CN111189566B - Pressure sensor based on self-assembled cellulose nanocrystals and preparation method thereof - Google Patents
Pressure sensor based on self-assembled cellulose nanocrystals and preparation method thereof Download PDFInfo
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
- G01L1/00—Measuring force or stress, in general
- G01L1/18—Measuring force or stress, in general using properties of piezo-resistive materials, i.e. materials of which the ohmic resistance varies according to changes in magnitude or direction of force applied to the material
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Abstract
The invention discloses a pressure sensor based on self-assembled cellulose nanocrystals and a preparation method thereof. The pressure sensor takes hydrogel as an elastic base material, and takes reversible left-handed polarized light wavelength reflected by a self-assembled cellulose nanocrystal-based chiral nematic liquid crystal structure as a response signal transmission path. The preparation method comprises the following steps: the method comprises four stages of preparation of a cellulose nanocrystal dispersion system, synthesis of a hydrogel precursor, evaporation-induced self-assembly of cellulose nanocrystals, polymerization of the hydrogel precursor and the like; the sensitivity of the pressure sensor of the invention is-0.07 kPa‑1~‑0.16kPa‑1The response time is 50 ms-80 ms, and the working pressure range is 0 kPa-12 kPa; the pressure sensor based on the self-assembly cellulose nanocrystalline not only reduces the dependence of the pressure sensor on metal materials and semiconductor materials, but also obviously reduces the production cost and meets the requirements of sustainable development.
Description
Technical Field
The invention belongs to the technical field of cellulose-based functional materials, and particularly relates to a pressure sensor taking hydrogel as an elastic base material and taking reversible left-handed polarized light wavelength reflected by a self-assembled cellulose nanocrystal-based chiral nematic liquid crystal structure as a response signal transmission path and a preparation method thereof.
Background
In recent years, along with the popularization of smart terminals, flexible devices such as wearable devices have a huge market prospect [ Li, d., Lai, w. y., Zhang, y. z., Huang, w. Printable flexible conductive films for flexible electronics, Advanced Materials, 2018, 10 ]. As a core component of wearable devices, pressure sensors capable of responding to signals such as external mechanical force have been receiving much attention from researchers [ qian, sumeng, leeward, songbing.
According to different working principles, common pressure sensors mainly include piezoresistive pressure sensors [ Gong, s., Schwalb, w., Wang, y., Chen, y., Tang, y., Si, j., shirnzadeh, b., Cheng, w. a wearable and high sensitive pressure sensor with ultra thin gold electrodes, Nature Communications, 2014, 5; liu, w. j, Liu, n. s, Yue, y, Rao, j, Cheng, f, Su, j, Liu, z, Gao, y, piezoresponsive pressure sensor based on synthetic in-situ interaction with polyvinyl alcohol capillary/graphene file, Small, 2018, 15; wang, t, Li, j, h, Zhang, y, Liu, f, Zhang, b, Wang, y, Jiang, r, Zhang, g, Sun, r, Wong, c.p. high ordered 3D porous graphene junction for a Capacitive piezoelectric transducer application, Chemistry-a European Journal, 2019, 25, Capacitive pressure sensors that change the distance between the two electrodes and further affect their capacitance by applying an external force [ front, a, Muth, j.t., Vogt, d.m., meng. ç, y., Campo, a, Walsh, a. d.d., c.j.j.g., c.j.a. cable, c.a. ceramic, a. piezoelectric transducer 27, piezoelectric transducer 2016, piezoelectric transducer 27, nano piezoelectric transducer 27, piezoelectric transducer 27, nano piezoelectric transducer; pan, c, Dong, l, Zhu, g, Niu, s, Yu, r, Yang, q, Liu, y, Wang, z.l. High-resolution electronic imaging of pressure distribution using a piezoelectric nanowire LED array, Nature Photonics, 2013, 7] and triboelectric and self-generating pressure sensors [ Fan, f.r., Lin, l.s., Zhu, g, Wu, w, Zhang, r, wave, z.l. transducer, triboelectric nanoparticles and selected-powered sensor on microscopic filters, and the like, are subject to various types of process-related structural changes based on various types of operational factors, such as signal sensitivity, signal-response-level, and the like, which are influenced by process-related changes in the operating range.
