CN105671654B - A kind of ion induction type artificial skin array structure and preparation method thereof - Google Patents

Abstract

The invention discloses an ion-inductive artificial skin array structure and a preparation method thereof, which is characterized in that: it is an array structure composed of composite electrode fibers cross-arranged, or is composed of composite electrode fibers and flexible fibers made of conductive materials An array structure composed of cross-arranged electrodes, or a fabric structure woven from composite electrode fibers, or a fabric structure woven from composite electrode fibers and flexible fiber electrodes made of conductive materials; wherein, the composite electrode fibers are composed of It consists of a core layer and a sheath layer; the core layer is a flexible fiber electrode made of conductive material, and the sheath layer is a wrapping layer of a flexible fiber electrode made of polyelectrolyte; the sheath layer is wrapped on the outer surface of the core layer and the two ends of the core layer exposed. The invention is an ion-sensing artificial skin array based on ion migration movement, which can simulate the principle of biological skin tactile bioelectricity induction. Compared with other types of artificial skin materials, the sensing ability is stronger and the response is more sensitive.

Description

An ion-inductive artificial skin array structure and its preparation method

technical field

The invention relates to a novel electroactive material and its preparation technology, in particular to an artificial skin array structure based on ion-induced electricity generation and its preparation method.

Background technique

Artificial skin can simulate the tactile perception function of biological skin, and has great application potential and industrialized market in the fields of robots, modern medical health monitoring, limbs and organs of the disabled, surgical control arms and wearable electronic products.

Traditional artificial skin materials do not match well with the human body in terms of flexibility, there is no advantage in simulating the dynamic frequency of human skin, and the tactile perception function of the skin is unreal. In recent years, artificial skins based on polymer films have improved these problems to some extent.

According to different sensing principles, artificial skin materials are mainly divided into two types: parametric and self-generating. Among them, the parameter formula is based on the resistive artificial skin material developed by Lipomi DJ et al. (Lipomi DJ, et al.Nat Nano, 2011, 6(12):788-792) and the capacitive artificial skin material studied by Takamatsu S et al. (Takamatsu S,etal.Sensors and Actuators A:Physical,2012,184(0):57-63) as a representative, in the active case, by measuring the change of electrical properties (capacitance or resistance) of the material caused by stress and strain, indirectly Detects changes in applied pressure. The self-generating formula is based on Gao Q et al. (Gao Q, et al.Langmuir, 2012, 28(51): 17593-17596) and Mandal D et al. (Mandal D, et al. Macromolecular Rapid Communications, 2011, 32 (11) :831-837) etc. as representatives, divided into piezoelectric and ionic.

All parametric flexible sensors require an external power supply, which consumes a lot of energy. However, the intelligence and multi-functionalization of advanced equipment have particularly severe restrictions on reducing the energy consumption of sensing elements. Among the two different types of flexible sensing materials that can generate electricity spontaneously, the ion-based artificial skin material based on ion transport has better temperature stability and anti-interference ability.

Ionic electro-active polymer (EAP, Electro-active Polymer) is a new type of ionic flexible material. It is similar to the tactile perception mechanism of the skin. Under the action of pressure, the internal ions will move, so that the material will generate a potential difference in the direction of pressure, so it has the advantage of developing new flexible artificial skin materials. However, the traditional ionic EAP directly used as an artificial skin sensor has two disadvantages: 1) most of them are measured separately, and it is difficult to form an array; 2) they are not sensitive enough to small local deformations. The present invention will design an ion-inductive artificial skin array structure based on the basic principle of ion-type EAP, which has important engineering significance.

Contents of the invention

The purpose of the present invention is to propose an ion-sensing artificial skin array structure and a preparation method thereof, so as to more truly realize the pressure-tactile sensing function and overcome the deficiencies of the prior art.

In order to realize the above-mentioned purpose of the invention, the present invention adopts following technical scheme:

The present invention proposes an ion-sensing artificial skin array structure, which is characterized in that: the artificial skin array structure is an array structure composed of composite electrode fibers cross-arranged, or is made of composite electrode fibers and flexible conductive materials. An array structure formed by cross-arrangement of fiber electrodes, or a fabric structure woven by composite electrode fibers, or a fabric structure mixed by composite electrode fibers and flexible fiber electrodes made of conductive materials;

Wherein, the composite electrode fiber is composed of a core layer and a sheath layer; the core layer is a flexible fiber electrode made of conductive material, and the sheath layer is a wrapping layer of a flexible fiber electrode made of polyelectrolyte; The sheath wraps the outer surface of the core layer and the two ends of the core layer are exposed.

