Preparation method and application of flexible strain film sensor
By introducing SWCNT and PEO in PEDOT:PSS, flexible strain film sensors are prepared, which solves the problems of dryness and human incompatibility of traditional medical electrodes during long-term use, and achieves efficient electrocardiogram recording and adaptability for long-term use.
Patent Information
- Application Number
- CN202510020289.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-01-07
- Publication Date
- 2025-04-01
AI Technical Summary
Traditional medical electrodes have drying problems and human incompatibility during long-term use, and are complex in operation, which limits their application in wearable devices.
SWCNT is used to build a conductive network inside PEDOT:PSS, PEO is added to build a bicontinuous phase structure, and a flexible strain film sensor is prepared for recording the electrocardiogram of the human body.
It achieves excellent conductivity, mechanical flexibility and machining capabilities, can clearly identify all stages of the heartbeat, and is suitable for long-term use.
Smart Images
Figure CN119735847A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to a preparation method and application of a flexible strain film sensor, belonging to the technical field of functional polymer materials. Background Art
[0002] Medical electrodes are crucial signal acquisition components in electrocardiogram (ECG) detection. Their function is to extract bioelectric signals from the surface of human skin and transmit them to the recording device for processing. At present, medical electrodes are mainly divided into two types: wet electrodes and dry electrodes. Wet electrodes are widely used in clinical practice. Their main structure includes conductive materials (such as Ag / AgCl electrodes) and conductive gel. Conductive gel acts as a medium, filling between the electrode and the skin to form an ion conduction path. Conductive gel usually contains water and electrolytes (such as potassium chloride), which help to reduce the contact impedance of the skin-electrode interface. The core of the working principle of the wet electrode is to achieve the ion-electron conversion of bioelectric signals through electrochemical reactions. For example, in the Ag / AgCl electrode, silver (Ag) and chloride ions (Cl - ) reacts to generate silver chloride (AgCl). This process not only efficiently captures signals but also provides a stable electrode potential, thereby improving the accuracy and reliability of the signal.
[0003] Although wet electrodes have superior performance, the drying problem of their conductive gel limits their long-term use, and their ingredients may cause skin irritation or allergic reactions. In addition, wet electrodes usually require skin cleaning and application of conductive gel before use, which increases the complexity of operation. Due to these limitations, wet electrodes are more suitable for short-term high-precision ECG monitoring, and their application in long-term monitoring scenarios such as wearable devices is challenged.
[0004] Dry electrodes do not rely on conductive gels, but capture signals directly through conductive materials in contact with the skin. Such electrodes are usually made of metals, conductive polymers or graphene, and the contact area is increased by designing micro-nano structures (such as nanopores or microneedles) to reduce contact impedance and improve signal acquisition efficiency. The main advantage of dry electrodes is that they are easy to use, do not require the application of conductive gel, are more comfortable to wear, and are non-irritating to the skin, making them suitable for long-term monitoring and wearable device applications. Summary of the invention
[0005] In view of the limitations of traditional medical electrodes on long-term use and the lack of good human compatibility, the present invention proposes a method for preparing and applying a flexible strain film sensor, namely, using SWCNT to construct a conductive network inside PEDOT:PSS to enhance its conductivity to the level of metallic conductivity, adding PEO to construct a dual-continuous phase structure, using PEO as the mechanical reinforcement phase and PEDOT:PSS / SWCNT as the conductive phase. When the flexible strain film sensor is used to record the human electrocardiogram, each stage of the heartbeat can be clearly identified.
[0006] A method for preparing a flexible strain film sensor, the specific steps are as follows: (1) adding single-walled carbon nanotubes (SWCNT) to ethanol, ultrasonically treating in an ice-water bath for 1 to 3 hours, and then mechanically stirring for 2 to 4 hours to uniformly disperse the single-walled carbon nanotubes in the ethanol to obtain a single-walled carbon nanotube dispersion; (2) Adding a fluorinated nonionic surfactant solution (FS-31) and a dimethyl sulfoxide solution to a poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) PEDOT:PSS aqueous solution and stirring to mix well, then adding a single-walled carbon nanotube dispersion, ultrasonically treating for 1 to 4 hours, and then adding polyethylene oxide PEO and stirring for 4 to 6 hours to obtain a PEDOT:PSS / SWCNT / PEO ternary composite solution; (3) The PEDOT:PSS / SWCNT / PEO ternary composite solution was uniformly coated on a polydimethylsiloxane (PDMS) flexible substrate and heat treated at a temperature of 100-130°C for 5-30 min to obtain a flexible strain film sensor.
[0007] Preferably, the concentration of the single-walled carbon nanotube dispersion in step (1) is 0.6-1 g / L.
