阅读说明：本技术 多孔结构皮芯导电纤维及织物基传感器 (Skin-core conductive fiber with porous structure and fabric-based sensor ) 是由 王栋 钟卫兵 明晓娟 丁新城 蒋海青 李沐芳 于 2021-10-08 设计创作，主要内容包括：本发明提供了一种多孔结构皮芯导电纤维及织物基传感器。多孔结构皮芯导电纤维包括芯层和具有多孔结构的皮层,皮层的多孔结构通过气相诱导相分离法制备；织物基传感器通过若干组上下交错的多孔皮芯导电纤维织造成传感单元,组成传感整列,得到传感器。本发明提供的多孔结构皮芯导电纤维皮层厚度及孔隙调控简单,导电性能好。织物基传感器的感应效果好,灵敏度高,响应区间宽；且结构牢固,耐用性好,柔性好,能用于人体微信号、人体大动作及外界压力/拉力信号的检测；传感器便于集成,传感性能便于调控,可根据实际需求制备得到传感性能多样化的传感器,实际应用价值高；另外,传感器的制备工艺简单,成本低,适用于大规模的工业化生产。(The invention provides a skin-core conductive fiber with a porous structure and a fabric-based sensor. The skin-core conductive fiber with the porous structure comprises a core layer and a skin layer with the porous structure, wherein the porous structure of the skin layer is prepared by a gas-phase induced phase separation method; the fabric-based sensor is formed by weaving a plurality of groups of porous sheath-core conductive fibers which are staggered up and down into sensing units to form a sensing array, so that the sensor is obtained. The skin-core conductive fiber with the porous structure provided by the invention has the advantages of simple regulation and control of the thickness and the pores of the skin layer and good conductivity. The fabric-based sensor has good sensing effect, high sensitivity and wide response interval; the structure is firm, the durability is good, the flexibility is good, and the device can be used for detecting human body micro signals, human body large actions and external pressure/tension signals; the sensor is convenient to integrate, the sensing performance is convenient to regulate and control, the sensors with diversified sensing performances can be prepared according to actual requirements, and the actual application value is high; in addition, the sensor has simple preparation process and low cost, and is suitable for large-scale industrial production.)

1. A skin-core conductive fiber with a porous structure is characterized in that: comprises a core layer and a skin layer with a porous structure; and the cortex layer is formed by coating cortex layer slurry on the surface of the core layer, and the porous structure of the cortex layer is regulated and controlled by a gas-phase induced phase separation method in the curing process.

2. The porous structure skin-core conductive fiber according to claim 1, wherein: the gas phase induced phase separation method comprises: coating the surface of the core layer with the skin layer slurry, placing the core layer slurry in vapor flow of a vapor phase precipitator, and controlling the porous structure of the skin layer by controlling the mass concentration and the introduction time of the vapor flow; wherein the vapor phase precipitant is miscible with the solvent in the skin layer slurry and does not dissolve the solute in the skin layer slurry.

3. The porous structure skin-core conductive fiber according to claim 2, wherein: the solvent in the cortex slurry is one or more of N-2-methyl pyrrolidone, N-dimethylformamide and N, N-dimethylacetamide; the vapor phase precipitator is water, ethanol or acetone.

4. The porous-structure core-sheath conductive fiber according to any one of claims 1 to 3, wherein: the skin layer having a porous structure has electrical conductivity; the porous structure skin-core conductive fiber is used for preparing a fabric-based pressure sensor, and the pressure sensing detection is realized by changing the resistance value caused by the change of the pore space of the porous structure of the skin layer.

5. A fabric-based sensor comprises a sensing unit and a signal acquisition unit for acquiring signals of the sensing unit, and is characterized in that: the sensing unit comprises at least two porous conductive fibers which are staggered up and down; when the sensing unit deforms, the pore space between the porous conductive fibers which are staggered up and down changes, so that the change of the resistance value is generated, and the pressure sensing detection is realized.

6. The fabric-based sensor of claim 5, wherein: the porous conductive fiber is a sheath-core conductive fiber, the skin layer of the sheath-core conductive fiber is of a porous structure, and the core layer is an electrode.