The cross-arrangement method is a layered arrangement up and down, the composite electrode fibers and/or flexible fiber electrodes located in the same layer are parallel to each other, and the arrangement angle of the composite electrode fibers and/or flexible fiber electrodes between the upper and lower layers is 10°～ 90°. The fabric structure is a two-dimensional warp and weft fabric structure, a three-dimensional and multi-dimensional warp and weft fabric structure or a non-warp and weft fabric structure.

The cross section of the flexible fiber electrode and the composite electrode fiber is circular, oval or rectangular. The cross-sectional structure of flexible fiber electrodes and/or composite electrode fibers constituting the same skin array structure can be the same or different, and can be selected arbitrarily

The radial length of the flexible fiber electrode is 10-500 μm, and the axial length is not less than 2 cm; the thickness of the sheath is 10-500 μm; the overall thickness of the artificial skin array structure is not greater than 2 mm.

The conductive material can be selected from metal materials (such as gold, copper, silver, platinum or alloys thereof), carbon nanotubes or a mixture of carbon nanotubes and graphene;

Described polyelectrolyte material is ion-exchange membrane material (such as Dupont company Nafion series, the Aciplex series ion membrane of AsahiChemical company, the Flemion series ion membrane of Asahi Glass company and the Aquivion series ion membrane of SolvaySolexis company), or neutral polymer (PVDF , chitosan) and ionic liquid (EMITFSI, etc) mixture.

The ion induction principle of the artificial skin material of the present invention is that under the action of external force, the pressure sensing point generates electric induction, and the electric induction is conducted to the external circuit control system through the conductive core layer flexible fiber electrode. Wherein the pressure sensing point is a contact point composed of composite electrode fibers and/or flexible fiber electrodes crossing in pairs.

The preparation method of the above-mentioned artificial skin array structure is:

(1) The conductive material is made into a flexible fiber electrode by electrospinning technology; or based on a filament (such as yarn), a layer of conductive material (such as silver-plated yarn, plated Platinum yarn, copper-plated yarn) to make flexible fiber electrodes; metal wires can also be used directly as flexible fiber electrodes;

(2) Wrap the polyelectrolyte on the flexible fiber electrode to form a sheath layer through solution evaporation to form a film, and make a composite electrode fiber; for other materials, extrusion, high-temperature melting, etc. can also be used to obtain the core layer of the flexible fiber electrode-poly Electrolyte sheath composite structure.

(3) Composite electrode fibers or composite electrode fibers and flexible fiber electrodes are layered and cross-arranged into an array structure, and then different layers are pressed together at the contact points by hot pressing forming technology to form an ion-inductive artificial skin array structure ; The composite electrode fibers and/or flexible fiber electrodes located in the same layer are parallel to each other, and the arrangement angle between the composite electrode fibers and/or flexible fiber electrodes between the upper and lower layers is 10°-90°.

Or: Weave composite electrode fibers or composite electrode fibers and flexible fiber electrodes into a fabric structure, and then press the different layers at the contact points by hot pressing to form an ion-sensing artificial skin array structure;

(4) Post-processing the ion-sensing artificial skin array structure prepared in step (3) to improve performance, that is, the preparation is completed.

In order to adjust the resolution of the artificial skin array structure and increase the tensile strength of the artificial skin array structure, yarns or insulating polymer fibers are added during the process of cross-arranging into an array structure or weaving into a fabric structure in step (3).

The post-treatment in step (4) is to first soak the artificial skin array structure prepared in step (3) in hydrochloric acid (0.1mol/L) or sulfuric acid (0.05mol/L) (not less than 1h), and then Then soak in the alkali metal or alkaline earth metal cation solution (not less than 1h). The purpose of first soaking with acid is to remove the impurities of the artificial skin material, and then soaking in an alkali metal or alkaline earth metal cation solution is to replace the cations inside, such as sodium ions for conduction.

