CN111121870A

CN111121870A - Bionic multifunctional flexible sensor based on collagen aggregate and preparation method thereof

Info

Publication number: CN111121870A
Application number: CN201911354981.9A
Authority: CN
Inventors: 王学川; 岳欧阳; 刘新华; 侯梦迪; 郑漫辉
Original assignee: Shaanxi University of Science and Technology
Current assignee: Shaanxi University of Science and Technology
Priority date: 2019-12-25
Filing date: 2019-12-25
Publication date: 2020-05-08
Anticipated expiration: 2039-12-25
Also published as: CN111121870B

Abstract

The patent discloses a bionic multifunctional flexible sensor based on a collagen aggregate and a preparation method thereof, which are different from the conventional sensor at present and are characterized in that the natural collagen aggregate with excellent biocompatibility and a three-dimensional network structure is organically doped with a polyaniline-carbon nano tube composite conductive material with excellent conductivity and dispersibility. Sensor element materials with high sensitivity to pressure and humidity are respectively prepared by a specific processing method, a piezoelectric layer multi-layer structure and an internal three-dimensional network structure are constructed by assembling the two materials, and a novel flexible multifunctional sensor sensitive to pressure and humidity is successfully prepared. The multifunctional sensor has excellent biological characteristics, and can be widely applied to the fields of intelligent artificial limbs, high-end robots, virtual reality, wearable sensors and the like.

Description

Bionic multifunctional flexible sensor based on collagen aggregate and preparation method thereof

Technical Field

The invention relates to the technical field of resource utilization of leather industry solid waste and manufacturing of flexible sensors, in particular to a bionic multifunctional flexible sensor based on a collagen aggregate and a preparation method thereof.

Background

The sensor plays the most fundamental and important role in the era of intellectual association, is used for simulating the perception of human skin on external environment (including pressure, humidity and temperature), and reasonably analyzes the external environment through artificial intelligence, and finally, big data of the intelligent internet of things can be continuously constructed. The system can be widely applied to artificial intelligence and medical diagnosis, and comprises the fields of intelligent artificial limbs, high-end robots, wearable health monitors, virtual reality and the like. Pressure sensors are key components of sensors that determine the characteristics and performance of the system. Heretofore, pressure sensors having different mechanisms of operation, including capacitive, piezoelectric, frictional and piezoresistive, have received the most attention. Among them, piezoresistive sensors are more promising due to their simplicity of manufacturing process, high sensitivity and operational stability. The change in resistance of piezoresistive sensors is typically due to a change in contact resistance or material structure. According to recent reports, melamine, polydimethylsiloxane, ionic liquid, polyvinylidene fluoride, silicone rubber, polyimide, and the like have been widely used in the preparation of piezoelectric sensors, and the prepared products have excellent flexibility and sensing sensitivity. However, large scale manufacturing of pressure sensors still presents significant challenges due to issues of biocompatibility, degradation, and raw material cost.

Moreover, the sensors reported at present generally have a single function, such as the high-precision piezoresistive sensor provided by CN 109443609A. These sensors typically do not react as well to a variety of external signals as human skin does. Humidity sensing is also an essential function of the skin, and various types of humidity sensors are widely reported today, such as capacitive or resistive electrical sensors, and optical sensors based on transmission or reflection. However, there are few reports of multifunctional humidity sensors, so that the progress of integration and intelligence of the sensors is hindered. In view of the above, there is a need for a biomimetic multifunctional sensor with high sensitivity, low price and wide response range for pressure detection and humidity sensing.

Biomass materials, particularly animal collagen aggregates, are receiving increasing attention due to their high biocompatibility, excellent biodegradability, good sustainability and low antigenicity. The amount of leather solid waste produced in China is up to 140 million tons each year, wherein 30 million tons of the leather solid waste are chromium-containing high-risk waste, and more than 80 percent of the solid waste is composed of natural skin collagen. If the collagen aggregate purified from the part of waste is applied to the development of the bionic material, the aim of changing waste into valuable is fulfilled, and the novel bionic multifunctional flexible sensor based on the collagen aggregate and the preparation method thereof can be prepared.

Disclosure of Invention

The bionic multifunctional flexible sensor prepared by the invention is mainly characterized in that: a multifunctional flexible sensor which has a multi-layer structure and an internal three-dimensional structure and is sensitive to humidity and pressure is prepared in a simple and convenient mode. The sensor can detect compression, bending and torsion strains, and has the advantages of high sensitivity, large detection range and short response time. In addition, it also has excellent performance as a humidity sensitive device, with higher sensitivity and extremely low short hysteresis. Due to the unique biological characteristics of the collagen aggregate, the multifunctional flexible sensor has better water vapor permeability and comfort when being used as a wearing device, and has degradability and durability, which are not possessed by the traditional flexible multifunctional flexible sensor. These extraordinary functions show that the recognition and detection of complex motion and control action of human body can be realized by means of multi-analysis statistical analysis method, and the multifunctional flexible sensor can be widely used for intelligent robot, health monitoring and human body motion monitoring.

In order to achieve the purpose, the invention adopts the technical scheme that:

a bionic multifunctional flexible sensor based on collagen aggregates comprises a natural collagen aggregate matrix with a three-dimensional net structure and a polyaniline-acidified carbon nanotube composite conductive matrix dispersed in the matrix, sensor element materials with high sensitivity to pressure and humidity are respectively prepared by different treatment methods, and the multifunctional sensor sensitive to pressure and humidity is successfully prepared by assembling the two materials.