7. The fabric-based sensor of claim 6, wherein: the porous structure is prepared by coating the surface layer slurry on the surface of the core layer and regulating and controlling the surface layer slurry by a gas-phase induced phase separation method in the curing process; the sensing performance of the fabric-based sensor is regulated and controlled by regulating and controlling the pore size and the porosity of the porous structure.

8. The fabric-based sensor of claim 6, wherein: the core layer is inorganic, organic, metal or plating layer conductive yarn.

9. The fabric-based sensor of claim 7, wherein: the skin layer slurry comprises a polymer and a conductive filler; the treatment time of the gas-phase induced phase separation method is 5-60min, and the mass concentration of steam flow is 20-100%.

10. The fabric-based sensor of claim 5, wherein: the sensing unit is formed by weaving a plurality of groups of porous conductive fibers which are staggered up and down in a weaving, sewing or embroidering mode, and finally the sensing array is obtained.

Technical Field

The invention relates to the technical field of sensors, in particular to a porous structure skin-core conductive fiber and a fabric-based sensor, and more particularly relates to a porous structure skin-core conductive fiber and a fabric-based pressure sensor prepared from the porous structure skin-core conductive fiber.

Background

Fabric-based sensors are prepared by embedding or integrating conductive materials into the fabric. Compared with the traditional rigid sensor, the fabric-based sensor has the advantages of better flexibility, easy bending, light weight, ventilation, durability, high sensitivity and the like. Based on the advantages, the fabric-based sensor can adapt to the wearing performance of human bodies and skins, and is more and more widely applied to the fields of human body motion monitoring, soft robot skins, medical physiological signal monitoring, human-computer interaction and the like.

The carbon nano material has special physical and chemical properties, and when external conditions change, the self conductive network structure changes, so that the resistance changes. Based on the performances, the carbon nano material becomes an ideal material for preparing the conductive layer of the fabric-based sensor. The traditional method for preparing the carbon nano material is to spin, and then to form holes by methods such as stretching and extracting, the process flow is complicated, and the obtained conductive polymer composite fiber has poor performance.

The invention patent with the application number of CN201910359126.0 discloses a conductive polymer composite fiber with a skin-core structure and a preparation method thereof, and the thickness of the skin layer and the core layer is controlled through wet spinning to prepare the conductive polymer composite fiber with a hollow, porous and skin-core structure. The porous material prepared by the method has uneven pore size and limited conductive effect.

The invention patent with the application number of CN202010420987.8 discloses a fibrous flexible strain sensor and a preparation method thereof, wherein the strain sensor with a skin-core structure is prepared by utilizing a wet spinning technology and coaxial spinning, a core layer of the sensor is a non-conductive layer composed of elastic polymers, a skin layer is a conductive composite material, and the sensing effect is controlled according to the proportion of the conductive composite material in the skin layer. The sensor has the sensing principle that: when the sensor is subjected to external pressure, the elastic deformation of the core layer of the conductive fiber is utilized to cause the resistance change of the cortex layer, and then the pressure is measured, so that the requirements on the types of the raw materials of the conductive fiber are high, the controllability of the sensing performance is not high, the sensitivity of the sensor is low, and the effect is poor.

In view of the above, there is a need for an improved porous structure core-sheath conductive fiber and fabric-based sensor to solve the above problems.

Disclosure of Invention

The invention aims to provide a skin-core conductive fiber with a porous structure and a fabric-based sensor, and solves the problems that the existing porous skin-core conductive fiber is uneven in pore size and limited in conductive effect, and the fabric-based sensor is complicated in preparation process and low in sensing efficiency.

In order to achieve the above object, the present invention provides a skin-core conductive fiber with a porous structure, comprising a core layer and a skin layer with a porous structure; and the cortex layer is formed by coating cortex layer slurry on the surface of the core layer, and the porous structure of the cortex layer is regulated and controlled by a gas-phase induced phase separation method in the curing process.

As a further refinement of the present invention, the gas phase induced phase separation method comprises: coating the surface of the core layer with the skin layer slurry, placing the core layer slurry in vapor flow of a vapor phase precipitator, and controlling the porous structure of the skin layer by controlling the mass concentration and the introduction time of the vapor flow; wherein the vapor phase precipitant is miscible with the solvent in the skin layer slurry and is incapable of dissolving the solute in the slurry.

