CN111364156B

CN111364156B - Double-helix conductive textile, pressure sensor and pressure sensor manufacturing method

Info

Publication number: CN111364156B
Application number: CN202010210684.3A
Authority: CN
Inventors: 胡金莲; 陈剑铭
Original assignee: Shenzhen Qidi Huijia Technology Co ltd
Current assignee: Shenzhen Qidi Huijia Technology Co ltd
Priority date: 2020-03-24
Filing date: 2020-03-24
Publication date: 2022-09-06
Anticipated expiration: 2040-03-24
Also published as: CN111364156A

Abstract

The invention provides a double-spiral conductive textile fabric, a pressure sensor and a preparation method of the pressure sensor, wherein the double-spiral conductive textile fabric is knitted by DNA type double-spiral yarn, two bundles of metal coated yarn multifilaments are arranged in parallel in pairs, and then the two bundles of metal coated yarn multifilaments are transferred to a winding machine with the twist value of 450tpm in the S direction and the spindle rotating speed of 8000rpm to obtain the DNA type double-spiral yarn, the pressure sensor comprises a substrate, a metal electrode layer, a conductive textile layer and a packaging layer which are sequentially stacked, the conductive textile layer is formed by the double-spiral conductive textile fabric, and the DNA double-spiral structure of the double-spiral conductive textile fabric enables the metal coated yarn multifilaments to have enough strong twisting force, can quickly and effectively overcome friction force, realizes high-speed response/recovery, and has good stability, durability, reusability and low hysteresis.

Description

Double-helix conductive textile, pressure sensor and pressure sensor manufacturing method

Technical Field

The invention relates to the field of sensors, in particular to a double-spiral conductive textile for a pressure sensor, the pressure sensor and a preparation method of the pressure sensor.

Background

In recent years, smart electrical sensing technology for portable, long-term healthcare, and remote medical diagnostics has received increased attention by monitoring physiological signals. Among them, pulse waves, an important human signal, can be collected with optical and pressure sensors, but the optical sensors usually operate at 10 to 100mW power, and there are limited applications where the signal requirements are high. However, the pressure sensors developed in recent years are not ideal in the aspects of sensitivity, linearity, conductivity, mechanical properties and the like under moderate pressure states such as in vivo blood pressure, pulse pressure and the like, and carbon black particles, Carbon Nanotubes (CNTs), graphene and other carbon-based materials are dispersed in a polymer matrix to prepare a conductive composite material for manufacturing the pressure sensors, so that the conductivity and mechanical properties of the sensors can be really improved.

Disclosure of Invention

The invention aims to provide a double-helix conductive textile fabric for a pressure sensor, which can improve the performance of an electronic device, and provide the pressure sensor with excellent performances such as sensitivity, hysteresis, response/recovery time and the like so as to meet the requirements of the existing market.

In order to achieve the above object, the present invention provides a double-spiral conductive textile fabric for a pressure sensor, which is knitted from a DNA-type double-spiral filament yarn, wherein two bundles of metal-coated filament multifilaments are arranged in parallel, and then transferred to a bobbin winder with a twist value of 450tpm in the S direction and a spindle rotation speed of 8000rpm to obtain the DNA-type double-spiral filament yarn, each bundle of metal-coated filament multifilaments form a DNA-type double-spiral structure, each monofilament in each metal-coated filament multifilament comprises a nylon core and a metal sheath, the metal sheath is coated outside the nylon core, and the conductivity of each metal-coated filament multifilament is 900-1500 ohm/cm.

Preferably, the specification of the metal-clad filament multifilament is 40-100D/10-40F.

More preferably, the fineness of the metal-clad filament multifilament is 20 to 60 Tex.

Preferably, the metal-coated wire multifilament is a copper-coated wire multifilament, a gold-coated wire multifilament, a silver-coated wire multifilament or an aluminum-coated wire multifilament.

The invention also provides a pressure sensor, which comprises a substrate, a metal electrode layer, a conductive textile layer and a packaging layer, wherein the metal electrode layer is arranged on the substrate, the conductive textile layer is arranged on the metal electrode layer, the packaging layer is arranged on the conductive textile layer and packages the conductive textile layer, the metal electrode layer is an Au interdigital electrode, the conductive textile layer is the double-spiral conductive textile fabric, and a PEN film is arranged on the packaging layer.

