FABRIC-BASED BREATHABLE AND WASHABLE WEARABLE SENSOR AND MANUFACTURING METHOD THEREFOR

Description

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority benefit to Chinese Patent Application No. 202211139041.X, filed on Sep. 19, 2022, and entitled “FABRIC-BASED BREATHABLE AND WASHABLE WEARABLE SENSOR AND MANUFACTURING METHOD THEREFOR”, the entire contents of which are incorporated herein by reference.

FIELD OF DISCLOSURE

The present invention relates to a field of flexible wearable fabric sensors technology, relates to a field of flexible conductive materials as well as printed electronic products, and in particular relates to a fabric-based breathable and washable wearable sensor and a manufacturing method therefor, which are mainly used for human movement information detection. It has great application prospects in a field of sports and fitness equipment such as yoga wear, sportswear, sports bracelets, swimsuits, swim trunks and so on.

BACKGROUND

With a promotion of flexible electronic devices, flexible wearable fabric sensors have attracted widespread attention. In a field of flexible wearable devices, properties such as “no feeling”, “high elasticity”, “freshness” and “softness” are important features of future sensors that can increase wearers'comfort and aesthetics, and fabrics can meet these requirements. Therefore, development of flexible wearable fabric sensors is of great significance.

However, so far, researchers'exploration of flexible wearable fabric sensors is still unsatisfactory in terms of large operating range, washability, and breathability. An operating range is too small to meet requirements of practical applications. Poor washability will lead to a decrease in sensing performance after several washings. Poor breathability will reduce comfort of the wearer.

For example, Chinese Patent Publication No. CN111678623A provides an ultra-long-life self-healing stress sensor based on a printable nanocomposite material and a preparation method thereof. A one-dimensional metal nanowire, a two-dimensional inorganic nanosheet, a polymer material containing host-guest interactions, and a corresponding high-boiling-point solvent are composited to prepare nanocomposite colloidal inks with rheological properties. A stress sensor with in-situ self-healing ability and long cycle service life is manufactured by a screen printing method. During an operating process of the sensor, the host-guest polymer material contained in the sensor can repair internal defects in real time and in situ, which greatly extends service life of the material. At the same time, it is characterized by an operating strain range >50%, sensitivity (gauge factor) >100, strong self-repairing ability, and strong anti-interference ability to sweat. The preparation is simple and is used in fields such as smart wearable devices.

For example, Chinese Patent Publication No. CN204757997U discloses a fabric resistance sensor. The fabric resistance sensor described has an operating range of only 10%.

Non-patent document 1 (Journal of materials science, 2018, 53(12): 9026-9033) introduces a stretchable and wearable strain sensor prepared by integrating a conductive graphene network on spandex/nylon fabric. The strain sensor described has an operating range of 40.6% and sensitivity of up to 18.6. However, no further research has been conducted on washability of this strain sensor.

Non-patent document 2 (Fibers and Polymers, 2019, 20(3): 562-568) introduces a strain fabric sensor prepared by electroless Ni-P plating on the surface of polyester and polyester/spandex woven fabrics. The presence of an amorphous layer composed of Ni and phosphorus atoms on the surface of the strain fabric sensor resulted in a good hydrophobicity of the strain fabric sensor with a contact angle greater than 140°. However, the strain fabric sensor has decreased porosity due to the encapsulation of Ni and P atoms, which in turn leads to decreased breathability of the strain fabric sensor.

However, fabric sensors with a large operating range, good washability and high breathability have not yet been reported.

SUMMARY

In order to solve the deficiencies of the prior art, one objective of the present invention is to provide a fabric-based breathable and washable wearable sensor, which has characteristics of being water-resistant and comfortable to wear while satisfying sensitivity of the sensor.

To attain the above objective, a technical solution of the present invention is: the present invention provides a fabric-based breathable and washable wearable sensor including a fabric and a nano conductive layer, wherein an elastic fabric is configured as a substrate material, a nano conductive active layer is attached to a surface of the substrate material, and a hydrophobic layer on the surface, and has water-resistance of not less than 25 times of washing; an operating range of not less than 100%; a service life of not less than 500 times under a strain greater than 40%; breathability of not less than 100 mm/s; and a contact angle of the hydrophobic layer of greater than 90°.