Furthermore, the natural skin collagen aggregate is prepared from leather solid waste, and has the structural characteristic of a typical light and shade connected cross grain structure.

Furthermore, the mass ratio of the natural skin collagen aggregate, polyaniline, the acidified carbon nano tube and the hydrophobic cross-linking agent is (0.1-30): 0.1-5): 0.01-10, and the processing mode is a freeze drying method.

Furthermore, the mass ratio of the natural skin collagen aggregate, polyaniline, the acidified carbon nano tube and glycerol is (0.1-30): 0.1-5): 0.01-10, and the treatment method is drying at room temperature.

Furthermore, the piezoresistive sensor material is attached to the upper side of the humidity-sensitive sensor material under the adsorption action of protein, and a piezoelectric layer multi-layer structure and an internal three-dimensional network structure are constructed after the pressure of 1-10 MPa, so that the multifunctional sensor is prepared.

The invention also provides a bionic multifunctional flexible sensor based on the collagen aggregate and a preparation method thereof, wherein the preparation method comprises the following steps:

aniline is used as a monomer, ammonium persulfate is used as an oxidant, and the polyaniline-acidified carbon nanotube composite conductive matrix material is prepared by reaction in a dispersion containing sulfosalicylic acid and acidified carbon nanotubes; dropwise adding dispersion liquid of polyaniline-acidified carbon nanotube composite conductive matrix material and glycerol into collagen solution, fully stirring, drying at room temperature to obtain high-precision humidity sensor material based on collagen aggregates, and spraying conductive graphite by using a spray gun to prepare a cross electrode; dropwise adding dispersion liquid of polyaniline-acidified carbon nanotube composite conductive matrix material into collagen solution, fully stirring, uniformly coating on the surface of the humidity sensing material, and freeze-drying to obtain the strain hypersensitive flexible bionic multifunctional flexible sensor with the humidity sensitive function.

Further, in the dispersion for preparing the polyaniline-acidified carbon nanotube composite conductive matrix material: the mass ratio of the multi-wall carbon nano tube to the aniline is 1 (0.5-2); the molar ratio of the aniline to the sulfosalicylic acid is 1 (1-5); the molar ratio of the aniline to the ammonium persulfate is 1 (0.5-2).

Further, when the dispersion liquid of the polyaniline-acidified carbon nanotube composite conductive matrix material is dropwise added into the collagen solution, the mass ratio of the collagen to the polyaniline-acidified carbon nanotube composite conductive matrix material is 1 (0.03-1).

Further, the polyaniline-acidified carbon nanotube composite conductive matrix material is obtained by a method comprising the following steps:

(1) placing multi-walled carbon nanotubes, concentrated sulfuric acid and concentrated nitric acid in a mass ratio of (0.1-1): 0.1-100) into a reactor, performing ultrasonic dispersion for 20-90 min, and then stirring and refluxing for 2-20 h at a constant temperature of 35-80 ℃; cooling to normal temperature, diluting with 300-1000 mL of deionized water, and centrifuging for multiple times at a rotation speed of 5000-20000 Xg until the supernatant is neutral; and after filtering, carrying out freeze drying for 10-20 h, and collecting the lower-layer precipitate to obtain the acidified carbon nanotube.

(2) Placing 0.2-1.5 g of acidified carbon nano tube into 50-200 mL of deionized water, adding aniline in an amount which is 0.5-2 times the mass of the acidified carbon nano tube and sulfosalicylic acid in an amount which is 1-5 times the mass of an aniline monomer, performing ultrasonic dispersion for 20-90 min, transferring to a reactor, and rapidly stirring at normal temperature; melting ammonium persulfate oxidant in an amount which is 0.5-2 times of that of aniline monomer into 20-100 mL of deionized water, dropwise adding the mixture into a reaction system, and stirring and reacting for 5-20 hours at the temperature of 0-10 ℃; filtering and washing the polyaniline-acidified carbon nanotube composite conductive matrix material by using absolute ethyl alcohol and distilled water respectively, freeze-drying the mixture for 10-20 hours, and collecting a sample to obtain the polyaniline-acidified carbon nanotube composite conductive matrix material;

further, the preparation method comprises the following steps:

(1) adding a polyaniline-acidified carbon nanotube composite conductive matrix material and glycerol into the collagen aggregate solution, uniformly mixing, and drying to obtain a humidity sensitive layer;

(2) spraying conductive graphite on the surface of the humidity sensitive layer to obtain an electrode layer;

(3) adding a polyaniline-acidified carbon nanotube composite conductive matrix material into the collagen aggregate solution to obtain a precursor solution of the mechanical sensitive material;

(4) and constructing a precursor solution of the mechanical sensitive material on the surface of the electrode layer, freeze-drying, and press-forming to obtain the mechanical sensitive layer with the three-dimensional network structure.