[0008] Preferably, the concentration of the fluorinated nonionic surfactant solution in step (2) is 0.02-0.05 vol%, and the concentration of the dimethyl sulfoxide solution is 2-6 vol%.
[0009] More preferably, the volume ratio of the fluorinated nonionic surfactant solution (FS-31), the dimethyl sulfoxide solution and the poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) PEDOT:PSS aqueous solution is 0.0002~0.0005:0.02~0.06:1.
[0010] Preferably, the volume ratio of the single-walled carbon nanotube dispersion in step (2) to the poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate)PEDOT:PSS aqueous solution is 0.06-0.1:1, and the solid-liquid ratio g:mL of polyethylene oxide PEO to the poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate)PEDOT:PSS aqueous solution is 0.02-0.06:1.
[0011] The flexible strain film sensor is used as a medical electrode in recording a human electrocardiogram.
[0012] The beneficial effects of the present invention are: (1) The flexible strain film sensor of the present invention uses PEO as the mechanical reinforcement phase and PEDOT:PSS / SWCNT as the conductive phase, which has excellent conductivity, mechanical flexibility and processing and forming ability; (2) When the flexible strain film sensor of the present invention is used to record the electrocardiogram of a human body, each stage of the heartbeat can be clearly identified and can be fully utilized. BRIEF DESCRIPTION OF THE DRAWINGS
[0013] Figure 1 This is the structure diagram of PEDOT:PSS / SWCNT / PEO ternary composite film; Figure 2 This is a partial human electrocardiogram detected by commercially available medical electrodes in Example 1; Figure 3 This is a partial human electrocardiogram detected by the flexible strain film sensor in Example 1; Figure 4 This is a partial human electrocardiogram detected by the flexible strain film sensor in Example 2; Figure 5 for Figure 4 A magnified ECG in the middle; Figure 6 This is a partial human electrocardiogram detected by the flexible strain film sensor in Example 3. DETAILED DESCRIPTION
[0014] The present invention is further described in detail below in conjunction with specific implementation modes, but the protection scope of the present invention is not limited to the described contents.
[0015] Embodiment 1: A method for preparing a flexible strain film sensor, the specific steps are as follows: (1) adding single-walled carbon nanotubes (SWCNT) to ethanol, ultrasonically treating in an ice-water bath for 3 h, and then mechanically stirring for 4 h to uniformly disperse the single-walled carbon nanotubes in the ethanol to obtain a single-walled carbon nanotube dispersion with a concentration of 1 g / L; (2) A 0.05 vol% fluorinated nonionic surfactant solution (FS-31) and a 6 vol% dimethyl sulfoxide solution were added to a poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) PEDOT:PSS aqueous solution and stirred to mix well. Then, a single-walled carbon nanotube dispersion was added and ultrasonically treated for 4 h. Then, polyethylene oxide (PEO) was added and stirred for 6 h to obtain a PEDOT:PSS / SWCNT / PEO ternary composite solution. The fluorinated nonionic surfactant solution (FS-31) , the volume ratio of the dimethyl sulfoxide solution and the poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate)PEDOT:PSS aqueous solution is 0.0005:0.06:1; the volume ratio of the single-walled carbon nanotube dispersion and the poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate)PEDOT:PSS aqueous solution is 0.1:1, and the solid-liquid ratio g:mL of polyethylene oxide PEO and poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate)PEDOT:PSS aqueous solution is 0.06:1; (3) The PEDOT:PSS / SWCNT / PEO ternary composite solution was uniformly coated on a polydimethylsiloxane (PDMS) flexible substrate, and heat treated at 100°C for 30 min to form a PEDOT:PSS / SWCNT / PEO ternary composite film on the polydimethylsiloxane (PDMS) flexible substrate (see Figure 1 ), and obtain the flexible strain film sensor; The thickness of the PEDOT:PSS / SWCNT / PEO ternary composite film on the polydimethylsiloxane PDMS flexible substrate of the flexible strain film sensor in this embodiment is 150 nm; The ADS1292R ECG acquisition module is an analog front-end (AFE) chip specifically used for bioelectric signals and ECG measurement. It integrates data processing modules such as multi-channel signal conditioning circuits, 24-bit Δ-Σ analog-to-digital converters and digital filters, and can collect and process weak bioelectric signals with high fidelity and low noise. In this embodiment, the flexible strain film sensor is used as a medical electrode and a commercially available medical electrode and connected to ADS1292R respectively, and a 3-electrode ECG test method is used to measure the ECG electrocardiogram of the human body. Two electrode sheets are attached to the lower part of the human clavicle, and the other electrode sheet is attached to the left side of the lower abdomen of the human body. The signal is connected to the ECG signal acquisition module ADS1292R, and ADS1292R can draw an ECG electrocardiogram by collecting biopotentials; Some human electrocardiograms detected by commercially available medical electrodes are shown in Figure 2 , some human electrocardiograms detected by the flexible strain film sensor of this embodiment are shown in Figure 3 ,from Figure 2 and 3It can be seen that when the flexible strain film sensor is used as a medical electrode to record the human electrocardiogram, it can achieve the detection accuracy of the current medical electrodes.
