阅读说明：本技术 一种利用生物质材料制备柔性应变传感器的方法 (Method for preparing flexible strain sensor by using biomass material ) 是由 赵春霞 李思雨 李云涛 向东 李辉 毛洁 于 2019-09-09 设计创作，主要内容包括：本发明公开了一种利用生物质材料制备柔性应变传感器的方法,包括步骤：S1、将生物质材料研磨成粉末；S2、在惰性气氛中对粉末状生物质材料进行高温碳化处理；S3、制备聚合物弹性体溶液；S4、浇注封装,包括如下步骤：S41、将聚合物弹性体溶液分为三份；S42、将碳化粉末与一份聚合物弹性体溶液进行共混,形成共混液；S43、取另一份聚合物弹性体溶液浇注到指定形状的模具中,进行固化,形成基底薄片；S44、将共混液涂覆在基底薄片上,并安装上导线；S45、将最后一份聚合物弹性体溶液浇注进模具,在80-120℃下固化20-30min,得到柔性应变传感器。本发明使用的生物质材料来源广泛,价格低廉,并且作为农业废弃物,对环境保护有重要意义。(The invention discloses a method for preparing a flexible strain sensor by using a biomass material, which comprises the following steps: s1, grinding the biomass material into powder; s2, performing high-temperature carbonization treatment on the powdery biomass material in an inert atmosphere; s3, preparing a polymer elastomer solution; s4, pouring and packaging, comprising the following steps: s41, dividing the polymer elastomer solution into three parts; s42, blending the carbonized powder with one part of polymer elastomer solution to form a blended solution; s43, pouring the other part of the polymer elastomer solution into a mold with a specified shape, and curing to form a substrate sheet; s44, coating the blend solution on a substrate sheet, and installing a lead; and S45, pouring the last part of polymer elastomer solution into a mould, and curing for 20-30min at 80-120 ℃ to obtain the flexible strain sensor. The biomass material used by the invention has wide source and low price, and has important significance for environmental protection as agricultural waste.)

1. a method for preparing a flexible strain sensor by using a biomass material is characterized by comprising the following steps:

s1, grinding a biomass material to powder which is sieved by a 200-mesh sieve, wherein the biomass material is one of walnut shells, sunflower inner cores, corn inner cores and vegetable sponge;

S2, performing high-temperature carbonization treatment on the powdery biomass material in an inert atmosphere to obtain carbonized powder;

S3, preparing a polymer elastomer solution;

S4, pouring and packaging, comprising the following steps:

S41, dividing the polymer elastomer solution into three parts;

s42, blending the carbonized powder with one part of polymer elastomer solution to form a blended solution;

S43, pouring another part of polymer elastomer solution into a mold with a specified shape, and curing the solution to form a substrate sheet;

S44, coating the blend obtained in the step S4 on a substrate sheet, installing a lead and curing;

S45, pouring the last part of polymer elastomer solution into a mold, putting the mold into a vacuum oven, removing bubbles at normal temperature under reduced pressure, and curing at 80-120 ℃ for 20-30min to obtain the flexible strain sensor.

2. the method for preparing a flexible strain sensor by using biomass material according to claim 1, wherein the step S42 is specifically operated as follows:

(1) Adding the carbonized powder into a dichloromethane solvent, and performing ultrasonic dispersion for 30min to obtain a solution A;

(2) Dissolving one part of polymer elastomer solution in dichloromethane solvent, and uniformly stirring to obtain solution B;

(3) mixing the solution A and the solution B, performing ultrasonic dispersion for 30min, and then evaporating to remove dichloromethane, so that the volume of the dichloromethane remained in the mixed solution is one tenth of the original volume.

3. The method for preparing a flexible strain sensor by using biomass material according to claim 1, wherein in the step S43, before curing, the mold for pouring the polymer elastomer solution is placed in a vacuum oven to remove bubbles at normal temperature and reduced pressure, and then curing is performed at 80-120 ℃ for 20-30 min.

4. the method for preparing a flexible strain sensor by using biomass material as claimed in claim 1, wherein the step S44 is specifically performed by: and (4) coating the blended solution obtained in the step (S42) on a substrate sheet, coating conductive paste at two ends to connect with a lead, then putting the substrate sheet into a vacuum oven, removing bubbles at normal temperature under reduced pressure, and then curing for 20-30min at 80-120 ℃.

5. the method for preparing a flexible strain sensor by using biomass material as claimed in claim 1, wherein in step S2, high temperature carbonization is performed in nitrogen or argon atmosphere, the temperature rising and lowering rate is 2-5 ℃/min, the heat treatment temperature is 600-1000 ℃, and the temperature is kept constant for 2 h.

