Flexible and stretchable metal nanowire-based resistive sensor and preparation method thereof

Abstract

The present invention discloses a flexible, stretchable metal nanowire-based resistive sensor, comprising, arranged in ascending order, a flexible, stretchable substrate, a conductive layer, and an encapsulation layer. The fabrication method comprises the following steps: preparing the flexible, stretchable substrate; preparing a laser direct writing ink; preparing a conductive layer precursor positioned on the flexible, stretchable substrate; subjecting the conductive layer precursor to a laser direct writing process to form a conductive layer pattern, followed by rinsing with deionized water and ethanol, drying, and then depositing metal electrodes electrically connected to the conductive layer pattern; and finally, encapsulation. This invention can address common sensor issues such as low sensitivity and slow response speed.

Description

Technical Field

[0001] The present invention belongs to the technical field of flexible stretchable sensors, and in particular relates to a flexible stretchable metal nanowire-based resistive sensor and a preparation method thereof. Background Art

[0002] In recent years, the development of wearable electronics has significantly transformed our daily lives. Leveraging their inherent flexibility, wearable electronics can be incorporated into a variety of wearable items. Furthermore, these devices can sense and monitor human physiological signals, enabling important applications such as behavioral monitoring, health status monitoring, and medical assessment. External changes drive the deformation of flexible, stretchable resistive sensors, causing changes in their resistance. Monitoring systems collect and analyze this signal, linking its changing trend and shape to behavioral changes in the monitored area. This allows the physiological signal to be converted into an electronic signal, ultimately delivering valuable information.

[0003] Current research on flexible sensors focuses on sensor sensitivity. Under the same deformation, the greater the change in resistance, the more pronounced the transmitted electrical signal, and the higher the sensitivity. Another crucial factor in practical applications is response speed, which reflects the immediacy of signal conversion. The shorter the response time, the better the sensor's performance. Therefore, the pursuit of these two properties is ongoing in both practical applications and scientific research.

[0004] CN 113483651 A introduces a three-layer structure, with a negative Poisson's ratio structural layer and a conductive film layer designed at both ends of the film layer. This ensures that when the sensor is stretched, a time difference exists between the expansion and deformation of the conductive film layers corresponding to the central portion of the chiral unit and the embedded unit. This allows the entire device to maintain a negative Poisson's ratio effect and high sensitivity within a large stretching range. However, its structural design is complex and requires high manufacturing technology.

[0005] ACS Appl.Mater.Interfaces 2022, 14, 15504-15516 prepared a MXene and carbon nanotube composite structure on porous thermoplastic polyurethane by vacuum filtration. The obtained sensor has a sensing range of 330% and a maximum sensitivity factor of 2911, but its initial sensitivity is relatively low, the response time of 80ms is not outstanding, and its raw material cost is high, which is not suitable for large-scale application.

[0006] ACS Appl. Mater. Interfaces 2022, 13, 18021-18032 used silver nanoparticles to be sintered at room temperature under the action of chemical reagents to obtain a sensor with good stretchability (800%), but its sensitivity was low.

[0007] Therefore, there is a need to improve the existing technology. Summary of the Invention

[0008] The technical problem to be solved by the present invention is to provide a flexible and stretchable metal nanowire-based resistive sensor to solve the problems of low sensitivity and slow response speed of common sensors.

[0009] In order to solve the above technical problems, the present invention provides a flexible and stretchable metal nanowire-based resistive sensor, comprising a flexible and stretchable substrate, a conductive layer and an encapsulation layer arranged in sequence from bottom to top.

[0010] The present invention also provides a method for preparing the above-mentioned flexible and stretchable metal nanowire-based resistive sensor, comprising the following steps:

[0011] 1) Preparation of flexible stretchable substrate:

[0012] The flexible substrate used as a template was ultrasonically cleaned in acetone, deionized water, and ethanol in sequence (each cleaning time was 20 to 30 minutes), and then dried (in an oven) to obtain a dried flexible substrate;

[0013] The flexible stretchable substrate precursor is uniformly coated on a single surface of the dried flexible substrate to form a substrate precursor wet film with a thickness of 100 to 800 μm; the substrate is heated and cured at 50 to 70° C. for 3 to 7 hours, and then cleaned in an oxygen plasma cleaning machine for 5 to 10 minutes to obtain a flexible stretchable substrate with a hydrophilic surface;