The method comprises the following specific steps:

(1) slowly stirring 0.1-30 g of natural skin collagen aggregate at 30-70 ℃ for 5-60 min to disperse the natural skin collagen aggregate in 10-100 mL of deionized water, and transferring the deionized water to a reactor; taking a polyaniline-acidified carbon nanotube composite conductive matrix material with 0.03-1 time of the mass of collagen, ultrasonically dispersing the polyaniline-acidified carbon nanotube composite conductive matrix material in 30-150 mL of deionized water for 20-90 min, dropwise adding the polyaniline-acidified carbon nanotube composite conductive matrix material into a collagen solution, adding 0.01-10 g of glycerol, and stirring at normal temperature for 2-10 h; and collecting the mixed solution, and drying the mixed solution in a mold at normal temperature to obtain the humidity sensing film with the thickness of 0.1-1 mm. Spraying conductive graphite on a substrate by using a spray gun by taking a humidity sensing film of 1cm multiplied by 2cm as the substrate to form a crossed electrode; the interval between adjacent electrodes is 1-5 mm, and the width of the interdigital electrode is 1-2 mm;

(2) slowly stirring 0.1-30 g of natural skin collagen aggregate at 30-70 ℃ for 5-60 min to disperse the natural skin collagen aggregate in 10-100 mL of deionized water, and transferring the deionized water to a reactor; taking a polyaniline-acidified carbon nanotube composite conductive matrix material with 0.03-1 time of the mass of collagen, ultrasonically dispersing the polyaniline-acidified carbon nanotube composite conductive matrix material in 30-150 mL of deionized water for 20-90 min, dropwise adding the polyaniline-acidified carbon nanotube composite conductive matrix material into a collagen solution, and stirring the mixture at normal temperature for 2-10 hours; collecting a sample; and uniformly spin-coating 0.1-5 g of the prepared mixture on a base film, freeze-drying, and forming under the compression of 1-10 MPa.

Still further, the method comprises the steps of:

(1) acidifying the multi-wall carbon nano tube: placing the multi-walled carbon nano tube, concentrated sulfuric acid and concentrated nitric acid in a mass ratio of 0.1-1: 0.1-100 into a reactor, performing ultrasonic dispersion for 20-90 min, and stirring and refluxing for 2-20 h at a constant temperature of 35-80 ℃. Cooling to normal temperature, diluting with 300-1000 mL deionized water, and centrifuging for multiple times at a rotation speed of 5000-20000 Xg until the supernatant is neutral. Filtering, freeze-drying for 10-20 h, and collecting the lower-layer precipitate for later use;

(2) placing 0.2-1.5 g of the sample collected in the step (1) into 50-200 mL of deionized water, adding aniline with the mass being 0.5-2 times of that of the multi-walled carbon nanotube and sulfosalicylic acid with the mass being 1-5 times of that of an aniline monomer, performing ultrasonic dispersion for 20-90 min, transferring the mixture to a reactor, performing rapid stirring at normal temperature, melting ammonium persulfate oxidant with the mass being 0.5-2 times of that of the aniline monomer into 20-100 mL of deionized water, dropwise adding the mixture into a reaction system, and performing stirring reaction for 5-20 h at the temperature of 0-10 ℃. Filtering and washing the mixture by using absolute ethyl alcohol and distilled water respectively, freeze-drying the mixture for 10-20 hours, and collecting a sample for later use;

(3) slowly stirring 0.1-30 g of natural skin collagen aggregate at 30-70 ℃ for 5-60 min to disperse the natural skin collagen aggregate in 10-100 mL of deionized water, and transferring the mixture to a reactor. Taking a sample which is 0.03-1 time of the collagen in mass and collected in the step (2), ultrasonically dispersing the sample in 30-150 mL of deionized water for 20-90 min, dropwise adding the sample into a collagen solution, adding 0.01-10 g of glycerol, and stirring at normal temperature for 2-10 h; and collecting the mixed solution, and drying the mixed solution in a mold at normal temperature to obtain a novel collagen aggregate-conductive polyaniline-carbon nanotube-glycerin humidity sensitive layer with a multilayer structure and an internal three-dimensional structure, wherein the thickness of the novel collagen aggregate-conductive polyaniline-carbon nanotube-glycerin humidity sensitive layer is 0.1-1 mm. Conductive graphite was sprayed on the substrate using a spray gun using a humidity sensing film of 1 × 2cm as a substrate to form a cross electrode. The interval between adjacent electrodes is 1-5 mm, and the width of interdigital electrode is 1-2 mm.

(4) Slowly stirring 0.1-30 g of natural skin collagen aggregate at 30-70 ℃ for 5-60 min to disperse the natural skin collagen aggregate in 10-100 mL of deionized water, and transferring the deionized water to a reactor; taking a sample which is 0.03-1 time of the mass of the collagen and collected in the step (2), ultrasonically dispersing the sample in 30-150 mL of deionized water for 20-90 min, dropwise adding the sample into a collagen solution, adding 0.01-10 g of a hydrophobic cross-linking agent, and stirring at normal temperature for 2-10 h; the sample was collected. And uniformly and spirally coating 0.1-5 g of the prepared mixture on a base membrane, freeze-drying, and forming under compression of 1-10 MPa to obtain the novel pressure sensitive layer of the collagen aggregate, the conductive polyaniline, the carbon nanotube and the hydrophobic cross-linking agent with the multilayer structure and the internal three-dimensional structure.

Furthermore, the natural skin collagen aggregate is derived from chromium-containing waste skin residues of pigs, cattle, sheep and the like in the leather industry.

Furthermore, the optimal mass ratio of the novel collagen skin aggregate, the conductive polyaniline, the carbon nano tube and the glycerin humidity sensitive layer with the multilayer structure and the internal three-dimensional structure is (0.1-30): (0.1-5): 0.01-10.

Furthermore, the optimal mass ratio of the novel skin collagen aggregate, the conductive polyaniline, the carbon nano tube and the pressure sensitive layer of the hydrophobic cross-linking agent with the 'multi-layer structure' and the internal 'three-dimensional structure' is (0.1-30): (0.1-5): (0.01-10).