At present, researchers mainly improve the response performance of pressure sensors by means of micro-processing technologies such as photolithography to prepare complex conductive parts and fine internal structures or to obtain electronic paths with excellent conductivity by using noble metals and the like [ Xiao, j. l., Tan, y. q., Song, y. h., Zheng, q. a flash and super elastic graphene aerogen as a high-capacity adsorption and high-capacity sensitive sensitivity sensor, Journal of Materials Chemistry a, 2018, 19 ]. However, relying on micromachining techniques to improve the performance of pressure sensors leads to a significant increase in production costs [ zhao academic peak, treble, high flying, zhangxidong, yan tree, flexible pressure sensing characteristic studies based on CNTs/PDMS dielectric layers, academic papers on sensing techniques, 2017, 7], and in addition, electrodes and electronic paths based on noble metals or semiconductors in the structure of pressure sensors are also subject to an environment-friendly dilemma of undegradeability and difficult recycling [ Liu, s, b, Wu, x, Zhang, d, Guo, c, Wang, p, Hu, w, Li, x, Zhou, x, Xu, h, lo, c, Zhang, j, Chu, j, ultra fast gases sensor based on bridged graphics structure, ACS, Materials & 28, 2017 ]. Therefore, under the dual constraints of cost and environment, the performance improvement and wide popularization of the traditional pressure sensor face huge pressure, and efficient and environment-friendly pressure response is difficult to realize.
Disclosure of Invention
The invention aims to solve the technical problems of cost increase and environmental pressure caused by excessive dependence on complex internal structures and electrode materials such as metal and the like for performance improvement of the traditional pressure sensor, and provides a pressure sensor based on self-assembly cellulose nanocrystals and a preparation method thereof. In particular to a pressure sensor which takes hydrogel as an elastic base material and takes reversible left-handed polarized light wavelength reflected by a self-assembled cellulose nanocrystal-based chiral nematic liquid crystal structure as a response signal transmission path and a preparation method thereof. The pressure sensor can show a visual pressure response based on stable structural color under the action of external pressure.
In order to solve the technical problems, the invention adopts the following technical scheme:
a pressure sensor based on self-assembly cellulose nanocrystals takes hydrogel as an elastic base material and takes reversible left-handed polarized light wavelength reflected by a self-assembly cellulose nanocrystal-based chiral nematic liquid crystal structure as a response signal transmission path. The sensitivity of the pressure sensor based on the self-assembled cellulose nanocrystals is-0.07 kPa-1~-0.16kPa-1The response time is 50 ms-80 ms, and the working pressure range is 0 kPa-12 kPa.
A pressure sensor based on self-assembled cellulose nanocrystals is prepared by the following steps:
(1) firstly, hydrolyzing microcrystalline cellulose with the polymerization degree of 200-220 by using a sulfuric acid aqueous solution, and washing the hydrolyzed microcrystalline cellulose to a pH value of 7 by using distilled water through vacuum filtration;
(2) drying the washed hydrolyzed microcrystalline cellulose at low temperature to constant weight, and preparing a hydrolyzed microcrystalline cellulose dispersion system by using distilled water;
(3) carrying out high-pressure homogenization treatment on the hydrolyzed microcrystalline cellulose dispersion system to obtain a cellulose nanocrystalline dispersion system;
(4) mixing a hydrogel precursor formed by mixing a hydrogel monomer, a cross-linking agent and an initiator with the cellulose nanocrystal dispersion system prepared in the step (3) in a dark room at the temperature of 20 ℃, and mechanically stirring to obtain a cellulose nanocrystal/hydrogel precursor composite with a uniform structure;
(5) under the conditions of light protection and nitrogen protection, carrying out evaporation induction on the cellulose nanocrystal/hydrogel precursor composite prepared in the step (4) to obtain a self-assembled cellulose nanocrystal-based chiral nematic liquid crystal structure/hydrogel precursor composite;
(6) and (3) processing the self-assembly cellulose nanocrystalline-based chiral nematic liquid crystal structure/hydrogel precursor compound obtained in the step (5) in an ultraviolet irradiation mode, initiating polymerization of a hydrogel monomer in the compound, and preparing the self-assembly cellulose nanocrystalline-based chiral nematic liquid crystal structure/hydrogel compound, namely the pressure sensor based on the self-assembly cellulose nanocrystalline.
