A magnetically controlled telescoping contact decortical implantable neuroelectrode device
An implantable neural electrode device that uses magnetically controlled telescopic contact to detach from the cerebral cortex utilizes magnetostrictive materials and elastic components to achieve controllable contact and detachment between the neural electrode and the cerebral cortex. This solves the problems of tissue damage and slippage associated with traditional electrodes and improves the detection quality and stability of EEG signals.
Patent Information
- Application Number
- CN202411981538.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-31
- Publication Date
- 2025-12-30
- Estimated Expiration
- 2044-12-31
AI Technical Summary
Existing implantable neural electrodes are prone to nerve tissue damage and mechanical strain when in long-term contact with the cerebral cortex. Furthermore, the sliding of traditional electrodes during patient movement is not conducive to stable recording of EEG signals. There is a lack of novel neural electrode structures for high-quality detection, as well as a lack of methods for precisely applying piezoelectric deformation to induce piezoelectric effects.
An implantable neural electrode device that uses magnetically controlled telescopic contact to detach from the cerebral cortex is fixed under the dura mater using magnetostrictive materials and elastic components. Through the magnetostrictive base, the electrode is driven by a magnetic field to deform and bend in contact with the cerebral cortex. After testing, the reverse magnetic field causes the electrode to retract and return to a planar state, avoiding long-term contact friction.
This method achieves effective contact between the neural electrodes and the cerebral cortex, improving the detection quality and stability of EEG signals. Simultaneously, the bent state induces piezoelectric deformation in the neural electrodes, ensuring effective contact with the cerebral cortex and avoiding tissue damage caused by long-term contact friction, thus further enhancing the detection quality and stability of EEG signals.
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Figure CN119867767B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of brain signal research technology, specifically relating to an implantable neural electrode device that is magnetically controlled to extend and retract from the cerebral cortex. Background Technology
[0002] Brain diseases have become one of the greatest challenges facing health in my country and globally, and implantable neural electrodes are a key fundamental tool for neuroscience research. For implantable neural electrodes, a high-quality contact interface between the electrode and neural tissue is a prerequisite for high-quality monitoring of neural electrical signals. Effective contact between flexible electrodes and the cerebral cortex helps obtain high-quality EEG signals. However, long-term contact / friction between flexible electrodes and the cerebral cortex can cause mechanical strain on the tissue, increasing the risk of neural tissue damage, chronic inflammation, and glial scarring. Traditional semi-invasive electrodes made of metal electrodes such as platinum and silicone rubber substrates often slide on the cortical surface during patient movement due to mechanical properties, hindering stable recording of EEG signals. Currently, there is a lack of novel neural electrode structures that can simultaneously achieve high-quality EEG signal detection with minimal damage to neural tissue during long-term implantation. Furthermore, while the sensing performance of neural sensors based on one-dimensional semiconductor nanowires can be significantly improved through piezoelectric effect modulation, there is currently no method to precisely apply piezoelectric deformation to implanted devices to induce the piezoelectric effect.
[0003] In 2019, Gao et al. proposed a magnetically actuated flexible microelectrode array for neural activity recordings (Nano Letters, 2019, 19(11): 8032-8039). In this work, a single probe electrode could be remotely driven by magnetism and connected to a biological system in vivo, enabling the recording of neural activity in the peripheral nerves and cerebral cortex of mice. In 2023, Liu et al. proposed an injectable electronic device based on magneto-actuated magneto-actu ... Summary of the Invention
[0004] This invention aims to address the shortcomings of existing technologies by proposing a magnetically controlled, stretchable, contact-detaching implantable neural electrode device. Based on the principle of magnetically deformable microrobots, magnetic particles are mixed with elastomers to construct a substrate for the neural electrode using a magnetically deformable material. The neural electrode structure is planar and can be fixed under the dura mater. Driven by a magnetic field, it deforms and arches, allowing the middle and top electrodes to effectively contact the cerebral cortex. The deformed state can be fixed by a polyimide film and rectangular grooves after the magnetic field is removed, preventing instability at the neural-electrode interface caused by magnetic field changes. After the EEG signal test is completed, a reverse magnetic field can be applied to bend the neural electrode in the opposite direction, causing the polyimide film to be pulled out of the rectangular grooves, and an elastic component to restore the neural electrode to its planar structure.
