CN114322742A

CN114322742A - Novel fiber type resistance strain sensor and preparation method thereof

Info

Publication number: CN114322742A
Application number: CN202111657292.2A
Authority: CN
Inventors: 吴俊�; 陶妍; 梁校通
Original assignee: Southeast University
Current assignee: Southeast University
Priority date: 2021-12-31
Filing date: 2021-12-31
Publication date: 2022-04-12

Abstract

The invention discloses a novel fiber type resistance strain sensor and a preparation method thereof, wherein a spandex fiber resistance strain sensor comprises a substrate layer, an adhesion layer, a conductive layer and a packaging insulating layer. By analyzing the resistance properties of the two ends of the sensor, the strain state of the sensor can be obtained. The invention has high sensitivity and wider detection range, can react to external stress in time, and has certain application value in the fields of intelligent fabrics, medical rehabilitation, wearable equipment and the like.

Description

Novel fiber type resistance strain sensor and preparation method thereof

Technical Field

The invention relates to the technical field of flexible sensors, in particular to a novel fiber type resistance strain sensor and a preparation method thereof.

Background

The development of intelligent wearing equipment has put forward higher and higher requirement to flexible device, wherein, uses the most general flexible force sensing resistance sensor to divide into resistance-type force sensing resistance sensor and strain type force sensing resistance sensor according to the difference of handling mechanical signal, corresponds with detection pressure signal and detection tensile signal respectively. However, due to the limitation of the microstructure of the device, it is difficult to simultaneously achieve high detection sensitivity and human body surface conformability for the flexible force-sensitive resistance sensor made of the traditional flexible material.

The liquid metal EGaIn is a metal compound with liquid fluidity, can ensure higher conductivity while having fluidity, has higher biological safety compared with mercury Hg, and has excellent mechanical property and electrical property. However, the wettability of EGaIn to the flexible material is not high, so that the device structure made of the EGaIn is difficult to stabilize the shape.

Disclosure of Invention

The purpose of the invention is as follows: the utility model provides a novel fibre formula resistance type strain transducer and preparation method thereof, solves strain transducer can't bear the problem that complicated weaving is difficult to constitute the fabric circuit.

The technical scheme is as follows: the novel fiber type resistance strain sensor comprises a substrate layer, an adhesion layer, a conductive layer and a packaging insulating layer; the adhesion layer, the conductive layer and the packaging insulating layer are sequentially coated on the surface of the base layer from inside to outside; the conductive layer is liquid metal EGaIn.

Further, the substrate layer is formed by spirally winding and weaving spandex fibers.

Furthermore, the adhesion layer and the packaging insulating layer are both water-based polyurethane coatings.

Furthermore, the novel fiber type resistance strain sensor also comprises two sections of conducting wires which are respectively positioned at two ends of the conducting layer, and the conducting wires are bonded with the conducting layer through the conducting silver adhesive.

The preparation method of the novel fiber type resistance strain sensor comprises the following steps:

step 1, manufacturing a substrate layer;

taking spandex fiber to rotate and wind, and weaving the spandex fiber into a spandex fiber multi-strand rope to form a basal layer.

The method specifically comprises the following steps: and folding one spandex coated yarn in equal parts, rotating two ends in opposite directions at the same time, and weaving the spandex coated yarn into a two-strand rope to form the woven spandex coated yarn as a substrate layer.

Step 2, manufacturing an adhesive layer;

immersing the substrate layer of the spandex multi-strand rope in the waterborne polyurethane, taking out the substrate after the substrate surface is fully soaked, horizontally suspending the substrate in a fume hood for air drying, and obtaining the fiber substrate attached with the polyurethane after water is evaporated.

Step 3, manufacturing a conductive layer;

and (3) placing the fiber substrate obtained in the step (2) on a clean glass plate, coating the fiber substrate with liquid metal EGaIn to uniformly cover the surface of the fiber with a liquid metal thin layer, standing for 3 minutes to oxidize and adhere the surface of the liquid metal to the fiber, and thus obtaining the spandex fiber covered yarn covered with the conductive layer.

Step 4, leading out an electrode;

setting a heating table at 75 ℃, placing spandex fiber covered yarns covered with the conductive layer on the heating table, respectively placing leads at two ends of the spandex fiber covered yarns, wherein the length of each lead in contact with the covered yarns is 5mm, dripping conductive silver-electrode glue on the positions of the leads in contact with the covered yarns for covering, and heating for 30min to fix the covered yarns and the leads together. The conducting wire adopts a copper sheet.

Step 5, manufacturing a packaging insulating layer;

and (4) immersing the conductive spandex fiber covered yarn obtained in the step (4) into waterborne polyurethane, taking out the spandex fiber covered yarn, horizontally suspending the spandex fiber covered yarn in a fume hood for air drying, uniformly attaching a polyurethane film packaging insulating layer on the surface of the spandex fiber covered yarn, and only exposing the lead electrode to obtain the sensor.

Has the advantages that: the invention can realize high-sensitivity detection of tensile strain, when the tensile strain is 25%, the resistance of the device changes by about 26%, and when the tensile strain is 50%, the resistance of the device changes by about 49.2%; the sensor substrate adopts two strands of braided spandex coated yarn fibers, the contact area of the substrate and the liquid metal is increased by the two strands of braiding, and the adhesiveness of the liquid metal conducting layer to the fiber substrate is ensured; the liquid metal is used as a conductive layer material, and the liquid metal has good fluidity, so that the device can bear large-scale strain and complex deformation, can be compatible with a weaving process in the textile industry, and has a certain application value in the fields of intelligent fabrics, medical rehabilitation, wearable equipment and the like.