Another objective of the present invention is to provide a method for manufacturing above-described fabric-based breathable and washable wearable sensor.

The present invention also provides the method for manufacturing the fabric-based breathable and washable wearable sensor, which mainly includes:

• • (1) formulating a dispersion of conductive material, and allowing the conductive material to be adsorbed on a surface of an elastic fabric material to form a conductive film by a printing method or a vacuum filtration method, so as to obtain a conductive fabric;
  • (2) hydrophobically modifying a surface of conductive fabric material obtained in step (1), using a hydrophobic modifier to hydrophobically modify the surface, so as to obtain a fabric-based breathable and washable sensor.

The present invention also provides applications of the fabric-based breathable and washable wearable sensor to be used in wearable use close to skin in order to detect human motion signals, including fingers or knees bending-type strain signals; or to be used on intelligent products such as electronic skin, bionic robots, etc.

The present invention manufactures a fabric-based breathable and washable wearable sensor, mainly including: an elastic fabric substrate material, a conductive active layer composed of nano conductive active materials, and a hydrophobic layer. The wearable sensor has: a large stretch range (>100%), high sensitivity (gauge factor>40), high breathability (>100 mm/s), good water-resistance (more than 25 times of washing), and a long service life. The device has excellent linearity in an operating curve, good stretch repeatability, and ability to detect weak signals such as human pulse and large deformations such as joints, and high breathability that provides the wearer with a good level of comfort, which is not achievable with most current sensors. The sensor of the present invention has the following attributes:

• • Having good water-resistance, with more than 25 times of washing;
  • Having good sensing performance: sensitivity greater than 40; an operating range greater than 100%; and a service life greater than 500 times under the strain greater than 40%;
  • Having good breathability: breathability >100 mm/s;
  • Having good water-resistance: a contact angle >90°.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic structural diagram of a fabric-based breathable and washable wearable sensor, wherein FIG. 1a is a schematic diagram of a sample and FIG. 1b is a partially enlarged diagram.

FIG. 2 is an operating curve of the fabric-based breathable and washable wearable sensor of Embodiment 1.

FIG. 3 is a service life of the fabric-based breathable and washable wearable sensor of Embodiment 1.

FIG. 4 is a contact angle of the fabric-based breathable and washable wearable sensor of Embodiment 1.

FIG. 5 is a product of the fabric-based breathable and washable wearable sensor of Embodiment 3.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

The present invention provides a fabric-based breathable and washable wearable sensor, which has characteristics of being water-resistant and comfortable to wear while satisfying sensitivity of the sensor.

The invention provides a fabric-based breathable and washable wearable sensor including a fabric and a nano conductive layer, wherein an elastic fabric is configured as a substrate material, a nano conductive active layer is attached to a surface of the substrate material, and a hydrophobic layer on the surface, and has water-resistance of not less than 25 times of washing; an operating range of not less than 100%; a service life of not less than 500 times under a strain greater than 40%; breathability of not less than 100 mm/s; and a contact angle of the hydrophobic layer of greater than 90°.

The invention adsorbs nano conductive active materials on an elastic fabric substrate material and forms a hydrophobic layer on a surface of nano conductive active materials, so that the fabric-based breathable and washable wearable sensor has a lower sheet resistance; the elastic fabric substrate material provides a larger operating range and good breathability; the hydrophobic layer improves washability of the sensor, and the resulting fabric-based breathable and washable wearable sensor has a large operating range (>100%), high sensitivity (gauge factor >40), and high breathability (>100 mm/s), good washability (more than 25 times of washing) and good stretch stability (more than 500 times of service life under greater than 40% strain).

The substrate material includes one or more of diene elastomeric fibers, polyurethane fibers, polyetherester elastomeric fibers, polyolefin elastomeric fibers, polypropylene fibers, polyethylene fibers, polyamide fibers, natural latex fibers, polyacrylonitrile fibers, polyvinyl alcohol fibers, aramid fibers, same type of sub-fiber; and/or

One or two of cotton, kapok; and/or

One or more of flax, hemp, apocynum, ramie, and sisal; and/or

Animal hair, such as one or more of sheep wool, cashmere, rabbit hair, camel hair, yak hair and/or alpaca hair; and/or

Glandular secretions of silkworms, such as mulberry silk, and/or tussah silk; and/or

One or more of viscose fibers, acetate fibers, lyocell fibers, modal fibers, cupro fibers, soy fibers, and corn fibers.