Compared with the prior art, the invention has the beneficial effects that:

(1) compared with the existing synthetic material, the high-precision piezoresistive sensor material based on the collagen aggregate has the advantages that the collagen aggregate is adopted and is derived from chromium-containing waste leather residues, the high-value resource recycling of waste is realized, and the prepared high-precision piezoresistive sensor material based on the collagen aggregate has better biocompatibility and biodegradability than the synthetic material.

(2) The invention prepares a novel multifunctional flexible sensor which has a multilayer structure and an internal three-dimensional structure and is sensitive to humidity and pressure.

(3) The conductive matrix is a polyaniline-acidified carbon nanotube composite material, and compared with the traditional conductive particles and conductive fibers, the conductive matrix has the advantages of smaller resistance, higher mechanical strength and greatly increased recycling times.

(4) The invention has the application fields of artificial limbs, intelligent robots, wearable sensors and the like, and has wider application range.

Drawings

Fig. 1 is a schematic structural diagram of a biomimetic multifunctional sensor of the present invention.

Fig. 2 is a partially enlarged schematic view of the bionic multifunctional sensor of the invention.

Fig. 3 shows the sensing mechanism of the multifunctional sensor of the present invention after being stressed.

FIG. 4 is a scanning electron microscope of the microstructure of the cross section of the multifunctional sensor of the present invention.

Fig. 5 is a deformation model of the multifunctional sensor under different stress conditions.

Fig. 6 is an output signal of the multifunctional sensor of the present invention under different pressure conditions.

Fig. 7 is a graph showing the output signals of the multifunctional sensor of the present invention under different humidity conditions.

Fig. 8 is a schematic cross-sectional view of a biomimetic multifunctional sensor of the present invention.

In the figure, 1-piezoelectric layer with multi-layer structure, 2-electrode, 3-base layer, 4-conducting path with higher potential in three-dimensional structure, 5-three-dimensional structure inside piezoelectric layer, 6-conducting path with lower potential in three-dimensional structure.

Detailed Description

The present invention will be described in detail below by way of examples.

Referring to fig. 1-5 and 8, the invention aims to disclose a bionic multifunctional flexible sensor based on a collagen aggregate. Different from the conventional sensor at present, the sensor is characterized in that the natural skin collagen aggregate with excellent biocompatibility and three-dimensional network structure is doped with excellent conductivity. Sensor element materials with high sensitivity to pressure and humidity are respectively prepared by a specific processing method, a piezoelectric layer multi-layer structure and an internal three-dimensional network structure are constructed by assembling the two materials, and a novel flexible multifunctional sensor sensitive to pressure and humidity is successfully prepared. The multifunctional sensor has excellent biological characteristics, and can be widely applied to the fields of intelligent artificial limbs, high-end robots, virtual reality, wearable sensors and the like.

Referring to fig. 1, 2 and 8, the bionic multifunctional flexible sensor based on the collagen aggregate comprises three parts, namely a piezoelectric layer 1, an electrode 2 and a basal layer 3. The piezoelectric layer 1 is a mechanical sensitive layer with a multi-layer structure and an internal three-dimensional reticular structure. The piezoelectric layer 1 may be obtained by modifying a collagen aggregate having a resilient three-dimensional network structure as a matrix so that the collagen aggregate has conductivity.

Referring to fig. 2-4, the conductive paths in the piezoelectric layer 1 are primarily multi-sheet contacts and collagen fibers with conductive material attached in a three-dimensional network structure. In the normal state, the contact of the sheets in the piezoelectric layer 1 is small and the three-dimensional network structure 5 is in a natural extension state, and the number of the connection points of the conductive paths in the three-dimensional piezoelectric layer 1 is also stable, and the conductive paths 4 with the higher electric potential and the conductive paths 6 with the lower electric potential are in a stable state respectively.

When the piezoelectric layer 1 is acted by an external force F, the multiple layers of layers contact (28 Pa < F < 20 KPa), the three-dimensional reticular structure 5 deforms (20 KPa < F < 100 KPa), so that the conductive paths in the structure contact with each other, and the connecting points among the conductive paths are increased. The contact between the conductive path 4 with higher potential and the conductive path 6 with lower potential causes the potential of the mechanically sensitive layer to change, generating an electrical signal.

The mechanical sensitive material can be a high-precision piezoresistive sensor material based on collagen. Such materials can be prepared by the following method: dropwise adding dispersion liquid of the polyaniline-acidified carbon nanotube composite conductive matrix material into the collagen solution, fully stirring, uniformly coating on the surface of the humidity sensing material, and freeze-drying.

The obtained material is characterized in that: the material has the advantages that natural skin collagen with a three-dimensional network structure is used as a matrix, and the conductivity of the material is improved by the polyaniline-acidified carbon nanotube composite conductive matrix dispersed in the matrix.

The substrate layer 3 is made of a humidity sensitive material. The humidity sensitive material is required to have both conductivity and hygroscopicity, and when the humidity in the material changes, the electrical property or potential in the humidity sensitive material changes to generate an electrical signal.

The humidity sensitive material of the present embodiment is different from the mechanical sensitive material mainly in that the humidity sensitive material should have a moisture absorption property, and when the humidity changes, the moisture absorption of the material causes the change of the electrical property. Whereas a mechanically sensitive material should change its electrical properties as the material deforms.

