Preparation method and system of multifunctional rubber-based flexible sensor for fetal movement monitoring
A rubber-based flexible sensor prepared by modifying multi-walled carbon nanotubes, combined with a deep learning system, solves the problems of accuracy and electromagnetic radiation in fetal movement monitoring, and realizes convenient monitoring of fetal movement frequency and pressure, which is suitable for health monitoring of pregnant women.
Patent Information
- Application Number
- CN202511499782.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-10-20
- Publication Date
- 2026-01-13
AI Technical Summary
Existing methods for monitoring fetal movement rely on the pregnant woman's subjective feelings, which are easily affected by interference and have large errors. Furthermore, pregnant women are exposed to electromagnetic radiation, which can affect their health.
A rubber-based flexible sensor with both electromagnetic shielding and Joule heating properties was designed. A uniform reinforcement network was formed by modifying multi-walled carbon nanotubes with sodium alginate. The sensor was combined with a deep learning system for fetal movement monitoring and a Bluetooth module was used to achieve real-time data transmission and analysis.
It enables rapid and accurate fetal movement monitoring, reduces the impact of electromagnetic radiation, and provides portable information on fetal movement frequency and pressure, making it suitable for pregnant women's health monitoring.
Smart Images
Figure CN121319480A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of vital sign monitoring technology, and relates to a multifunctional flexible sensor for wearable electronic devices, health monitoring, electromagnetic protection, bacterial inhibition, and intelligent fetal movement monitoring, as well as its preparation method. Background Technology
[0002] Electromagnetic waves are the cornerstone of modern information and digital technology, playing a crucial role in signal transmission. However, with the rapid development of electronic devices and wireless communication technologies, mobile phones, satellite communications, navigation, and the medical field constantly generate electromagnetic waves. While these waves ensure the normal operation of electronic devices, radiation also accumulates continuously. Today, electromagnetic interference pollution poses a serious threat to human health, attracting increasing attention. Electromagnetic radiation is harmful to human health, leading to nausea, headaches, eye problems, and even cancer, especially affecting the developing brain of infants.
[0003] Fetal movement, the actions of the fetus impacting the uterine wall as it moves within the uterus, is an important indicator of fetal vital signs, making its monitoring crucial. Changes in fetal movement are related to a range of fetal health issues, including fetal distress, growth restriction, hypoxia, and placental dysfunction. For example, normal fetal movement indicates that the fetus is developing well in the uterus, the placenta is functioning normally, and it is providing the fetus with sufficient oxygen and nutrients. When the fetus experiences abnormal conditions such as hypoxia in the uterus, the frequency of fetal movement initially surges, then gradually decreases or even disappears—this is an important distress signal from the fetus. Currently, the most common and widely used method for quantifying fetal movement is through the pregnant woman's sensation, and it is used by many pregnant women worldwide. However, this method is highly dependent on the patient, especially with slight or gentle fetal movements, and requires the pregnant woman to maintain concentration for extended periods, making it susceptible to interference and errors.
[0004] Therefore, a portable multifunctional sensor with electromagnetic shielding, Joule heating performance, high sensitivity and wide response was designed for fetal movement monitoring. This sensor can effectively help pregnant women obtain fetal movement pressure and frequency anytime and anywhere to quickly understand the fetus's condition, while reducing the electromagnetic radiation from surrounding electronic devices to meet the ergonomic needs of pregnant women. Summary of the Invention
[0005] In view of this, the present invention provides a multifunctional flexible sensor, its preparation method, and a system for intelligent fetal movement monitoring. Based on this multifunctional sensor, fetal movement monitoring utilizes machine deep learning to classify and analyze the measured data, achieving a wide response range and fast response speed. This allows pregnant women to conveniently and quickly measure fetal movement frequency, enabling them to rapidly understand the fetus's condition. Furthermore, the sensor also possesses excellent electromagnetic shielding capabilities and a rapid electrothermal response.
[0006] To achieve the above objectives, the present invention provides a method for preparing a rubber-based flexible strain sensor and a system for monitoring fetal movement, which includes a waist belt, sensor material, control circuit and deep learning system.
[0007] The present invention provides a method for preparing a rubber-based flexible strain sensor, characterized in that it comprises various raw materials in the following weight fractions:
[0008]
[0009] The sodium alginate needs to be prepared into a 1% w / v sodium alginate solution, which is used to modify multi-walled carbon nanotubes.