Further, in the step (1), the mass fraction of the sulfuric acid aqueous solution is 35%, the mass ratio of the microcrystalline cellulose to the sulfuric acid aqueous solution is 1:4, the hydrolysis time is 3 hours, and the water bath temperature is 55 ℃; the whole hydrolysis process needs mechanical stirring, and the rotating speed is 30 r/min.
Further, in the step (2), the drying temperature is 45 ℃, the drying time is 48 hours, and the mass fraction of the hydrolyzed microcrystalline cellulose dispersion system prepared by using distilled water is 1.0%.
Further, in the step (3), the pressure of the high-pressure homogenization treatment is 100MPa, and the cycle number is 3; the obtained cellulose nanocrystal has the length of 100 nm-200 nm and the diameter of 30 nm-40 nm.
Further, in the step (4), the light transmission wavelength range of the safety lamp light filter of the darkroom is 600 nm-800 nm, and the hydrogel monomer is a nonionic hydrogel monomer and comprises acrylamide, N-isopropylacrylamide, acrylic acid and vinyl pyrrolidone; the cross-linking agent is N, N-methylene bisacrylamide, and the initiator is 2, 2-diethoxyacetophenone.
Further, in the step (4), the mass ratio of the cellulose nanocrystalline particles, the hydrogel monomer, the cross-linking agent and the initiator in the cellulose nanocrystalline/hydrogel precursor composite is (60-65): 30-35): 1.5-2: 3-3.5; the mechanical stirring speed in the mixing process is 30 r/min.
Further, in the step (5), the flow of the protective nitrogen is 20ml/min, the time of evaporation induction is 5-7 days, the temperature is 35 ℃, and the relative humidity is 55%.
Further, in the step (6), the power of the ultraviolet irradiation is 1000w, the wavelength is 365nm, and the distance between the light source and the self-assembled cellulose nanocrystal-based chiral nematic liquid crystal structure/hydrogel precursor composite is 35 cm.
The invention has the beneficial effects that: (1) the invention provides an effective way for preparing a pressure sensor by using self-assembled cellulose nanocrystals and hydrogel; (2) the hydrogel is used as an elastic base material, and reversible left-handed polarized light wavelength reflected by a self-assembled cellulose nanocrystal-based chiral nematic liquid crystal structure is used as a pressure response signal transmission path, so that an efficient and environment-friendly visual pressure response mechanism is provided; (3) the pressure sensor based on the self-assembled cellulose nanocrystals is mainly prepared from cellulose nanocrystals obtained by hydrolyzing natural cellulose with sulfuric acid, so that the dependence of the pressure sensor on metal materials and semiconductor materials in the preparation process is remarkably reduced; (4) the pressure sensor based on the self-assembly cellulose nanocrystalline realizes low-cost and high-efficiency structural order by utilizing an evaporation-induced self-assembly process, and can obviously improve the response performance of the pressure sensor and reduce the production cost.
Drawings
FIG. 1 is an SEM image of the cross section of the self-assembled cellulose nanocrystal-based chiral nematic liquid crystal structure/hydrogel composite of the present invention.
FIG. 2 is a flow chart of the preparation of the pressure sensor based on the self-assembled cellulose nanocrystals according to the present invention.
Detailed Description
The present invention will be further described with reference to the following examples. It is to be understood that the following examples are illustrative only and are not intended to limit the scope of the invention, which is to be given numerous insubstantial modifications and adaptations by those skilled in the art based on the teachings set forth above.