Therefore, the humidity sensitive material according to the present example can be prepared by the following method: dropwise adding the dispersion liquid of the polyaniline-acidified carbon nanotube composite conductive matrix material and a moisture absorbent (such as ethylene glycol, glycerol and the like) into the collagen solution, fully stirring, and drying at room temperature to obtain the high-precision humidity sensor material based on the collagen skin aggregate.

The obtained material is characterized in that: the natural skin collagen is used as a matrix, the polyaniline-acidified carbon nanotube composite conductive matrix dispersed in the matrix improves the conductivity of the material, and the hygroscopicity of the moisture absorbent combined in the conductive matrix is utilized to influence the electrical performance of the product.

Preferably, in order to prevent moisture absorption of the piezoelectric layer 1 from affecting the accuracy of the humidity sensor of the substrate layer 3, the piezoelectric layer 1 may be subjected to a hydrophobic treatment. For example, a hydrophobic segment, a hydrophobic group, or the like may be introduced into the mechanically sensitive material.

The electrode layer 2 is arranged between the mechanical sensitive layer and the humidity sensitive layer and is simultaneously connected with the mechanical sensitive layer and the humidity sensitive layer respectively. The electrode selected for the electrode layer 2 is preferably an interdigital electrode.

Example one

(1) Acidifying the multi-wall carbon nano tube: putting 0.2 g, 20 g and 0.02 g of multi-walled carbon nano-tube, concentrated sulfuric acid and concentrated nitric acid in a reactor, ultrasonically dispersing for 20 min, and then stirring and refluxing for 2 h at the constant temperature of 80 ℃. Cooling to normal temperature, diluting with 300 mL deionized water, and centrifuging for multiple times at a rotation speed of 5000 Xg until the supernatant is neutral. Filtering, freeze-drying for 10 h, and collecting the lower-layer precipitate for later use;

(2) placing 0.15 g of the sample collected in the step (1) into 50 mL of deionized water, adding aniline with the mass of 0.3 g and sulfosalicylic acid with the mass of 4.44 g, ultrasonically dispersing for 20 min, transferring to a reactor, rapidly stirring at normal temperature, melting ammonium persulfate oxidant with the mass of 1.58 g into 100 mL of deionized water, dropwise adding to the reaction system, and stirring and reacting at 0 ℃ for 5 h. Filtering and washing with absolute ethyl alcohol and distilled water respectively, freeze-drying for 10 h, and collecting samples for later use;

(3) 0.1 g of natural skin collagen aggregate is taken and slowly stirred for 5 min at the temperature of 70 ℃ so as to be dispersed in 10 mL of deionized water, and then the mixture is transferred to a reactor. Taking a sample with the mass of 0.1 g and collected in the step (2), dispersing the sample in 30mL of deionized water by ultrasonic treatment for 20 min, dropwise adding the sample into a collagen solution, adding 0.01 g of glycerol, and stirring at normal temperature for 2 h; and collecting the mixed solution, and drying in a mold at normal temperature to obtain the humidity sensing film with the thickness of 0.1 mm. Conductive graphite was sprayed on the substrate using a spray gun using a humidity sensing film of 1 × 2cm as a substrate to form a cross electrode. The interval between the adjacent electrodes is 1mm, the width of the interdigital electrode is 2 mm,

(4) slowly stirring 0.1 g of natural skin collagen aggregate at 70 ℃ for 5 min to disperse the natural skin collagen aggregate in 10 mL of deionized water, and transferring the mixture to a reactor; taking a sample which is 0.03-1 time of the mass of the collagen and collected in the step (2), ultrasonically dispersing the sample in 30mL of deionized water for 20 min, dropwise adding the sample into a collagen solution, adding 0.01 g of KH570 hydrophobic cross-linking agent, and stirring the mixture at normal temperature for 2 hours; the sample was collected. 0.1 g of the prepared mixture was uniformly spin-coated on a base film, freeze-dried, and molded under compression of 1 MPa.

Example two

(1) Acidifying the multi-wall carbon nano tube: placing 1 g, 40 g and 10 g of multi-walled carbon nano-tube, concentrated sulfuric acid and concentrated nitric acid in a reactor, ultrasonically dispersing for 40 min, and then stirring and refluxing for 5h at the constant temperature of 65 ℃. Cooling to normal temperature, diluting with 400 mL deionized water, and centrifuging to obtain supernatant at 9500 Xg for several times. Filtering, freeze-drying for 12 h, and collecting the lower-layer precipitate for later use;

(2) placing 0.5 g of the sample collected in the step (1) into 80 mL of deionized water, adding aniline with the mass of 0.8 g and sulfosalicylic acid with the mass of 6.46 g, ultrasonically dispersing for 40 min, transferring to a reactor, rapidly stirring at normal temperature, melting ammonium persulfate oxidant with the mass of 1.75 g into 80 mL of deionized water, dropwise adding into a reaction system, and stirring and reacting for 7 h at the temperature of 2.5 ℃. Filtering and washing with absolute ethyl alcohol and distilled water respectively, freeze-drying for 12 h, and collecting samples for later use;

(3) 8 g of the natural skin collagen aggregate is slowly stirred for 20 min at the temperature of 60 ℃ and dispersed in 30mL of deionized water, and then the mixture is transferred to a reactor. Taking a sample with the mass of 0.35 g and collected in the step (2), dispersing the sample in 60 mL of deionized water by ultrasonic wave for 40 min, dropwise adding the sample into a collagen solution, adding 2 g of glycerol, and stirring at normal temperature for 4 hours; and collecting the mixed solution, and drying in a mold at normal temperature to obtain the humidity sensing film with the thickness of 0.3 mm. Conductive graphite was sprayed on the substrate using a spray gun using a humidity sensing film of 1 × 2cm as a substrate to form a cross electrode. The interval between the adjacent electrodes is 1.5 mm, the width of the interdigital electrode is 1.75 mm,