More preferably, the metal electrode layer is an Au interdigital electrode, and the thickness of Cr/Au is 5/100 nm; the electrode width is 200 μm; the interval is 100 μm; the effective pressure-sensitive area is 3mm × 3 mm.

More preferably, the substrate is a Pi substrate, and the thickness thereof is 2 to 5 μm.

A preparation method of a pressure sensor is used for preparing the pressure sensor and comprises the following steps: step 1, aligning two bundles of metal coated yarn multifilaments in parallel, and obtaining a DNA type double-spiral silk yarn through a twisting technology; step 2, preparing the DNA type double spiral yarn into conductive textile by a small circular knitting machine by adopting a common knitting method; step 3, carrying out photoetching composition on the Au interdigital electrode, and then thermally evaporating the Au interdigital electrode onto the collecting plate to form a metal electrode layer; step 4, assembling the conductive textile obtained in the step 2 on the top of the Au interdigital electrode to form a conductive textile layer; step 5, packaging the conductive textile layer obtained in the step 4 by using 1.0mil acrylic PSA adhesive to form a packaging layer; and 6, finally covering the pressure sensor with a 1-2 mu m PEN film to obtain the pressure sensor.

Further preferably, the method for obtaining the DNA-type double-spiral filament yarn in the step 1 is to arrange two metal-coated filament multifilaments in parallel and then transfer the two metal-coated filament multifilaments to a winder with a twist value of 300-.

Further preferably, before the conductive textile obtained in step 2 is assembled on top of the Au interdigital electrode in step 4, the method further includes connecting the Au interdigital electrode to a standard dupont needle by using an anisotropic conductive film.

The double-spiral conductive knitted fabric is knitted by a predetermined number of metal-coated-wire multifilaments with the specification of 20-60Tex/40-100D/10-40F, each metal-coated-wire multifilament forms a DNA double-spiral structure, and the double-spiral conductive knitted fabric has good torsion force and elastic restoring force and strong repeatability, can greatly prolong the service life of electronic equipment such as a sensor and provides a foundation for improving the performance research of the electronic equipment such as the sensor.

The conductive textile layer in the pressure sensor has a DNA double-spiral structure, so that the metal-clad filament multifilament has a strong enough torsion force, can quickly and effectively overcome friction force, realizes high-speed response/recovery, good stability, durability and reusability, and low hysteresis, and simultaneously fibers in the double-spiral filament yarn are regularly aligned, so that the linearity of the pressure sensor is increased, and when the applied pressure is 30KPa, the sensitivity of the pressure sensor is 0.57KPa ^-1 Delay of 4.8-5.7%, linearity of 4.7-5.4%, response/recovery time of 2ms, durability of 6600, and high reusability, practicability and applicability.

The pressure sensor has high flexibility, can be attached to a human body by means of medical adhesive tapes and the like, is also beneficial to providing wearable and portable medical sensing equipment for human, and achieves the purpose of health detection by sensing and monitoring human body pulses.

The pressure sensor is simple in preparation method and suitable for large-scale mass production.

Drawings

FIG. 1 is a schematic diagram of a pressure sensor according to the present invention;

FIG. 2 is a schematic view of the structure of the conductive textile layer in the pressure sensor provided by the present invention;

FIG. 3 is a schematic diagram of the DNA double helix structure of the metal-coated filament multifilament in the conductive textile layer;

FIG. 4 is a load-unload transfer curve of a conventional prevention sensor of untwisted yarn or a pressure sensor provided by the present invention (A, three successive load-unload cycles of a conventional textile sensor at 800KPa pressure; B, typical step sensitivity of a conventional textile sensor; C, disorder and fluctuation data collected for a conventional textile sensor at 30KPa pressure; D/E, typical load-unload cycles of the pressure sensor at 800KPa and 70KPa pressures; F, three successive load-unload cycles of the pressure sensor at 30KPa pressure);

FIG. 5 shows the response/recovery time stability test results of the pressure sensor provided by the present invention (A, the response/recovery time of the pressure sensor (1KHz sampling rate); B, 6600 cycles stability test is performed on the pressure sensor under 1Hz trigger (1 cycle per second));

fig. 6 shows the results of epidermal pulse detection (a, wrist pulse signals monitored before and after exercise, B, pulse detected at the neck and wrist, respectively, C, wrist pulse signals collected from normal female subjects and male subjects, D, peak values of correlation signals of both male/female subjects in each complete cycle).