As a further improvement of the invention, the solvent in the cortex slurry is one or more of N-2-methyl pyrrolidone, N-dimethylformamide and N, N-dimethylacetamide; the vapor phase precipitator is water, ethanol or acetone.

As a further improvement of the present invention, the skin layer having a porous structure has electrical conductivity; the porous structure skin-core conductive fiber is used for preparing a fabric-based pressure sensor, and the pressure sensing detection is realized by changing the resistance value caused by the change of the pore space of the porous structure of the skin layer.

The invention also provides a fabric-based sensor, which comprises a sensing unit and a signal acquisition unit for acquiring signals of the sensing unit, wherein the sensing unit comprises at least two porous conductive fibers which are staggered up and down; when the sensing unit deforms, the pore space between the porous conductive fibers which are staggered up and down changes, so that the change of the resistance value is generated, and the pressure sensing detection is realized.

As a further improvement of the invention, the porous conductive fiber is a sheath-core conductive fiber, the sheath layer of the sheath-core conductive fiber is a porous structure, and the core layer is an electrode.

As a further improvement of the invention, the porous structure is prepared by coating the surface layer slurry on the surface of the core layer and regulating and controlling the surface layer slurry by a gas-phase induced phase separation method in the curing process; the sensing performance of the fabric-based sensor is regulated and controlled by regulating and controlling the pore size and the porosity of the porous structure.

In a further improvement of the present invention, the core layer is an inorganic, organic, metallic or plated conductive yarn.

As a further improvement of the present invention, the skin layer slurry comprises a polymer and a conductive filler; the treatment time of the gas-phase induced phase separation method is 5-60min, and the mass concentration of steam flow is 20-100%.

As a further improvement of the invention, the sensing unit is formed by weaving a plurality of groups of porous conductive fibers which are staggered up and down in a weaving, sewing or embroidering way, and finally a sensing array is obtained.

The invention has the beneficial effects that:

(1) according to the skin-core conductive fiber with the porous structure, provided by the invention, the core layer is directly coated with the slurry as the skin layer, and the pore structure of the skin layer is controlled by a gas-phase induced phase separation technology. In addition, the addition of polymer to the slurry imparts elastic properties to the skin material and a stronger skin structure.

(2) According to the skin-core conductive fiber with the porous structure, the skin layer and the core layer can be made into the conductive layers, so that the prepared skin-core conductive fiber with the porous structure has a better conductive effect, and the sensitivity of the fabric-based sensor is improved.

(3) The fabric-based sensor provided by the invention is a sensing unit formed by vertically staggering the sheath-core conductive fibers, and uniform pores are formed on the skin layer of the sheath-core conductive fibers. So set up, even sensing element produces small deformation, the change of pore space between the cortex fibre intersect also can cause the resistance value to change, and then transmits to the signal acquisition unit through the electrode that sets up in the sandwich layer, realizes that pressure sensing detects, and the response of sensor is effectual, and sensitivity is high, and the response interval is wide. In addition, the sensing unit of the sensor is formed by weaving at least two porous conductive fibers which are staggered up and down, and the sensing array is of a net structure, so that the fabric-based sensor is firmer and has good durability. The fabric-based sensor prepared by the method is convenient to integrate, the sensing performance is also convenient to regulate and control, the sensors with diversified sensing performances can be prepared according to actual requirements, and the practical application value is high.

(4) The fabric-based sensor provided by the invention has good flexibility, and can be used for human body micro-signal detection (such as pulse, heart rate and the like), human body gross movement detection (walking, sitting, lying, bending and stretching and the like), external pressure/tension signal detection and the like.

(5) The preparation method of the fabric-based sensor provided by the invention has the advantages of simple process and low cost, and is suitable for large-scale industrial production.

Drawings

FIG. 1 is a diagram of a pore-forming mechanism of a sheath-core conductive fiber sheath.

Fig. 2 is a diagram of a sensing unit and a sensing mechanism of the sensor.

FIG. 3 is a scanning electron microscope image of the sheath layer of the sheath-core conductive fiber and a pressure sensing comparison image of the porous sheath-core conductive fiber when the vapor phase precipitator is treated for different times.

