Flexible PEDOT: PSS microneedle collecting electrode deformed under driving of body temperature
The flexible PEDOT:PSS microneedle electrode, which is driven to deform by body temperature, solves the problems of insufficient mechanical adaptability and interface electrical properties of traditional electrodes, realizes low-impedance, minimally invasive bioelectric signal acquisition, simplifies operation and reduces costs.
Patent Information
- Application Number
- CN202511011346.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-07-22
- Publication Date
- 2025-09-16
AI Technical Summary
Existing bioelectric signal collection electrodes have problems such as mechanical adaptability defects, insufficient interface electrical performance, and complicated driving mechanisms. Traditional rigid microneedles are prone to induce inflammatory reactions, precious metal electrodes have high impedance and low signal-to-noise ratio in the low frequency band, conductive polymers have poor cyclic stability, and deformable electrodes rely on external stimulation and are complex to operate.
The flexible PEDOT:PSS microneedle electrode, which is driven by body temperature to deform, includes a shape memory polymer base layer, a PEDOT:PSS conductive layer and a wire. The deformation of the microneedle is achieved through the temperature responsiveness of the shape memory polymer, combined with the low impedance conductivity of PEDOT:PSS, to achieve minimally invasive collection without external drive.
It achieves a low-impedance interface and minimally invasive penetration, reduces tissue damage and noise, improves the signal-to-noise ratio, simplifies operation, reduces material costs, and is suitable for large-scale manufacturing.
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Figure CN120643233A_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the technical field of biomedical devices, and specifically relates to a flexible PEDOT:PSS microneedle collection electrode that is deformed by body temperature. The device is used to be placed outside a living body or implanted inside a living body to collect bioelectric signals. Background Art
[0002] Electrodes for collecting bioelectrical signals have always attracted widespread attention. Currently, electrophysiological signal collection technology faces three technical bottlenecks: mechanical compatibility defects, insufficient interface electrical performance, and complex driving mechanisms. Traditional rigid microneedle electrodes, such as those made of silicon or stainless steel, are prone to triggering local inflammatory reactions when puncturing tissue. Clinical data show that when the puncture depth exceeds 100 μm, the concentration of TNF-α, a tissue damage marker, increases by 3.2 times. Although flexible planar electrodes have emerged, they have difficulty penetrating the epidermal barrier, resulting in a signal attenuation rate of up to 40%. Precious metal electrodes such as gold and platinum materials have a significant increase in impedance at low frequencies below 100 Hz, resulting in a low signal-to-noise ratio of the collected bioelectrical signals. Although conductive polymers such as polypyrrole developed in recent years can reduce impedance, their cyclic stability is poor. After 200 bends, the conductivity decays by 62%. Furthermore, existing deformable electrodes rely heavily on external stimuli. For example, magnetic actuation requires a strong magnetic field of 300mT or higher, approaching the human body's safety limit. Electrothermal actuation requires an external power source, and a local temperature rise exceeding 45°C can cause protein denaturation. Electrodes using shape memory alloys require a recovery temperature of over 80°C, far exceeding the body's temperature threshold. Therefore, there is an urgent need to develop a new electrode that can utilize the body's own temperature to trigger deformation, while also possessing a low-impedance interface and minimally invasive penetration capabilities. Summary of the Invention
[0003] The purpose of the present invention is to provide a flexible PEDOT:PSS microneedle collection electrode that can be deformed by body temperature to solve the problems of existing bioelectric signal collection electrodes, such as: traditional rigid microneedle electrodes are prone to induce inflammatory reactions when puncturing tissues; noble metal electrodes have high impedance and low signal-to-noise ratio in the low frequency band, and the conductive polymer has poor cyclic stability; deformable electrodes rely on external stimulation, are complex to operate, and have low biosafety.