Example 1
The preparation method of the pressure sensor based on the self-assembled cellulose nanocrystals of the present embodiment is as follows:
(1) uniformly mixing 100g of 35% sulfuric acid aqueous solution and 25g of microcrystalline cellulose, hydrolyzing for 3h at 55 ℃, mechanically stirring at a rotating speed of 30r/min during the hydrolysis process, and washing the hydrolyzed microcrystalline cellulose to a pH value of 7 by using distilled water through vacuum filtration after the hydrolysis is finished;
(2) drying the washed hydrolyzed microcrystalline cellulose at 45 ℃ for 48h to constant weight to obtain 18.2g of hydrolyzed microcrystalline cellulose, and preparing a hydrolyzed microcrystalline cellulose dispersion system with the mass fraction of 1.0% from 5g of hydrolyzed microcrystalline cellulose and 495g of distilled water;
(3) carrying out high-pressure homogenization treatment on the hydrolyzed microcrystalline cellulose dispersion system under the condition of 100MPa, wherein the cycle number is 3 times, and 487.2g of cellulose nanocrystalline dispersion system is obtained;
(4) under the conditions of a dark room and a temperature of 20 ℃, 400g of the cellulose nanocrystal dispersion system is mixed with 2.3g of acrylamide, 0.13g of N, N-methylene bisacrylamide and 0.21g of 2, 2-diethoxyacetophenone, and the mixture is mechanically stirred at a rotating speed of 30r/min to obtain 401.8g of the cellulose nanocrystal/hydrogel precursor composite with a uniform structure;
(5) standing the cellulose nanocrystal/hydrogel precursor composite prepared in the step (4) for 5 days under the conditions of light shielding, nitrogen flow of 20ml/min, temperature of 35 ℃ and relative humidity of 55% for evaporation induction to obtain 17.9g of the self-assembled cellulose nanocrystal-based chiral nematic liquid crystal structure/hydrogel precursor composite;
(6) and (3) placing the self-assembled cellulose nanocrystalline-based chiral nematic liquid crystal structure/hydrogel precursor compound obtained in the step (5) under the ultraviolet illumination condition with the power of 1000w and the wavelength of 365nm to perform hydrogel precursor initiated polymerization, wherein the distance between a light source and the self-assembled cellulose nanocrystalline-based chiral nematic liquid crystal structure/hydrogel precursor compound is 35cm, and 16.5g of the self-assembled cellulose nanocrystalline-based chiral nematic liquid crystal structure/hydrogel precursor compound is initiated.
The sensitivity of the self-assembled cellulose nanocrystalline-based chiral nematic liquid crystal structure/hydrogel composite is-0.07 kPa-1The response time is 80ms, and the working pressure range is 0-12 kPa.
Example 2
The preparation method of the pressure sensor based on the self-assembled cellulose nanocrystals of the present embodiment is as follows:
(1) uniformly mixing 60g of 35% sulfuric acid aqueous solution and 15g of microcrystalline cellulose, hydrolyzing for 3h at 55 ℃, mechanically stirring at a rotating speed of 30r/min during the hydrolysis process, and washing the hydrolyzed microcrystalline cellulose to a pH value of 7 by using distilled water through vacuum filtration after the hydrolysis is finished;
(2) drying the washed hydrolyzed microcrystalline cellulose at 45 ℃ for 48h to constant weight to obtain 11.6g of hydrolyzed microcrystalline cellulose, and preparing a hydrolyzed microcrystalline cellulose dispersion system with the mass fraction of 1.0% from 8g of hydrolyzed microcrystalline cellulose and 792g of distilled water;
(3) carrying out high-pressure homogenization treatment on the hydrolyzed microcrystalline cellulose dispersion system under the condition of 100MPa, wherein the cycle number is 3 times, and 791.5g of cellulose nanocrystalline dispersion system is obtained;
(4) mixing 500g of cellulose nanocrystal dispersion with 2.9g of N-isopropylacrylamide, 0.15g of N, N-methylenebisacrylamide and 0.27g of 2, 2-diethoxyacetophenone in a dark room at the temperature of 20 ℃, and mechanically stirring at the rotating speed of 30r/min to obtain 501.3g of cellulose nanocrystal/hydrogel precursor composite with a uniform structure;
(5) standing the cellulose nanocrystal/hydrogel precursor composite prepared in the step (4) for 7 days for evaporation induction under the conditions of light shielding, nitrogen flow of 20ml/min, temperature of 35 ℃ and relative humidity of 55% to obtain 13.6g of the self-assembled cellulose nanocrystal-based chiral nematic liquid crystal structure/hydrogel precursor composite;
(6) and (3) placing the self-assembled cellulose nanocrystalline-based chiral nematic liquid crystal structure/hydrogel precursor compound obtained in the step (5) under the ultraviolet illumination condition with the power of 1000w and the wavelength of 365nm to perform hydrogel precursor initiated polymerization, wherein the distance between a light source and the self-assembled cellulose nanocrystalline-based chiral nematic liquid crystal structure/hydrogel precursor compound is 35cm, and 12.9g of the self-assembled cellulose nanocrystalline-based chiral nematic liquid crystal structure/hydrogel precursor compound is initiated.
