Electrode with stimulation and recording functions and method for manufacturing the same
By forming a micro-nano structured platinum-iridium oxide coating on the electrode surface and combining it with a flexible substrate material, the problem of brain-computer interface electrodes being unable to simultaneously achieve high-resolution recording and efficient stimulation has been solved, thus improving the long-term stability and control precision of the electrodes.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- HEZE QIYUAN (BEIJING) TECH CO LTD
- Filing Date
- 2025-09-30
- Publication Date
- 2026-06-09
Smart Images
Figure CN121295283B_ABST
Abstract
Description
Technical Field
[0001] This disclosure relates to the field of electrode technology, specifically to an electrode with stimulation and recording functions and a method for preparing the same. Background Technology
[0002] In recent years, brain-computer interface (BCI) technology has shown great potential in the treatment of neurological diseases, functional rehabilitation, and brain science research. Stimulating electrodes and recording electrodes, as core components of BCI systems, respectively undertake the key functions of neural modulation and signal acquisition. Stimulating electrodes modulate neural activity through electrical pulses and are widely used in deep brain stimulation (DBS), closed-loop intervention for epilepsy, and sensory function recovery (such as cochlear and retinal implants), but their long-term stability and charge injection capabilities still face challenges. Recording electrodes are used for high-precision detection of neuronal spikes and local field potentials (LFP), providing data support for motion decoding and closed-loop control, but signal attenuation and biocompatibility issues limit their long-term reliability.
[0003] Traditional techniques employ metal electrodes, but the platinum black layer on these electrodes is prone to detachment, leading to performance degradation. In recent years, flexible materials and nanostructured coatings have been introduced to improve biocompatibility and electrochemical performance. However, existing technologies still struggle to simultaneously meet the demands for high-resolution recording and efficient, safe stimulation. Therefore, there is an urgent need to develop novel electrode structures to integrate high signal-to-noise ratio recording with high charge injection stimulation, while also improving long-term stability. Summary of the Invention
[0004] This disclosure provides an electrode with stimulation and recording functions and a method for preparing the same.
[0005] In a first aspect, this disclosure provides a method for preparing an electrode with stimulation and recording functions, comprising the following steps: preparing an electroplating solution: the electroplating solution contains chloroplatinic acid, iridium trichloride, nitric acid, potassium nitrate, sodium citrate, and deionized water; electrochemical deposition: placing a brain-computer interface electrode with conductive sites in the electroplating solution, using a constant current mode, first co-depositing platinum-iridium metal on the conductive sites, and then oxidizing it to form a platinum-iridium oxide coating with a micro-nano structure on the surface of the conductive sites; post-treatment: annealing the deposited brain-computer interface electrode in an air atmosphere.
[0006] In some optional embodiments, each 200 mL of the electroplating solution contains the following components: sodium citrate: 10-30 g; chloroplatinic acid: 0.2-0.6 g; iridium trichloride: 0.1-0.5 g; nitric acid: 5-15 mL; potassium nitrate: 5-20 g; hydrogen peroxide: 0.03-0.1 mL; the balance being deionized water; and the pH value of the electroplating solution is 1.5-2.0. If other volumes of electroplating solution need to be prepared, the above contents can be calculated proportionally.
[0007] In some optional embodiments, the steps of preparing the electroplating solution include: adding sodium citrate as a complexing agent to deionized water and stirring until completely dissolved; then adding chloroplatinic acid and iridium trichloride as metal salts and stirring until transparent; then adding nitric acid while stirring, and cooling to room temperature; then adding potassium nitrate as a supporting electrolyte and stirring until completely dissolved; then adding hydrogen peroxide as an oxidizing agent and stirring gently; finally, adding deionized water to confirm that the pH of the solution is 1.5-2.0; wherein, if the pH is too high, nitric acid is added.
[0008] In some alternative embodiments, the electrochemical deposition step is performed in an electrochemical device comprising a three-electrode system, the three-electrode system including: a working electrode, which is the brain-computer interface electrode; a counter electrode, which is a platinum sheet or platinum mesh; and a reference electrode, which is a silver / silver chloride electrode.
[0009] In some alternative embodiments, the electrochemical deposition step further includes, before placing the brain-computer interface electrode with conductive sites in the electroplating solution, performing plasma cleaning on the surface of the brain-computer interface electrode using an argon / oxygen mixed gas.
