CVD coating process of biocompatible nanodiamond composite diaphragm and application thereof

Abstract

This invention discloses a CVD deposition process for a biocompatible nanodiamond composite diaphragm, comprising the following steps: S1: surface activation and nucleation enhancement pretreatment of the substrate; S2: deposition of nanodiamond grains on the substrate surface using microwave plasma chemical vapor deposition in a reaction atmosphere containing carbon source gas and hydrogen; S3: monitoring deposition environment parameters and dynamically adjusting deposition temperature, gas pressure, and carbon source concentration to allow the nanodiamond grains to accumulate and form a porous diamond layer with controllable porosity; S4: in-situ introduction of biocompatible dopant elements during the growth of the porous diamond layer, followed by co-deposition to obtain a biocompatible nanodiamond composite diaphragm. The advantages of this invention compared to existing technologies are: providing a CVD deposition process for a biocompatible nanodiamond composite diaphragm that meets the requirements of biocompatibility, mechanical stability, and piezoelectric signal conversion performance for implantable devices, and its application.

Description

Technical Field

[0001] This invention relates to the field of diamond functional film preparation technology, specifically to a CVD coating process for a biocompatible nanodiamond composite diaphragm and its application. Background Technology

[0002] With the rapid development of implantable medical devices, the performance of the core functional diaphragm used for in vivo electrical signal acquisition, electrical stimulation modulation, ultrasound imaging and treatment directly determines the safety and effectiveness of the device.

[0003] Currently, commonly used diaphragm substrates are mostly medical titanium alloys, piezoelectric ceramics, and polymers. Among them, titanium alloys have excellent biocompatibility but insufficient piezoelectric conversion performance, piezoelectric ceramics have excellent piezoelectric performance but are prone to degradation and inflammatory reactions after long-term implantation, and polymer materials have low mechanical strength and short service life. None of them can simultaneously meet the multiple requirements of implantable devices for biosafety, mechanical stability, and piezoelectric conversion performance.

[0004] Nanodiamond materials possess extremely high mechanical strength, excellent chemical stability, and good biocompatibility. Furthermore, they can be endowed with stable piezoelectric response characteristics through elemental doping, making them an ideal substrate for implantable functional diaphragms.

[0005] However, the existing CVD preparation process for nanodiamond films is difficult to achieve precise control of film porosity, and cannot match the acoustic impedance and adhesion requirements of biological tissues.

[0006] Meanwhile, most doping processes involve late-stage ion implantation, which can easily cause damage to the thin film structure and poor doping uniformity, making it difficult to achieve both excellent biocompatibility and stable piezoelectric properties.

[0007] In addition, the bonding force between nanodiamonds and medical substrates is insufficient, and long-term implantation may lead to the risk of detachment, which cannot meet the requirements for long-term use of implantable medical devices. Summary of the Invention

[0008] The technical problem to be solved by the present invention is to overcome the above-mentioned technical defects and provide a CVD coating process for a biocompatible nanodiamond composite diaphragm that meets the requirements of biocompatibility, mechanical stability and piezoelectric signal conversion performance for implantable devices, as well as its application.

[0009] To solve the above-mentioned technical problems, the technical solution provided by the present invention is: a CVD coating process for a biocompatible nanodiamond composite diaphragm, comprising the following steps:

[0010] S1: Pretreatment of the substrate for surface activation and nucleation enhancement;

[0011] S2: Microwave plasma chemical vapor deposition is used to deposit nanodiamond grains on the substrate surface in a reaction atmosphere containing carbon source gas and hydrogen.

[0012] S3: Monitor deposition environment parameters and dynamically adjust deposition temperature, gas pressure and carbon source concentration to enable nanodiamond grains to accumulate and form a porous diamond layer with controllable porosity.

[0013] S4: Biocompatible dopant elements are introduced in situ during the growth of porous diamond layers, and biocompatible nanodiamond composite diaphragms are obtained through co-deposition.

