Method for preparing low-toughness conductive hydrogel, blood pressure monitoring device and system
By preparing a low-toughness conductive hydrogel as an electrode material, the problems of incompatibility between metal electrodes and skin and signal noise in the prior art have been solved, and the high conductivity, adhesion and comfort of the blood pressure monitoring device have been achieved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- TIANJIN UNIV
- Filing Date
- 2024-06-07
- Publication Date
- 2026-04-21
AI Technical Summary
Existing wristband-type self-diagnostic devices typically use metal electrodes, which can cause discomfort upon skin contact and generate signal noise, affecting the accuracy and comfort of data acquisition.
Low-toughness conductive hydrogels were used as electrode materials. The hydrogels were prepared by adding trehalose, AM, crosslinking agents and photoinitiators to deionized water and then combining them with ultraviolet light polymerization. The hydrogels were used for ECG signal acquisition in blood pressure monitoring devices.
This improves the adaptive contact between the electrodes and the skin, reduces noise during signal acquisition, and ensures comfort and signal stability during long-term wear.
Smart Images
Figure CN118496529B_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of blood pressure monitoring technology, and more specifically, to a method for preparing a low-toughness conductive hydrogel, a blood pressure monitoring device, and a system. Background Technology
[0002] With the rise of the Internet of Things and wearable devices, the demand for portable biometric detection is increasing in people's daily lives, such as smartwatches and wristbands.
[0003] Currently, wristband-type self-diagnostic devices such as watches typically use metal electrodes. However, in addition to lacking adaptability to skin contact, metal electrodes can also generate significant signal noise during use, leading to data loss during post-processing. Summary of the Invention
[0004] In view of this, this application provides a method for preparing a low-toughness conductive hydrogel and a blood pressure monitoring device, which provides a hydrogel with high conductivity, high adhesion, high tensile strength and low toughness, as well as a blood pressure monitoring device with high comfort.
[0005] To achieve the above objectives, the following solution is proposed:
[0006] A method for preparing a low-toughness conductive hydrogel, comprising:
[0007] S1. Add an appropriate amount of trehalose to deionized water to prepare a trehalose solution;
[0008] S2. Add AM to the trehalose solution prepared in step S1 and stir until homogeneous;
[0009] S3. Add crosslinking agent and photoinitiator to the solution obtained in step S2, and stir until homogeneous;
[0010] S4. Add anhydrous LiCl to the solution obtained in step S3, stir thoroughly to obtain a hydrogel precursor solution, and then perform ultrasonic treatment.
[0011] S5. Transfer the hydrogel precursor solution obtained in step S4 into a mold, place the mold under ultraviolet light for polymerization, and obtain the hydrogel.
[0012] Preferably, the trehalose solution has a mass fraction of 10%-40%.
[0013] Preferably, the crosslinking agent is MBAA and the photoinitiator is IR2959;
[0014] The molar ratio of MBAA to AM is 0.01-0.05%, and the molar ratio of IR2959 to AM is 0.1%.
[0015] Preferably, the concentration of anhydrous LiCl in the hydrogel precursor solution is 5-30 mg / ml.
[0016] Preferably, the ultraviolet light has a power of 20 W and a wavelength of 365 nm.
[0017] A blood pressure monitoring device includes: a power supply module, a first voltage conversion module, a second voltage conversion module, a third voltage conversion module, a control module, a communication module, an ECG detection module, a PPG detection module, and an ECG signal acquisition electrode, wherein the ECG signal acquisition electrode is provided with a hydrogel prepared by the aforementioned low-toughness conductive hydrogel preparation method on its outer side.
[0018] The ECG signal acquisition electrode comes into contact with the skin of the person being tested so that the ECG detection module can acquire the ECG signal of the person being tested;
[0019] The power supply module provides the initial voltage to each module;
[0020] The first voltage conversion module converts the initial voltage into the target voltages for the control module, communication module, ECG detection module, and PPG detection module, and then supplies power to them.
[0021] The control module receives ECG and PPG signals collected by the ECG and PPG detection modules, and sends them to the user terminal via the communication module so that the user terminal can predict blood pressure based on the ECG and PPG signals.