[0016] Embodiment 2: A method for preparing a flexible strain film sensor, the specific steps are as follows: (1) adding single-walled carbon nanotubes (SWCNT) to ethanol, ultrasonically treating in an ice-water bath for 2 h, and then mechanically stirring for 3 h to uniformly disperse the single-walled carbon nanotubes in the ethanol to obtain a single-walled carbon nanotube dispersion with a concentration of 0.8 g / L; (2) A 0.035 vol% fluorinated nonionic surfactant solution (FS-31) and a 4 vol% dimethyl sulfoxide solution were added to a poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) PEDOT:PSS aqueous solution and stirred to mix well. Then, a single-walled carbon nanotube dispersion was added and ultrasonically treated for 2.5 h. Then, polyethylene oxide (PEO) was added and stirred for 5 h to obtain a PEDOT:PSS / SWCNT / PEO ternary composite solution. The fluorinated nonionic surfactant solution (FS-31) , the volume ratio of the dimethyl sulfoxide solution and the poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate)PEDOT:PSS aqueous solution is 0.00035:0.04:1; the volume ratio of the single-walled carbon nanotube dispersion and the poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate)PEDOT:PSS aqueous solution is 0.08:1, and the solid-liquid ratio g:mL of polyethylene oxide PEO and poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate)PEDOT:PSS aqueous solution is 0.04:1; (3) The PEDOT:PSS / SWCNT / PEO ternary composite solution was uniformly coated on a polydimethylsiloxane (PDMS) flexible substrate, and heat treated at 110°C for 20 min to form a PEDOT:PSS / SWCNT / PEO ternary composite film on the polydimethylsiloxane (PDMS) flexible substrate (see Figure 1 ), and obtain the flexible strain film sensor; The thickness of the PEDOT:PSS / SWCNT / PEO ternary composite film on the polydimethylsiloxane PDMS flexible substrate of the flexible strain film sensor in this embodiment is 150 nm; In this embodiment, the flexible strain film sensor is connected to ADS1292R as a medical electrode, and a 3-electrode ECG test method is used to measure the ECG electrocardiogram of the human body. Two electrode sheets are attached below the human clavicle, and another electrode sheet is attached to the left side of the human lower abdomen. The signal is connected to the ECG signal acquisition module ADS1292R. ADS1292R can draw an ECG electrocardiogram by collecting biopotentials; Some human electrocardiograms detected by the flexible strain film sensor of this embodiment are shown in Figure 4, Figure 4 The enlarged ECG at A in the middle is shown in Figure 5 ,from Figure 5 It can be seen that the QRS complex, T wave, PR period, QT period, P wave, and ST segment are clearly distinguished in the recorded ECG electrocardiogram; the PR interval refers to the time interval from the beginning of atrium depolarization to the beginning of ventricle depolarization; the normal PR interval range is usually 120 to 200 milliseconds. The QRS complex represents the process of ventricular depolarization; the time of the QRS complex is usually less than 120 milliseconds; the shape and amplitude of the QRS complex can provide information about ventricular depolarization; under normal circumstances, the shape of the QRS complex should be smooth and continuous, without abnormal setbacks or deformation; doctors can detect basic heart problems based on the changes in these signals, such as, arrhythmia, myocardial infarction, cardiomyopathy, etc.