The textile method of the elastic fabric substrate material is one of: knitting: warp knitting, weft knitting; woven: plain weave, twill weave, and satin weave.

The nano conductive active layer is a film composed of nano conductive active material, wherein the nano conductive active material is one of a zero-dimensional metal nanoparticle, a one-dimensional metal nanowire, and a two-dimensional conductive material.

The zero-dimensional metal nanoparticle includes one of gold, silver, copper, iron, chromium, nickel, aluminum, tungsten, platinum, gallium, indium, gallium-indium alloy, and gallium-indium-tin alloy metal nanoparticles, with a particle size of 1-1000 nm.

The one-dimensional metal nanowire includes one of gold, silver, copper, iron, nickel, platinum, palladium, and aluminum metal nanowires. The metal nanowire has a diameter of 1-300 nm and a length of 2-100 μm.

The two-dimensional conductive material includes one of graphene, graphene oxide, molybdenum disulfide, and a two-dimensional transition metal carbide or nitride (MXene), wherein the two-dimensional transition metal carbide or nitride (MXene) is a two-dimensional structure similar to graphene with a chemical formula of M_n+1X_nT_z, n=1,2,3, wherein M is an early transition metal element, X is a carbon or nitrogen element, and T is a surface-linked —F or —OH activity functional group, including one of Ti₂C, Ti₃C₂, Ti₃CN, V₂C, Nb₂C, TiNbC, Nb₄C₃, Ta₄C₃, (Ti_0.5Nb_0.5)₂C or (V_0.5Cr_0.5)₃C₂.

The hydrophobic layer is one or more of a graft copolymer layer, a sol-gel deposition layer, a dip-coating deposition layer, a spray-coating deposition layer, a plasma-treated post-coating layer, a chemical vapor deposition (CVD) layer, and an in-situ nanoparticle growth layer, or a silanization layer, formed using a hydrophobic modifier.

The hydrophobic modifier is one of a silicone resin, a silane coupling agent, a metal oxide nanoparticle, a metal complex of long-chain fatty acid, a long-chain aliphatic chain quaternary amine compound, a methyl hydrogen-containing polysiloxane, an ethyl-hydrogen-containing silicone oil, a dimethyl-hydrogen-containing polysiloxane, an acrylic fluoropolymer, and a polyurethane;

Wherein, the silicone resin includes a polyalkyl silicone resin, a polyaryl silicone resin, and a polyalkyl aryl silicone resin. The silane coupling agent includes KH-570 (γ-methacryloyloxypropyltrimethoxysilane), a fluorosilane coupling agent (heptadecafluorodecyltrimethoxysilane), trichloromethylsilane, and trichloro (1H,1H,2H,2H-perfluorooctyl) silane (PFOTS). The metal oxide nanoparticle includes oxides of nickel, chromium, iron, zinc, titanium, platinum, magnesium, and copper. The metal complex of the long-chain fatty acid includes a chromium oxide complex of stearic acid, a water-repellent agent CR, a water-repellent agent AC, a water-repellent agent AZ, etc. The long-chain aliphatic chain quaternary amine compound includes a water-repellent agent PF (stearamide methylpyridinium chloride).

The present invention manufactures a fabric-based breathable and washable wearable sensor, mainly including: an elastic fabric substrate material, a conductive active layer composed of nano conductive active materials, and a hydrophobic layer. The wearable sensor has: a large stretch range (>100%), high sensitivity (gauge factor>40), high breathability (>100 mm/s), good water-resistance (more than 25 times of washing), and a long service life. The device has an excellent linearity in an operating curve, good stretch repeatability, and ability to detect weak signals such as human pulse and large deformations such as joints, and high breathability that provides the wearer with a good level of comfort, which is not achievable with most current sensors. The sensor of the present invention has the following attributes:

• • Having good water-resistance, with more than 25 times of washing;
  • Having good sensing performance: sensitivity greater than 40; an operating range greater than 100%; and a service life greater than 500 times under the strain greater than 40%;
  • Having good breathability: breathability >100 mm/s;
  • Have good water-resistance: a contact angle >90°.