The present invention further proposes that the above-mentioned artificial skin array structure is used in bionic robots, pressure sensors or wearable flexible electronic devices.

The beneficial effects of the present invention are reflected in:

The invention is an ion-sensing artificial skin array based on ion migration movement, which can simulate the principle of biological skin tactile bioelectrical induction. Compared with other types of artificial skin materials, its sensing principle is closer to the tactile sensing principle of real skin, and its sensing ability is stronger. , the response is more sensitive.

The artificial skin of the present invention is mainly based on the basic principle of ion-type electro-actuated polymers, and the fabric-type skin array is designed, and the anisotropy of the electrode fibers is skillfully used to manufacture a composite material with sufficient sensing resolution and mechanical strength. It can well simulate the tactile function of biological skin.

Description of drawings

Fig. 1 is the structural representation of composite electrode fiber;

Fig. 2 and Fig. 3 are the schematic diagrams of two structural forms of the ion-inductive artificial skin array structure of the present invention;

Fig. 4 is a diagram of the electrical response results after pressure is applied to the artificial skin array structure in Example 1 of the present invention;

5 is a schematic diagram of a composite electrode fiber production device in Example 2 of the present invention;

Figure 6a and Figure 6b are schematic diagrams of the array structure of the artificial skin material in Example 2 of the present invention;

Figure 7 is a diagram of the internal ion state of the artificial skin material array structure before and after stress in Example 2 of the present invention, wherein Figure 7(a) is before stress, and Figure 7(b) is after stress;

Fig. 8 is a schematic diagram of the array structure of the artificial skin material in Example 3 of the present invention;

Fig. 9 is a schematic diagram of the array structure of the artificial skin material in Example 4 of the present invention;

Numbers in the figure: 1 is the feed inlet, 2 is the heating mold, 3 is the heating sheet, 4 is the valve, 5 is the valve handle, 6 is the flexible fiber electrode, 7 is the composite electrode fiber, and 8 is the yarn.

Detailed ways

The artificial skin array structure of the present invention is an array structure (as shown in Figure 2) formed by the cross arrangement of composite electrode fibers (as shown in Figure 1), or a flexible fiber electrode made of composite electrode fibers and conductive materials The array structure formed by cross-arrangement is either a fabric structure woven by composite electrode fibers, or a fabric structure mixed by composite electrode fibers and flexible fiber electrodes made of conductive materials (as shown in Figure 3).

As shown in Figure 1, the composite electrode fiber is composed of a core layer and a sheath layer; the core layer is a flexible fiber electrode made of conductive material, and the sheath layer is a wrapping layer of a flexible fiber electrode made of polyelectrolyte; the sheath layer is wrapped in The outer surface of the core layer and both ends of the core layer are exposed.

The technical solution of the present invention will be described in more detail below in combination with several embodiments.

Example 1

The present embodiment prepares the ion-sensing type artificial skin array structure based on metal wire and Nafion ionic membrane material according to the following steps:

(1) Prepare adhesive sheet, copper wire and Nafion D520 (5%) solution (produced by DuPont, USA), and use copper wire (about 150 μm in diameter, 10 cm in length) directly as a flexible fiber electrode.

(2) Use Nafion D520 (5%) solution (produced by DuPont, USA) as the polyelectrolyte solution, drop it on the copper wire, bake at 50°C for 3 hours, evaporate to form a film, form a sheath, and make a composite electrode fiber ;

(3) Using the glass plate as the base, first arrange three composite electrode fibers in parallel on the glass plate, the distance between adjacent composite electrode fibers is 5mm, and the ends are fixed with two adhesive sheets. Then, the other three composite electrode fibers were arranged vertically crossing at 90° on the composite electrode fibers of the lower layer, and the distance between adjacent composite electrode fibers was also 5 mm.

The arranged array structure is hot-pressed at 50°C, so that the two layers are pressed together at the contact point to form an ion-sensing artificial skin array structure;

(4) Peel off the entire array structure from the glass plate, soak in 0.1mol/L HCl for 2 hours; then soak in 0.2mol/L NaCl solution for 2 hours, and obtain a finished ion-sensing artificial skin array with good performance structure.