[0014] Description: The substrate precursor wet film is heated and cured and cleaned in an oxygen plasma cleaning machine to form a hydrophilic surface;

[0015] 2) Laser direct writing ink preparation:

[0016] 1.7±0.1 g of AgNO3 and 2.2±0.1 g of PVP were weighed and added to 10 ml of a mixed solvent, and ultrasonically dispersed and dissolved to form ink I; the mixed solvent consisted of ethanol and deionized water, wherein the volume content of ethanol in the mixed solvent was 88-92%;

[0017] Hydroxypropyl methylcellulose (100,000 mPa·s) was prepared into a 10 ± 1 mg / ml solution as ink II;

[0018] Metal nanowire dispersion with a concentration of 10 ± 1 mg / ml was used as ink III;

[0019] Evenly mix inks I, II, and III to obtain laser direct writing ink IV;

[0020] Ink I: ink II: ink III = 2-24:1:1-20 in volume ratio;

[0021] 3) coating the laser direct writing ink IV obtained in step 2) on the hydrophilic surface of the flexible stretchable substrate obtained in step 1) to form a conductive layer wet film with a thickness of 300 to 1500 nm, and drying at 35 to 50° C. for 3 to 7 hours to obtain a conductive layer precursor located on the flexible stretchable substrate;

[0022] 4) Adjusting the laser direct writing parameters to: laser power 1.1-5.5W, scanning speed 0.5-5cm / s, performing laser direct writing on the conductive layer precursor to form a conductive layer pattern, then rinsing with deionized water and ethanol, and after drying, providing a metal electrode (e.g., a copper electrode) that is conductive to the conductive layer pattern;

[0023] 5) The encapsulation layer precursor is evenly coated on the upper surface of the resultant in step 4) to form an encapsulation layer precursor wet film with a thickness of 100 to 800 μm, and the conductive layer pattern and the metal electrode are covered by the encapsulation layer precursor wet film; after heating and curing at 50 to 70° C. for 3 to 7 hours, a flexible and stretchable metal nanowire-based resistive sensor is obtained.

[0024] As an improvement to the method for preparing the flexible and stretchable metal nanowire-based resistive sensor of the present invention, in step 1):

[0025] The flexible substrate (template substrate) is polycarbonate, polyethylene terephthalate, polymethyl methacrylate, colorless and transparent polyimide, polydimethylsiloxane, or polyurethane;

[0026] The precursors of the flexible and stretchable substrate are Ecoflex A / B glue, thermoplastic polyurethane, rubber, and polydimethylsiloxane.

[0027] As a further improvement to the preparation method of the flexible stretchable metal nanowire-based resistive sensor of the present invention: the metal nanowire (conductive network metal nanowire) described in step 2) is a silver nanowire, copper nanowire or gold nanowire with a diameter of 20 to 100 nm.

[0028] As a further improvement to the method for preparing the flexible and stretchable metal nanowire-based resistive sensor of the present invention: the encapsulation layer precursor in step 5) is Ecoflex, thermoplastic polyurethane, rubber, and polydimethylsiloxane.

[0029] As a further improvement to the method for preparing the flexible and stretchable metal nanowire-based resistive sensor of the present invention:

[0030] In the step 1), the flexible stretchable substrate precursor is coated by blade coating, spin coating, dip coating, or slit coating;

[0031] In the step 3), the laser direct writing ink IV is coated by blade coating, spin coating, drop coating, spray coating, or slit coating;

[0032] In the step 5), the encapsulation layer precursor is coated by blade coating, spin coating, dip coating, or slit coating.

[0033] In the present invention: flexible stretchable substrate: after solidification and molding, the substrate can achieve >50% stretching deformation and can restore to its original shape and stably stretch and rebound tens of thousands of times; conductive layer: composed of metal nanowires and reduced metal Ag particles, with excellent conductivity; encapsulation layer: can be stretched and deformed, and has tens of thousands of stretching and rebound stability.

[0034] Based on existing research, the present invention utilizes low-cost raw materials, explores simple preparation technology, simplifies the preparation process, and utilizes the high sensitivity of metal materials to prepare resistive sensors with short response time and resistance to stretching. Therefore, it is very important for the large-scale development and application of sensors.