[0022] Preferably, it further includes: a monitoring housing and a base plate;
[0023] The power supply module, the first voltage conversion module, the second voltage conversion module, the third voltage conversion module, the control module, the communication module, the ECG detection module, the PPG detection module, and the ECG signal acquisition electrodes are all located inside the monitoring housing and fixed to the base plate.
[0024] The base plate has two horizontally distributed through-holes to allow the ECG signal acquisition electrodes to contact the skin.
[0025] Preferably, it further includes:
[0026] The elastic band secures the blood pressure monitoring device to the person being tested.
[0027] A blood pressure monitoring system includes: the aforementioned blood pressure monitoring device and a user terminal;
[0028] The blood pressure monitoring device detects the ECG and PPG signals of the person being tested and sends the detected signals to the user terminal.
[0029] The user terminal predicts blood pressure based on ECG and PPG signals and displays the ECG, PPG, and blood pressure data.
[0030] Preferably, the process of blood pressure prediction by the user terminal based on ECG and PPG signals includes:
[0031] The ECG signal and PPG signal are filtered by a bandpass filter to obtain the ECG filtered signal and the PPG filtered signal.
[0032] Extract the contraction and diastolic peaks of the PPG filtered signal, extract the RR interval and SDSD of the ECG filtered signal, and extract the time difference PTT between the PPG filtered signal and the ECG filtered signal.
[0033] The extracted feature data is input into a pre-trained blood pressure prediction model. The blood pressure prediction model uses multiple Transformer-XL layers to process the feature data and uses position encoding to preserve temporal information. Then, the feature data of the two signals are merged through a fully connected layer to predict the blood pressure of the person being tested.
[0034] As can be seen from the above technical solutions, the low-toughness conductive hydrogel preparation method, blood pressure monitoring device and system provided in this application have the following beneficial effects:
[0035] 1. The hydrogel prepared by the low-toughness conductive hydrogel preparation method provided in this application has excellent conductivity, tensile properties, adhesion and low toughness.
[0036] 2. The blood pressure monitoring device provided in this application uses hydrogel as electrodes for signal acquisition. Hydrogel is highly similar to biological tissue, thus reducing skin irritation. Compared to metal electrodes, this significantly improves the adaptability of the electrodes to the skin, ensuring comfort during prolonged wear; it also reduces noise during signal acquisition, guaranteeing comfort for extended periods. Attached Figure Description
[0037] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of this application. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.
[0038] Figure 1-3 The tensile stress-strain properties of the hydrogels prepared in Examples 1-3 of this application are as follows;
[0039] Figure 4The toughness test results are for the hydrogel prepared in Example 3 of this application;
[0040] Figure 5 The conductivity test results are for the hydrogel prepared in Example 3 of this application;
[0041] Figure 6 This is a schematic diagram of a blood pressure monitoring device provided in an embodiment of this application;
[0042] Figure 7 A flowchart of a user terminal blood pressure prediction process is provided as an embodiment of this application;
[0043] Figure 8 This is a schematic diagram of a user terminal interface provided in an embodiment of this application. Detailed Implementation
[0044] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.
[0045] Example 1
[0046] S1. Add 4.42g AM (polymeric monomer acrylamide) to 20ml of deionized water and stir well.
[0047] S2. Add crosslinking agent MBAA (N,N'-methylenebisacrylamide) and 14 mg photoinitiator IR2959 (2-hydroxy-4'-(2-hydroxyethoxy)-2-methylphenylacetone) to each of the solutions obtained in step S1, and stir until homogeneous. The molar ratios of MBAA to AM are 0.01%, 0.02%, 0.03%, 0.04%, and 0.05%, respectively.
[0048] S3. Sonicate each solution obtained in step S2 for 10 min to remove air bubbles.
[0049] S4. Use a disposable dropper to transfer each portion of the solution obtained in step S3 into the mold, and then place the mold under ultraviolet light at a power of 20 W and a wavelength of 365 nm for 1 h to polymerize and obtain a hydrogel.
[0050] Tensile stress-strain properties were tested on the hydrogels obtained in the examples of this application, and the test results are as follows: Figure 1 As shown, the tensile deformation range of the hydrogel is approximately 1050%-1760%, with the tensile deformation of the hydrogel being approximately 1760% when the molar ratio of MBAA to AM is 0.03%.
[0051] Example 2
[0052] S1. Add an appropriate amount of trehalose to 20 ml of deionized water to prepare trehalose solutions with mass fractions of 10%, 20%, 30%, and 40%.