6. The method for preparing a flexible strain sensor by using biomass material according to claim 5, wherein the step S2 is specifically as follows: putting the powdery biomass material into a tubular heating furnace, taking nitrogen as inert gas, heating the powdery biomass material from room temperature to 200 ℃ at the heating rate of 5 ℃/min at a nitrogen flow rate of 100mL/min, heating the powdery biomass material to 900 ℃ at the heating rate of 2 ℃/min, keeping the temperature for 2h, and finally cooling the powdery biomass material to room temperature at the cooling rate of 5 ℃/min to obtain carbonized powder.

7. The method of claim 1, wherein in step S1, the biomass material is screened, cleaned with deionized water, and dried before being ground.

8. The method of claim 1, wherein the polymer elastomer is one of rubber, a silicon-based polymer elastomer, VHB, or polyvinyl alcohol.

9. the method of using a biomass material to make a flexible strain sensor of claim 1 wherein the biomass material is walnut shells.

Technical Field

The invention belongs to the technical field of sensors, and particularly relates to a method for preparing a strain sensor by using a biomass carbonized material.

Background

Flexible strain sensors have developed very rapidly over the years. Compared with the traditional sensor, the flexible strain sensor has obvious advantages, which are mainly reflected in good flexibility and stretchability, strong wearability, good biocompatibility and the like. The disadvantages of conventional sensors therefore greatly limit the fields in which they can be developed and applied. With the continuous progress of science and the continuous effort of scientific research personnel, the research technology of the flexible strain sensor is further improved. In the scientific research field, people pay more and more attention to flexible strain sensors. Exploring sensor principles and selecting materials for flexible electronic strain sensors is a major direction being investigated. The materials were studied for two reasons: the better conductive material of the flexible electronic sensor can optimize the performance of the strain sensor, and the mechanical performance of the sensor is improved. The active materials of the flexible strain sensors reported so far include: metal nanomaterials (metal nanoparticles, metal nanowires), nanocarbon materials (carbon black, carbon nanotubes, graphene), and organic materials, among others.

Biomass char-based (biochar) is a solid product obtained by thermochemical conversion of biomass, with very little oxygen. The biomass charcoal base is the most remarkable characteristic of the biomass charcoal base, namely, the biomass charcoal base is a difficultly soluble solid substance. The biochar is a material with extremely low pollution, strong popularization and low cost. The biomass charcoal base is a biopolymer material which is widely researched nowadays. Common biochar comprises charcoal and straw charcoal, and coconut shell charcoal, bamboo charcoal and the like which are common in life are branches of biochar and are usually formed by pyrolysis at the temperature of less than 700 ℃ under the condition of oxygen deficiency. The traditional carbon material is mainly prepared by processing traditional energy materials such as coal, petroleum and the like. But the world today has long presented new challenges to traditional carbon materials due to, among other things, modern energy crisis and environmental challenges. Walnuts are common nuts and can also be used in the processing industry. The walnut shell has the characteristics of rich carbon content and low price. The carbon material prepared by pyrolyzing the walnut shell powder in inert gas at high temperature has better conductivity.

Disclosure of Invention

The invention aims to provide a method for preparing a strain sensor by using a biomass carbonized material.

The invention provides a method for preparing a strain sensor by using a biomass carbonized material, which comprises the following steps:

s1, screening the biomass material, removing impurities, washing with deionized water, drying, and then grinding the biomass material into powder which is sieved by a 200-mesh sieve, wherein the biomass material is one of walnut shells, sunflower inner cores, corn inner cores and loofah pulp.

S2, carrying out high-temperature carbonization treatment in nitrogen or argon atmosphere, wherein the heating and cooling rate is 2-5 ℃/min, the heat treatment temperature is 600-;

S3, preparing a polymer elastomer solution, wherein the polymer elastomer is one of rubber, silicon-based polymer elastomer, VHB or polyvinyl alcohol.

s4, pouring and packaging, comprising the following steps:

S41, dividing the polymer elastomer solution into three parts;

S42, blending the carbonized powder with one part of polymer elastomer solution to form a blended solution; the specific operation is as follows:

(1) Adding the carbonized powder into a dichloromethane solvent, and performing ultrasonic dispersion for 30min to obtain a solution A;

(2) dissolving one part of polymer elastomer solution in dichloromethane solvent, and uniformly stirring to obtain solution B;

(3) Mixing the solution A and the solution B, performing ultrasonic dispersion for 30min, and then evaporating to remove dichloromethane, so that the volume of the dichloromethane remained in the mixed solution is one tenth of the original volume. Note that this operation did not completely evaporate the methylene chloride liquid, and it was necessary to leave a small portion in the flask for subsequent operations.