Detailed Description

The embodiments described below are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Example 1

Referring to fig. 2, the present embodiment provides a double-spiral conductive textile knitted from a predetermined number of metal-clad filament multifilaments, each of the metal-clad filament multifilaments constitutes a DNA-type double-spiral structure two by two, each of the monofilaments in each of the metal-clad filament multifilaments includes a nylon core and a metal sheath, the metal sheath is coated outside the nylon core, the conductivity of each of the metal-clad filament multifilaments is 900-1500ohm/cm, preferably 1200ohm/cm, the specification of the metal-clad filament multifilaments is 40-100D/10-40F, and the fineness is 20-60 Tex. The double helix conductive textile fabric structure configuration can improve the performance of response/recovery, hysteresis, repeatability and the like of electronic equipment such as a sensor, and is described by taking a pressure sensor as an example.

Referring to fig. 1, fig. 2 and fig. 3, the present embodiment further provides a pressure sensor, which includes a substrate 1, a metal electrode layer 2, a conductive textile layer 3 and an encapsulation layer 4, wherein the metal electrode layer 2 is disposed on the substrate 1, the conductive textile layer 3 is disposed on the metal electrode layer 2, the encapsulation layer 4 is disposed on the conductive textile layer 3, and encapsulates the conductive textile layer 3, the metal electrode layer 2 is an Au interdigital electrode, the conductive textile layer 3 is a double-spiral conductive textile, and a PEN film 5 is disposed on the encapsulation layer 4, and a thickness of the PEN film is 1-2 μm, preferably 1.4 μm. The metal-clad silk multifilament comprises a nylon core and a metal sheath, wherein the metal sheath is clad outside the nylon core. The interdigital electrode is an Au interdigital electrode, the thickness of Cr/Au is 5/100nm, the electrode width is 200 mu m, the interval is 100 mu m, and the effective pressure-sensitive area is 3mm multiplied by 3 mm. The substrate 1 is a Pi substrate having a thickness of 2 to 5 μm, preferably 2.3 μm. The metal-coated wire multifilament can be copper-coated wire multifilament, gold-coated wire multifilament, silver-coated wire multifilament, aluminum-coated wire multifilament and the like, and the pressure sensor selects the copper-coated wire multifilament.

Example 2

This example provides a method for preparing a pressure sensor as described in example 1, specifically as follows:

raw materials:

copper-clad filament multifilament: the specification is 20-60tex/40-100D/10-40F, the conductivity is 900-; interdigital Au electrode: the thickness of Cr/Au is 5/100 nm; the electrode width is 200 μm; the interval is 100 μm; effective pressure-sensitive area is 3mm x 3 mm; an acrylic PSA binder; the thickness of the PEN film is 1-2 μm.

The method comprises the following steps:

step 1, aligning two bundles of copper-clad silk multifilament 31 in parallel, and obtaining a DNA type double-spiral silk yarn through a twisting technology;

step 2, preparing the DNA type double-spiral yarn into double-spiral conductive textile by a small circular knitting machine by adopting a common knitting method;

step 3, carrying out photoetching composition on the Au interdigital electrode, and then thermally evaporating the Au interdigital electrode to the collecting plate to form a metal electrode layer 2;

step 4, assembling the double-helix conductive textile obtained in the step 2 on the top of the Au interdigital electrode to form a conductive textile layer 3;

step 5, packaging the conductive textile layer 3 obtained in the step 4 by using 1.0mil acrylic PSA adhesive to form a packaging layer 4;

and 6, finally covering with a PEN film to obtain the pressure sensor.