[0010] This invention provides a method for fabricating a rubber-based flexible strain sensor, the method comprising:
[0011] Weigh 100g of deionized water, heat it to 70℃ and stir at high speed. Weigh 1g of sodium alginate and slowly add it to the constantly stirred deionized water until it is completely dissolved.
[0012] Weigh out multi-walled carbon nanotubes and add them to sodium alginate solution. Stir continuously to obtain a suspension. Disperse the suspension by ultrasonication to obtain uniformly dispersed multi-walled carbon nanotubes.
[0013] Potassium laurate, potassium hydroxide, zinc diethyldithioamino acid formate, sulfur and zinc oxide were weighed out according to the weight proportions, poured into a ball mill jar and ball-milled to obtain the vulcanization aid;
[0014] Weigh out the natural latex according to the weight proportions and place it in a mixing device for stirring. Add the vulcanization aid and continue stirring until matured to obtain pre-vulcanized natural latex.
[0015] Casein and multi-walled carbon nanotubes were added to pre-vulcanized natural latex and stirred until evenly dispersed. The mixture was then poured into a mold and vulcanized to obtain a rubber-based flexible strain sensor.
[0016] By using the above technical solution, sodium alginate is used to modify multi-walled carbon nanotubes, introducing oxygen-containing groups of hydroxyl groups on the surface of the multi-walled carbon nanotubes. π-π conjugation interaction is used to modify the multi-walled carbon nanotubes with non-covalent bonds, enabling the multi-walled carbon nanotubes to be uniformly dispersed in natural latex and form a uniform reinforcing network in the composite material, effectively improving the antibacterial and mechanical properties of the material.
[0017] This invention provides a system for fetal movement monitoring, such as Figure 2As shown, it includes a sensing device, an Arduino Uno, a power module, and a data analysis platform. The fetal movement monitoring sensor is connected to the fetal movement signal acquisition instrument using a medical-grade ECG cable, which effectively shields it from external interference and noise. The fetal movement signal generated by the sensor is amplified and output as an analog signal. The Arduino Uno converts the analog signal into a digital signal, and the collected data is wirelessly transmitted in real-time to the data analysis platform via its built-in Bluetooth module for monitoring, providing data reference for remote medical guidance.
[0018] The sensing device is sewn and glued into the waistband fixing strap. For the sensing device, a fixed resistor is selected to form a voltage divider circuit with the strain sensing film to convert the resistance change into a voltage change. The resistance value of the fixed resistor should be approximately close to the resistance value of the strain film in the unstrained state. A first wire and a second wire are connected to both ends of the strain sensing film, respectively. The first wire is connected to the fixed resistor and then to the input pin of the Arduino Uno, and the second wire is connected to the GND pin of the Arduino Uno.
[0019] Using the HM-10 Bluetooth module, connect the module's VCC to the Arduino Uno's 5V, the module's TXD to the Arduino Uno's digital pin 0, and the module's RXD to the Arduino Uno's digital pin 1. This module features low power consumption and good compatibility, enabling wireless transmission of fetal movement data with low power consumption while also supporting wired connections to meet high data processing needs.
[0020] Considering the portability and safety of the fetal movement signal acquisition equipment, the fetal movement detection system is powered by a lithium battery. The power module mainly consists of three parts: a regulated power supply, a charging circuit, and a power on / off control circuit.
[0021] The Qt-based data analysis platform connects to the HM-10 via Bluetooth to collect and graphically display fetal movement information in real time, helping pregnant women and medical personnel understand the fetus's health status. The platform comprises several core modules: a Bluetooth communication module using QtBluetooth to achieve wireless communication with the sensing device, responsible for data search, connection, and reception, ensuring stable transmission; a graphical user interface module built on QtWidgets or QtQuick (QML) to create an intuitive user interface, displaying real-time curves, historical data tables, and statistical information, supporting parameter settings and personalized displays; a data storage module using QtSQL or a file storage system to save data to a local database or file system, supporting the export of CSV or PDF reports; and a built-in deep learning system to categorize and analyze the collected data, reading the number of fetal movements within an hour to determine if fetal movement is normal. The system also includes an alarm module with a threshold library for fetal movement frequency and amplitude, alerting the user via sound or message when abnormalities are detected.