[0035] In the preparation of the conductive layer of the present invention, the metal nanowire conductive layer is subjected to laser direct writing treatment with the aid of laser direct writing, thereby achieving welding and patterning of the metal nanowire conductive layer and strengthening the bonding between the conductive layer and the substrate. That is, after the laser direct writing treatment, a silver nanowire network of metal silver welding is formed, and the silver nanowire network is firmly bonded to the flexible stretchable substrate.

[0036] Compared to methods like inkjet printing and chemical vapor deposition, the method of the present invention is simpler, with a streamlined preparation process and lower production costs. Compared to methods like spin coating or doctor blade coating, the method of the present invention allows for patterned design, resulting in stronger bonding between the conductive layer and the substrate. The stretchable sensor device produced using this method exhibits excellent sensitivity and stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] The specific embodiments of the present invention are further described in detail below with reference to the accompanying drawings.

[0038] Figure 1 It is a preparation flow chart of the present invention.

[0039] Figure 2 This is an electron microscope morphology image of the sensor of Example 1.

[0040] Figure 3 This is an example of the motion sensing of the sensor of Example 2;

[0041] Figure 3Middle: The lower data represents a stable signal from the sensor's resistance change when the sensor is worn at the first joint of the thumb and the joint is regularly bent. The upper data represents a stable signal from the sensor's resistance change when the sensor is worn at the second joint of the thumb and the joint is repeatedly moved. The sensor delivers excellent signal stability during the same movements.

[0042] Figure 4 This is a diagram showing the tensile sensitivity of the sensor of Example 2.

[0043] Figure 5 This is a test diagram of the sensor stretch response time of Example 2. DETAILED DESCRIPTION

[0044] The present invention is further described below with reference to specific embodiments, but the protection scope of the present invention is not limited thereto:

[0045] In the following example: the template size is set to 5cm×2cm.

[0046] Example 1: A method for preparing a flexible and stretchable metal nanowire-based resistive sensor, comprising the following steps:

[0047] 1) Preparation of flexible stretchable substrate:

[0048] The flexible polycarbonate substrate used as the template was ultrasonically cleaned in acetone (about 50 ml), deionized water (about 50 ml), and ethanol (about 50 ml) for 20 minutes, and then dried in an oven (50°C for 15 minutes). The flexible stretchable substrate Ecoflex precursor (commercial Ecoflex-30A and B glue were uniformly mixed in a 1:1 mass ratio for 20 minutes) was evenly coated on the dried template substrate using a slit coating technique to form a substrate precursor wet film with a thickness of 100 μm; heated to 50°C for 3 hours, and then placed in an oxygen plasma cleaner for 5 minutes to obtain a flexible stretchable substrate with a hydrophilic surface.

[0049] Description: The substrate precursor wet film is heated and cured and cleaned in an oxygen plasma cleaning machine to form a hydrophilic surface;

[0050] The parameters of the oxygen plasma cleaning machine are as follows: Power: 50W, RF frequency: 13.56MHz, Final vacuum: 5×10 -2 Pa, cleaning time is 5min.

[0051] 2) Laser direct writing ink preparation:

[0052] Ethanol and deionized water were mixed in a volume ratio of 9:1 as a mixed solvent. 1.7 g of AgNO 3 and 2.2 g of PVP were weighed and added to 10 ml of the mixed solvent, and ultrasonic dispersion and dissolution were performed to obtain ink I.

[0053] Hydroxypropyl methylcellulose (100,000 mPa·s) was prepared into a 10 mg / ml aqueous solution to obtain Ink II.

[0054] A copper nanowire (100 nm) aqueous dispersion with a concentration of 10 mg / ml was used as ink III.

[0055] Inks I, II, and III were uniformly mixed in a volume ratio of 2:1:20 to obtain the desired laser direct writing ink IV;

[0056] 3) Spray coating the laser direct writing ink IV obtained in step 2) on the hydrophilic surface of the flexible stretchable substrate obtained in step 1) to form a conductive layer wet film with a thickness of 300 nm, and drying at 35° C. for 3 h to obtain a conductive layer precursor located on the flexible stretchable substrate (obtaining a conductive layer precursor that can be subjected to laser direct writing);

[0057] 4) Adjust the laser direct writing parameters, laser power 1.1 W, scanning speed 5 cm / s, and perform laser direct writing on the conductive layer precursor obtained in step 3) to form a conductive layer pattern, and then rinse it with deionized water and ethanol (so that no metal nanowires are attached to the part other than the patterned conductive layer). After drying, two copper electrodes (conductively connected to the conductive layer pattern) are glued to both ends of the upper surface of the pattern with silver glue.