[0004] To achieve the above object, the present invention adopts the following technical solutions:
[0005] A flexible PEDOT:PSS microneedle electrode with body temperature-driven deformation, comprising a shape memory polymer substrate layer, a PEDOT:PSS conductive layer, and a conductor;
[0006] The shape memory polymer substrate layer includes a carrier plate, the carrier plate is provided with a through hole and a plurality of microneedle structures, the plurality of microneedle structures are arranged in an array of m rows x n columns, and the plurality of microneedle structures and the carrier plate are integrally formed of the shape memory polymer;
[0007] The PEDOT:PSS conductive layer is conformally disposed on the shape memory polymer base layer and is closely adhered to the shape memory polymer base layer;
[0008] The wires are connected via the through holes to form a tight electrical connection with the PEDOT:PSS conductive layer.
[0009] Furthermore, the shape memory polymer layer material is a mixture of epoxy resin and polyetheramine in a mass ratio of 1:1-1:1.3.
[0010] Furthermore, the microneedle structure is a conical microneedle structure with a height of 80 μm-1.5 mm and a needle tip curvature radius of ≤20 μm.
[0011] Furthermore, the shape memory polymer base layer is prepared by a mold method.
[0012] Furthermore, the preparation process of the PEDOT:PSS conductive layer is as follows:
[0013] The raw materials are a PEDOT:PSS aqueous dispersion modified with 10% w / w dimethyl sulfoxide and 5% w / w isopropyl alcohol, with 0.5% w / w Tween 20 added as a surfactant and 1% w / w (3-glycidyloxy)propyltrimethoxysilane added as a crosslinker.
[0014] The raw materials are coated on the surface of the microneedles and the non-needle area of the substrate by spin coating or drop coating; the coating is formed into a dense film by constant temperature heating treatment, and the film thickness is controlled at 0.8-2μm.
[0015] Shape memory polymers have the property that their elastic modulus decreases significantly as the temperature rises. Based on this property, the present invention uses shape memory polymers to prepare a carrier plate and multiple microneedle structures, and the carrier plate and multiple microneedle structures are integrally formed, which makes the entire microneedle electrode have a higher modulus when it is at room temperature before use, and can effectively penetrate the stratum corneum of the skin, reducing the interface impedance between the skin and the electrode. Afterwards, the temperature of the entire microneedle electrode is driven by body temperature to rise, causing the elastic modulus of the entire microneedle electrode to decrease, thereby achieving the effect of conformal fitting with the skin, reducing the noise generated by the mismatch between the electrode and the skin, and improving the signal-to-noise ratio of the signal. The PEDOT:PSS conductive layer has excellent conductive properties and can construct a low-impedance conductive path between the needle tip and the skin, thereby collecting changes in bioelectric signals, and then transmitting the collected bioelectric signal changes to an external device through a wire to achieve conduction and recording, ultimately forming a flexible electrophysiological acquisition system that does not require external drive, is minimally invasive, efficient, and biocompatible.
[0016] After adopting the above technical solution, the present invention has the following beneficial effects compared with the prior art:
[0017] (1) The present invention uses a shape memory polymer with a glass transition temperature close to the human body temperature range to prepare an electrode. First, it can directly respond to human body temperature and trigger deformation without the need for external energy, avoiding local temperature rise, ensuring biosafety, simplifying the system structure, and improving portability and wearability. Second, the deformed microneedle structure after use can be restored to a flat state by heating it to above 60°C, thereby achieving the function of reuse.
[0018] (2) The present invention adopts a conical microneedle structure with a height of 80μm-1.5mm and a needle tip curvature radius of ≤20μm, which can reduce tissue damage. At the same time, body temperature drives the bending to fit the complex tissue curvature, thereby improving signal acquisition efficiency.