The self-assembled cellulose nanocrystalline-based chiral nematic liquid crystalThe sensitivity of the structure/hydrogel composite was-0.13 kPa-1The response time is 60ms, and the working pressure range is 0-9 kPa.
Example 3
The preparation method of the pressure sensor based on the self-assembled cellulose nanocrystals of the present embodiment is as follows:
(1) uniformly mixing 80g of 35% sulfuric acid aqueous solution and 20g of microcrystalline cellulose, hydrolyzing for 3h at 55 ℃, mechanically stirring at a rotating speed of 30r/min during the hydrolysis process, and washing the hydrolyzed microcrystalline cellulose to a pH value of 7 by using distilled water through vacuum filtration after the hydrolysis is finished;
(2) drying the washed hydrolyzed microcrystalline cellulose at 45 ℃ for 48h to constant weight to obtain 15.3g of hydrolyzed microcrystalline cellulose, and preparing 10g of hydrolyzed microcrystalline cellulose and 990g of distilled water into a hydrolyzed microcrystalline cellulose dispersion system with the mass fraction of 1.0%;
(3) carrying out high-pressure homogenization treatment on the hydrolyzed microcrystalline cellulose dispersion system under the condition of 100MPa, wherein the cycle number is 3 times, and 982.6g of cellulose nanocrystalline dispersion system is obtained;
(4) mixing 600g of the cellulose nanocrystal dispersion system with 2.8g of acrylic acid, 0.16g of N, N-methylene bisacrylamide and 0.31g of 2, 2-diethoxyacetophenone in a dark room at the temperature of 20 ℃, and mechanically stirring at the rotating speed of 30r/min to obtain 600.7g of the cellulose nanocrystal/hydrogel precursor composite with a uniform structure;
(5) standing the cellulose nanocrystal/hydrogel precursor composite prepared in the step (4) for 5 days under the conditions of light shielding, nitrogen flow of 20ml/min, temperature of 35 ℃ and relative humidity of 55% for evaporation induction to obtain 22.5g of the self-assembled cellulose nanocrystal-based chiral nematic liquid crystal structure/hydrogel precursor composite;
(6) and (3) placing the self-assembled cellulose nanocrystalline-based chiral nematic liquid crystal structure/hydrogel precursor compound obtained in the step (5) under the ultraviolet illumination condition with the power of 1000w and the wavelength of 365nm to perform hydrogel precursor initiated polymerization, wherein the distance between a light source and the self-assembled cellulose nanocrystalline-based chiral nematic liquid crystal structure/hydrogel precursor compound is 35cm, and 19.7g of the self-assembled cellulose nanocrystalline-based chiral nematic liquid crystal structure/hydrogel precursor compound is initiated.
The sensitivity of the self-assembled cellulose nanocrystalline-based chiral nematic liquid crystal structure/hydrogel composite is-0.11 kPa-1The response time is 75ms, and the working pressure range is 0-10 kPa.