[0005] To achieve the above objectives, the present invention provides the following solution: an implantable neural electrode device for magnetically controlled telescopic contact detachment from the cerebral cortex, comprising: a flexible substrate, a magnetostrictive substrate, a magnetostrictive film, an elastic component, and electrodes;
[0006] The flexible substrate has several neatly arranged rectangular grooves on one side;
[0007] Two magnetostrictive films are respectively attached to both sides of the magnetostrictive substrate, and one of the magnetostrictive films is used to fix the magnetostrictive substrate in the rectangular groove of the flexible substrate;
[0008] The electrodes are fixed to the magnetostrictive substrate and are used to collect electroencephalogram (EEG) signals.
[0009] The elastic component is used to restore the magnetostrictive substrate to a planar state after traction deformation.
[0010] More preferably, the flexible substrate is made of PDMS material with a thickness of 0.6 mm.
[0011] More preferably, the magnetostrictive substrate is a polyimide film with a thickness of 0.025 mm.
[0012] More preferably, the method for fabricating the magnetostrictive thin film includes:
[0013] After mixing 400# neodymium iron boron magnetic particles with PDMS liquid at a mass ratio of 1:1, the mixture was poured into a mold and dried in a 60°C oven. A strong magnetic field of 1T was applied to magnetize the mixture, thus preparing the magnetodeformable film that was deformed by the magnetic field.
[0014] More preferably, the elastic component is cut into an S-shape using a laser cutting machine from a 0.5 mm thick polyimide film.
[0015] More preferably, the electrode is a magnetically controlled neural electrode or a magnetically controlled piezoelectric zinc oxide nanowire sensor.
[0016] More preferably, the driving method of the neural electrode device includes:
[0017] In the absence of a magnetic field, the neural electrode device is in a planar state. A magnetic field perpendicular to the plane is applied to the neural electrode device, and the magnetic field strength is gradually increased. As the magnetic field strength increases, the magnetostrictive substrate gradually bends, and the magnetostrictive film on one side of the rectangular groove is inserted into the rectangular groove of the flexible substrate at 60 mT. The magnetic field strength is further increased, and when the magnetic field strength reaches 120 mT, the magnetostrictive film is inserted into the rectangular groove on the right side of the flexible substrate.
[0018] When a reverse 120mT magnetic field is applied, the magnetostrictive substrate bends in the opposite direction, and the magnetostrictive film detaches from the rectangular groove of the flexible substrate; after the reverse magnetic field disappears, the neural electrode device returns to a planar state under the traction of the elastic component.
[0019] Compared with the prior art, the beneficial effects of the present invention are as follows:
[0020] This invention's device, fixed under the dura mater, can bend under magnetic field drive, achieving effective contact between the neural electrode and the cerebral cortex. Compared to traditional semi-invasive neural electrodes, this improves the detection quality and stability of EEG signals. Simultaneously, the bending state induces piezoelectric deformation, effectively enhancing the sensitivity of piezoelectric semiconductor nanowire-based neurobiosensors in detecting neurotransmitters and neural electrical signals. Applying a reverse magnetic field causes the neural electrode to detach from brain tissue and retract into the cerebral cortex, ensuring that the electrode only contacts the cortex when testing is required, avoiding prolonged contact and friction between the implanted flexible neural electrode and the cortex. This structure can induce a change in the state of the neural electrode through a brief application of a magnetic field, avoiding the negative effects of long-term strong magnetic field loading to maintain deformation. Attached Figure Description
[0021] To more clearly illustrate the technical solution of the present invention, the drawings used in the embodiments are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0022] Figure 1 This is a schematic diagram of the implantable neural electrode device according to an embodiment of the present invention;
[0023] Among them, (a) is a planar schematic diagram; (b) is a hierarchical structure schematic diagram; (c) is a schematic diagram of the fabricated magnetodeformable electrode; and (d) is a schematic diagram of the fabricated magnetodeformable zinc oxide nanowire neural biosensor.