[0019] (3) The flexible PEDOT:PSS microneedle electrode of the present invention is prepared by combining a mold method and a spin coating process, which simplifies the production process, reduces material costs, is suitable for large-scale manufacturing, and has the advantages of simple process and low cost. BRIEF DESCRIPTION OF THE DRAWINGS
[0020] Figure 1 Schematic diagram of the flexible PEDOT:PSS microneedle electrode of Example 1;
[0021] Figure 2 Flow chart of the preparation of the flexible PEDOT:PSS microneedle electrode of Example 1;
[0022] Figure 3 This is a magnified image of the microneedle array in the flexible PEDOT:PSS microneedle electrode of Example 1 using a high-depth-of-field microscope;
[0023] Figure 4 Figure 1 shows the shape memory test of the flexible PEDOT:PSS microneedle electrode of Example 1 in Experiment 1, where a is a scanning electron microscope image of the shape memory process of the local microneedle array, and b is an image of the electrode shape memory process at a normal scale;
[0024] Figure 5 In Experiment 1, the deformation of the elastic modulus of the flexible PEDOT:PSS microneedle electrode of Example 1 at different temperatures was tested;
[0025] Figure 6 In Experiment 1, the flexible PEDOT:PSS microneedle electrode of Example 1 was tested for its 5 Impedance data plot in Hz frequency range;
[0026] Figure 7 This is the electrocardiogram signal image collected during the actual application test of the flexible PEDOT:PSS microneedle electrode of Example 1 in Experiment 1. DETAILED DESCRIPTION
[0027] The present invention will be described in detail below with reference to the accompanying drawings and embodiments.
[0028] like Figure 1 As shown, this embodiment provides a body temperature-driven flexible PEDOT:PSS microneedle electrode, comprising a shape memory polymer substrate layer, a microneedle array layer, a PEDOT:PSS conductive layer, and conductive through-holes. The shape memory polymer substrate layer and the microneedle array layer are integrally formed and tightly bonded to the PEDOT:PSS conductive layer.
[0029] like Figure 1 As shown, this embodiment provides a body temperature-driven deformation-resistant flexible PEDOT:PSS microneedle electrode, comprising a shape memory polymer substrate, a PEDOT:PSS conductive layer, and a conductive wire. The shape memory polymer substrate comprises a carrier plate having a through-hole extending therethrough and a plurality of microneedle structures arranged in an array of m rows by n columns, and the plurality of microneedle structures and the carrier plate are integrally formed from a shape memory polymer. The PEDOT:PSS conductive layer is conformally disposed on the shape memory polymer substrate and is tightly bonded to the shape memory polymer substrate. The conductive wire is connected to the PEDOT:PSS conductive layer via the through-hole, forming a tight electrical connection.
[0030] In this embodiment, the shape memory polymer base layer is made of a mixture of epoxy resin and polyetheramine in a mass ratio of 1:1-1:1.3. The higher the quality of the epoxy resin, the higher the initial elastic modulus of the shape memory polymer. Therefore, during implementation, the corresponding mass ratio is selected according to the needs. In terms of process, it is prepared by a mold method, that is, after pouring the epoxy resin and polyetheramine mixture into a pre-prepared mold, it is first cured by constant temperature heating, and then demolded to form the shape memory polymer base layer. The raw material of the PEDOT:PSS conductive layer is a PEDOT:PSS aqueous dispersion modified with 10% w / w dimethyl sulfoxide and 5% w / w isopropyl alcohol, with 0.5% w / w Tween 20 added as a surfactant and 1% w / w (3-glycidyloxy)propyltrimethoxysilane added as a crosslinker. The raw material is coated on the surface of the microneedles and the non-needle area of the substrate by spin coating or drop coating. The coating is then heated at a constant temperature to form a dense film with a film thickness controlled to be 0.8-2 μm.