[0053] S2. Add 4.42 g AM to each portion of trehalose solution obtained in step S1 and stir until homogeneous.
[0054] S3. Add crosslinking agent MBAA and 14 mg photoinitiator IR2959 to each of the solutions obtained in step S2, wherein the molar ratio of MBAA to AM is 0.03%.
[0055] S4. Sonicate each solution obtained in step S3 for 10 min to remove air bubbles.
[0056] S5. Use a disposable dropper to transfer each portion of the solution obtained in step S4 into a mold, and then place the mold under ultraviolet light at a power of 20 W and a wavelength of 365 nm for 1 h to polymerize and obtain a hydrogel.
[0057] Tensile stress-strain properties were tested on the hydrogels obtained in the examples of this application, and the test results are as follows: Figure 2 As shown, the tensile deformation range of the hydrogel is approximately 1750%-3900%, with the tensile deformation of the hydrogel being approximately 3900% when the trehalose mass fraction is 30%.
[0058] Example 3
[0059] S1. Add an appropriate amount of trehalose to 20 ml of deionized water to prepare a trehalose solution with a mass fraction of 30%.
[0060] S2. Add 4.42 g AM to each portion of trehalose solution obtained in step S1 and stir until homogeneous.
[0061] S3. Add crosslinking agent MBAA and 14 mg of photoinitiator IR2959 to each of the solutions obtained in step S2, and stir until homogeneous. The molar ratio of MBAA to AM is 0.03%.
[0062] S4. Add anhydrous LiCl to each of the solutions obtained in step S3, stir thoroughly to obtain hydrogel precursor solutions, and sonicate for 10 min to remove air bubbles. The concentrations of anhydrous LiCl are 5 mg / ml, 10 mg / ml, 15 mg / ml, 20 mg / ml, 25 mg / ml, and 30 mg / ml, respectively. The stirring time should be at least 10 min, the stirring speed should be 600 r / min, and the stirring temperature should be ≥25℃.
[0063] S5. Using a disposable dropper, transfer each portion of the hydrogel precursor solution obtained in step S4 into a mold, and then place the mold under ultraviolet light at a power of 20 W and a wavelength of 365 nm for 1 h to polymerize and obtain the hydrogel.
[0064] Tensile stress-strain properties were tested on the hydrogels obtained in the examples of this application, and the test results are as follows: Figure 3 As shown, after adding anhydrous LiCl, the tensile deformation range of the hydrogel decreased slightly, to approximately 1195%-3360%. Specifically, when the LiCl concentration was 20 mg / ml, the tensile strain of the hydrogel was approximately 3360%. The toughness, conductivity, and adsorption properties of the hydrogels obtained in the embodiments of this application were tested. The toughness test results are as follows: Figure 4 As shown, the hydrogel toughness is affected by the LiCl concentration; the hydrogel toughness at 20 mg / ml LiCl is approximately 0.63 MJ / m³. The conductivity test results are as follows... Figure 5 As shown, the conductivity of the hydrogel is affected by the LiCl concentration, reaching a maximum of 11.1 S / m. Specifically, when the LiCl concentration is 20 mg / ml, the conductivity of the hydrogel is approximately 7.6 S / m. The adhesion properties of the hydrogels were tested, and the highest adhesion strength for each hydrogel was around 60 kPa.
[0065] The molds used in Examples 1-3 can be silicone molds. As can be seen from Examples 1-3, the low-toughness conductive hydrogel of this application has the following advantages:
[0066] (1) It has excellent tensile properties and relatively low toughness, and can be stretched about 33 times without breaking, so that the hydrogel exerts less pressure on the skin during the wearing of the blood pressure monitoring device.
[0067] (2) Excellent conductivity enables stable and efficient signal acquisition during blood pressure monitoring.
[0068] (3) Excellent adhesion properties allow the blood pressure monitoring device to be directly connected to the skin, increasing the adaptive contact between the electrode and the skin.
[0069] Next, combined Figure 6 The blood pressure monitoring device provided in the embodiments of this application will be described. The device may include: a monitoring housing 1, an elastic band 2, a circuit board 3, a power supply module 4, a base plate 5, and an ECG signal acquisition electrode 6.