[0010] In some optional embodiments, the electrochemical deposition step includes: co-depositing platinum-iridium metal with a negative current in a constant current mode for 20-30 minutes; followed by oxidation with a positive current for 300-500 seconds; wherein the current density is 2 ± 0.1 mA / cm². 2 The temperature was 40±2℃, and stirring was maintained during the deposition process at a speed of 300±30 rpm.
[0011] In some optional embodiments, the post-processing steps include: first cleaning the deposited brain-computer interface electrode with deionized water and drying it with nitrogen; then annealing it in an air atmosphere at an annealing temperature of 350±20℃ for 55-65 min at a heating rate of 4.5-5.5℃ / min, so that the platinum-iridium oxide coating is transformed into a stable crystalline state.
[0012] In a second aspect, this disclosure provides an electrode with stimulation and recording functions, the electrode being prepared by the method described in the first aspect, the electrode comprising a flexible substrate, a gold-plated layer disposed on the flexible substrate, and an insulating layer disposed on the gold-plated layer, the gold-plated layer comprising conductive sites, the insulating layer having openings exposing the conductive sites, and a micro / nano-structured platinum-iridium oxide coating formed on the surface of the conductive sites.
[0013] In some alternative embodiments, the diameter of the conductive site is not less than 10 micrometers, and the thickness of the platinum-iridium oxide coating is not less than 1 micrometer.
[0014] In some optional embodiments, the charge storage capacity (CSC) of the platinum-iridium oxide coating is greater than or equal to 100 mC / cm². 2 The charge injection capacity (CIC) is greater than or equal to 6.3 mC / cm. 2 The impedance at 1000Hz is less than or equal to 19kΩ.
[0015] As mentioned above, to address the problems of insufficient long-term stability and difficulty in simultaneously achieving stimulation and recording functions in existing brain-computer interface electrode technologies, this disclosure proposes an electrode with both stimulation and recording functions and its fabrication method. The electrode fabricated by this method integrates high signal-to-noise ratio recording and high charge injection stimulation functions. Furthermore, through optimized material and interface structure design, it can effectively improve the long-term stability and control precision of brain-computer interface systems, promoting the clinical application of brain-computer interface technology.
[0016] The technical effects achieved by the disclosed technical solution include, but are not limited to:
[0017] ① Integration of stimulation and recording functions: Traditional electrodes often focus on a single function (stimulation only or recording only). This disclosure optimizes the electrode interface material and interface structure to form a platinum-iridium oxide coating with micro-nano structure, rough surface and high specific surface area on the surface of the conductive site. This enables the same electrode to achieve the dual functions of high signal-to-noise ratio neural signal acquisition and efficient and safe electrical stimulation. It can detect microvolt-level neural signals with high sensitivity and provide safe stimulation with high charge injection, meeting the real-time interaction requirements of closed-loop brain-computer interfaces.
[0018] ② Improved long-term stability: This disclosure uses a flexible substrate material with excellent biocompatibility (such as polyimide) combined with a corrosion-resistant conductive coating platinum-iridium oxide, which can reduce signal attenuation after long-term implantation and improve long-term stability.
[0019] ③ The electrode disclosed herein has a platinum-iridium oxide coating deposited on the surface of its conductive sites, which possesses high CSC (Charge Storage Capacity).
[0020] ④ The electrode disclosed herein has a platinum-iridium oxide coating deposited on the surface of its conductive sites, which has a high CIC (Charge Injection Capacity).
[0021] ⑤ The electrode of this disclosure has a low impedance due to the platinum-iridium oxide coating deposited on the surface of its conductive sites. Attached Figure Description
[0022] Other features, objects, and advantages of this disclosure will become more apparent from the following detailed description of non-limiting embodiments, taken with reference to the accompanying drawings. The drawings are for illustrative purposes only and are not intended to limit the scope of this disclosure. In the drawings:
[0023] Figure 1 This is a schematic flowchart of a method for preparing an electrode with stimulation and recording functions according to an embodiment of the present disclosure;
[0024] Figure 2 This is a schematic diagram of the structure of an electrochemical workstation according to an embodiment of the present disclosure;
[0025] Figure 3 This is a schematic diagram showing the effect of a brain-computer interface electrode and its conductive sites after electrochemical deposition according to an embodiment of the present disclosure.
[0026] Figure 4 This is a schematic diagram of the results observed by a scanning electron microscope (SEM) according to an embodiment of the present disclosure;
[0027] Figure 5 This is a schematic diagram of energy dispersive X-ray spectroscopy (EDS) scanning results according to an embodiment of the present disclosure;
[0028] Figure 6 This is a schematic diagram of calculating CSC using cyclic voltammetry (CV) according to an embodiment of this disclosure;
[0029] Figure 7 This is a schematic diagram of the impedance under the test electrode according to an embodiment of the present disclosure. Detailed Implementation
[0030] The present disclosure will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and not intended to limit it. Furthermore, it should be noted that, for ease of description, only the parts relevant to the invention are shown in the accompanying drawings.
