Humidity sensing fiber based on PEDOT-PANI compound as well as preparation method and application of humidity sensing fiber

Abstract

The invention discloses a humidity sensing fiber based on a PEDOT-PANI compound as well as a preparation method and application thereof, and the preparation method comprises the following steps: mixing polyaniline powder and a PEDOT: PSS solution in deionized water, stirring to form a mixed solution, putting the mixed solution into a fiber, soaking, stirring, standing, taking out the fiber, and drying to obtain the humidity sensing fiber. As a sensor, the humidity sensing fiber shows higher sensitivity and quick response capability, maintains cost effectiveness and operation convenience, and has good stability, durability, biological compatibility and comfort, so that the sensor is particularly suitable for being used as a part of wearable equipment, and the application prospect is wide. The method is used for health monitoring and environment control.

Description

Technical Field

[0001] The present invention relates to a humidity-sensing fiber based on a PEDOT-PANI composite, its preparation method and application, which are mainly applied to intelligent textiles and health monitoring devices, and belong to the fields of intelligent materials and thermoelectric materials. Background Art

[0002] In many fields such as environmental monitoring, industrial control, medical health and smart home, humidity sensors play a crucial role. They measure the moisture content in the air through different technical principles, including capacitive, resistive, dew point detection, fiber optic, electrochemical, thermal conductivity, mechanical, semiconductor, ultrasonic and infrared and other types. Each technology has its specific application scenarios, advantages and disadvantages. For example, capacitive sensors are favored for their fast response and high sensitivity, while resistive sensors are widely used due to their cost-effectiveness and ease of manufacture. Dew point sensors provide high-precision measurements, but the equipment is relatively complex and costly. Fiber optic sensors have attracted attention for their electromagnetic interference resistance and remote monitoring capabilities, but the cost and technical complexity are relatively high.

[0003] Although certain progress has been made in existing humidity sensor technologies, there are still some challenges in their practical applications. Capacitive and resistive sensors may be affected by temperature changes, resulting in a decrease in measurement accuracy. Although dew point sensors have high measurement accuracy, their complex equipment and high cost limit their popularity in a wider range of application scenarios. Although electrochemical sensors have high sensitivity, they may require regular maintenance, increasing the usage cost. The response speed of mechanical sensors is relatively slow and may not meet the requirements of a rapidly changing environment. In addition, the stability and durability of most sensors under extreme environmental conditions still need to be improved. Summary of the Invention

[0004] Aiming at the problems existing in the above-mentioned prior art, the present invention provides a humidity-sensing fiber based on a PEDOT-PANI composite, its preparation method and application.

[0005] In order to achieve the above object, a preparation method of a humidity-sensing fiber based on a PEDOT-PANI composite adopted by the present invention includes the following steps: mixing polyaniline powder and a PEDOT:PSS solution in deionized water, stirring to form a mixed solution, then putting fibers into it for soaking and stirring, taking out the fibers after standing, and drying to obtain the humidity-sensing fibers.

[0006] As an improvement, the mass of the polyaniline powder is 100 - 300 mg, the volume of the PEDOT:PSS solution is 3 - 5 ml, and the volume of deionized water is 5 - 10 ml.

[0007] As an improvement, the polyaniline powder and the PEDOT:PSS solution are mixed in deionized water and then magnetically stirred; the time for the fiber to be soaked and stirred in the mixed solution is 20 - 40 min.

[0008] As an improvement, the fiber is made of cotton thread or nylon thread.

[0009] As an improvement, the taken-out fiber is placed in a vacuum drying oven at 50°C - 70°C and dried for 1 - 3 hours.

[0010] As an improvement, it specifically includes the following steps: Add 100 - 300 mg of polyaniline powder and 3 - 5 ml of PEDOT:PSS solution to 5 - 10 ml of deionized water, place it on a magnetic stirrer, after stirring for 20 - 40 min, put the fiber in and continue to stir for 20 - 40 min, then let it stand for 40 - 60 min, take out the fiber, and dry it in a vacuum drying oven at 50°C - 70°C for 1 - 3 hours to obtain the humidity-sensing fiber.

[0011] As an improvement, the stirring speed of the magnetic stirrer is 1000 - 1200 rpm.

[0012] In the second aspect of the present invention, a humidity-sensing fiber prepared by the described preparation method is also provided.

[0013] In the third aspect of the present invention, an application of the humidity-sensing fiber is also provided, which is used for wearable devices, or respiration monitoring, or humidity monitoring, or as a power generation device.

[0014] The principle of humidity detection of the present invention is as follows: The conductive channels inside the fiber carry negative charges, which enables it to attract hydroxide ions in water molecules to move towards it. Under certain conditions, the higher the moisture content on one side of the fiber, the faster the migration rate of hydroxide ions. This acceleration of ion migration leads to an increase in the charge difference at both ends of the fiber, thus causing the voltage value displayed on the voltmeter to increase accordingly.