[0024] Figure 2 This is a schematic diagram of the magnetization process according to an embodiment of the present invention;
[0025] Among them, (a) is a schematic diagram of the magnetization principle; (b) is a schematic diagram of the magnetostrictive film without a magnetic field; (c) is a schematic diagram of the bending of the magnetostrictive film when a magnetic field is applied; and (d) is a schematic diagram of the bending of the magnetostrictive film when a reverse magnetic field is applied.
[0026] Figure 3 This is a schematic diagram of the magnetically controlled neural electrode in different magnetic drive states according to an embodiment of the present invention;
[0027] Figure 4 This is a schematic diagram illustrating the magnetic drive of the magnetron-controlled piezoelectric zinc oxide nanowire sensor according to an embodiment of the present invention.
[0028] Among them, (a) is a schematic diagram of different magnetic drive states; (b) is a schematic diagram of the band structure changes of the zinc oxide nanowire sensor under compressive and tensile strains caused by magnetic fields in opposite directions; (c) is a schematic diagram of the IV curves of the zinc oxide nanowire sensor under different states; and (d) is a schematic diagram of the Schottky barrier changes of the zinc oxide nanowire sensor under different states.
[0029] Figure 5 This is a schematic diagram illustrating the controllable contact / detachment between the magnetically driven neural electrode and the cerebral cortex tissue in an embodiment of the present invention;
[0030] Figure 6 This is a schematic diagram illustrating the performance of the zinc oxide nanowire sensor in detecting dopamine according to an embodiment of the present invention.
[0031] Among them, (a) is a schematic diagram of the performance of zinc oxide nanowire sensor in detecting dopamine enhanced by piezoelectric effect; (b) is a schematic diagram of IV curve of zinc oxide nanowire sensor at initial dopamine concentration; (c) is a schematic diagram of IV curve of zinc oxide nanowire sensor at tensile strain of 0.24% dopamine concentration; and (d) is a schematic diagram of IV curve of zinc oxide nanowire sensor at tensile strain of 0.36% dopamine concentration.
[0032] Figure 7 This is a schematic diagram illustrating the performance of the zinc oxide nanowire sensor in detecting neural electrical signals according to an embodiment of the present invention.
[0033] Among them, (a) is a schematic diagram of the performance of zinc oxide nanowire sensor in detecting nerve electrical signals enhanced by piezoelectric effect; (b) is a schematic diagram of IV curve of zinc oxide nanowire sensor under different tensile strain; (c) is a schematic diagram of current response obtained by measuring nerve electrical pulses with zinc oxide nanowire sensor under different voltage pulse stimulation of bullfrog sciatic nerve (0.2V, 0.4V) and different tensile strain.
[0034] Figure 8 This is a schematic diagram illustrating the state transition of a magnetically controlled neural electrode / sensor driven by a magnet under the attenuation effect of 2cm thick pork, as described in an embodiment of the present invention. Detailed Implementation
[0035] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0036] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.
[0037] Example 1:
[0038] like Figure 1 The diagram shown is a schematic of an implantable neural electrode device for magnetically controlled telescopic contact detachment from the cerebral cortex proposed in this embodiment, including: a flexible substrate, a magnetostrictive substrate, a magnetostrictive film, an elastic component, and electrodes.