Use a multi-function recorder GL900 to measure and record the voltage response of the artificial skin material, place the material on a plastic plate, connect a pair of vertical copper wire ends to the recorder, and apply pressure at the contact point of the two copper wires, the results are shown in the figure 4. It can be seen that after the pressure is applied, the voltage first has a rapidly rising peak and then rapidly decays, which is similar to the traditional IPMC material, and the voltage peak is related to the applied pressure.

Example 2

The present embodiment prepares the ion-sensing type artificial skin array structure based on silver-plated fiber and Nafion ion membrane material according to the following steps:

(1) Soak several fiber filaments in the Ag nanoparticle dispersion, then evaporate the solvent to obtain silver-plated fibers as flexible fiber electrodes;

(2) Use the composite electrode fiber production device shown in Figure 5, open the valve 4 through the valve handle 5, insert the flexible fiber electrode 6 into the heating mold 2, close the valve 4, place it horizontally, and then put Nafion D520 (5%) The solution (produced by DuPont Company of the United States) is poured into the heating mold from the feed port 1 through the funnel, heated by the heating plate 3, first kept at 80°C for 30min, then raised to 120°C for 6h, and finally raised to 140°C And keep warm for 30min. After the device is cooled, add an appropriate amount of deionized water and boil for 5 minutes to obtain composite electrode fibers.

(3) As shown in Figure 6a and Figure 6b, the composite electrode fibers are arranged in two layers crosswise to form an array structure, each layer is arranged in parallel, the layers are vertically arranged, and the composite electrodes are tightly connected. Then, the different layers are pressed together at the contact points by hot pressing at 50°C to form an ion-sensing artificial skin array structure.

(4) Soak the ion-sensing artificial skin array structure made in step (3) in 0.1mol/L HCl for 2 hours; then soak it in 0.2mol/L NaCl solution for 2 hours to obtain the finished ion Inductive artificial skin array structure.

Figure 7a and Figure 7b are diagrams of the internal ion movement of the sample of this embodiment before and after being stressed. It can be seen from the figure that when the contact point is under force, the cations in the polyelectrolyte (sodium ions in this example) will move to the center with the water molecules, that is, charge transfer occurs, and current is generated, which is transmitted to the external circuit.

Example 3

In this example, an ion-sensing artificial skin array structure composed of composite electrode fibers and flexible fiber electrodes is prepared according to the following steps:

(1) prepare silver-plated fiber by the mode in embodiment 2, as flexible fiber electrode 6;

(2) Use Nafion D520 (5%) solution (produced by DuPont, USA) as a polyelectrolyte solution, drop it on the silver-plated fiber, bake at 50°C for 3 hours, evaporate to form a film, form a sheath, and make a composite electrode fiber 7;

(3) As shown in Figure 8(a) and Figure 8(b), the composite electrode fiber 7 is used as the lower layer, the flexible fiber electrode 6 is used as the upper layer, and the two layers are vertically arranged in an array structure; then the arranged The array structure is melted at a high temperature of 50°C, so that the two layers are pressed together at the contact point to form an ion-sensing artificial skin array structure;

(4) Soak the ion-sensing artificial skin array structure made in step (3) in 0.1mol/L HCl for 2 hours; then soak it in 0.2mol/L NaCl solution for 2 hours to obtain the finished ion Inductive artificial skin array structure.

After applying pressure to the artificial skin material, the voltage is measured through the flexible fiber electrode-composite electrode fiber contact point.

Example 4

In this example, an ion-sensing artificial skin array structure based on composite electrode fibers with added yarns is prepared according to the following steps:

(1) Use copper wire directly as a flexible fiber electrode, use Nafion D520 (5%) solution (produced by DuPont, USA) as a polyelectrolyte solution, drop it on the copper wire, bake at 50 ° C for 3 hours, and evaporate the solvent to form a sheath layer to make a composite electrode fiber;

(2) As shown in FIG. 9 , the yarn 8 , the composite electrode fiber 7 , and the flexible fiber electrode 6 are hand-knitted to obtain a one-warp-one-weft fabric structure in which the three are closely arranged. Then, the different layers are pressed together at the contact points by hot pressing to form an ion-sensing artificial skin array structure;

(3) Soak the ion-sensing artificial skin array structure made in step (2) in 0.1mol/L HCl for 2 hours; then soak it in 0.2mol/L NaCl solution for 2 hours to obtain the finished ion Inductive artificial skin array structure.