The present invention also provides a method for manufacturing a fabric-based breathable and washable wearable sensor, which mainly includes the following embodiments.

Material preparation: absorbing a certain amount of conductive material, formulating the conductive material into a dispersion and mixing it thoroughly, such as using ultrasonic oscillation, high-speed stirring and so on to disperse it evenly, and using a printing method or a vacuum filtration method to make the conductive material adsorbed on the surface of the elastic fabric material to form a conductive film.

Embodiment 1

A fabric-based breathable and washable wearable sensor, as shown in FIG. 1, is manufactured by using an elastic fabric as a substrate material, including from inside to outside: a fabric fiber bundle 1, a nano conductive active layer 2, and a surface hydrophobic layer 3, according to following steps:

• • (1) Weighing 100 mL of aqueous dispersion of a two-dimensional transition metal carbide (MXene) with a concentration of 10 mg/mL, ultrasonically oscillating to disperse it evenly, and dip-coating a substrate material of polyester/spandex cloth with an elastic fiber fabric size of 5*2 cm in the aqueous dispersion of the two-dimensional transition metal carbide (MXene) for 30 minutes and then drying the substrate material of polyester/spandex cloth at 60° C., and the fabric fiber is coated with a nano conductive active layer 2, so as to obtain a MXene conductive film of a fabric substrate;
  • wherein, in step (1), the printing method includes one of: screen printing, inkjet printing, blade coating, dip coating, Meyer rod coating, spray coating, slit-type coating, and direct writing printing.
  • (2) Hydrophobically modifying a surface of conductive fabric material obtained in step (1), wherein the MXene conductive film obtained in step (1) is placed in a plasma cleaning machine and treated with oxygen plasma for 90 minutes at a power of 150 watts to complete the hydrophobic modification, so as to obtain a MXene conductive film treated with oxygen plasma;

Wherein, in step (2), the hydrophobic modification includes one or more of the following methods: graft copolymerization, sol-gel deposition, dip-coating deposition, spray deposition, plasma treatment and coating, chemical vapor deposition (CVD), and in-situ nanoparticle growth.

• • (3) Weighing 100 μL of perfluorooctane sulfonyl compound (PFOTS) solution, dropping the perfluorooctane sulfonyl compound solution on a glass slide, placing the glass slide and the MXene conductive film treated with oxygen plasma in step (2) in a vacuum drying pot, and lasting for 4 hours at 100° C. in a vacuum environment, so as to obtain a fabric-based breathable and washable wearable sensor.

An operating curve of the breathable and washable wearable sensor is shown in FIG. 2.

FIG. 4 a contact angle of the breathable and washable wearable sensor in Embodiment 1.

A printable transparent stress sensor has water-resistance of not less than 25 times of washing; and an operating range of not less than 100%.

As shown in FIG. 3, the printable transparent stress sensor has a long service life of not less than 1000 times at 50% strain, and breathability of not less than 100 mm/s.

The contact angle of the breathable and washable wearable sensor obtained in step (3) was tested by a VAC optima static contact angle meter. As shown in FIG. 4, the contact angle can reach 124.6°, and the contact angle of the hydrophobic layer is large. The breathability of the breathable and washable wearable sensor obtained in step (3) was tested by a 4110N breathability tester, and the breathability can reach 866.68 mm/s.

Embodiment 2

A fabric-based breathable and washable wearable sensor is manufactured according to the following steps:

• • (1) Weighing 5 mL of silver nanowire/ethanol dispersion with a concentration of 8 mg/mL, ultrasonically oscillating to disperse it evenly, using 4*2 cm spandex/cotton cloth as the substrate material, and printing the dispersion on the substrate material by using inkjet printing, drying the dispersion at 80° C., and repeating the operation three times, so as to obtain a silver nanowire conductive film on a fabric substrate;

Wherein, the silver nanowire/ethanol dispersion is a dispersion liquid formed by silver nanowires dispersed in an ethanol matrix.

• • (2) Hydrophobically modifying a surface of conductive fabric material obtained in step (1) by weighing 100 mL of polyurethane A 85/DMF solution with a concentration of 10 wt %, dip-coating the silver nanowire conductive film obtained in step (1) for 20 minutes, and drying the silver nanowire conductive film at 80° C., so as to obtain a fabric-based breathable and washable wearable sensor;

Wherein, the polyurethane A85/DMF solution is a solution formed by dissolving polyurethane A85 in DMF with a concentration of 10 wt%.