Example 4
The preparation method of the pressure sensor based on the self-assembled cellulose nanocrystals of the present embodiment is as follows:
(1) uniformly mixing 120g of 35% sulfuric acid aqueous solution and 30g of microcrystalline cellulose, hydrolyzing for 3h at 55 ℃, mechanically stirring at a rotating speed of 30r/min during the hydrolysis process, and washing the hydrolyzed microcrystalline cellulose to a pH value of 7 by using distilled water through vacuum filtration after the hydrolysis is finished;
(2) drying the washed hydrolyzed microcrystalline cellulose at 45 ℃ for 48h to constant weight to obtain 23.1g of hydrolyzed microcrystalline cellulose, and preparing 12g of hydrolyzed microcrystalline cellulose and 1188g of distilled water into a hydrolyzed microcrystalline cellulose dispersion system with the mass fraction of 1.0%;
(3) carrying out high-pressure homogenization treatment on the hydrolyzed microcrystalline cellulose dispersion system under the condition of 100MPa, wherein the cycle number is 3 times, and 1157.6g of cellulose nanocrystalline dispersion system is obtained;
(4) mixing 800g of cellulose nanocrystal dispersion with 3.7g of vinyl pyrrolidone, 0.24g of N, N-methylene bisacrylamide and 0.37g of 2, 2-diethoxyacetophenone in a dark room at the temperature of 20 ℃, and mechanically stirring at the rotating speed of 30r/min to obtain 802.3g of cellulose nanocrystal/hydrogel precursor composite with a uniform structure;
(5) standing the cellulose nanocrystal/hydrogel precursor composite prepared in the step (4) for 7 days for evaporation induction under the conditions of light shielding, nitrogen flow of 20ml/min, temperature of 35 ℃ and relative humidity of 55% to obtain 20.8g of the self-assembled cellulose nanocrystal-based chiral nematic liquid crystal structure/hydrogel precursor composite;
(6) and (3) placing the self-assembled cellulose nanocrystalline-based chiral nematic liquid crystal structure/hydrogel precursor compound obtained in the step (5) under the ultraviolet illumination condition with the power of 1000w and the wavelength of 365nm to perform hydrogel precursor initiated polymerization, wherein the distance between a light source and the self-assembled cellulose nanocrystalline-based chiral nematic liquid crystal structure/hydrogel precursor compound is 35cm, and 18.1g of the self-assembled cellulose nanocrystalline-based chiral nematic liquid crystal structure/hydrogel compound is initiated.
The sensitivity of the self-assembled cellulose nanocrystalline-based chiral nematic liquid crystal structure/hydrogel composite is-0.16 kPa-1The response time is 50ms, and the working pressure range is 0-7 kPa.
The foregoing shows and describes the general principles and features of the present invention, together with the advantages thereof. It will be understood by those skilled in the art that the present invention is not limited to the embodiments described above, which are described in the specification and illustrated only to illustrate the principle of the present invention, but that various changes and modifications may be made therein without departing from the spirit and scope of the present invention, which fall within the scope of the invention as claimed. The scope of the invention is defined by the appended claims and equivalents thereof.
Claims (9)
1. A preparation method of a pressure sensor based on self-assembled cellulose nanocrystals is characterized by comprising the following steps: the pressure sensor firstly utilizes the water phase environment provided by hydrogel to complete the self-assembly process of cellulose nanocrystals, then obtains the self-assembly cellulose nanocrystal-based chiral nematic liquid crystal structure/hydrogel composite material by ultraviolet-initiated hydrogel monomer polymerization, and comprises the following specific steps: firstly, hydrolyzing microcrystalline cellulose with the polymerization degree of 200-220 by using a sulfuric acid aqueous solution, and washing the hydrolyzed microcrystalline cellulose to a pH value of 7 by using distilled water through vacuum filtration;
(2) drying the washed hydrolyzed microcrystalline cellulose at low temperature to constant weight, and preparing a hydrolyzed microcrystalline cellulose dispersion system by using distilled water;
(3) carrying out high-pressure homogenization treatment on the hydrolyzed microcrystalline cellulose dispersion system to obtain a cellulose nanocrystalline dispersion system;
(4) mixing a hydrogel precursor formed by mixing a hydrogel monomer, a cross-linking agent and an initiator with the cellulose nanocrystal dispersion system prepared in the step (3) in a dark room at the temperature of 20 ℃, and mechanically stirring to obtain a cellulose nanocrystal/hydrogel precursor composite with a uniform structure;
(5) under the conditions of light protection and nitrogen protection, carrying out evaporation induction on the cellulose nanocrystal/hydrogel precursor composite prepared in the step (4) to obtain a self-assembled cellulose nanocrystal-based chiral nematic liquid crystal structure/hydrogel precursor composite;
(6) processing the self-assembled cellulose nanocrystalline-based chiral nematic liquid crystal structure/hydrogel precursor compound obtained in the step (5) in an ultraviolet irradiation mode, initiating polymerization of a hydrogel monomer in the compound, and preparing the self-assembled cellulose nanocrystalline-based chiral nematic liquid crystal structure/hydrogel compound, namely the pressure sensor based on the self-assembled cellulose nanocrystalline;
the pressure sensor takes hydrogel as an elastic base material, takes reversible left-handed polarized light wavelength reflected by a self-assembled cellulose nanocrystalline-based chiral nematic liquid crystal structure as a response signal transmission path, and can show visual pressure response based on stable structural color under the action of external pressure.