[0070] Specifically, the power supply module 4 can be a 3.7V lithium battery. The power supply module 4 provides a power supply with an initial voltage of 3.7V to the circuit board 3. The power supply module 4 and the circuit board 3 are disposed inside the monitoring housing 1 and fixed to the base plate 5.
[0071] Circuit board 3 includes: a first voltage conversion module, a second voltage conversion module, a third voltage conversion module, a control module, a communication module, an ECG detection module, a PPG detection module, and an ECG signal acquisition electrode 6. The PPG detection module and the ECG signal acquisition electrode 6 are mounted on the back of circuit board 3, and the outer side of the ECG signal acquisition electrode 6 is coated with hydrogel prepared using the aforementioned low-toughness conductive hydrogel preparation method. Two square through-holes can be horizontally distributed on the base plate 5 to allow the ECG signal acquisition electrode 6 to contact the skin of the person being tested. The ECG detection module acquires the ECG signal of the person being tested through the ECG signal acquisition electrode 6.
[0072] The first voltage conversion module converts the initial voltage from 3.7 V to 3.3 V and then supplies 3.3 V power to the control module and communication module; the second voltage conversion module converts the initial voltage from 3.7 V to ±2.5 V and then supplies ±2.5 V power to the ECG detection module; the third voltage conversion module converts the 3.3 V converted by the first voltage conversion module to 1.8 V and then supplies power to the PPG detection module.
[0073] The control module interacts with the ECG detection module, PPG detection module, and communication module via SPI, IIC, and UART communication. The communication module sends ECG and PPG signals to the user terminal, enabling the user terminal to predict blood pressure based on these signals. The communication module can communicate with the user terminal via Bluetooth.
[0074] Elastic band 2 can secure the blood pressure monitoring device to the person being tested.
[0075] The blood pressure monitoring device provided in this application uses hydrogel as an electrode for signal acquisition. The hydrogel electrode is highly similar to biological tissue, thus reducing skin irritation. Compared to metal electrodes, it significantly improves the adaptive contact between the electrode and the skin, ensuring comfort during prolonged wear; it also reduces noise during signal acquisition, guaranteeing comfort for extended periods.
[0076] Next, this application will describe a blood pressure monitoring system, which may include a user terminal and the aforementioned blood pressure monitoring device.
[0077] The blood pressure monitoring device detects the ECG and PPG signals of the person being tested and sends the detected signals to the user terminal.
[0078] The user terminal predicts blood pressure based on ECG and PPG signals and displays the ECG, PPG, and blood pressure data.
[0079] like Figure 7 As shown, the process of blood pressure prediction by the user terminal based on ECG and PPG signals may include:
[0080] Signal analysis: The ECG and PPG signals are filtered using bandpass filters to obtain the ECG filtered signal and the PPG filtered signal.
[0081] Feature extraction: Extract the contraction and diastolic peaks of the PPG filtered signal, extract the RR interval and SDSD of the ECG filtered signal, and extract the time difference PTT between the PPG filtered signal and the ECG filtered signal. , It represents the difference between two consecutive heartbeats. This represents the mean of all heart rate changes in the ECG filtered signal.
[0082] Model Processing: The extracted feature data is input into a pre-trained blood pressure prediction model. This model uses multiple Transformer-XL layers to process the feature data and employs positional encoding to preserve temporal information. Then, a fully connected layer merges the feature data from both signals to predict the blood pressure of the person being tested. The model predicts both diastolic blood pressure (DBP) and systolic blood pressure (SBP). Additionally, it can predict blood oxygen saturation data.
[0083] This application provides a user terminal display method, which enables the user terminal to control the blood pressure monitoring device and wirelessly transmit, store, and intelligently analyze the detection data, thereby achieving real-time blood pressure monitoring. For example... Figure 8 As shown: The user terminal mainly consists of two interfaces:
[0084] (1) Bluetooth search interface a, b. The main page has buttons for avatar, nickname, and Bluetooth search at the top. When clicking the avatar and nickname buttons, users can choose their own avatar and nickname according to their needs. In addition, when starting to use the cuffless blood pressure monitoring system, users need to click the Bluetooth search button first to connect to the system via Bluetooth.