[0022] The beneficial effects of this invention are as follows:
[0023] By modifying multi-walled carbon nanotubes with sodium alginate, oxygen-containing groups with hydroxyl groups are introduced on the surface of the multi-walled carbon nanotubes. Utilizing π-π conjugation interactions, non-covalent modification of the multi-walled carbon nanotubes is carried out, enabling the multi-walled carbon nanotubes to be uniformly dispersed in natural latex and form a uniform reinforcing network in the composite material, effectively improving the mechanical properties and antibacterial ability of the material.
[0024] This invention incorporates magnetic nanoparticles into the sensor. The inherent magnetic response and conductivity of these nanoparticles facilitate the absorption and reflection of electromagnetic waves. Through reasonable particle distribution and structural design, a continuous or semi-continuous shielding layer can be formed, protecting the sensor's internal signals from external interference. Microwave vector analyzers demonstrate that the flexible sensor of this invention exhibits excellent high-frequency adaptability in the X-band (8~12GHz), making it suitable for high-frequency electromagnetic interference (EMI) suppression scenarios. During fetal movement monitoring, it can effectively shield electromagnetic waves emitted by surrounding electronic products, reducing radiation exposure to pregnant women and infants.
[0025] Based on the conductive network formed by the introduced conductive filler, heat is generated through the Joule heating effect after an electric current is applied. By precisely controlling the continuity and current density of the conductive network, a rapid-response, uniformly distributed local heating function can be achieved, meeting the application requirements of temperature control, dehumidification, or low-temperature protection. The Joule heating effect enables the sensor to generate heat efficiently in a short time, making it ideal for applications requiring rapid temperature regulation, such as localized heating of the knees, abdomen, and lower back of pregnant women, providing a warm and comfortable experience while maintaining low-voltage operation to ensure safety. Attached Figure Description
[0026] Figure 1 This is a schematic diagram illustrating the fabrication of a flexible strain sensor.
[0027] Figure 2 This is a schematic diagram of the structure of a fetal movement monitoring system;
[0028] Figure 3 This is a schematic diagram simulating the structure of a tire movement device;
[0029] Figure 4 Electrical signals detected at different fetal movement frequencies;
[0030] Figure 5 To improve the accuracy of deep learning systems in recognizing different fetal movement frequencies;
[0031] Figure 6 To enhance the antibacterial ability and biocompatibility of the fetal movement sensor;
[0032] Figure 7 For the water resistance of the tire movement sensor;
[0033] Figure 8 The electromagnetic interference shielding effectiveness curve of the tire movement sensor;
[0034] Figure 9 This refers to the Joule thermal properties of the tire movement sensor. Detailed Implementation
[0035] To make the technical problems solved by the present invention, the technical solutions, and the beneficial effects clearer, the following specific embodiments provide a further detailed description of the present invention. It should be understood that the specific embodiments described herein are merely illustrative and are not intended to limit the scope of the invention.
[0036] This invention provides a method for fabricating a flexible strain sensor that combines electromagnetic shielding and Joule heating, comprising the following steps:
[0037] Step 1: Weigh 100g of deionized water, heat it to 70℃ and stir at high speed. Weigh 1g of sodium alginate and slowly add it to the deionized water. Stir continuously for 30 minutes at 400rpm using mechanical stirring.
[0038] Step 2: Weigh 6-15 phr of multi-walled carbon nanotubes and add them to a sodium alginate solution. Stir continuously at 400 rpm for 5 hours to obtain a suspension. Then, sonicate the suspension at 100 W for 5 minutes to obtain uniformly dispersed multi-walled carbon nanotubes.
[0039] Step 3: Weigh out potassium laurate, potassium hydroxide, zinc diethyldithioamino acid formate, sulfur and zinc oxide according to the weight proportions, pour them into a ball mill jar and ball mill at 500 rpm for 5 hours to obtain the vulcanization aid;
[0040] Step 4: Weigh the natural latex according to the specified weight and place it in a mixing device for stirring. Add the vulcanization aid and stir continuously at room temperature for 24 hours to mature, thus obtaining pre-vulcanized natural latex.
[0041] Step 5: Add casein and multi-walled carbon nanotubes to the pre-vulcanized natural latex and stir continuously until evenly dispersed. Pour into a mold and vulcanize to obtain a rubber-based flexible strain sensor.