(4) taking 8 g of natural skin collagen aggregate, slowly stirring for 20 min at 60 ℃ to disperse the natural skin collagen aggregate in 30mL of deionized water, and transferring the natural skin collagen aggregate to a reactor; taking a sample which is 0.5 time of the mass of the collagen and is collected in the step (2), dispersing the sample in 60 mL of deionized water by ultrasonic wave for 40 min, dropwise adding the sample into a collagen solution, adding 2.5 g of KH570 hydrophobic cross-linking agent, and stirring the mixture at normal temperature for 3.5 h; the sample was collected. 1.5 g of the prepared mixture was uniformly spin-coated on a base film, freeze-dried, and molded under compression of 3 MPa.

EXAMPLE III

(1) Acidifying the multi-wall carbon nano tube: placing 1.5 g, 75 g and 75 g of multi-walled carbon nano-tube, concentrated sulfuric acid and concentrated nitric acid in a reactor, ultrasonically dispersing for 60 min, and then stirring and refluxing for 10 h at the constant temperature of 50 ℃. Cooled to normal temperature, diluted with 500 mL of deionized water, and centrifuged several times to neutralize the supernatant at 13500 Xg. Filtering, freeze-drying for 15 h, and collecting the lower-layer precipitate for later use;

(2) putting 1 g of the sample collected in the step (1) into 120 mL of deionized water, adding aniline with the mass of 1 g and sulfosalicylic acid with the mass of 8.87 g, ultrasonically dispersing for 60 min, transferring to a reactor, rapidly stirring at normal temperature, melting ammonium persulfate oxidant with the mass of 2.01 g into 60 mL of deionized water, dropwise adding to a reaction system, and stirring and reacting for 10 h at the temperature of 5 ℃. Filtering and washing with absolute ethyl alcohol and distilled water respectively, freeze-drying for 15 h, and collecting a sample for later use;

(3) 15 g of the natural skin collagen aggregate is taken and slowly stirred for 30 min at the temperature of 50 ℃ so as to be dispersed in 50 mL of deionized water, and then the mixture is transferred to a reactor. Taking a sample with the mass of 0.75 g and collected in the step (2), dispersing the sample in 90 mL of deionized water by ultrasonic for 60 min, dropwise adding the sample into a collagen solution, adding 5 g of glycerol, and stirring at normal temperature for 5 hours; and collecting the mixed solution, and drying in a mold at normal temperature to obtain the humidity sensing film with the thickness of 0.5 mm. Conductive graphite was sprayed on the substrate using a spray gun using a humidity sensing film of 1 × 2cm as a substrate to form a cross electrode. The interval between adjacent electrodes is 2.5 mm, and the width of interdigital electrode is 1.5 mm.

(4) Taking 15 g of natural skin collagen aggregate, slowly stirring for 30 min at 50 ℃ to disperse the natural skin collagen aggregate in 50 mL of deionized water, and transferring the natural skin collagen aggregate to a reactor; taking a sample which is 0.75 time the mass of collagen and collected in the step (2), ultrasonically dispersing the sample in 90 mL of deionized water for 60 min, dropwise adding the sample into a collagen solution, adding 5 g of KH570 hydrophobic cross-linking agent, and stirring the mixture at normal temperature for 5 hours; the sample was collected. 2.5 g of the prepared mixture was uniformly spin-coated on a base film, freeze-dried, and molded under compression of 5 MPa.

Example four

(1) Acidifying the multi-wall carbon nano tube: placing 2 g, 100 g and 30 g of multi-walled carbon nano-tube, concentrated sulfuric acid and concentrated nitric acid in a reactor, ultrasonically dispersing for 75 min, and then stirring and refluxing for 15 h at the constant temperature of 45 ℃. Cooling to normal temperature, diluting with 750 mL deionized water, and centrifuging to obtain supernatant at 17500 Xg for multiple times. Filtering, freeze-drying for 17 h, and collecting the lower-layer precipitate for later use;

(2) placing 1.3 g of the sample collected in the step (1) into 160 mL of deionized water, adding aniline with the mass of 0.85 g and sulfosalicylic acid with the mass of 3.45 g, ultrasonically dispersing for 75 min, transferring to a reactor, rapidly stirring at normal temperature, melting ammonium persulfate oxidant with the mass of 1.4 g into 40 mL of deionized water, dropwise adding to the reaction system, and stirring and reacting at 7.5 ℃ for 15 h. Filtering and washing with anhydrous ethanol and distilled water, freeze drying for 17.5 h, and collecting sample;

(3) the 24 g of natural skin collagen aggregate is slowly stirred for 45 min at 40 ℃ and dispersed in 75 mL of deionized water, and then transferred to a reactor. Taking a sample with the mass of 0.85 g and collected in the step (2), ultrasonically dispersing for 75 min in 120 mL of deionized water, dropwise adding the sample into a collagen solution, adding 7.5 g of glycerol, and stirring at normal temperature for 7.5 h; and collecting the mixed solution, and drying in a mold at normal temperature to obtain the humidity sensing film with the thickness of 0.75 mm. Conductive graphite was sprayed on the substrate using a spray gun using a humidity sensing film of 1 × 2cm as a substrate to form a cross electrode. The interval between adjacent electrodes is 4 mm, and the width of interdigital electrode is 1.25 mm.