2. The method for preparing the pressure sensor based on the self-assembled cellulose nanocrystals, as claimed in claim 1, wherein: the sensitivity of the pressure sensor based on the self-assembled cellulose nanocrystals is-0.07 kPa-1~-0.16kPa-1The response time is 50 ms-80 ms, and the working pressure range is 0 kPa-12 kPa.
3. The method for preparing the pressure sensor based on the self-assembled cellulose nanocrystals, as claimed in claim 1, wherein: in the step (1), the mass fraction of the sulfuric acid aqueous solution is 35%, the mass ratio of the microcrystalline cellulose to the sulfuric acid aqueous solution is 1:4, the hydrolysis time is 3h, and the water bath temperature is 55 ℃; the whole hydrolysis process needs mechanical stirring, and the rotating speed is 30 r/min.
4. The method for preparing the pressure sensor based on the self-assembled cellulose nanocrystals, as claimed in claim 1, wherein: in the step (2), the drying temperature is 45 ℃, the drying time is 48 hours, and the mass fraction of the hydrolyzed microcrystalline cellulose dispersion system prepared by distilled water is 1.0%.
5. The method for preparing the pressure sensor based on the self-assembled cellulose nanocrystals, as claimed in claim 1, wherein: in the step (3), the high-pressure homogenization treatment pressure is 100MPa, and the cycle times are 3 times; the obtained cellulose nanocrystal has the length of 100 nm-200 nm and the diameter of 30 nm-40 nm.
6. The method for preparing the pressure sensor based on the self-assembled cellulose nanocrystals, as claimed in claim 1, wherein: in the step (4), the light transmission wavelength range of the safety lamp optical filter of the darkroom is 600 nm-800 nm, the hydrogel monomer is a non-ionic hydrogel monomer and comprises acrylamide, N-isopropyl acrylamide, acrylic acid and vinyl pyrrolidone, the cross-linking agent is N, N-methylene bisacrylamide, and the initiator is 2, 2-diethoxyacetophenone.
7. The method for preparing the pressure sensor based on the self-assembled cellulose nanocrystals, as claimed in claim 1, wherein: in the step (4), the mass ratio of the cellulose nanocrystalline particles, the hydrogel monomer, the cross-linking agent and the initiator in the cellulose nanocrystalline/hydrogel precursor composite is (60-65): (30-35): (1.5-2): (3-3.5); the mechanical stirring speed in the mixing process is 30 r/min.
8. The method for preparing the pressure sensor based on the self-assembled cellulose nanocrystals, as claimed in claim 1, wherein: in the step (5), the flow of the protective nitrogen is 20ml/min, the time of evaporation induction is 5-7 days, the temperature is 35 ℃, and the relative humidity is 55%.
9. The method for preparing the pressure sensor based on the self-assembled cellulose nanocrystals, as claimed in claim 1, wherein: in the step (6), the power of ultraviolet irradiation is 1000w, the wavelength is 365nm, and the distance between a light source and the self-assembled cellulose nanocrystalline-based chiral nematic liquid crystal structure/hydrogel precursor compound is 35 cm.
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