[0031] It should be readily understood that the meanings of “on,” “above,” and “on top of” in this disclosure should be interpreted in the broadest sense, such that “on” means not only “directly on something,” but also “on something” including intermediate components or layers existing between the two.
[0032] Furthermore, for ease of description, spatial relative terms such as “below,” “under,” “lower,” “above,” and “upper” may be used herein to describe the relationship of one component or part to another component or part shown in the accompanying drawings. In addition to the orientations described in the figures, spatial relative terms are also intended to cover different orientations of the device during use or operation. The device may be oriented in other ways (rotated 90° or otherwise), and the spatial relative descriptive terms used herein may be interpreted accordingly.
[0033] It should be noted that the structures, proportions, sizes, etc., depicted in the accompanying drawings are only for illustrative purposes to aid those skilled in the art in understanding and reading the content described herein, and are not intended to limit the implementation conditions of this disclosure. Therefore, they have no substantial technical significance. Any modifications to the structure, changes in proportions, or adjustments to size, without affecting the effectiveness and purpose of this disclosure, should still fall within the scope of the technical content disclosed herein. Furthermore, terms such as "above," "first," "second," and "a" used in this specification are merely for clarity of description and are not intended to limit the scope of this disclosure. Changes or adjustments to their relative relationships, without substantially altering the technical content, should also be considered within the scope of this disclosure's implementation.
[0034] It should be noted that, unless otherwise specified, the embodiments and features described in this disclosure can be combined with each other. This disclosure will now be described in detail with reference to the accompanying drawings and embodiments.
[0035] refer to Figure 1 This disclosure provides a method for fabricating an electrode with both stimulation and recording functions. The method involves depositing a platinum-iridium oxide coating on the surface of a microelectrode, such as a brain-computer interface electrode, to obtain an electrode structure that simultaneously possesses stimulation and recording functions. Figure 1 As shown, the method disclosed herein includes the following steps.
[0036] Step 110: Prepare the electroplating solution.
[0037] In this step, the electroplating solution formulation may include: chloroplatinic acid (H₂PtCl₆), iridium trichloride (IrCl₃), nitric acid, potassium nitrate, hydrogen peroxide, sodium citrate, and deionized water. Sodium citrate is used as a complexing agent, chloroplatinic acid and iridium trichloride are metal salts, potassium nitrate is used as a supporting electrolyte, and hydrogen peroxide is used as an oxidizing agent. Here, hydrogen peroxide is an optional component.
[0038] Taking the preparation of 200ml of target electroplating solution as an example, the preparation steps may include:
[0039] Dissolving complexing agent: Take 100mL of deionized water, add 10-30g of sodium citrate, and stir until completely dissolved.
[0040] Add metal salts: Add 0.2-0.6g H2PtCl6 and 0.1-0.5g lrCl3 in sequence, and stir until transparent.
[0041] Adding nitric acid: Slowly add 5-15 mL of concentrated nitric acid while stirring (this releases heat, so it needs to be cooled to room temperature). The concentrated nitric acid here can be 65% concentrated nitric acid (where nitric acid accounts for 65% of the total mass).
[0042] Add supporting electrolyte: Add 5-20g KNO3 and stir until completely dissolved.
[0043] Add oxidant (optional): Add 0.03-0.1 mL (about 46 μL) of 30% H2O2 using a micropipette and stir gently.
[0044] Volume adjustment and pH adjustment: Add deionized water to a final volume of 200 mL, and use a pH meter to confirm that the solution pH is 1.5-2.0. If the pH is too high, add nitric acid; if the pH is too low, adjust it with dilute NaOH (sodium hydroxide).
[0045] Filtration and storage: Store in a brown glass bottle away from light.
[0046] Step 120: Electrochemical deposition.
[0047] The purpose of this step is to form a platinum-iridium oxide coating with a micro / nano structure on the surface of the brain-computer interface electrode, specifically on the surface of its conductive sites, through electrochemical deposition. Here, the diameter of the conductive sites on the brain-computer interface electrode can be greater than 10 micrometers; for example, conductive sites with a diameter of 20 micrometers can be used.
[0048] Prior to electrochemical deposition, a pretreatment step may be included, namely, plasma cleaning of the brain-computer interface electrode surface using an argon / oxygen (Ar / O2) gas mixture.