[0058] The copper electrode has a width of 5 mm and a length of 50 mm.

[0059] 5) The Ecoflex encapsulation layer precursor is evenly coated on the upper surface of the structure obtained in step 4) by a blade coating technique, thereby forming an Ecoflex encapsulation layer precursor wet film with a thickness of 100 μm; the conductive layer pattern and the copper electrode are both covered by the encapsulation layer precursor wet film; after heating and curing at 50° C. for 3 hours, a flexible and stretchable metal nanowire-based resistive sensor is obtained.

[0060] Experiment 1: The performance of the flexible and stretchable metal nanowire-based resistive sensor (hereinafter referred to as the sensor) obtained in Example 1 was tested:

[0061] Test method: The sensor is placed on a stretching instrument with adjustable stretching length and rate. The copper wires at both ends are connected to a current source meter. A 0.5V DC voltage is applied to both ends of the sensor using the current source meter, and the resistance change curve of the sensor during uniform stretching is recorded. The sensitivity factor is calculated according to GF=ΔR / R0 / ε (ΔR is the difference between the resistance after the change and the initial resistance, R0 is the initial resistance of the sensor, and ε is the length strain rate of the sensor); the time required for the sensor resistance to change from R0+10% (ΔR) to R0+90% (ΔR) is measured when the touch sensor is rapidly stretched from its original state to a 110% stretched state.

[0062] The results are: sensor sensitivity factor GF = 322, response time T = 60ms.

[0063] Example 2: A method for preparing a flexible and stretchable metal nanowire-based resistive sensor, comprising the following steps:

[0064] 1) Preparation of flexible stretchable substrate:

[0065] A polyethylene terephthalate (PET) flexible substrate, serving as a template, was ultrasonically cleaned in acetone, deionized water, and ethanol for 20 minutes, followed by oven drying. A polydimethylsiloxane (PDMS) precursor, a commercially available PDMS, was evenly coated onto the dried template using a doctor blade technique, forming a 400 μm thick wet film of the substrate precursor. The film was then heated to 70°C for 7 hours and then cleaned in an oxygen plasma cleaner for 5 minutes, resulting in a flexible, stretchable substrate with a hydrophilic surface.

[0066] 2) Laser direct writing ink preparation

[0067] Ethanol and deionized water were mixed in a volume ratio of 9:1 as a mixed solvent, 1.7 g of AgNO3 and 2.2 g of PVP were weighed and added to 10 ml of the mixed solvent, and ultrasonic dispersion and dissolution were performed to obtain ink I.

[0068] Hydroxypropyl methylcellulose (100,000 mPa·s) was prepared into a 10 mg / ml aqueous solution to serve as ink II.

[0069] A 10 mg / ml aqueous dispersion of silver nanowires (20 nm) was used as Ink III. Inks I, II, and III were uniformly mixed in a 24:1:8 volume ratio to obtain the desired laser direct writing ink IV.

[0070] 3) applying the laser direct writing ink IV obtained in step 2) on the hydrophilic surface of the flexible stretchable substrate obtained in step 1) by drop coating to form a conductive layer wet film with a thickness of 1500 nm, and drying at 35° C. for 3 h to obtain a conductive layer precursor on the flexible stretchable substrate;

[0071] 4) Adjust the laser direct writing parameters, laser power 3.3 W, scanning speed 2.55 cm / s, and perform laser direct writing treatment on the conductive layer precursor obtained in step 3) to form a conductive layer pattern, then rinse it with deionized water and ethanol, and after drying, paste two copper electrodes at both ends of the upper surface of the pattern with silver glue.

[0072] The copper electrode has a width of 5 mm and a length of 50 mm.

[0073] 5) The encapsulation layer polydimethylsiloxane precursor is evenly coated on the upper surface of the structure obtained in step 4) by a blade coating technique to form a polydimethylsiloxane encapsulation layer precursor wet film with a thickness of 800 μm; after heating and curing at 70° C. for 3 hours, a flexible and stretchable metal nanowire-based resistive sensor is obtained.

[0074] The test was carried out according to the method described in Experiment 1, and the results obtained were: sensor sensitivity factor GF = 623.2, response time T = 51 ms.