[0042] Using the above technical solution, sodium alginate is used to modify multi-walled carbon nanotubes (MWCNTs). Hydroxyl groups are introduced onto the surface of the MWCNTs, and non-covalent modifications are performed using π-π conjugation interactions. This allows the MWCNTs to be uniformly dispersed in natural latex, forming a uniform reinforcing network in the sensor, effectively improving the antibacterial and mechanical properties of the strain sensor. Due to the biosynthesis process of natural latex, many non-rubber components (including proteins, phospholipids, inorganic salts, etc.) are retained and bound to the surface of the latex particles, containing some Ca... 2+ Sodium alginate can form a unique "egg-box" structure with divalent and trivalent metal ions. The G unit in the alginate molecular chain reacts with Ca... 2+ Coordination occurs. Two alginate molecular chains are linked by Ca... 2+ The coordination interactions between the alginate and sodium alginate components are interconnected, much like two eggshells interlocking, forming a cross-linked structure that allows the alginate solution to form a stable gel. During solvent evaporation, the alginate gel shrinks and collapses in the hydrogel microregions, creating a porous structure that extends the path of electromagnetic waves within the material, thereby improving its electromagnetic shielding performance. In summary, the described flexible sensing material achieves the goals of strain sensing, electromagnetic shielding, and Joule heating simultaneously; its preparation process is simple, economical, and efficient, demonstrating promising prospects for industrialization.
[0043] Example 1
[0044] Step 1: Weigh 100g of deionized water, heat it to 70℃ and stir at high speed. Weigh 1g of sodium alginate and slowly add it to the deionized water. Stir continuously for 30 minutes at 400rpm using mechanical stirring.
[0045] Step 2: Weigh 6 phr of multi-walled carbon nanotubes and add them to a sodium alginate solution. Stir continuously at 400 rpm for 5 hours to obtain a suspension. Then, sonicate the suspension at 100 W for 5 minutes to obtain uniformly dispersed multi-walled carbon nanotubes.
[0046] Step 3: Weigh out potassium laurate, potassium hydroxide, zinc diethyldithioamino acid formate, sulfur and zinc oxide according to the weight proportions, pour them into a ball mill jar and ball mill at 500 rpm for 5 hours to obtain the vulcanization aid;
[0047] Step 4: Weigh the natural latex according to the specified weight and place it in a mixing device for stirring. Add the vulcanization aid and stir continuously at room temperature for 24 hours to mature, thus obtaining pre-vulcanized natural latex.
[0048] Step 5: Add casein and multi-walled carbon nanotubes to the pre-vulcanized natural latex and stir continuously until evenly dispersed. Pour into a mold and vulcanize to obtain a rubber-based flexible strain sensor. The sample is labeled SC6N.
[0049] Example 2
[0050] Step 1: Weigh 100g of deionized water, heat it to 70℃ and stir at high speed. Weigh 1g of sodium alginate and slowly add it to the deionized water. Stir continuously for 30 minutes at 400rpm using mechanical stirring.
[0051] Step 2: Weigh 9 phr of multi-walled carbon nanotubes and add them to a sodium alginate solution. Stir continuously at 400 rpm for 5 hours to obtain a suspension. Then, sonicate the suspension at 100 W for 5 minutes to obtain uniformly dispersed multi-walled carbon nanotubes.
[0052] Step 3: Weigh out potassium laurate, potassium hydroxide, zinc diethyldithioamino acid formate, sulfur and zinc oxide according to the weight proportions, pour them into a ball mill jar and ball mill at 500 rpm for 5 hours to obtain the vulcanization aid;
[0053] Step 4: Weigh the natural latex according to the specified weight and place it in a mixing device for stirring. Add the vulcanization aid and stir continuously at room temperature for 24 hours to mature, thus obtaining pre-vulcanized natural latex.
[0054] Step 5: Add casein and multi-walled carbon nanotubes to the pre-vulcanized natural latex and stir continuously until evenly dispersed. Pour into a mold and vulcanize to obtain a rubber-based flexible strain sensor. The sample is labeled SC9N.
[0055] Example 3
[0056] Step 1: Weigh 100g of deionized water, heat it to 70℃ and stir at high speed. Weigh 1g of sodium alginate and slowly add it to the deionized water. Stir continuously for 30 minutes at 400rpm using mechanical stirring.