[0049] This electrochemical deposition step can be performed in an electrochemical device containing a three-electrode system, such as an electrochemical workstation. (Reference) Figure 2 An exemplary structure of the electrochemical workstation was described. The three-electrode system may include:
[0050] Working electrodes: These are brain-computer interface electrodes;
[0051] Counter electrode: It is a platinum sheet / platinum mesh;
[0052] Reference electrode: It is a silver / silver chloride (Ag / AgCl) electrode.
[0053] The process parameters for this electrochemical deposition are as follows:
[0054] Deposition mode: constant current electroplating.
[0055] Current density: 2 ± 0.1 mA / cm² 2 First, Pt-Ir metal co-deposition is performed (negative current deposition, time is 20-30 minutes), followed by oxidation (positive current oxidation, time is 300-500 seconds).
[0056] Temperature: 40±2℃ (water bath temperature control).
[0057] Stirring: Magnetic stirring (300±30 rpm). Stirring should be maintained throughout the deposition process.
[0058] Total time: 20-30 minutes, e.g., 30 minutes.
[0059] Objective: To deposit a platinum-iridium oxide coating (or thin film) with a thickness of 1 micrometer or more.
[0060] refer to Figure 3 (a) and (b) in the figure show schematic diagrams of the brain-computer interface electrodes and their conductive sites after electrochemical deposition.
[0061] Step 130: Post-processing.
[0062] Post-processing steps mainly include cleaning and heat treatment. These may include:
[0063] A. Cleaning: For example, rinse the deposited brain-computer interface electrodes three times with deionized water, and then dry them with nitrogen.
[0064] B. Heat treatment:
[0065] ① Conditions: Air atmosphere (or air environment), annealing at 350±20℃ for 1 hour (55-65min), heating rate 5±0.5℃ / min.
[0066] ②Objective: To generate PtO2-IrO2 (platinum oxide-iridium oxide) mixed oxide crystals, so that the platinum-iridium oxide coating is transformed into a stable crystalline state, thereby enhancing the bonding force.
[0067] The above provides a brief overview of the steps involved in preparing the electrode with stimulation and recording functions as disclosed in this disclosure.
[0068] The testing and characterization scheme will be further introduced below.
[0069] 1. Morphological and compositional analysis
[0070] Surface morphology: such as Figure 4 As shown, the results of the observation using scanning electron microscopy (SEM) show that the surface morphology of the coating (i.e., the platinum-iridium oxide coating) is rough, exhibiting a rough and porous micro-nano structure with a large specific surface area and no cracks.
[0071] Elemental analysis: such as Figure 5 As shown, surface scanning was performed using energy-dispersive X-ray spectroscopy (EDS). The scanning results confirmed that the coating contains platinum (Pt) and iridium (Ir) elements, with the Pt peak and Ir peak being similar and uniformly distributed.
[0072] Oxidation state analysis: X-ray photoelectron spectroscopy (XPS) analysis confirmed that the coating composition was platinum-iridium oxide.
[0073] 2. Electrochemical testing
[0074] Charge storage capacity (CSC): The CSC value of the platinum-iridium oxide coating, calculated using cyclic voltammetry (CV), is ≥100 mC / cm². 2 ,like Figure 6 As shown.
[0075] Impedance: The impedance was measured at 1000 Hz using an impedance analyzer (nano Z), an electrochemical workstation, or an Intan system, and the impedance under the electrode was ≤19 kΩ.
[0076] Charge injection capacity (CIC): Calculated using a stimulation system by measuring the limiting current that the thin film (platinum-iridium oxide coating) can withstand before irreversible side reactions occur. CIC ≥ 6.3 mC / cm² 2 .
[0077] Long-term stability testing: A comprehensive evaluation was conducted through in vivo implantation testing, long-term immersion in phosphate-buffered saline (PBS), and agar-simulated in vivo environment testing to determine whether the following standards were met: stability period ≥ 1 year, 20-micron conductive sites, and fatigue stimulation times of 100 microamp current > 800 million times.
[0078] One embodiment of this disclosure also provides an electrode (neuroelectrode) with stimulation and recording functions. The electrode is prepared by the method described in the above embodiments. The electrode includes a flexible substrate, a gold-plated layer disposed on the flexible substrate, and an insulating layer disposed on the gold-plated layer. The gold-plated layer includes conductive sites, and the insulating layer has openings that expose the conductive sites. A micro-nano structured platinum-iridium oxide coating is formed on the surface of the conductive sites.