[0075] Place the sensor in Figure 3 Detection is performed as shown, Figure 3 Middle: The lower data represents a stable signal from the sensor's resistance change when the sensor is worn at the first joint of the thumb and the joint is regularly bent. The upper data represents a stable signal from the sensor's resistance change when the sensor is worn at the second joint of the thumb and the joint is repeatedly moved. The sensor delivers excellent signal stability during the same movements.

[0076] Example 3: A method for preparing a flexible and stretchable metal nanowire-based resistive sensor, comprising the following steps:

[0077] 1) Preparation of flexible stretchable substrate:

[0078] The flexible polymethyl methacrylate substrate used as the template was ultrasonically cleaned in acetone, deionized water, and ethanol for 20 minutes, followed by drying in an oven. A stretchable polydimethylsiloxane precursor (commercial PDMS) was evenly coated onto the dried template substrate using a spin coating technique to form a 100 μm thick wet film of the substrate precursor. The substrate was then heated to 50°C for 7 hours and then cleaned in an oxygen plasma cleaner for 5 minutes to obtain a flexible stretchable substrate with a hydrophilic surface.

[0079] 2) Laser direct writing ink preparation:

[0080] Ethanol and deionized water were mixed in a ratio of 9:1 as a mixed solvent. 1.7 g of AgNO 3 and 2.2 g of PVP were weighed and added to 10 ml of the mixed solvent. Ink I was obtained by ultrasonic dispersion and dissolution.

[0081] Hydroxypropyl methylcellulose (100,000 mPa·s) was prepared into a 10 mg / ml aqueous solution to obtain Ink II.

[0082] A 10 mg / ml aqueous dispersion of silver nanowires (45 nm) was used as Ink III. Inks I, II, and III were uniformly mixed in a 2:1:1 volume ratio to obtain the desired laser direct writing ink IV.

[0083] 3) Spray-coating the laser direct writing ink IV obtained in step 2) on the hydrophilic surface of the flexible stretchable substrate obtained in step 1) to form a conductive layer wet film with a thickness of 800 nm, and drying the film at 50° C. for 3 h to obtain a conductive layer precursor on the flexible stretchable substrate;

[0084] 4) Adjust the laser direct writing parameters, laser power 5.5 W, scanning speed 0.5 cm / s, and perform laser direct writing treatment on the conductive layer precursor obtained in step 3) to form a conductive layer pattern, then rinse it with deionized water and ethanol, and after drying, paste two copper electrodes at both ends of the upper surface of the pattern with silver glue.

[0085] The copper electrode has a width of 5 mm and a length of 50 mm.

[0086] 5) The encapsulation layer polydimethylsiloxane precursor is evenly coated on the upper surface of the structure obtained in step 4) by a blade coating technique, thereby forming a polydimethylsiloxane encapsulation layer precursor wet film with a thickness of 500 μm; the conductive layer pattern and the copper electrode are both covered by the encapsulation layer precursor wet film; after heating and curing at 70° C. for 3 hours, a flexible and stretchable metal nanowire-based resistive sensor is obtained.

[0087] The test was carried out according to the method described in Experiment 1, and the results obtained were: sensor sensitivity factor GF = 402, response time T = 83ms.

[0088] Example 4: The precursor of the flexible stretchable substrate in step 1) of Example 2 is changed from "polydimethylsiloxane precursor" to the one described in Table 1 below; the rest is the same as Example 2.

[0089] Table 1

[0090]

[0091] Example 5: The ratio of inks I, II, and III in step 2) of Example 2 is changed, as shown in Table 2; the rest is the same as Example 2.

[0092] Table 2

[0093]

[0094] Example 6: Change the laser power in step 4) of Example 2 to 2W, and the rest is the same as Example 2.

[0095] The final sensor obtained has GF=226 and response time T=86ms.

[0096] Example 7: Change the scanning speed in step 4) of Example 2 to 5 cm / s, and the rest is the same as Example 2.

[0097] The final sensor obtained: GF = 620, response time T = 77ms.

[0098] Comparative Example 1: The laser direct writing process step in step 4) of Example 2 is removed, and the rest is the same as Example 2.

[0099] The conductive layer falls off during the cleaning process and cannot be stably attached to the flexible stretchable substrate, making it impossible to prepare a stable and reusable sensor device.

[0100] Comparative Example 2: The laser direct writing step (step 4) and the subsequent deionized water and ethanol rinsing steps of Example 2 were removed, and the rest was the same as Example 2.