Embodiment 3

A fabric-based breathable and washable wearable sensor, as shown in FIG. 5, is manufactured according to the following steps:

• • (1) Weighing 10 mL of graphene/DMF dispersion with a concentration of 6 mg/mL, ultrasonically oscillating to disperse it evenly, using cotton/polyester/spandex cloth 1′ as the substrate material, and screen printing the dispersion on the substrate material with a screen printing machine, drying the dispersion at 50° C., and repeating the operation five times, so as to obtain a graphene conductive film 2′ on a fabric substrate;

Wherein, the graphene/DMF dispersion is a dispersion liquid formed by graphene dispersed in DMF.

• • (2) Hydrophobically modifying a surface of conductive fabric material obtained in step (1) by weighing 100 mL of polyurethane A 65/DMF solution with a concentration of 15 wt %, dip-coating the graphene conductive film obtained in step (1) for 15 minutes, drying the dispersion at 70° C. to form a surface hydrophobic layer 3′, so as to obtain a fabric-based breathable and washable wearable sensor;

Wherein, the polyurethane A85/DMF solution is a solution formed by dissolving polyurethane A65 in DMF with a concentration of 15wt %.

Embodiment 4

A fabric-based breathable and washable wearable sensor is manufactured according to the following steps:

• • (1) Weighing 50 mL of copper nanowire/water dispersion with a concentration of 4 mg/mL, ultrasonically oscillating to disperse it evenly, and then filtering it with a vacuum filter on cotton/polyester cloth, and drying it at 40° C., so as to obtain a copper nanowire conductive film on a fabric substrate;

Wherein, the copper nanowire/water dispersion is a dispersion formed by the copper nanowires dispersed in water.

• • (2) Hydrophobically modifying a surface of conductive fabric material obtained in step (1): placing the copper nanowire conductive film obtained in step (1) into a plasma cleaning machine and treating it with oxygen plasma for 120 minutes at a power of 120 watts, so as to obtain a copper nanowire conductive film treated with oxygen plasma;
  • (3) Weighing 150 μL of perfluorooctane sulfonyl compound (PFOTS) solution, dropping the perfluorooctane sulfonyl compound (PFOTS) solution on the glass slide and placing the glass slide and the copper nanowire conductive film treated with oxygen plasma in step (2) in a vacuum drying pot, and lasting for 2 hours at 100° C. in a vacuum environment, so as to obtain a fabric-based breathable and washable wearable sensor.

The mechanism of action of the fabric-based breathable and washable wearable sensor of the present invention is as follows: the nano conductive active materials have a good and strong effect on the elastic fabric material, such as hydrogen bonding; the elastic fabric material has good stretch properties and large porosity, which provides a larger operating range and high breathability; the nano conductive active materials are adsorbed on a surface of the elastic fabric material to form a conductive active layer. During the stretch process, slippage, phenomena such as slippage and cracks occur between nano conductive active materials, resulting in an increase in resistance; the hydrophobic modification on the surface forms a hydrophobic layer, which improves the water repellent performance of the sensor, thus achieving the effect of water-resistance.

The present invention also provides applications of the fabric-based breathable and washable wearable sensor to be used in wearable use close to skin in order to detect human motion signals, including fingers or knees bending-type strain signals; or to be used on intelligent products such as electronic skin, bionic robots, etc.

The fabric-based breathable and washable wearable sensor are worn close to the skin and can detect human motion signals, such as strain signals from bending fingers or knees.

The fabric-based breathable and washable wearable sensor can not only be used in running fitness equipment such as yoga wear, tight sportswear, and tight-fitting sportswear, as well as swimming sports equipment such as swimsuits and swimming trunks, to detect human motion signals, but also can be used in new products such as electronic skin, bionic robots, etc.

The above embodiments are only to further illustrate the present invention and should not be limited to the contents disclosed in the embodiments. Each specific substance in the product components disclosed in the technical solution of the present invention can be implemented by the present invention, and the same technical effect can be obtained as in the embodiments, and the embodiments are not individually cited herein for illustration. Therefore, any equivalent or modification thereof, without departing from the spirit and principle in the present invention, falls within the scope of protection of the present invention.