S43, pouring the other part of the polymer elastomer solution into a mold with a specified shape, putting the mold into which the polymer elastomer solution is poured into a vacuum oven, removing bubbles at normal temperature under reduced pressure, and curing at 80-120 ℃ for 20-30 min; a base sheet is formed.

S44, coating the blend obtained in the step S42 on a substrate sheet, coating conductive paste at two ends to connect with a lead, then putting the substrate sheet into a vacuum oven, removing bubbles at normal temperature under reduced pressure, and then curing for 20-30min at 80-120 ℃.

S45, pouring the last part of polymer elastomer solution into a mold, putting the mold into a vacuum oven, removing bubbles at normal temperature under reduced pressure, and curing at 80-120 ℃ for 20-30min to obtain the flexible strain sensor.

Preferably, the step S2 is specifically: putting the powdery biomass material into a tubular heating furnace, taking nitrogen as inert gas, heating the powdery biomass material from room temperature to 200 ℃ at the heating rate of 5 ℃/min at a nitrogen flow rate of 100mL/min, heating the powdery biomass material to 900 ℃ at the heating rate of 2 ℃/min, keeping the temperature for 2h, and finally cooling the powdery biomass material to room temperature at the cooling rate of 5 ℃/min to obtain carbonized powder.

The preparation flow of the flexible strain sensor of the invention is shown in figure 1.

Compared with the prior art, the invention has the advantages that:

(1) The biomass raw materials such as walnut shells, sunflower inner cores, corn inner cores, loofah and the like adopted by the invention have the characteristics of rich carbon content and low price. The biomass raw material is pyrolyzed in inert gas at high temperature to obtain the carbonized material with a sheet structure, the original shape of which is basically kept, and the carbonized material has better conductivity. When the carbonized material deforms under tension and the like, the structure of the carbonized material is easy to collapse and damage, the conductivity of the carbonized material is seriously influenced, the conductivity is easy to influence by deformation, and the carbonized material has good strain sensing performance and becomes a better active material for preparing a flexible strain sensor; on the other hand, the sheet structure of the carbonized material is beneficial to the polymer elastomer prepolymer liquid to be soaked into the material, so that the polymer elastomer prepolymer liquid can be tightly combined with the carbonized material after being solidified, the sheet structure can be effectively recovered after being damaged, and the flexible sensor has better fatigue resistance.

(2) The flexible strain sensor prepared by the method has the advantages that the shape and the size of the flexible strain sensor can be adjusted by changing the shape of the die, different strain forms can be monitored (stretching, bending, twisting, compressing and the like), and the defects of the existing sensor in the aspects of application range, single function and the like are overcome; meanwhile, the strain sensor has the advantages of good flexibility, high sensitivity, short response time, good fatigue resistance and the like, and can monitor the joint movement of a human body by being directly attached to skin or clothes; and the preparation process is simple, and the method is stable and reliable.

(4) the walnut shell used by the invention has wide raw material source and low price, and achieves the purpose of recycling agricultural wastes.

additional advantages, objects, and features of the invention will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention.

Drawings

FIG. 1 is a schematic flow chart of the present invention for preparing a flexible strain sensor.

FIG. 2, a is a scanning electron microscope image of the walnut shell powder of example 1 before carbonization; b and c are scanning electron micrographs of the walnut shell powder after carbonization in example 1; d is a cross-sectional scanning electron microscope image of the flexible strain sensor of example 1.

Fig. 3 is a schematic structural view of a flexible compressive strain sensor prepared in example 1.

Fig. 4 shows the detection result of the flexible strain sensor prepared in example 1 on the signals of the elbow joint of the left hand of a human body.

Fig. 5 shows the result of detecting the motion of the right knee of the human body by the flexible strain sensor prepared in example 1.

FIG. 6, the detection result of the flexible strain sensor prepared in example 1 on the movement of human throat

Fig. 7 shows the detection result of the flexible strain sensor prepared in example 1 on the signal of the right wrist of a human body.

Fig. 8, the variation of the relative current of the flexible strain sensor prepared in example 2 in different tensile strain ranges.

Detailed Description

The preferred embodiments of the present invention will be described in conjunction with the accompanying drawings, and it will be understood that they are described herein for the purpose of illustration and explanation and not limitation.