[0039] Specifically, the plan view of the neural electrode device is as follows: Figure 1 As shown in (a); Figure 1 (b) is a schematic diagram of the hierarchical structure, in which several neatly arranged rectangular grooves are provided on one side of the flexible substrate, which is made of PDMS material with a thickness of 0.6 mm. Electrodes are fixed on the magnetostrictive substrate for acquiring EEG signals; the magnetostrictive substrate is made of polyimide film with a thickness of 0.025 mm. Two magnetostrictive films are attached to the magnetostrictive substrate, each with a thickness of 0.5 mm; the magnetostrictive film on one side of the rectangular groove can be inserted into the rectangular groove to fix the magnetic field-induced deformation. The elastic component is cut into an S-shape from the 0.5 mm thick polyimide film using a laser cutter to pull the deformed magnetostrictive substrate back to a planar state. All parts are solidified by PDMS liquid. In this embodiment, the electrodes can be magnetically controlled neural electrodes or magnetically controlled piezoelectric zinc oxide nanowire sensors. Figure 1 (c) is a schematic diagram of the fabricated magnetostrictive electrode. Figure 1 (d) is a schematic diagram of the prepared magnetodeformable zinc oxide nanowire neurobiosensor.
[0040] In this embodiment, the method for fabricating the magnetostrictive thin film includes:
[0041] Based on the existing principle of magnetostrictive thin films, 400# neodymium iron boron magnetic particles were mixed with PDMS liquid in a 1:1 mass ratio, poured into a mold, and dried in a 60℃ oven. A strong magnetic field of 1T was then applied for magnetization to prepare a magnetostrictive thin film deformed by a magnetic field. The magnetization process and principle are as follows: Figure 2 As shown in (a); the magnetodeformable thin film without a magnetic field is as follows Figure 2 As shown in (b); the bending of the magnetized thin film under different directions and magnetic fields is as follows. Figure 2 (c) and Figure 2 As shown in (d).
[0042] Example 2:
[0043] In this embodiment, as Figure 3 As shown, the driving method of the neural electrode device includes:
[0044] Without a magnetic field, the neural electrode device is in a planar state (initial state, i.e., state ①). A magnetic field perpendicular to the plane is applied to the neural electrode device, and the magnetic field strength is gradually increased. As the magnetic field strength increases, the magnetostrictive substrate gradually bends. At 60 mT, the magnetostrictive film on one side of the rectangular groove inserts into the rectangular groove of the flexible substrate. At this point, the magnetostrictive substrate is in state ② – slightly bent. It is noteworthy that state ② can still be maintained after the magnetic field is removed. Continuing to increase the magnetic field strength, when it reaches 120 mT, the magnetostrictive film inserts into the right rectangular groove of the flexible substrate; at this point, the magnetostrictive substrate is in state ③ – significantly bent.
[0045] When it is necessary to switch to a planar state, a reverse magnetic field of 120mT can be applied to the neural electrode device in state ③, causing the magnetostrictive substrate to bend in the reverse direction to state ④, and the magnetostrictive film to detach from the rectangular groove of the flexible substrate; after the reverse magnetic field disappears, the magnetostrictive substrate returns to a planar state under the traction of the elastic component.
[0046] Among them, images of the magnetodeformable zinc oxide nanowire neurobiosensor under different magnetic drive states are shown below. Figure 4 As shown in (a). Figure 4(b) shows the band structure changes of the zinc oxide nanowire sensor under compressive and tensile strains induced by magnetic fields in opposite directions. The fabricated zinc oxide nanowire sensor is in top electrode mode, and the contact areas formed between the silver paste electrode and the two ends of the zinc oxide nanowire are marked with red dots. When compressive and tensile strains are applied, the piezoelectric potentials formed in the electrical contact areas are negative and positive, respectively, and the Schottky barriers at the two ends of the zinc oxide nanowire sensor increase and decrease, respectively. Therefore, compared to state ①, the magnetic field-induced tensile piezoelectric deformation gradually increases in states ② and ③. Figure 4 (c) indicates that the IV curve of the zinc oxide nanowire sensor shows an upward trend, according to Figure 4 (c) The calculated Schottky barrier at both ends gradually decreases, which realizes the effective control of the Schottky barrier and helps to improve its sensing performance.