[0031] During use, since the carrier and microneedle structure in the shape memory polymer base layer have the characteristic that the elastic modulus decreases with increasing temperature, the microneedle electrode at room temperature before use has a higher modulus, which can effectively penetrate the stratum corneum of the skin and reduce the interface impedance between the skin and the electrode. During use, the temperature of the microneedle electrode rises due to body temperature, which causes the elastic modulus of the microneedle electrode to decrease, thereby achieving the effect of conformal fit with the skin, reducing the noise generated by the mismatch between the electrode and the skin, and improving the signal-to-noise ratio. The PEDOT:PSS conductive layer has excellent conductive properties, and a low-impedance conductive path is constructed between the needle tip and the skin to collect changes in bioelectric signals and transmit them to external equipment through wires to achieve signal conduction and recording. The preparation process of the above-mentioned body temperature-driven deformation flexible PEDOT:PSS microneedle electrode is as follows: Figure 2 As shown, the following steps are included:
[0032] Step 1, preparing a shape memory polymer: mixing epoxy resin and polyetheramine in a mass ratio of 1:1, placing the mixture in a 60° C. water bath and stirring for 10 minutes to obtain a shape memory polymer liquid;
[0033] Step 2: pouring the shape memory polymer liquid into a pre-prepared mold having multiple microneedle structures;
[0034] Step 3, placing the microneedle mold obtained in step 2 in a vacuum environment for degassing;
[0035] Step 4: After the degassing process is completed, the mold is placed in a constant temperature environment of 100°C and heated for 1 hour. Then the temperature is raised to 130°C and heated for another hour to complete the curing before being taken out.
[0036] Step 5: After the temperature drops to room temperature, the solidified shape memory polymer is demolded to obtain a shape memory polymer base layer;
[0037] Step 6: Drill a through hole at any position in the non-microneedle structure area of the shape memory polymer substrate layer, connect a wire, and then spin-coat the prepared PEDOT:PSS conductive solution;
[0038] Step 7: After the spin coating is completed, the layer is dried at 60° C. to form a PEDOT:PSS conductive layer conforming to the shape memory polymer base layer on the shape memory polymer layer and the microneedle array layer.
[0039] Figure 3 This is a high-depth-of-field microscope magnified image of the microneedle structure array in the flexible PEDOT:PSS microneedle electrode of Example 1; Figure 3 It can be seen that the microneedle structure array in the flexible PEDOT:PSS microneedle electrode of this embodiment is regularly distributed and has a regular and intact morphology.
[0040] To better illustrate the effect of the body temperature-driven deformation of the flexible PEDOT:PSS microneedle electrode in this embodiment, we conducted experiments 1 and 2. Experiment 1 was used to verify the shape memory effect of the flexible PEDOT:PSS microneedle electrode in Example 1. Experiment 2 was used to verify the temperature-dependent change in the elastic modulus of the flexible PEDOT:PSS microneedle electrode in Example 1.
[0041] Experiment 1: The shape memory effect of the carrier plate and the microneedle structure array in the shape memory polymer base layer of Example 1 was tested as follows:
[0042] like Figure 4 As shown in Figure a, a scanning electron microscope was used to photograph the microneedle array. The photography was divided into three stages. First, in the initial state, the microneedle structure of the array was normal and evenly distributed. After use, the microneedle structure was deformed, bending and falling over. Finally, by heating at 60°C for 20 seconds, a shape memory effect was generated and the microneedle structure of the array was restored to its initial state. Figure 4 As shown in Figure b, a standard camera was used to photograph the carrier and microneedle structure within the shape memory polymer substrate. The photography was divided into three stages. First, in its initial state, the shape memory polymer substrate structure was normal, showing no deformation. After use, the shape memory polymer substrate deformed, producing a bend. Finally, by heating at 60°C for 20 seconds, a shape memory effect was generated, and the substrate returned to its initial state. The structure of the shape memory polymer substrate was normal, returning to its original form. In this experiment, the electrode exhibited a shape memory effect, capable of rapidly returning to its preset shape by increasing the temperature.