[0101] The final sensor obtained: GF = 30, response time T = 150ms, but the device cannot be stretched and used repeatedly, and its performance degrades seriously during repeated stretching.

[0102] Finally, it should be noted that the above examples are merely specific embodiments of the present invention. Obviously, the present invention is not limited to the above examples and is subject to numerous variations. All variations that can be directly derived or conceived by a person of ordinary skill in the art from the disclosure of the present invention are considered to be within the scope of protection of the present invention.

Claims

1. A method for preparing a flexible and stretchable metal nanowire-based resistive sensor, characterized in that The following steps are involved: 1) Preparation of flexible stretchable substrate: The flexible substrate used as a template is ultrasonically cleaned in acetone, deionized water, and ethanol in sequence, and then dried to obtain a dried flexible substrate; The flexible stretchable substrate precursor is uniformly coated on a single surface of the dried flexible substrate to form a substrate precursor wet film with a thickness of 100 to 800 μm; the substrate is heated and cured at 50 to 70° C. for 3 to 7 hours, and then cleaned in an oxygen plasma cleaning machine for 5 to 10 minutes to obtain a flexible stretchable substrate with a hydrophilic surface; 2) Laser direct writing ink preparation: 1.7±0.1 g of AgNO3 and 2.2±0.1 g of PVP were weighed and added to 10 ml of a mixed solvent, and ultrasonically dispersed and dissolved to form ink I; the mixed solvent consisted of ethanol and deionized water, wherein the volume content of ethanol in the mixed solvent was 88-92%; Hydroxypropyl methylcellulose with a concentration of 100,000 mPa·s was prepared into a 10 ± 1 mg / ml solution as ink II. Metal nanowire dispersion with a concentration of 10 ± 1 mg / ml was used as ink III; Evenly mix inks I, II, and III to obtain laser direct writing ink IV; Ink I: ink II: ink III = 2-24:1:1-20 in volume ratio; 3) coating the laser direct writing ink IV obtained in step 2) on the hydrophilic surface of the flexible stretchable substrate obtained in step 1) to form a conductive layer wet film with a thickness of 300 to 1500 nm, and drying at 35 to 50° C. for 3 to 7 hours to obtain a conductive layer precursor located on the flexible stretchable substrate; 4) Adjusting the laser direct writing parameters to: laser power 1.1-5.5W, scanning speed 0.5-5cm / s, performing laser direct writing on the conductive layer precursor to form a conductive layer pattern, then rinsing with deionized water and ethanol, and after drying, setting a metal electrode that is conductive to the conductive layer pattern; 5) The encapsulation layer precursor is evenly coated on the surface of the product obtained in step 4) to form an encapsulation layer precursor wet film with a thickness of 100 to 800 μm, and the conductive layer pattern and the metal electrode are covered by the encapsulation layer precursor wet film; after heating and curing at 50 to 70° C. for 3 to 7 hours, a flexible and stretchable metal nanowire-based resistive sensor is obtained.

2. The method for preparing a flexible and stretchable metal nanowire-based resistive sensor according to claim 1, characterized in that In step 1): The flexible substrate is polycarbonate, polyethylene terephthalate, polymethyl methacrylate, colorless and transparent polyimide, polydimethylsiloxane, and polyurethane; The precursors of the flexible and stretchable substrate are Ecoflex A / B glue, thermoplastic polyurethane, rubber, and polydimethylsiloxane.

3. The method for preparing a flexible and stretchable metal nanowire-based resistive sensor according to claim 2, wherein: The metal nanowires in step 2) are silver nanowires, copper nanowires or gold nanowires, and have a diameter of 20 to 100 nm.

4. The method for preparing a flexible and stretchable metal nanowire-based resistive sensor according to claim 3, wherein: The encapsulation layer precursors in step 5) are Ecoflex, thermoplastic polyurethane, rubber, and polydimethylsiloxane.

5. The method for preparing a flexible and stretchable metal nanowire-based resistive sensor according to claim 4, wherein: In the step 1), the flexible stretchable substrate precursor is coated by blade coating, spin coating, dip coating, or slit coating; In the step 3), the laser direct writing ink IV is coated by blade coating, spin coating, drop coating, spray coating, or slit coating; In the step 5), the encapsulation layer precursor is coated by blade coating, spin coating, dip coating, or slit coating.

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