[0015] The humidity-sensing fiber of the present invention combines the fiber soaking technology and the conductive characteristics of the PEDOT-PANI composite. Through the PEDOT-PANI solution, the relatively loose and insulating fiber inside becomes a semiconductor from an insulator. At the same time, PEDOT:PSS is hydrophilic, and after binding with the fiber, it can better sense the change of moisture. Compared with the traditional technology, the humidity-sensing fiber of the present invention, as a sensor, exhibits higher sensitivity and fast response ability, while maintaining cost-effectiveness and simplicity of operation, and has good stability, durability, biocompatibility and comfort, making the sensor of the present invention particularly suitable as a part of wearable devices for health monitoring and environmental control.

[0016] The humidity-sensing fiber of the present invention demonstrates extensive applicability and great market potential in practical applications. Its potential for multi-functional integration and strong environmental adaptability indicate that this technology is expected to play an important role in multiple fields such as health monitoring, environmental control, and smart homes.

[0017] The humidity-sensing fiber of the present invention has a simple preparation process and is easy to mass-produce, which helps to reduce costs and can obtain high performance by optimizing the concentration of the mixed solution, accelerating the popularization of humidity sensor technology. Brief Description of the Drawings

[0018] Figure 1 is the preparation flow chart of the humidity-sensing fiber of the present invention;

[0019] Figure 2 is the ultra-high resolution scanning electron image of the humidity-sensing fiber prepared in Example 1 of the present invention; Figure (a) is the cotton thread fiber, Figure (b) is the fiber after soaking, and Figure (c) is the particles attached to the fiber after soaking;

[0020] Figure 3 is the output voltage after measurement by the measurement device of the humidity-sensing fiber prepared in the examples of the present invention; Figure (a) is prepared in Example 1, and Figure (b) is prepared in Example 2. Detailed Embodiments

[0021] The following embodiments are further descriptions of the content of the present invention to illustrate the technical content of the present invention. However, the substantial content of the present invention is not limited to what is described in the following embodiments. Those of ordinary skill in the art can and should know that any simple changes or substitutions based on the substantial spirit of the present invention should fall within the scope of protection required by the present invention.

[0022] Example 1

[0023] As Figure 1 shown, a preparation method of a humidity-sensing fiber based on a PEDOT-PANI composite includes the following steps:

[0024] ① Material preparation: Prepare 200 mg of polyaniline powder. Polyaniline powder is a commonly used conductive polymer with good electrochemical properties;

[0025] At the same time, prepare 3 ml of poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) solution. This is a commercially available conductive polymer solution widely used in the fields of electronics and biosensors;

[0026] ② Solution preparation: Add weighed polyaniline powder and PEDOT:PSS solution into 5 ml of deionized water, stir at 1200 rpm for 30 min at room temperature using a magnetic stirrer to fully mix and dissolve to form a uniform conductive mixed solution;

[0027] ③ Fiber soaking: Take a piece of clean fiber material (such as cotton thread or nylon thread, cotton thread is used in this embodiment), immerse it completely in the prepared conductive mixed solution, and continue to stir with a magnetic stirrer for 30 minutes to ensure that the fiber fully absorbs the conductive material in the solution;

[0028] ④Standing and drying: The fiber is placed in the solution for 1 hour to promote the formation of the conductive channel inside the fiber. After that, the fiber is placed in a vacuum drying oven and dried at 60°C for 2 hours to remove excess moisture and solidify the conductive layer to obtain the humidity sensing fiber. It should be noted that the formation of the conductive channel inside the fiber can be connected to the LED circuit by using the fiber as a guide. When the LED becomes bright, it proves that the conductive channel is formed.

[0029] The ultra-high resolution scanning electron image of the cotton thread and the humidity sensing fiber used in Example 1 is as follows: Figure 2 As shown, Figure (a) is cotton thread, Figure (b) is the fiber after soaking, and Figure (c) is the particles attached to the fiber after soaking. The granular material is PANI, and PEDOT:PSS is attached inside the fiber and is very smooth.

[0030] Performance test: The dried humidity sensing fiber is connected to a simple circuit, which includes a power supply and a voltmeter. By simulating breathing near the fiber (i.e. blowing air into the fiber), the changes in the voltmeter are observed. Due to the hydrophilic nature of the fiber, water vapor will accumulate on the fiber surface, resulting in a humidity difference on both sides of the fiber, which will produce a voltage change in the circuit.

[0031] Result analysis: Through multiple tests, the voltage changes at both ends of the fiber under different breathing conditions were recorded. The results show that the humidity sensing fiber of the present invention has a rapid and obvious response to the humidity changes caused by breathing, and the voltage change is proportional to the breathing frequency and depth, such as Figure 3 (a) When the fiber detects moisture in the breath, there will be a voltage response. The more water content, the more dramatic the voltage change and the longer the response time; the less water content, the shorter the response time.