[0047] Example 3:
[0048] This embodiment demonstrates the controllable contact / detachment of magnetically driven neural electrodes from the cerebral cortex through experiments.
[0049] A magnetically controlled neural electrode was fixed above the head of an SD rat. When the electrode was in a planar position, the metal electrode did not come into contact with the exposed cerebral cortex of the anesthetized rat. Figure 5 As shown in the upper left part of the diagram, only the noise signal is obtained, such as... Figure 5 As shown in the upper right illustration, when the magnetically controlled neural electrodes are temporarily driven into a bent state by an applied magnetic field, the metal electrodes make full contact with the exposed cerebral cortex, as... Figure 5 As shown in the lower left diagram, electrophysiological signals from the brain of anesthetized rats can be recorded using magnetically controlled neural electrodes, such as... Figure 5 The lower right part of the illustration is shown.
[0050] Example 4:
[0051] like Figure 6 As shown in (a), the piezoelectric effect induced by a magnetic field can enhance the sensitivity of a magnetically controlled piezoelectric zinc oxide nanowire sensor in detecting dopamine (DA) molecules. In the initial state, as... Figure 6 As shown in (b), the IV curves corresponding to 0M and 100nM almost overlap, while the IV curve corresponding to 10μM decreases to its limit, with the output current approaching zero in the range of -1V to 1V. From this IV curve, it can be seen that the lowest and highest DA concentrations detectable by the sensor are above 100nM and below 10μM, respectively. When the tensile strain increases from 0.00 to 0.24% and 0.36%, the IV curves corresponding to 0M and 100nM become separated, while the IV curve corresponding to 10μM still has room for further decrease. The results indicate that the detection range of DA is greater than 100nM to 10μM, and the detection range can be expanded through the piezoelectric effect, such as... Figure 6 (c) and Figure 6 As shown in (d).
[0052] Example 5:
[0053] like Figure 7 As shown in (a), the piezoelectric effect induced by a magnetic field enhances the performance of the piezoelectric zinc oxide nanowire sensor in detecting neural electrical signals. When the stimulation voltage is 0.2V, a strong contraction of the frog's peroneal muscle is observed, indicating the generation and flow of an action potential through the zinc oxide nanowire. However, in the absence of external strain and with a tensile strain of 0.124%, the zinc oxide nanowire biosensor fails to detect the weak characteristic signal of the action potential. When the tensile strain reaches 0.248%, the amplitude of the characteristic signal is approximately 0.08 nA, increasing to 0.35 nA with further increases in tensile strain. The piezoelectric effect induced by tensile strain improves the detection capability of the zinc oxide nanowire biosensor for weak neural electrical signals. Figure 7 (b) The IV curves of the zinc oxide nanowire sensor under different tensile strains; Figure 7 (c) The current response obtained by measuring the nerve electrical pulses using a zinc oxide nanowire sensor under different voltage pulses (0.2V, 0.4V) and different tensile strains on the bullfrog sciatic nerve.