[0085] (2) Data display interface c, d, e, f. This section mainly includes four parts: ECG signal display, PPG signal display, blood pressure data, and blood oxygen data. Among them, the ECG signal display and PPG signal display have a start button on the right. Clicking the corresponding button will immediately start data analysis. After algorithm analysis, the final blood pressure data will be displayed in the corresponding area.
[0086] Finally, it should be noted that in this paper, relational terms such as first and second are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations.
[0087] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.
[0088] The above description of the disclosed embodiments enables those skilled in the art to make or use this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
Claims
1. A method for preparing a low-toughness conductive hydrogel, characterized in that, include: S1. Add an appropriate amount of trehalose to 20 ml of deionized water to prepare a trehalose solution with a mass fraction of 30%; S2. Add 4.42g AM to each portion of trehalose solution obtained in step S1 and stir until homogeneous; S3. Add crosslinking agent MBAA and 14 mg photoinitiator IR2959 to each of the solutions obtained in step S2, and stir until homogeneous, wherein the molar ratio of MBAA to AM is 0.03%; S4. Add anhydrous LiCl to each of the solutions obtained in step S3, stir thoroughly to obtain a hydrogel precursor solution, and sonicate for 10 min to remove air bubbles. The concentrations of anhydrous LiCl are 5 mg / ml, 10 mg / ml, 15 mg / ml, 20 mg / ml, 25 mg / ml, and 30 mg / ml, respectively. The stirring time is at least 10 min, the stirring speed is 600 r / min, and the stirring temperature should be ≥25℃. S5. Using a disposable dropper, transfer each portion of the hydrogel precursor solution obtained in step S4 into a mold, and then place the mold under ultraviolet light at a power of 20 W and a wavelength of 365 nm for 1 h to polymerize and obtain the hydrogel.
2. A blood pressure monitoring device, characterized in that, include: The system comprises a power supply module, a first voltage conversion module, a second voltage conversion module, a third voltage conversion module, a control module, a communication module, an ECG detection module, a PPG detection module, and an ECG signal acquisition electrode, wherein the outer side of the ECG signal acquisition electrode is provided with a hydrogel prepared by the low-toughness conductive hydrogel preparation method described in claim 1. The ECG signal acquisition electrode comes into contact with the skin of the person being tested so that the ECG detection module can acquire the ECG signal of the person being tested; The power supply module provides the initial voltage to each module; The first voltage conversion module converts the initial voltage into the target voltages for the control module, communication module, ECG detection module, and PPG detection module, and then supplies power to them. The control module receives ECG and PPG signals collected by the ECG and PPG detection modules, and sends them to the user terminal via the communication module so that the user terminal can predict blood pressure based on the ECG and PPG signals.
3. The blood pressure monitoring device according to claim 2, characterized in that, Also includes: Monitor the casing and base plate; The power supply module, the first voltage conversion module, the second voltage conversion module, the third voltage conversion module, the control module, the communication module, the ECG detection module, the PPG detection module, and the ECG signal acquisition electrodes are all located inside the monitoring housing and fixed to the base plate. The base plate has two horizontally distributed through-holes to allow the ECG signal acquisition electrodes to contact the skin.
4. The blood pressure monitoring device according to claim 3, characterized in that, Also includes: The elastic band secures the blood pressure monitoring device to the person being tested.
5. A blood pressure monitoring system, characterized in that, include: The user terminal and the blood pressure monitoring device according to any one of claims 2-4; The blood pressure monitoring device detects the ECG and PPG signals of the person being tested and sends the detected signals to the user terminal. The user terminal predicts blood pressure based on ECG and PPG signals and displays the ECG, PPG, and blood pressure data.
6. The blood pressure monitoring system according to claim 5, characterized in that, The process by which a user terminal predicts blood pressure based on ECG and PPG signals includes: The ECG signal and PPG signal are filtered by a bandpass filter to obtain the ECG filtered signal and the PPG filtered signal. Extract the contraction and diastolic peaks of the PPG filtered signal, extract the RR interval and SDSD of the ECG filtered signal, and extract the time difference PTT between the PPG filtered signal and the ECG filtered signal; The extracted feature data is input into a pre-trained blood pressure prediction model. The blood pressure prediction model uses multiple Transformer-XL layers to process the feature data and uses position encoding to preserve temporal information. Then, the feature data of the two signals are merged through a fully connected layer to predict the blood pressure of the person being tested.
Citation Information
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