[0057] Step 2: Weigh 12 phr of multi-walled carbon nanotubes and add them to a sodium alginate solution. Stir continuously at 400 rpm for 5 hours to obtain a suspension. Then, sonicate the suspension at 100 W for 5 minutes to obtain uniformly dispersed multi-walled carbon nanotubes.
[0058] Step 3: Weigh out potassium laurate, potassium hydroxide, zinc diethyldithioamino acid formate, sulfur and zinc oxide according to the weight proportions, pour them into a ball mill jar and ball mill at 500 rpm for 5 hours to obtain the vulcanization aid;
[0059] Step 4: Weigh the natural latex according to the specified weight and place it in a mixing device for stirring. Add the vulcanization aid and stir continuously at room temperature for 24 hours to mature, thus obtaining pre-vulcanized natural latex.
[0060] Step 5: Add casein and multi-walled carbon nanotubes to the pre-vulcanized natural latex and stir continuously until evenly dispersed. Pour into a mold and vulcanize to obtain a rubber-based flexible strain sensor. The sample is labeled SC. 12 N.
[0061] Example 4
[0062] Step 1: Weigh 100g of deionized water, heat it to 70℃ and stir at high speed. Weigh 1g of sodium alginate and slowly add it to the deionized water. Stir continuously for 30 minutes at 400rpm using mechanical stirring.
[0063] Step 2: Weigh 15 phr of multi-walled carbon nanotubes and add them to a sodium alginate solution. Stir continuously at 400 rpm for 5 hours to obtain a suspension. Then, sonicate the suspension at 100 W for 5 minutes to obtain uniformly dispersed multi-walled carbon nanotubes.
[0064] Step 3: Weigh out potassium laurate, potassium hydroxide, zinc diethyldithioamino acid formate, sulfur and zinc oxide according to the weight proportions, pour them into a ball mill jar and ball mill at 500 rpm for 5 hours to obtain the vulcanization aid.
[0065] Step 4: Weigh the natural latex according to the specified weight and place it in a mixing device for stirring. Add the vulcanization aid and stir continuously at room temperature for 24 hours to mature, thus obtaining pre-vulcanized natural latex.
[0066] Step 5: Add casein and multi-walled carbon nanotubes to the pre-vulcanized natural latex and stir continuously until evenly dispersed. Pour into a mold and vulcanize to obtain a rubber-based flexible strain sensor. The sample is labeled SC. 15 N.
[0067] Comparative Example 1
[0068] Step 1: Weigh 100g of deionized water, heat it to 70℃ and stir at high speed. Weigh 1g of sodium alginate and slowly add it to the deionized water. Stir continuously for 30 minutes at 400rpm using mechanical stirring.
[0069] Step 2: Weigh 6-15 phr of multi-walled carbon nanotubes and add them to a sodium alginate solution. Stir continuously at 400 rpm for 5 hours to obtain a suspension. Then, sonicate the suspension at 100 W for 5 minutes to obtain uniformly dispersed multi-walled carbon nanotubes.
[0070] Step 3: Weigh out potassium laurate, potassium hydroxide, zinc diethyldithioamino acid formate, sulfur and zinc oxide according to the weight proportions, pour them into a ball mill jar and ball mill at 500 rpm for 5 hours to obtain the vulcanization aid;
[0071] Step 4: Weigh the natural latex according to the specified weight and place it in a mixing device for stirring. Add the vulcanization aid and stir continuously at room temperature for 24 hours to mature, thus obtaining pre-vulcanized natural latex.
[0072] Step 5: Multi-walled carbon nanotubes are continuously stirred in the pre-vulcanized natural latex until they are evenly dispersed. After being poured into a mold and vulcanized, a rubber-based flexible strain sensor is obtained, and the sample is labeled as SN.
[0073] This embodiment provides a system for fetal movement monitoring, such as Figure 2 As shown, it includes a sensing device, an Arduino Uno, a power module, and a deep learning system. The fetal movement monitoring sensor is connected to the fetal movement signal acquisition instrument using a medical-grade ECG lead cable, which effectively shields it from external interference and noise. The fetal movement signal generated by the sensor is amplified by a charge amplifier to output an analog fetal movement signal. The Arduino Uno converts the analog signal into a digital signal, and the collected data is wirelessly transmitted in real-time to a data analysis platform via its built-in Bluetooth module for monitoring, providing data reference for remote medical guidance.