[0054] Example 6:
[0055] Given that magnetically controlled neural electrodes / sensors are designed for high-sensitivity in vivo detection, remote or even transcranial control of implantable magnetically controlled neural electrodes / sensors via magnetic fields is of great significance. If the magnetically controlled neural electrodes / sensors are implanted under the human skull, the magnetic field needs to penetrate the scalp, skull, intracranial space, and arachnoid mater. It is known that magnetic fields are not attenuated or distorted by biological fluids and tissues; the key issue is the attenuation of the mid-frequency with distance. The thickness of the scalp and skull is between 2mm and 3mm, and 1cm and 1.5cm, respectively. In this work, the MCPD is switched between planar and curved states by a MF attenuated by a 2cm thick pigskin layer generated by a permanent magnet measuring 100mm*50mm*20mm. Figure 8 As shown, assuming a magnetically controlled neural electrode / sensor is implanted and attached to the dura mater and subarachnoid membrane, the distance between the arachnoid and pia mater in a human is approximately 0.5 cm. The stable bending state induced by the magnetic field of the magnetically controlled neural electrode / sensor can not only apply external strain to the piezoelectric biosensor, inducing the piezoelectric effect and improving sensing performance, but also achieve a high-quality biointerface between the neural electrode and brain tissue, enabling high-quality electrophysiological signal recording.
[0056] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made to the technical solutions of the present invention by those skilled in the art without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.
Claims
1. An implantable neural electrode device for contact decoupling of the cerebral cortex using magnetostrictive telescopic contact, characterized by, The application relates to a flexible substrate, a magnetostrictive substrate, a magnetostrictive film, an elastic component and an electrode. The flexible substrate is provided with a plurality of rectangular grooves arranged in an array on one side. Two pieces of the magnetostrictive film are respectively attached to the two sides of the magnetostrictive substrate, and the magnetostrictive film on one side is used for fixing the magnetostrictive substrate in the rectangular grooves of the flexible substrate. The electrode is fixed on the magnetostrictive substrate and used for collecting brain electrical signals. The elastic component is used for pulling the deformed magnetostrictive substrate to restore the planar state. The flexible substrate is made of PDMS material and has a thickness of 0.6 mm.
2. The implanted neural electrode device of claim 1, wherein the magnetic contact extension is configured to extend from the base to the brain cortex to contact the brain cortex. The magnetostrictive substrate is made of a polyimide film and has a thickness of 0.025 mm.
3. The implantable neural electrode device of claim 1, wherein the magnetic contact extension is configured to extend through the dura mater and the pia mater of the brain. The preparation method of the magnetostrictive film comprises the following steps:
4. The implantable neural electrode device of claim 1, wherein the magnetic contact extension is configured to extend through the dura mater and the pia mater of the brain. 400# neodymium iron boron magnetic particles are mixed with PDMS liquid in a mass ratio of 1:1, then the mixture is poured into a mold and placed in a 60 DEG C oven for drying, a 1T strong magnetic field is loaded for magnetization, and the magnetostrictive film driven by the magnetic field is prepared. The elastic component is made of a 0.5 mm-thick polyimide film cut into an S shape by a laser cutting machine.
5. The implantable neural electrode device of claim 1, wherein the magnetic contact extension is configured to extend through the dura mater and the pia mater of the brain. The electrode is a magnetic control neural electrode or a magnetic control piezoelectric zinc oxide nanowire sensor.
6. The implantable neural electrode device of claim 1, wherein the magnetic contact extension is configured to extend through the dura mater and the pia mater of the brain. The driving method of the neural electrode device comprises the following steps:
7. The implantable neural electrode device of claim 1, wherein the magnetic contact extension is configured to extend through the dura mater and the pia mater of the brain. Without the action of a magnetic field, the neural electrode device is in a planar state; a magnetic field perpendicular to the planar direction is applied to the neural electrode device, the magnetic field strength is gradually increased, the magnetostrictive substrate is gradually bent, the magnetostrictive film on one side of the rectangular groove is inserted into the rectangular groove of the flexible substrate at 60 mT; the magnetic field strength is continuously increased, and when the magnetic field strength reaches 120 mT, the magnetostrictive film is inserted into the right rectangular groove of the flexible substrate; A reverse 120 mT magnetic field is applied, the magnetostrictive substrate is reversely bent, and the magnetostrictive film is separated from the rectangular groove of the flexible substrate; after the reverse magnetic field disappears, the neural electrode device is pulled to the planar state by the elastic component.
Citation Information
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