membrane, wherein the inner diameter of the PES hollow fiber membrane is 0.5 mm, the outer diameter of the PES hollow fiber membrane is 1.5 mm, the diameter of a hollow fiber membrane component is 6 cm, the length of the hollow fiber membrane component is 15 cm, and the flow rate of a peristaltic pump is 90 mu L min -1 The filtration time is 6 h, and the CB-modified PVDF hollow fiber membrane is obtained after drying treatment.
(2) And (2) soaking the CB-modified PVDF hollow fiber membrane prepared in the step (1) into 40 mg/ml PSSNa solution, fully soaking for 4 h, and drying to obtain the PSSNa and CB composite PVDF hollow fiber membrane flexible humidity sensor.
Example 10
(1) Firstly, preparing 2 mg/ml conductive polymer polypyrrole (PPy) nanoparticle aqueous dispersion, filtering PPy nanoparticles on the surface of a PES hollow fiber membrane, wherein the PES hollow fiber membrane has an inner diameter of 0.4 mm and an outer diameter of 1.1 mm, the hollow fiber membrane component has a diameter of 5 cm and a length of 12 cm, and a peristaltic pump flow rate of 110 [ mu ] L.min is arranged -1 The filtration time is 9 h, and the PES hollow fiber membrane modified by the PPy nano particles is obtained after drying treatment.
(2) Immersing the PPy modified PES hollow fiber membrane prepared in the step 1) into 35 mg/ml PDDA: and (3) in a polystyrene sulfonic acid solution (PSS), fully soaking the mixture in 7 and h, and drying the mixture to obtain the PDDA/PSS/PPy composite PES hollow fiber membrane flexible humidity sensor.
FIG. 7 is a scanning electron microscope image of the outer surface of the PDDA, PSS and PPy composite PES hollow fiber membrane flexible humidity sensor prepared in example 10 of the invention. The large-size PPy conductive nano particles are trapped on the outer wall of the PES hollow fiber membrane, and PDDA is soaked in the PES hollow fiber membrane: after PSS solution, PDDA was used: PSS fixes PPy nano particles on the outer wall of the PES hollow fiber membrane.
Example 11
(1) Firstly, preparing 4 mg/ml PPy nano particle aqueous dispersion, filtering PPy nano particles on 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 a hollow fiber membrane component is 3 cm, the length of the PP hollow fiber membrane component is 17 cm, and the flow rate of a peristaltic pump is 280 [ mu ] L.min -1 The filtration time is 4 h, and the PPy modified PP hollow fiber membrane is obtained after drying treatment.
(2) And (2) 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 foregoing description may be further combined or replaced, and the embodiments are merely illustrative of the preferred embodiments of the present invention and are not intended to limit the spirit and scope of the present invention, and various changes and modifications made by those skilled in the art to which the present invention pertains without departing from the spirit of the present invention. The scope of the invention is given by the appended claims and any equivalents thereof.
Claims (4)
1. A high-efficiency preparation method of a hollow fiber membrane flexible humidity sensor is characterized by comprising the following steps of: the method comprises the following steps:
1) Sealing and fixing the polymer hollow fiber membrane port by using a glue material, cutting a part of the polymer hollow fiber membrane port at the fixing position after the polymer hollow fiber membrane port is completely solidified, and exposing the inner pore canal of the hollow fiber membrane to form a hollow fiber membrane filter assembly; the polymer hollow fiber membrane is hollow and cylindrical, and porous structures are distributed on the wall;
2) Inserting the hollow fiber membrane filter assembly prepared in the step 1) into a peristaltic pump, configuring an aqueous dispersion of a conductive material, starting the peristaltic pump, setting a flow rate, filtering the aqueous dispersion of the conductive material from the outer wall of the hollow fiber membrane to the inner wall under the driving of pressure, intercepting a large-size conductive material outside the wall of the hollow fiber membrane, filtering for a period of time, taking down the hollow fiber membrane assembly, and drying to obtain a hollow fiber membrane modified by the conductive material;
3) Preparing a polyelectrolyte solution, soaking the conductive material modified hollow fiber membrane prepared in the step 2) into the polyelectrolyte solution, taking out and drying to obtain a polyelectrolyte and conductive material modified hollow fiber membrane, cutting the polyelectrolyte and conductive material modified 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 is 5-20 cm; the concentration of the aqueous dispersion of the conductive material in the step 2) is 0.01-10 mg/ml, and the flow rate of the peristaltic pump is 60-500 [ mu ] L.min -1 The filtering 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 polymer hollow fiber membrane comprises polyvinylidene fluoride, polypropylene or polyethersulfone;
the conductive material comprises redox graphene, silver nanowires, metal carbide and metal nitride with two-dimensional layered structures, carbon nanotubes, carbon black, polyaniline conductive polymer nanofibers or conductive polymer polypyrrole nanoparticles;
the polyelectrolyte comprises polydimethyl diallyl ammonium chloride, polystyrene sulfonic acid, sodium polystyrene sulfonate and polydimethyl diallyl ammonium chloride: polystyrene sulfonic acid blends, polyacrylic acid or polymaleic acid.
2. The method according to claim 1, characterized in that: the glue material comprises hot melt glue, epoxy resin or paraffin.
3. A polyelectrolyte, conductive material composite hollow fiber membrane obtained according to the method of claim 1 or 2.
4. A flexible humidity sensor prepared from the polyelectrolyte and conductive material composite hollow fiber membrane according to claim 3, which is used in the field of wearable intelligent sensing.
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