Drawings

Fig. 1 is a schematic structural view of the present invention.

Wherein: 1. a base layer; 2. an adhesive layer; 3. a conductive layer; 4. and encapsulating the insulating layer.

Detailed Description

The invention will be further explained with reference to the drawings

As shown in fig. 1, the novel fiber-type resistive strain sensor provided by the present invention includes a substrate layer 1, an adhesive layer 2, a conductive layer 3, and an encapsulation insulating layer 4; the adhesion layer 2, the conductive layer 3 and the packaging insulating layer 4 are sequentially coated on the surface of the substrate layer 1 from inside to outside.

The base layer 1 is made of two strands of braided spandex-coated yarn fibers, and the braiding method comprises the steps of firstly folding the spandex-coated yarn fibers into two strands and then braiding the two strands into a strand of rope according to a twist braid method.

The adhesion layer 2 is made by soaking with aqueous polyurethane, and when the fiber is taken out of the aqueous polyurethane, no aqueous polyurethane liquid drop is left on the surface of the fiber, the aqueous polyurethane uniformly wraps the whole fiber, and when the fiber is hung and dried, the environment is kept clean and dry so as to avoid polluting the adhesion layer 2.

The conducting layer 3 is coated on the surface of the adhesion layer 2 by using liquid metal EGaIn, so that the liquid metal can fully infiltrate the spandex-coated yarn substrate, the spandex-coated yarn can be fully covered by the liquid metal, and a device has better stability. Only the substrate layer 1, the adhesive layer 2, the conductive layer 3 and the encapsulating insulating layer 4 are shown in fig. 1, and the wire electrode and its connection relationship with the conductive layer 3 are not shown.

The packaging insulating layer 4 is made of waterborne polyurethane, the whole sensing device is wrapped by the waterborne polyurethane, and only the copper sheet electrode is exposed.

The principle of the resistance change of the sensor is that the insulated spandex fiber surface is provided with a conductive liquid metal coating, so that the insulated spandex fiber surface can be regarded as a bent conductive film structure to be wrapped outside a device. And the spandex fibre can take place deformation under the external pulling force effect, because liquid metal coating and spandex fibre are closely laminated, the length can change in the vertical direction of conducting layer 3. The resistance value of the device is positively correlated with the length according to the resistance formula. As the strain increases, the overall resistance of the sensor of the present invention increases linearly.

Claims

1. The novel fiber type resistance strain sensor is characterized by comprising a substrate layer, an adhesion layer, a conductive layer and a packaging insulating layer;

the adhesion layer, the conductive layer and the packaging insulating layer are sequentially coated on the surface of the base layer from inside to outside;

the conductive layer is liquid metal EGaIn.

2. The novel fiber-type resistive strain sensor of claim 1, wherein the substrate layer is formed by spirally winding and weaving spandex fibers.

3. The fiber resistive strain sensor of claim 1, wherein the adhesive layer and the encapsulating insulating layer are both aqueous polyurethane coatings.

4. The fiber-type resistive strain sensor according to claim 1, further comprising two wires respectively disposed at two ends of the conductive layer, wherein the wires are bonded to the conductive layer by conductive silver paste.

5. The preparation method of the novel fiber type resistance strain sensor is characterized by comprising the following steps of:

step 1, manufacturing a substrate layer;

taking spandex fibers for rotary winding, and weaving the spandex fibers into a spandex fiber multi-strand rope to form a basal layer;

step 2, manufacturing an adhesive layer;

immersing the polyurethane multi-strand rope substrate layer into the waterborne polyurethane, taking out the polyurethane multi-strand rope substrate layer after the substrate surface is fully soaked, and air-drying to obtain a fiber substrate attached with the polyurethane;

step 3, manufacturing a conductive layer;

coating the fiber substrate obtained in the step (2) with liquid metal EGaIn to enable the surface of the fiber to be uniformly covered with a liquid metal thin layer, standing to enable the surface of the liquid metal to be oxidized and adhered to the fiber, and obtaining spandex fiber covered yarns covered with the conductive layer;

step 4, leading out an electrode;

placing the spandex fiber covered yarn covered with the conductive layer on a heating table, respectively placing leads at two ends of the spandex fiber covered yarn, dripping conductive silver glue at the contact position of the leads and the spandex fiber covered yarn for covering, and heating to fix the covered yarn and the leads together;

step 5, manufacturing a packaging insulating layer;

and (4) immersing the conductive spandex fiber covered yarn obtained in the step (4) into waterborne polyurethane, taking out the spandex fiber covered yarn, and air-drying to ensure that a polyurethane film packaging insulating layer is uniformly attached to the surface of the spandex fiber covered yarn and only the lead electrode is exposed.

6. The method for preparing the novel fiber type resistance strain sensor according to claim 5, wherein the step 1 comprises the following specific steps: and folding one spandex coated yarn in equal parts, rotating two ends in opposite directions at the same time, and weaving the spandex coated yarn into a two-strand rope to form the woven spandex coated yarn as a substrate layer.