(4) Taking 20 g of natural skin collagen aggregate, slowly stirring for 45 min at 40 ℃ to disperse the natural skin collagen aggregate in 75 mL of deionized water, and transferring the natural skin collagen aggregate to a reactor; taking a sample which is 0.9 time the mass of collagen and collected in the step (2), dispersing the sample in 120 mL of deionized water by ultrasonic wave for 80 min, dropwise adding the sample into a collagen solution, adding 7.5 g of KH570 hydrophobic cross-linking agent, and stirring at normal temperature for 7.5 h; the sample was collected. 4 g of the prepared mixture was uniformly spin-coated on a base film, freeze-dried, and molded under compression of 7.5 MPa.

EXAMPLE five

(1) Acidifying the multi-wall carbon nano tube: placing 2.5 g, 100 g and 200 g of multi-walled carbon nano-tube, concentrated sulfuric acid and concentrated nitric acid in a reactor, ultrasonically dispersing for 90 min, and then stirring and refluxing for 20 h at the constant temperature of 35 ℃. Cooling to normal temperature, diluting with 1000 mL deionized water, and centrifuging at 20000 × g for several times until the supernatant is neutral. Filtering, freeze-drying for 20 h, and collecting the lower-layer precipitate for later use;

(2) placing 1.5 g of the sample collected in the step (1) into 200 mL of deionized water, adding aniline with the mass of 0.75 g and sulfosalicylic acid with the mass of 2.22 g, ultrasonically dispersing for 90 min, transferring to a reactor, rapidly stirring at normal temperature, melting ammonium persulfate oxidant with the mass of 0.98 g into 20 mL of deionized water, dropwise adding to the reaction system, and stirring and reacting at 10 ℃ for 20 h. Filtering and washing with absolute ethyl alcohol and distilled water respectively, freeze-drying for 20 h, and collecting samples for later use;

(3) 30 g of natural skin collagen aggregate is taken and slowly stirred for 60 min at the temperature of 30 ℃ to be dispersed in 100 mL of deionized water, and then the mixture is transferred to a reactor. Taking a sample with the mass of 1 g collected in the step (2), dispersing the sample in 150 mL of deionized water by ultrasonic for 90 min, dropwise adding the sample into a collagen solution, adding 10 g of glycerol, and stirring at normal temperature for 10 hours; and collecting the mixed solution, and drying in a mold at normal temperature to obtain the humidity sensing film with the thickness of 1 mm. Conductive graphite was sprayed on the substrate using a spray gun using a humidity sensing film of 1 × 2cm as a substrate to form a cross electrode. The interval between adjacent electrodes is 5 mm, and the width of interdigital electrode is 1 mm.

(4) Taking 30 g of natural skin collagen aggregate, slowly stirring for 60 min at 30 ℃ to disperse the natural skin collagen aggregate in 100 mL of deionized water, and transferring the natural skin collagen aggregate to a reactor; taking a sample which is 1 time as much as the collagen and is collected in the step (2), dispersing the sample in 150 mL of deionized water by ultrasonic for 90 min, dropwise adding the sample into a collagen solution, adding 10 g of KH570 hydrophobic cross-linking agent, and stirring the mixture at normal temperature for 10 hours; the sample was collected. 5 g of the prepared mixture was uniformly spin-coated on a base film, freeze-dried, and molded under compression of 10 MPa.

It should be noted that the present embodiment is specifically and exclusively intended for further illustration of the invention and should not be construed as limiting the scope of the invention, since non-essential modifications and adaptations thereof will occur to those skilled in the art in light of the foregoing description.

Claims

1. A bionic multifunctional flexible sensor based on a collagen aggregate is characterized by comprising:

the mechanical sensitive layer is provided with a multi-layer structure and an internal three-dimensional reticular structure, and is obtained by taking a collagen aggregate with a rebound resilience three-dimensional reticular structure as a matrix and modifying the collagen aggregate to enable the collagen aggregate to have conductivity; when the mechanical sensitive layer deforms, the sheet layers in the sheet layer structure are in mutual contact and/or the three-dimensional net structure deforms, so that the potential of the mechanical sensitive layer changes, and an electric signal is generated;

the humidity sensitive layer is obtained by taking a collagen aggregate as a matrix and modifying the collagen aggregate to ensure that the collagen aggregate has both conductivity and hygroscopicity; when the humidity changes, the humidity sensitive layer absorbs moisture to cause the electrical property or the electric potential of the humidity sensitive layer to change, and an electric signal is generated;

and the electrode layer is arranged between the mechanical sensitive layer and the humidity sensitive layer and is respectively connected with the mechanical sensitive layer and the humidity sensitive layer.

2. The sensor of claim 1, wherein the mechanically sensitive layer is a high precision piezoresistive sensor material based on collagen.

3. The sensor of claim 2, wherein the high precision, collagen-based piezoresistive sensor material is hydrophobically treated.

4. The sensor of claim 1, wherein the moisture sensitive layer is formed by dispersing a polyaniline-acidified carbon nanotube composite conductive matrix in a collagen aggregate matrix to obtain conductivity and modifying to enhance hygroscopicity.