[0074] The sensing device prepared in Example 4 is sewn and glued into the waistband fixing strap. For the sensing device, a fixed resistor is selected to form a voltage divider circuit with the strain sensing film to convert the resistance change into a voltage change. The resistance value of the fixed resistor should be approximately close to the resistance value of the strain film in the unstrained state. A first wire and a second wire are connected to both ends of the strain sensing film, respectively. The first wire is connected to the fixed resistor and then to the input pin of the Arduino Uno, and the second wire is connected to the GND pin of the Arduino Uno.
[0075] In this embodiment, the Bluetooth module used is the HM-10. The VCC of the Bluetooth module is connected to the 5V pin of the Arduino Uno, the TXD of the Bluetooth module is connected to digital pin 0 of the Arduino Uno, and the RXD of the Bluetooth module is connected to digital pin 1 of the Arduino Uno. This module has the advantages of low power consumption and good compatibility. It enables wireless transmission of fetal movement data with low power consumption while also supporting wired connections, meeting the needs of high data processing.
[0076] Considering the portability and safety of the fetal movement signal acquisition equipment, the fetal movement detection system is powered by a lithium battery. The power module mainly consists of three parts: a regulated power supply, a charging circuit, and a power on / off control circuit.
[0077] The Qt-based data analysis platform connects to the HM-10 via Bluetooth to collect and graphically display fetal movement information in real time, helping pregnant women and medical personnel understand the fetus's health status. The platform comprises several core modules: a Bluetooth communication module using QtBluetooth to achieve wireless communication with the sensing device, responsible for data search, connection, and reception, ensuring stable transmission; a graphical user interface module built on QtWidgets or QtQuick (QML) to create an intuitive user interface, displaying real-time curves, historical data tables, and statistical information, supporting parameter settings and personalized displays; a data storage module using QtSQL or a file storage system to save data to a local database or file system, supporting the export of CSV or PDF reports; and a built-in deep learning system to categorize and analyze the collected data, reading the number of fetal movements within an hour to determine if fetal movement is normal. The system also includes an alarm module with a threshold library for fetal movement frequency and amplitude, alerting the user via sound or message when abnormalities are detected.
[0078] like Figure 3 As shown, a device simulating a pregnant woman's abdomen was created using balloons and jars. An abdominal model was constructed using balloons and jars, and an MCU controlled a stepper motor and a servo motor to simulate fetal kicking and wriggling movements, respectively. Sensors connected to the abdominal model detected the kicking movements and converted them into electrical signals for computer display. Figure 4 As shown. The built-in deep learning system categorizes and analyzes the read data, using the number of fetal movements within an hour to determine if fetal movement is normal. Figure 5 As shown, the accuracy rate for recognizing fetal movements at different frequencies reached 95.56%.
[0079] In addition, from Figure 9It can be seen that the sensor achieves an average electromagnetic shielding effectiveness of 22.7 dB in the 8–18 GHz range, indicating that the sensor has excellent high-frequency adaptability in the X-band (8.4–12.4 GHz) and is suitable for high-frequency electromagnetic interference (EMI) suppression scenarios. Verification using a vector network analyzer (VNA) under standard testing conditions shows that the sensor conforms to electromagnetic shielding effectiveness testing standards such as IEEE 299. The above data indicates that the sensor's EMI SE > 20 dB in the 8.4–12.4 GHz range meets industrial-grade high-frequency shielding requirements (EMI SE > 20 dB).
[0080] Performance testing
[0081] (1) Mechanical property testing: The tensile properties and elongation at break of the composite material were tested in accordance with GB / T528-1998 Determination of tensile stress-strain properties of vulcanized rubber or thermoplastic rubber.
[0082] (2) Antibacterial performance test: Escherichia coli and Staphylococcus aureus were cultured in LB medium. Tissue culture plates served as the control group. SN and SCN samples were placed in 24-well microplates and sterilized by UV irradiation for 1 hour. Subsequently, bacterial suspensions (10 µL, 10 μL) were cultured in LB medium. 8 CFU / mL was spotted onto the surface of each material and incubated at 37°C for 2 hours. Viable bacteria were resuspended in 2 mL of sterile PBS buffer, and 20 µL of the aliquot was diluted to 50 mL. 20 µL of the diluted suspension was spread onto LB agar plates and incubated at 37°C for 12 hours. Colony counts (Ce) were then performed. The colony count of the unexposed control group was labeled Cn. The decrease in bacterial count was calculated using the following formula:
[0083] (1)
[0084] (3) Biocompatibility test: Custom-prepared and pre-weighed samples were placed in 96-well plates. L929 cells were cultured at a density of 4000 cells / well on the membrane surface. Cell viability was assessed using CCK-8 assay on days 1, 2, and 3 of culture, and absorbance was measured at 450 nm using a microplate reader (n=3). Bioactivity was calculated using the following formula:
[0085] (2)
[0086] Table 1 Performance Testing
[0087]
[0088] This specific embodiment is merely an explanation of the present invention and is not intended to limit the invention. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they are within the scope of the claims of the present invention.