[0079] Here, the materials of the flexible substrate and the insulation material may include, but are not limited to, polyimide (PI).
[0080] Here, the diameter of the conductive site can be no less than 10 micrometers, and the thickness of the platinum-iridium oxide coating can be no less than 1 micrometer.
[0081] Here, the charge storage capacity (CSC) of the platinum-iridium oxide coating can be greater than or equal to 100 mC / cm. 2 The charge injection capacity (CIC) can be greater than or equal to 6.3 mC / cm. 2 The impedance at 1000Hz can be less than or equal to 19kΩ.
[0082] The above description is merely a preferred embodiment of this disclosure and an explanation of the technical principles employed. Those skilled in the art should understand that the scope of this disclosure is not limited to technical solutions formed by specific combinations of the above-described technical features, but should also cover other technical solutions formed by arbitrary combinations of the above-described technical features or their equivalents without departing from the above-described concept. For example, technical solutions formed by substituting the above features with (but not limited to) technical features disclosed in this disclosure that have similar functions.
Claims
1. A method for preparing an electrode with stimulation and recording functions, characterized in that, Includes the following steps: Preparation of electroplating solution: The components of the electroplating solution per 200mL are as follows: sodium citrate: 10-30g; chloroplatinic acid: 0.2-0.6g; iridium trichloride: 0.1-0.5g; nitric acid: 5-15mL; potassium nitrate: 5-20g; Hydrogen peroxide: 0.03-0.1 mL; the remainder is deionized water; and the pH value of the electroplating solution is 1.5-2.0; Electrochemical deposition: The brain-computer interface electrode with conductive sites is placed in the electroplating solution. Using a constant current mode, platinum-iridium metal is first co-deposited on the conductive sites with a negative current for 20-30 minutes, and then oxidized with a positive current for 300-500 seconds, thereby forming a platinum-iridium oxide coating with a micro-nano structure on the surface of the conductive sites. The current density is 2±0.1 mA / cm², the temperature is 40±2℃, and stirring is maintained during the deposition process at a stirring speed of 300±30 rpm. Post-processing: The deposited brain-computer interface electrode is annealed in an air atmosphere at a temperature of 350±20℃ for 55-65 min at a heating rate of 4.5-5.5℃ / min, so that the platinum-iridium oxide coating is transformed into a stable crystalline state.
2. The method according to claim 1, characterized in that, The steps for preparing the electroplating solution include: Add sodium citrate as a complexing agent to deionized water and stir until completely dissolved; Then add chloroplatinic acid and iridium trichloride as metal salts, and stir until transparent; Then add nitric acid while stirring, and cool to room temperature; Then add potassium nitrate as a supporting electrolyte and stir until completely dissolved; Then, add hydrogen peroxide as an oxidizing agent and stir gently; Finally, add deionized water to confirm the solution pH is 1.5-2.0; if the pH is too high, add nitric acid.
3. The method according to claim 1, characterized in that, The electrochemical deposition step is performed in an electrochemical device comprising a three-electrode system, the three-electrode system including: The working electrode is the brain-computer interface electrode; The counter electrode is a platinum sheet or platinum mesh; The reference electrode is a silver / silver chloride electrode.
4. The method according to claim 1, characterized in that, The electrochemical deposition step further includes, before placing the brain-computer interface electrode with conductive sites in the electroplating solution, performing plasma cleaning on the surface of the brain-computer interface electrode using an argon / oxygen mixed gas.
5. The method according to claim 1, characterized in that, The post-processing steps include: before annealing, cleaning the deposited brain-computer interface electrode with deionized water and drying it with nitrogen gas.
6. An electrode with stimulation and recording functions, characterized in that, The electrode is prepared by the method described in any one of claims 1-5. The electrode includes a flexible substrate, a gold plating layer disposed on the flexible substrate, and an insulating layer disposed on the gold plating layer. The gold plating layer includes conductive sites, and the insulating layer has openings that expose the conductive sites. A micro-nano structured platinum-iridium oxide coating is formed on the surface of the conductive sites.
7. The electrode according to claim 6, characterized in that, The diameter of the conductive site is not less than 10 micrometers, and the thickness of the platinum-iridium oxide coating is not less than 1 micrometer.
8. The electrode according to claim 7, characterized in that, The platinum-iridium oxide coating has a charge storage capacity (CSC) greater than or equal to 100 mC / cm², a charge injection capacity (CIC) greater than or equal to 6.3 mC / cm², and an impedance of less than or equal to 19 kΩ at 1000 Hz.