FIG. 4 is a scanning electron microscope image of the sheath layer of the sheath-core conductive fiber and a pressure sensing comparison image of the porous sheath-core conductive fiber when different steam mass concentrations are processed.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention will be described in detail with reference to the accompanying drawings and specific embodiments.

It should be noted that, in order to avoid obscuring the present invention with unnecessary details, only the structures and/or processing steps closely related to the aspects of the present invention are shown in the drawings, and other details not closely related to the present invention are omitted.

In addition, it is also to be noted that the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus.

The invention provides a skin-core conductive fiber with a porous structure, which comprises a core layer and a skin layer. At least one layer of the core layer and the skin layer can conduct electricity, preferably, both the core layer and the skin layer can conduct electricity, and the structure can improve the conductivity of the skin-core conductive fiber with the porous structure; at least one layer of the core layer and the skin layer is of a porous structure, preferably, the skin layer is of a porous structure, the pore structure is adjustable, the core layer is of a solid structure, and the stress degree of the skin-core conductive fiber of the porous structure can be improved. The porous structure of the skin layer is obtained by coating the skin layer slurry on the surface of the core layer and regulating and controlling the surface by a gas phase induced phase separation method (VIPS) in the curing process.

The gas phase induced phase separation process involves a ternary polymerization system, i.e., solute, solvent, and gas phase precipitant. The solvent is one or more of N-2-methyl pyrrolidone, N-dimethylformamide and N, N-dimethylacetamide; the vapor phase precipitator is water, ethanol or acetone. In some embodiments, the dispersoid is a mixture of a polymer and a conductive filler, the dispersing agent is N, N-dimethylformamide, and the vapor phase precipitator is preferably water, so that the conductive filler is green, environment-friendly, non-toxic and wide in source. And dissolving the mixture of the polymer and the conductive filler in N, N-dimethylformamide, and performing ultrasonic treatment to obtain uniform skin layer slurry.

Referring to the pore-forming mechanism diagram of the sheath-core conductive fiber shown in fig. 1, after coating the surface of the core layer with the sheath slurry, the core layer is placed in the vapor flow of vapor-phase precipitator water, as shown in fig. 1-a, and the vapor flow of water continuously passes through the sheath-core conductive fiber; as shown in fig. 1-b, with the continuous introduction of steam flow, water molecules gradually penetrate into the skin layer of the skin-core conductive fiber; as shown in fig. 1-c, water molecules are continuously embedded into the sheath layer of the sheath-core conductive fiber, the water molecules are mutually soluble with the N, N-dimethylformamide in the sheath layer, but cannot dissolve the mixture of the polymer and the conductive filler in the sheath layer, and then the rich phase (edge) and the poor phase (water molecules) of the N, N-dimethylformamide appear on the surface of the fiber; as shown in fig. 1-d, the water molecules take away part of the N, N-dimethylformamide, and the sheath-core conductive fiber with uniformly distributed pores is obtained. Finally, the regulation and control of the cortex porous structure are realized by controlling the mass concentration (namely the relative humidity, which refers to the ratio of the absolute humidity of the wet air to the maximum absolute humidity which can be reached at the same temperature; and when the vapor phase precipitator is other substances, the calculation method is similar) of the steam flow of the water and the introduction time. The prepared porous structure skin-core conductive fiber is used for preparing a fabric-based pressure sensor, and the pressure sensing detection is realized by the change of resistance values generated by the change of the pore space of the porous structure of the skin layer.

The invention also provides a fabric-based sensor which comprises a sensing unit and a signal acquisition unit for acquiring signals of the sensing unit. The sensing unit is an intersection point formed by at least two porous conductive fibers which are staggered up and down; and weaving a plurality of groups of porous conductive fibers staggered up and down into sensing units in a weaving, sewing or embroidering mode, and finally obtaining a sensing array. When the sensing unit deforms, the pore space between the porous conductive fibers staggered up and down changes, so that the resistance value changes, and pressure sensing detection is realized.

The invention provides a preparation method of a fabric-based sensor, which comprises the following steps:

s1, preparing skin layer slurry

And (3) uniformly mixing the polymer and the conductive filler, adding the obtained mixture into a solvent, and performing ultrasonic treatment to uniformly mix the mixture to obtain the cortex slurry.