Wherein the method for obtaining the double-spiral yarn in the step 1 is to arrange two bundles of the copper-clad multifilament 31 in parallel and then transfer the two bundles of the copper-clad multifilament to a winder with the twist value of 300-. And 4, before the conductive textile obtained in the step 2 is assembled on the top of the Au interdigital electrode, connecting the Au interdigital electrode to a standard DuPont needle by using an anisotropic conductive film.

Wherein, the specification of the copper-clad filament multifilament is preferably 26Tex/70D/24F, the twist value in step 1 is preferably 450tpm, and the rotating speed of a spindle is preferably 8000rpm, under the condition, the better DNA type double spiral filament yarn can be obtained, and thus the double spiral conductive textile fabric with better torsion force and elastic restoring force can be obtained.

The pressure sensors described in example 1 and example 2 were subjected to performance tests. The hysteresis and linearity indices are defined as:

Hys＝ΔFC _- BC/I _F.S. ×100％ (1)

wherein Δ FC _- BC is the forward and reverse transmission curve and I _F.S. The maximum difference between them. I is _F.S. Is a full scale current output. Δ δ is the maximum deviation of the output current, which is considered as an error in the linear fit region.

Referring to fig. 4, a conventional textile sensor made from untwisted yarn shows a stepped current profile with greater hysteresis and poor linearity (fig. 4A). Two different sensitivities can be obtained at different pressure stages (fig. 4B). Obviously, the performance of such sensors is difficult to meet application requirements. When the applied pressure was significantly reduced, worse results were observed using discrete data during all three consecutive load-unload cycles (fig. 4C).

The pressure sensor provided by the present invention exhibits improved linearity but still significant hysteresis compared to the conventional textile pressure sensor (FIG. 4D). The pressure sensor is significantly improved in both hysteresis and linearity when the applied pressure is reduced from 800KPa to 70KPa (fig. 4E), and its overall performance is at a lower pressure (<34Kpa) is much better. To further exploit this property, the pressure sensor was examined at a pressure of 30KPa (FIG. 4F), and when the applied pressure was 30KPa, the sensitivity of the pressure sensor was 0.57KPa ^-1 Retardation is 4.8-5.7%, and linearity is 4.7-5.4%. In addition, the response/recovery time and stability of the pressure sensor were examined, as shown in fig. 5. As shown in fig. 5A, the rapid response and recovery of the pressure sensor to applied pressure was determined to be 2ms, indicating its great potential for high frequency applications. Also, as shown in fig. 5B, the pressure sensor worked well even after 6600 cycles of testing, with an output signal almost the same as the initial signal, reflecting good stability and durability, with good reusability. This is because the conductive textile layer 3 in the pressure sensor has a DNA double helix structure, so that the copper-clad filament multifilaments have a sufficiently strong twisting force therebetween, and can rapidly and effectively overcome friction, achieve high-speed response/recovery, good stability and durability, and low hysteresis, while the fibers in the double-helix filament yarn are regularly aligned, and the twisting force between the copper-clad multifilaments inhibits deformation thereof under pressure, so that the linearity of the pressure sensor is increased. In summary, the pressure sensor has excellent sensitivity, stability, linearity, hysteresis, durability, reusability, long service life and high flexibility.