After applying pressure to the artificial skin material, the voltage is measured through the copper wire-composite electrode fiber contact point or the composite electrode fiber-composite electrode fiber contact point. The woven material is simple to make, and the tensile performance can be improved or the resolution can be adjusted by adjusting the yarn.

The foregoing is only a specific embodiment of the present invention. It should be pointed out that for those of ordinary skill in the art, some improvements and modifications can also be made without departing from the principle of the present invention. It should be regarded as the protection scope of the present invention.

Claims (6)

1. a kind of ion induction type artificial skin array structure, it is characterised in that：The artificial skin array structure is by compound Array architecture that electrode fiber crossovers are arranged to make up or by combination electrode fiber and the flexible fiber being made of an electrically conducting material Electrode cross arrangement form array architecture or by combination electrode fibrage into fabric construction or by compound electric Polar fibers and the flexible fiber electrode mixed weaving that is made of an electrically conducting material into fabric construction；

Wherein, the combination electrode fiber is made of sandwich layer and sheaths；The sandwich layer is the flexible fiber being made of an electrically conducting material Electrode, the sheaths are the wrapping layers of the flexible fiber electrode made of polyelectrolyte；The sheaths are wrapped in the appearance of sandwich layer Face and the exposing of sandwich layer both ends；

The mode of the cross arrangement is arranged for upper and lower layer-stepping, positioned at the combination electrode fiber and/or flexible fiber of same layer Electrode is mutually parallel, and the arrangement angle of combination electrode fiber and/or flexible fiber electrode is 10 °~90 ° between levels；

The radical length of the flexible fiber electrode is 10~500 μm, axial length is not less than 2cm；The thickness model of the sheaths Enclose is 10~500 μm；The integral thickness of the artificial skin array structure is not more than 2mm；

The conductive material is metal material, carbon nanotube or carbon nanotube and the mixture of graphene；

The mixing material that the polyelectrolyte is mixed for ion exchange membrane material or neutral polymer with ionic liquid.

2. ion induction type artificial skin array structure according to claim 1, it is characterised in that：The fabric construction is Two-dimentional longitudinal-latitudinal type fabric construction, three-dimensional and multidimensional longitudinal-latitudinal type fabric construction or non-longitudinal-latitudinal type fabric construction.

3. ion induction type artificial skin array structure according to claim 1, it is characterised in that：The flexible fiber electricity Pole and the section of the combination electrode fiber are round, ellipse or rectangle.

4. a kind of preparation method of artificial skin array structure described in any one in claims 1 to 3, it is characterised in that including Following steps：

(1) flexible fiber electrode is made by Electrospinning in conductive material；Or using filiform as base, on the filiform Layer of conductive material is plated, flexible fiber electrode is made；

(2) polyelectrolyte is evaporated into film technique by solution, is wrapped on flexible fiber electrode and forms sheaths, compound electric is made Polar fibers；

(3) by combination electrode fiber or by combination electrode fiber with flexible fiber electrode hierarchy cross arrangement into array structure, then Different layers are laminated at contact point by hot forming technology, ion induction type artificial skin array structure is made；

Or：Fabric construction is woven into, then pass through hot pressing by combination electrode fiber or by combination electrode fiber and flexible fiber electrode Different layers are laminated by forming technique at contact point, and ion induction type artificial skin array structure is made；

(4) ion induction type artificial skin array structure made from step (3) is post-processed to improve performance, that is, completes system It is standby；The post processing is first to impregnate the artificial skin array structure obtained by step (3) in hydrochloric acid or sulfuric acid, so It is impregnated in alkali or alkaline earth metal cationic solution again afterwards.

5. preparation method according to claim 4, it is characterised in that：In order to adjust the resolution of artificial skin array structure Rate, the tensile strength for increasing artificial skin array structure, into array structure or fabric construction is woven into step (3) cross arrangement During, add in yarn or insulating polymer fiber.

6. a kind of application of artificial skin array structure described in any one in claims 1 to 3, it is characterised in that：Used in imitative In raw robot, pressure sensor or wearing flexible electronic device.