5. The sensor of claim 4, wherein the humidity sensitive material used in the humidity sensitive layer is obtained by a method comprising the steps of: and adding the polyaniline-acidified carbon nanotube composite conductive matrix material and glycerol into the collagen aggregate solution, fully stirring and drying to obtain the collagen aggregate-based high-precision humidity sensor material.

6. A collagen aggregate-based high-precision humidity sensor material for use in the sensor according to any one of claims 1 to 5, wherein the humidity sensitive layer is obtained by dispersing a polyaniline-acidified carbon nanotube composite conductive matrix in a collagen aggregate matrix to obtain electrical conductivity and modifying to enhance the hygroscopicity.

7. The humidity sensor material of claim 6, obtained by a method comprising the steps of: adding a polyaniline-acidified carbon nanotube composite conductive matrix material and glycerol into the collagen aggregate solution, fully stirring and drying to obtain a collagen aggregate-based high-precision humidity sensor material; the mass ratio of the collagen aggregate, polyaniline, the acidified carbon nanotube and glycerol is (0.1-30): (0.1-5): 0.01-10).

8. A preparation method of a bionic multifunctional flexible sensor based on a collagen aggregate is characterized by comprising the following steps:

adding a polyaniline-acidified carbon nanotube composite conductive matrix material and glycerol into the collagen aggregate solution, uniformly mixing, and drying to obtain a humidity sensitive layer;

spraying conductive graphite on the surface of the humidity sensitive layer to obtain an electrode layer;

adding a polyaniline-acidified carbon nanotube composite conductive matrix material into the collagen aggregate solution to obtain a precursor solution of the mechanical sensitive material;

and constructing a precursor solution of the mechanical sensitive material on the surface of the electrode layer, freeze-drying, and press-forming to obtain the mechanical sensitive layer with the three-dimensional network structure.

9. The method according to claim 8, wherein a hydrophobic cross-linking agent is further added to the precursor solution of the mechanically sensitive material, and the mass ratio of the collagen aggregate, polyaniline, the acidified carbon nanotube and the hydrophobic cross-linking agent is (0.1-30): 0.1-5): 0.01-10.

10. The method of claim 8, comprising the steps of:

1) placing multi-walled carbon nanotubes, concentrated sulfuric acid and concentrated nitric acid in a mass ratio of (0.1-1): 0.1-100) into a reactor, performing ultrasonic dispersion for 20-90 min, and then stirring and refluxing for 2-20 h at a constant temperature of 35-80 ℃; cooling to normal temperature, diluting with 300-1000 mL of deionized water, and centrifuging for multiple times at a rotation speed of 5000-20000 Xg until the supernatant is neutral; filtering, freeze-drying for 10-20 h, and collecting the lower-layer precipitate to obtain an acidified carbon nanotube;

2) placing 0.2-1.5 g of acidified carbon nano tube into 50-200 mL of deionized water, adding aniline in an amount which is 0.5-2 times the mass of the acidified carbon nano tube and sulfosalicylic acid in an amount which is 1-5 times the mass of an aniline monomer, performing ultrasonic dispersion for 20-90 min, transferring to a reactor, and rapidly stirring at normal temperature; melting ammonium persulfate oxidant in an amount which is 0.5-2 times of that of aniline monomer into 20-100 mL of deionized water, dropwise adding the mixture into a reaction system, and stirring and reacting for 5-20 hours at the temperature of 0-10 ℃; filtering and washing the polyaniline-acidified carbon nanotube composite conductive matrix material by using absolute ethyl alcohol and distilled water respectively, freeze-drying the mixture for 10-20 hours, and collecting a sample to obtain the polyaniline-acidified carbon nanotube composite conductive matrix material;

3) slowly stirring 0.1-30 g of natural skin collagen aggregate at 30-70 ℃ for 5-60 min to disperse the natural skin collagen aggregate in 10-100 mL of deionized water, and transferring the deionized water to a reactor; taking a polyaniline-acidified carbon nanotube composite conductive matrix material with 0.03-1 time of the mass of collagen, ultrasonically dispersing the polyaniline-acidified carbon nanotube composite conductive matrix material in 30-150 mL of deionized water for 20-90 min, dropwise adding the polyaniline-acidified carbon nanotube composite conductive matrix material into a collagen solution, adding 0.01-10 g of glycerol, and stirring at normal temperature for 2-10 h; collecting the mixed solution, and drying the mixed solution in a mold at normal temperature to obtain a humidity sensing film with the thickness of 0.1-1 mm;

spraying conductive graphite on a substrate by using a spray gun by taking a humidity sensing film of 1cm multiplied by 2cm as the substrate to form a crossed electrode; the interval between adjacent electrodes is 1-5 mm, and the width of the interdigital electrode is 1-2 mm;

4) slowly stirring 0.1-30 g of natural skin collagen aggregate at 30-70 ℃ for 5-60 min to disperse the natural skin collagen aggregate in 10-100 mL of deionized water, and transferring the deionized water to a reactor; taking a polyaniline-acidified carbon nanotube composite conductive matrix material with 0.03-1 time of the mass of collagen, ultrasonically dispersing the polyaniline-acidified carbon nanotube composite conductive matrix material in 30-150 mL of deionized water for 20-90 min, dropwise adding the polyaniline-acidified carbon nanotube composite conductive matrix material into a collagen solution, adding 0.01-10 g of a hydrophobic cross-linking agent KH570, and stirring at normal temperature for 2-10 h; collecting a sample; and uniformly spin-coating 0.1-5 g of the prepared mixture on a base film, freeze-drying, and forming under the compression of 1-10 MPa.