The polymer is polyester, polypropylene, polyolefin, polyamide or polyvinyl chloride, preferably the polymer is polyurethane; the conductive filler is graphite, carbon nano tubes or conductive carbon black, preferably, the conductive filler is carbon nano tubes; the solvent is N-2-methyl pyrrolidone, N, N-dimethylformamide, N, N-dimethylacetamide or a mixed solvent of the above solvent and other solvents, preferably, the solvent is N, N-dimethylformamide, and the N, N-dimethylformamide can dissolve polyurethane.

S2, preparing skin-core conductive fibers with porous structures

Coating the cortex slurry obtained in the step S1 on a core layer to prepare conductive fibers with a skin-core structure, placing the conductive fibers with the skin-core structure in steam flow of a vapor-phase precipitator according to a pore-forming principle of a vapor-phase induced phase separation method in a curing process, wherein the vapor-phase precipitator is water, ethanol or acetone, preferably the vapor-phase precipitator is water, and controlling the mass concentration and the introducing time of the steam flow of the vapor-phase precipitator water, preferably the mass concentration of the steam flow of the vapor-phase precipitator is 20-100% (namely the relative humidity is 20-100%), and the introducing time is 5-60min, so that the amount of N, N-dimethylformamide taken away by the vapor-phase precipitator water is controlled, the pore size and the porosity of the cortex are further adjusted, and after static curing, the skin-core conductive fibers with the porous structure are obtained.

The core layer material of the skin-core conductive fiber with the porous structure is generally inorganic, organic and metal yarn or plating yarn which can conduct electricity, so that the conductive capacity of the conductive fiber is improved; in some embodiments, the core layer is an electrode. The skin layer material is a porous conductive structure with an adjustable pore structure.

S3, preparation of fabric-based sensor

And a plurality of groups of sensing units are formed by weaving, sewing or embroidering the up-and-down staggered porous structure skin-core conductive fibers, and the plurality of sensing units are connected with each other to form a sensing array, so that the fabric-based sensor is finally obtained. Wherein, the whole sensing array is a net structure, so that the fabric-based sensor is firmer and has good durability. Referring to the sensing unit and the sensing mechanism diagram shown in fig. 2, fig. 2-a is a cross-shaped sensing unit composed of vertically staggered porous core-sheath conductive fibers, and fig. 2-b shows a cross-sectional view of the sensing unit, in which the core layer is three electrodes with an interlaced structure. When the fabric-based sensor is pressed, the sensing unit deforms, the pore space between the porous conductive fibers staggered up and down changes, and further the resistance value changes, so that human body micro-signal detection (such as pulse, heart rate and the like), human body large-motion detection (walking, sitting, lying, bending and stretching and the like) and external pressure/tension detection are realized. Even there is even hole on the skin core conductive fiber's of sensor cortex, even the sensing element produces little deformation, the change of hole interval also can cause the resistance value to change, realizes the pressure sensing and detects, and the response of sensor is effectual, and sensitivity is high, and the response interval is wide.

Example 1

S1, preparing skin layer slurry

And uniformly mixing polyurethane and carbon nano tubes, adding the mixture into N, N-dimethylformamide for ultrasonic treatment, and uniformly distributing the polyurethane and the carbon nano tubes in the N, N-dimethylformamide to prepare the skin layer slurry.

S2, preparing skin-core conductive fibers with porous structures

Coating the obtained skin layer slurry on the core layer to obtain the skin-core structure conductive fiber, treating the obtained skin-core structure conductive fiber by water vapor with the mass concentration of 50% of steam flow (namely, the relative humidity is 50%) for 5min, and statically curing to obtain the porous structure skin-core conductive fiber.

S3, preparation of fabric-based sensor

Weaving a plurality of groups of vertically staggered porous structure skin-core conductive fibers to form sensing units, and mutually connecting a plurality of sensing units to form a sensing array to finally obtain the fabric-based sensor.

Examples 2 to 3

Compared with the embodiment 1, the difference of the preparation method of the fabric-based sensor is that in the step S2, the time for water vapor to pass through the skin-core structure fiber is different, and the treatment is respectively 20min and 40min, and the rest is substantially the same as the embodiment 1, and the description is omitted.