[0017] Embodiment 3: A method for preparing a flexible strain film sensor, the specific steps are as follows: (1) adding single-walled carbon nanotubes (SWCNT) to ethanol, ultrasonically treating in an ice-water bath for 1 h, and then mechanically stirring for 2 h to uniformly disperse the single-walled carbon nanotubes in the ethanol to obtain a single-walled carbon nanotube dispersion with a concentration of 0.6 g / L; (2) A 0.02 vol% fluorinated nonionic surfactant solution (FS-31) and a 2 vol% dimethyl sulfoxide solution were added to a poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) PEDOT:PSS aqueous solution and stirred to mix well. Then, a single-walled carbon nanotube dispersion was added and ultrasonically treated for 1 h. Then, polyethylene oxide (PEO) was added and stirred for 4 h to obtain a PEDOT:PSS / SWCNT / PEO ternary composite solution. The fluorinated nonionic surfactant solution (FS-31), The volume ratio of the dimethyl sulfoxide solution to the poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate)PEDOT:PSS aqueous solution is 0.0002:0.02:1; the volume ratio of the single-walled carbon nanotube dispersion to the poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate)PEDOT:PSS aqueous solution is 0.06:1, and the solid-liquid ratio g:mL of polyethylene oxide PEO to the poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate)PEDOT:PSS aqueous solution is 0.02:1; (3) The PEDOT:PSS / SWCNT / PEO ternary composite solution was uniformly coated on a polydimethylsiloxane (PDMS) flexible substrate, and heat treated at 130°C for 5 min to form a PEDOT:PSS / SWCNT / PEO ternary composite film on the polydimethylsiloxane (PDMS) flexible substrate (see Figure 1 ), and obtain the flexible strain film sensor; The thickness of the PEDOT:PSS / SWCNT / PEO ternary composite film on the polydimethylsiloxane PDMS flexible substrate of the flexible strain film sensor in this embodiment is 150 nm; In this embodiment, the flexible strain film sensor is connected to ADS1292R as a medical electrode, and a 3-electrode ECG test method is used to measure the ECG electrocardiogram of the human body. Two electrode sheets are attached below the human clavicle, and another electrode sheet is attached to the left side of the human lower abdomen. The signal is connected to the ECG signal acquisition module ADS1292R. ADS1292R can draw an ECG electrocardiogram by collecting biopotentials; In this embodiment, the flexible strain film sensor is connected to ADS1292R as a medical electrode, and a 3-electrode ECG test method is used to measure the ECG electrocardiogram of the human body. Two electrode sheets are attached below the human clavicle, and another electrode sheet is attached to the left side of the human lower abdomen. The signal is connected to the ECG signal acquisition module ADS1292R. ADS1292R can draw an ECG electrocardiogram by collecting biopotentials; Some human electrocardiograms detected by commercially available medical electrodes are shown in Figure 2 , some human electrocardiograms detected by the flexible strain film sensor of this embodiment are shown in Figure 6 ,from Figure 2 and 6 It can be seen that when the flexible strain film sensor is used as a medical electrode to record the human electrocardiogram, it can achieve the detection accuracy of the current medical electrodes.
[0018] The specific implementation modes of the present invention are described in detail above, but the present invention is not limited to the above implementation modes, and various changes can be made within the knowledge scope of ordinary technicians in this field without departing from the purpose of the present invention.
Claims
1. A method for preparing a flexible strain film sensor, characterized in that: The specific steps are as follows: (1) adding single-walled carbon nanotubes (SWCNT) to ethanol, ultrasonically treating in an ice-water bath for 1 to 3 hours, and then mechanically stirring for 2 to 4 hours to uniformly disperse the single-walled carbon nanotubes in the ethanol to obtain a single-walled carbon nanotube dispersion; (2) Adding the fluorinated nonionic surfactant solution and the dimethyl sulfoxide solution to the poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) PEDOT:PSS aqueous solution and stirring to mix well, then adding the single-walled carbon nanotube dispersion, ultrasonically treating for 1 to 4 hours, and then adding polyethylene oxide PEO and stirring for 4 to 6 hours to obtain a PEDOT:PSS / SWCNT / PEO ternary composite solution; (3) The PEDOT:PSS / SWCNT / PEO ternary composite solution was uniformly coated on a polydimethylsiloxane (PDMS) flexible substrate and heat treated at a temperature of 100-130°C for 5-30 min to obtain a flexible strain film sensor.
2. The method for preparing the flexible strain film sensor according to claim 1, characterized in that: The concentration of the single-walled carbon nanotube dispersion in step (1) is 0.6-1 g / L.
3. The method for preparing the flexible strain film sensor according to claim 1, characterized in that: The concentration of the fluorine-containing nonionic surfactant solution in step (2) is 0.02-0.05 vol%, and the concentration of the dimethyl sulfoxide solution is 2-6 vol%.
4. The method for preparing the flexible strain film sensor according to claim 3, characterized in that: The volume ratio of the fluorinated nonionic surfactant solution, the dimethyl sulfoxide solution and the poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) PEDOT:PSS aqueous solution is 0.0002~0.0005:0.02~0.06:
1.
5. The method for preparing the flexible strain film sensor according to claim 1, characterized in that: The volume ratio of the single-walled carbon nanotube dispersion in step (2) to the poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate)PEDOT:PSS aqueous solution is 0.06-0.10:1, and the solid-liquid ratio g:mL of polyethylene oxide PEO to the poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate)PEDOT:PSS aqueous solution is 0.02-0.06:
1.
6. Use of the flexible strain film sensor prepared by the method according to any one of claims 1 to 5 as a medical electrode in recording a human electrocardiogram.