[0032] Example 2

[0033] In Example 2, the amount of polyaniline powder was increased to 250 mg, and the remaining steps were the same as in Example 1. Example 2 was used to explore the effect of different polyaniline contents on sensor performance.

[0034] Example 2: Performance Test and Result Analysis of the Prepared Humidity Sensing Fibers:

[0035] The testing method is the same as that in Example 1. The results show that increasing the dosage of polyaniline can further improve the sensitivity of the sensor, but at the same time, it may also cause a slight prolongation of the response time. As shown in Figure 3 (a) and (b) therein, it can be clearly seen that during multiple breaths, Figure 3 (b) has a shorter response time, and the average response time is about 0.8 seconds. However, when the water content is relatively large, the response time and recovery time are significantly longer than those of Figure 3 (a).

[0036] Example 3

[0037] In Example 3, the dosage of the PEDOT:PSS solution is increased to 5 ml, and the remaining steps are the same as those in Example 1. Example 3 is used to explore the influence of the volume of the PEDOT:PSS solution on the performance of the sensor.

[0038] Performance Test and Result Analysis of the Prepared Humidity Sensing Fibers in Example 3:

[0039] The testing method is the same as that in Example 1. The results show that as the volume of the PEDOT:PSS solution increases, the performance tends to be stable, and it can reach the most stable state at about 4 ml.

[0040] Comparative Example 1

[0041] The same test is carried out using ordinary fibers (not treated by the method of the present invention).

[0042] The results show that ordinary fibers hardly respond to the humidity changes caused by breathing, which proves the importance of the PEDOT-PANI composite in improving the performance of the sensor.

[0043] The humidity sensor of the present invention is simple to manufacture, cost-effective, small in size and easy to integrate. It not only has excellent biocompatibility and environmental stability, but is also particularly suitable for continuously monitoring the breathing frequency and depth, and can distinguish different human states according to the waveform;

[0044] In addition, the humidity sensing fiber has multimodal applications. For example, it can be used for breathing monitoring when dry; moreover, it has good photothermal performance. Under sunlight, its surface temperature can reach about 30 °C, and it can also be used as a wire. It is a negative temperature coefficient (NTC) thermistor. When wet, it can also generate electricity. The power generation of a single fiber (about 1.5 cm) is about 200 μV, and when multiple fibers are connected in series, they can supply power to small devices.

[0045] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims

1. A preparation method of a humidity sensing fiber based on a PEDOT-PANI composite, characterized in that, It includes the following steps: Mix polyaniline powder and PEDOT:PSS solution in deionized water, stir to form a mixed solution, then put fibers into it for soaking and stirring. After standing, take out the fibers and obtain humidity-sensing fibers after drying.

2. The preparation method of a humidity-sensing fiber based on a PEDOT-PANI composite according to claim 1, characterized in that The mass of the polyaniline powder is 100 - 300 mg, the volume of the PEDOT:PSS solution is 3 - 5 ml, and the volume of deionized water is 5 - 10 ml.

3. The preparation method of a humidity-sensing fiber based on a PEDOT-PANI composite according to claim 1, characterized in that The polyaniline powder and PEDOT:PSS solution are mixed in deionized water and stirred magnetically; the soaking and stirring time of the fibers in the mixed solution is 20 - 40 min.

4. The preparation method of a humidity sensing fiber based on a PEDOT-PANI composite according to claim 1, characterized in that The fibers are made of cotton thread or nylon thread.

5. The preparation method of a humidity sensing fiber based on a PEDOT-PANI composite according to claim 1, characterized in that, The taken-out fibers are dried in a vacuum drying oven at 50°C - 70°C for 1 - 3 hours.

6. The preparation method of a humidity sensing fiber based on a PEDOT-PANI composite according to claim 1, wherein, Specifically, it includes the following steps: Add 100 - 300 mg of polyaniline powder and 3 - 5 ml of PEDOT:PSS solution to 5 - 10 ml of deionized water, place it on a magnetic stirrer, stir for 20 - 40 min, then put the fibers in and continue to stir for 20 - 40 min. After standing for 40 - 60 min, take out the fibers and dry them in a vacuum drying oven at 50°C - 70°C for 1 - 3 hours to obtain humidity-sensing fibers.

7. The preparation method of a humidity sensing fiber based on a PEDOT-PANI composite according to claim 6, characterized in that, The stirring speed of the magnetic stirrer is 1000 - 1200 rpm.

8. A humidity sensing fiber, characterized in that, Prepared by the preparation method according to any one of claims 1 - 7.

9. The application of the humidity sensing fiber according to claim 8, characterized in that, For wearable devices or respiratory monitoring or humidity monitoring or as a power generation device.

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