In FIG. 3, a-c are scanning electron micrographs of the conductive fiber after water vapor treatment for 5min, 20min and 40min, respectively. 3-a, the surface pores of the conductive fibers are smaller and closed after 5min of water vapor treatment; 3-b, after the water vapor treatment is carried out for 20min, the pores on the surface of the conductive fiber are larger and are uniformly distributed; after the water vapor treatment is carried out for 40min in the figure 3-c, the pores on the surface of the conductive fiber are different in size and are not uniformly distributed. It is known that the pore structure is present from the beginning as the water vapor treatment time increases, but the water vapor treatment time is too long, which results in too large pores and uneven distribution. Fig. 3-d are pressure sensing curves of three kinds of porous structure skin-core conductive fibers, and it can be known from the graphs that the conductive fibers processed for 20min have the highest relative current change amount and show better sensing performance under the same pressure state, and thus it can be known that the better the pore uniformity is, the better the sensing effect of the manufactured sensor is.

Examples 4 to 6

A method for manufacturing a fabric-based sensor, which is different from that of example 1 in that the mass concentration of water vapor is different in step S2, and the process is performed for 20min when the mass concentration of water vapor is 40%, 60% and 100% (i.e., the relative humidity is 40%, 60% and 100%, respectively), and the rest is substantially the same as that of example 1, and thus, the description thereof is omitted.

In FIG. 4, a-c are scanning electron micrographs of the conductive fibers treated at 40%, 60% and 100% relative humidity, respectively. It can be seen from fig. 4-a that the conductive fiber surface is smooth and free of any voids after the 40% rh treatment; after the 60% relative humidity treatment in fig. 4-b, the pores on the surface of the conductive fibers are larger and are uniformly distributed; after 100% rh treatment in fig. 4-c, the conductive fibers have uneven and non-uniform surface. It is known that, when the water vapor treatment time is the same, the pore structure is changed from the absence to the presence as the relative humidity increases, but too much relative humidity also causes the pores to be too large and to be unevenly distributed. Fig. 4-d are pressure sensing curves of three kinds of porous structure skin-core conductive fibers, and it can be known from the graphs that the conductive fibers treated with 60% relative humidity have the highest relative current change amount and show better sensing performance under the same pressure state, so that the better the pore uniformity is, the better the sensing effect of the manufactured sensor is.

In conclusion, the core-sheath conductive fiber with the porous structure provided by the invention has the advantages that the core layer is directly coated with the slurry as the sheath layer, and the pore structure of the sheath layer is controlled by the gas-phase induced phase separation technology, so that compared with the traditional spinning technology, the method has the advantages that the whole process flow is simple, the thickness of the sheath layer and the size of pores are convenient to regulate and control, and the uniformity of the pores is good; in addition, the polymer added into the slurry enables the skin layer material to have elastic performance and enables the skin layer structure to be firmer; the skin layer and the core layer can be conductive, so that the prepared skin-core conductive fiber with the porous structure has a better conductive effect, and the sensitivity of the fabric-based sensor is improved. According to the fabric-based sensor, even holes are formed in the skin layer of the skin-core conductive fibers of the sensing unit, and even if the sensing unit is slightly deformed, the change of the hole distance between the skin layer fiber cross points can also cause the change of the resistance value, so that the pressure sensing detection is realized, the sensing effect of the sensor is good, the sensitivity is high, and the response interval is wide; in addition, the sensing unit of the sensor is woven by at least two porous conductive fibers staggered up and down, and the sensing array is of a net structure, so that the fabric-based sensor is firmer and has good durability; the sensor is convenient to integrate, the sensing performance is also convenient to regulate and control, the sensors with diversified sensing performances can be prepared according to actual requirements, and the actual application value is high; the sensor has good flexibility, and can be used for human body micro-signal detection (such as pulse, heart rate and the like), human body gross movement detection (walking, sitting, lying, bending and stretching and the like), external pressure/tension signal detection and the like; the preparation method of the sensor has the advantages of simple process and low cost, and is suitable for large-scale industrial production.

Although the present invention has been described in detail with reference to the preferred embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the spirit and scope of the present invention.