[0043] Experiment 2: Testing the material properties of the flexible PEDOT:PSS microneedle electrode in Example 1, mainly testing the deformation of the elastic modulus at different temperatures; and 1-10 5 Impedance test in the Hz frequency range is as follows:
[0044] Under heating conditions of 20℃-100℃, the stress and strain of the electrode are tested by stretching within the elastic deformation range, and the elastic modulus value under the temperature condition is calculated, such as Figure 5 As shown, it can be seen that at room temperature, the electrode has a high elastic modulus, which facilitates the microneedle to penetrate the skin. As the temperature rises, the electrode elastic modulus decreases, thereby achieving a conformal fit with the skin. The electrode was connected to the electrochemical workstation and the electrodes with epoxy resin and polyetheramine mass ratios of 1:1, 1:1.1, 1:1.2, and 1:1.3 were tested respectively. Commercial silver chloride electrodes and copper electrodes were used as comparisons. 5 The impedance in the Hz frequency range is as follows Figure 6As shown in the figure, as the proportion of polyetheramine increases, the initial elastic modulus of the electrode decreases, so it can fit more perfectly with the skin, and the impedance tends to decrease accordingly. The performance is better than that of common silver chloride electrodes and copper electrodes.
[0045] Experiment 3: The electrode of Example 1 was subjected to practical application testing, as follows:
[0046] Three electrodes are placed on the two wrists and one ankle of the human body, and then connected to an external amplifier through wires to record the human body's electrocardiogram signals, such as Figure 7 As shown in the figure, we can see that the collected ECG signal is clear and accurate with high quality. The P, Q, R, S, and T intervals are clear and correct.
[0047] The above is only a specific embodiment of the present invention for collecting EEG signals. For the collection of other electrophysiological signals, adjustments can be made according to specific circumstances. Unless otherwise specified, any feature disclosed in this specification can be replaced by other equivalent or similar features. All features disclosed, or all steps in the methods or processes, except for mutually exclusive features and / or steps, can be combined in any way.
Claims
1. A flexible PEDOT:PSS microneedle electrode with body temperature-driven deformation, comprising a shape memory polymer substrate, a PEDOT:PSS conductive layer, and a conductive wire, characterized in that: The shape memory polymer substrate layer includes a carrier plate, the carrier plate is provided with a through hole and a plurality of microneedle structures, the plurality of microneedle structures are arranged in an array of m rows x n columns, and the plurality of microneedle structures and the carrier plate are integrally formed of the shape memory polymer; The PEDOT:PSS conductive layer is conformally disposed on the shape memory polymer base layer and is closely adhered to the shape memory polymer base layer; The wires are connected via the through holes to form a tight electrical connection with the PEDOT:PSS conductive layer.
2. The body temperature-driven deformation-promoting flexible PEDOT:PSS microneedle electrode according to claim 1, characterized in that: The shape memory polymer layer material is a mixture of epoxy resin and polyetheramine in a mass ratio of 1:1-1:1.
3.
3. The body temperature-driven deformation-promoting flexible PEDOT:PSS microneedle electrode according to claim 1, characterized in that: The microneedle structure is a conical microneedle structure with a height of 80 μm-1.5 mm and a needle tip curvature radius of ≤20 μm.
4. The body temperature-driven deformation-promoting flexible PEDOT:PSS microneedle electrode according to claim 1, characterized in that: The shape memory polymer base layer is prepared by a mold method.
5. The body temperature-driven deformation-prone flexible PEDOT:PSS microneedle electrode according to any one of claims 1 to 4, characterized in that: The preparation process of the PEDOT:PSS conductive layer is as follows: The raw materials are a PEDOT:PSS aqueous dispersion modified with 10% w / w dimethyl sulfoxide and 5% w / w isopropyl alcohol, with 0.5% w / w Tween 20 added as a surfactant and 1% w / w (3-glycidyloxy)propyltrimethoxysilane added as a crosslinker. The raw materials are coated on the surface of the microneedles and the non-needle area of the substrate by spin coating or drop coating; the coating is formed into a dense film by constant temperature heating treatment, and the film thickness is controlled at 0.8-2μm.