The pressure sensor is flexible in texture, can bear large deformation, can be used as a wearable electronic textile to detect slight pressure or movement, and achieves the purpose of medical care monitoring by detecting pulses. Our sensor device is assembled on the wound bed and can be easily attached to a person's wrist for pulse detection. A female subject (age: 27 years; height: 172 cm; weight: 56kg) was invited to a test to obtain pulse shape, frequency and repeatability. The current changes in the pressure sensor before and after subject movement are recorded in fig. 6A. Specifically, after 5 minutes of exercise, the pulse intensity and frequency increased significantly. The pressure sensor can also be used well around the neck to detect carotid artery pulsation other than the wrist (fig. 6B), which means a wide detection range. In addition to the female subjects, male subjects (age: 30 years; height: 178 cm; weight: 80kg) were invited to diagnose sinus bradycardia. Sinus bradycardia patients typically have slower heart rhythms, and this function (about 54 beats per minute) is also shown in fig. 6C. Under normal conditions, a radical arterial waveform was observed, including a typical strike peak (P1), a tidal peak (P2) and a diastolic peak (P3). Obviously, the output current curves of these two subjects are completely different (fig. 6D). By recording these three typical peaks in a single pulse, potential health problems of the human body (e.g. heart disease and hypertension) can be effectively distinguished. For example, we can accurately calculate a reinforcement index (defined as AIr P2/P1) to check the stiffness of the arteries, and finally diagnose vascular aging. Here, the average AIr of female subjects was 0.73, which is consistent with the literature reporting a healthy 27 year old female. Significant signal peak characteristics of male subjects were monitored. A range of cardiovascular factors including ejection fraction, peripheral vascular resistance, contractility of the heart and arterial compliance may be responsible for the different pulse waveforms. During various cardiovascular activities, an increase in peripheral vascular resistance may induce transient but significant systolic hypertension and left ventricular afterload. By using the pressure sensor, we can flexibly infer the presence or absence of a potential disease in a human body by analyzing the pulse waveform, intensity and frequency.

Example 3

The embodiment provides a wrist protector (not shown in the figures), which comprises a wrist protector main body and a pressure sensor arranged on the wrist protector main body and used for detecting human body pulses, wherein the pressure sensor is as described in the

embodiments

1 and 2, the wrist protector is convenient to carry and can be worn on the hand, and people can monitor pulses at any time when needed, so that the wrist protector is healthy and comfortable.

While the invention has been described with reference to a preferred embodiment, 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 scope of the invention.

Claims

1. The double-spiral conductive textile fabric for the pressure sensor is characterized by being knitted by a DNA type double-spiral filament yarn, two bundles of metal-coated filament multifilaments are arranged in parallel in pairs, and then the metal-coated filament multifilaments are transferred to a winding machine with the twist value of 450tpm and the main shaft rotating speed of 8000rpm in the S direction to obtain the DNA type double-spiral filament yarn, each monofilament in each metal-coated filament multifilament comprises a nylon core and a metal sheath, the metal sheath is coated outside the nylon core, the conductivity of the metal-coated filament multifilaments is 1200ohm/cm, and the specification of the metal-coated filament multifilaments is 26 Tex/70D/24F.

2. The double-spiral conductive textile for the pressure sensor according to claim 1, wherein the metal-coated wire multifilament is a copper-coated wire multifilament, a gold-coated wire multifilament, a silver-coated wire multifilament or an aluminum-coated wire multifilament.

3. A pressure sensor, the pressure sensor includes a substrate, a metal electrode layer, a conductive textile layer and a packaging layer, characterized in that, the metal electrode layer is disposed on the substrate, the conductive textile layer is disposed on the metal electrode layer, the packaging layer is disposed on the conductive textile layer, and packages the conductive textile layer, the metal electrode layer is an Au interdigital electrode, the conductive textile layer is the double helix conductive textile fabric of any one of claims 1-2, and a PEN film is disposed on the packaging layer.

4. A method for manufacturing a pressure sensor, wherein the method for manufacturing a pressure sensor is used for manufacturing the pressure sensor according to claim 3, and the steps comprise:

step 1, arranging two bundles of metal coated yarn multifilaments in parallel in an aligned mode, and then transferring the metal coated yarn multifilaments into a winding machine with the twist value of 450tpm in the S direction and the spindle rotating speed of 8000rpm to obtain a DNA type double-spiral yarn;

step 2, preparing the DNA type double spiral yarn into conductive textile by a small circular knitting machine by adopting a common knitting method;

step 3, carrying out photoetching composition on the Au interdigital electrode, and then thermally evaporating the Au interdigital electrode onto the substrate to form a metal electrode layer;

step 4, assembling the conductive textile obtained in the step 2 on the top of the Au interdigital electrode to form a conductive textile layer;

step 5, packaging the conductive textile layer obtained in the step 4 by using 1.0mil acrylic PSA adhesive to form a packaging layer;

and 6, finally covering the film with a 1-2 mu m PEN film to obtain the pressure sensor.