Claims
1. A method for preparing a multifunctional rubber-based flexible sensor for fetal movement monitoring, characterized in that, The following raw materials are included in the following weight fractions: 100 parts natural latex 1 part potassium laurate 0.25 parts potassium hydroxide 1.25 parts of zinc diethyldithioamino acid formate 1 part sulfur 1.5 parts zinc oxide 1 part sodium alginate 6-15 parts of multi-walled carbon nanotubes The sodium alginate needs to be prepared into a 1% w / v sodium alginate solution, which is used to modify multi-walled carbon nanotubes.
2. The preparation method according to claim 1, characterized in that: The sodium alginate solution is prepared as follows: Weigh 99g of deionized water, heat it to 70°C and stir at high speed, then weigh 1g of sodium alginate and slowly add it to the continuously stirred deionized water until it is completely dissolved.
3. The preparation method according to claim 1, characterized in that: The modification method of the multi-walled carbon nanotubes is as follows: multi-walled carbon nanotubes are added to sodium alginate solution and stirred continuously to obtain a suspension. The suspension is then ultrasonically dispersed to obtain uniformly dispersed multi-walled carbon nanotubes.
4. The preparation method according to any one of claims 1-3, characterized in that, Includes the following steps: S1. Preparation of vulcanization aid: Weigh potassium laurate, potassium hydroxide, zinc diethyldithioamino acid formate, sulfur and zinc oxide according to the weight parts, pour them into a ball mill jar and ball mill to obtain the vulcanization aid; S2. Pre-vulcanization of natural latex: Weigh out natural latex according to the weight proportions and place it in a mixing device for stirring. Add vulcanization aid and continue stirring until mature to obtain pre-vulcanized natural latex. S3. Vulcanization molding: Modified multi-walled carbon nanotubes are continuously stirred in pre-vulcanized natural latex until they are evenly dispersed. After being poured into a mold and vulcanized, a rubber-based flexible strain sensor is obtained.
5. A system for monitoring fetal movement, characterized in that, The device includes a waist support belt, a sensing device, a control circuit, and a data analysis system. The sensing device is attached to the waist support belt, which secures the sensing device to the abdomen. The sensing device is used for fetal movement signal monitoring. The obtained fetal movement signals are transmitted to the data analysis system via the control circuit. The data analysis system extracts features from the fetal movement monitoring data, identifies and classifies the fetal movement information, and displays the fetal movement information graphically. The sensing device includes a first multi-channel analog switch, a second multi-channel analog switch, and a plurality of multifunctional fabric-based flexible pressure sensors arranged in an array. Each of the multifunctional fabric-based flexible pressure sensors has a first wire and a second wire connected to its two ends, respectively. The first lead wire of each multifunctional fabric-based flexible pressure sensor is connected to the first flexible electrode through the first multi-channel analog switch; the second lead wire of each multifunctional fabric-based flexible pressure sensor is connected to the second flexible electrode through the second multi-channel analog switch; the first flexible electrode and the second flexible electrode are respectively connected to the control circuit, and the control circuit sequentially selects each multifunctional fabric-based flexible pressure sensor by controlling the multi-channel analog switch to read the electrical signal generated by each multifunctional fabric-based flexible pressure sensor.
6. The system according to claim 5, characterized in that, The control circuit includes a charge amplifier, a microcontroller, and a power management module. The charge amplifier is connected to the first flexible electrode and the second flexible electrode respectively, amplifies the electrical signal collected by the sensing device, and outputs it to the microcontroller. The microcontroller performs analog-to-digital conversion on the electrical signal, stores it, and transmits the collected data to the data analysis system via Bluetooth communication. The power management module is connected to the charge amplifier and the microcontroller respectively.