[0014] Preferably, the substrate is a titanium alloy substrate, and the pretreatment is a bias-enhanced nucleation treatment.

[0015] Preferably, the carbon source gas is methane, and the flow ratio of hydrogen to carbon source gas in the reaction atmosphere is 50:1 to 200:1.

[0016] The deposition temperature is 600℃~900℃, and the deposition time is 2h~8h.

[0017] Preferably, the biocompatible doping element includes at least one of nitrogen, silicon, or boron, and its doping concentration is adjusted by regulating the flow rate of the doping source gas.

[0018] Preferably, the nanodiamond grains have a particle size of 5 nm to 100 nm, the porous diamond layer has a porosity of 15% to 45%, and a thickness of 0.5 μm to 10 μm.

[0019] Preferably, the surface roughness Ra of the biocompatible nanodiamond composite diaphragm is less than 50 nm, and the atomic percentage content of the biocompatible dopant element is 0.5% to 8%.

[0020] Another aspect of the present invention discloses a biocompatible nanodiamond composite diaphragm, comprising a substrate and a porous diamond layer and a biocompatible element doping layer sequentially formed on its surface, which realizes electrical signal transmission with biological tissue through the piezoelectric effect.

[0021] Preferably, the substrate is a medical titanium alloy substrate, and the thickness of the medical titanium alloy substrate is 20μm to 100μm.

[0022] Preferably, the composite diaphragm is an implantable ultrasound transducer diaphragm, a functional diaphragm for neurophysiological recording electrodes or electrical stimulation electrodes, and its operating resonant frequency is 1MHz to 20MHz.

[0023] The advantages of this invention compared to existing technologies are as follows: This invention effectively strengthens the film-substrate bonding force through substrate surface activation and nucleation enhancement pretreatment, solving the industry pain point of easy detachment of nanodiamond films after long-term implantation.

[0024] This invention achieves precise control of the porosity of porous diamond layers by dynamically adjusting the core parameters of the deposition process, effectively optimizing the acoustic impedance matching between the composite diaphragm and biological tissues, and significantly reducing signal transmission loss in vivo.

[0025] The process of this invention is highly controllable and has good batch repeatability. The resulting diaphragm has high surface flatness and excellent biocompatibility, and can be applied on a large scale to the preparation of various implantable medical devices. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the CVD coating process for a biocompatible nanodiamond composite diaphragm. Detailed Implementation

[0027] The present invention will now be described in further detail with reference to the accompanying drawings.

[0028] Combined with appendix Figure 1 As shown, a CVD coating process for a biocompatible nanodiamond composite diaphragm and the composite diaphragm prepared by the process are described.

[0029] In its specific implementation, this invention includes surface activation and nucleation enhancement pretreatment of a titanium alloy substrate. Bias-enhanced nucleation technology is used to effectively remove surface oxides and increase surface energy, providing an ideal foundation for subsequent diamond deposition. Subsequently, in a microwave plasma chemical vapor deposition system, using methane as the carbon source gas, a deposition process is carried out at 600℃ to 900℃ for 2 to 8 hours in a reaction atmosphere with a hydrogen to carbon source gas flow ratio of 50:1 to 200:1, allowing nanodiamond grains to grow uniformly on the substrate surface.

[0030] During the deposition process, key parameters such as deposition temperature, gas pressure and carbon source concentration are monitored and dynamically adjusted in real time to ensure that the nanodiamond grains are stacked in a gradient manner to form a porous diamond layer with a porosity of 15% to 45%. The thickness of this layer is controlled within the range of 0.5 μm to 10 μm, and the particle size of the nanodiamond grains is maintained in the range of 5 nm to 100 nm.

[0031] During the growth of porous diamond layers, biocompatible doping elements such as nitrogen, silicon, or boron are introduced in situ, and the doping concentration is adjusted by precisely controlling the flow rate of the doping source gas. This results in a surface roughness Ra of less than 50 nm for the final biocompatible nanodiamond composite diaphragm, and the atomic percentage content of the biocompatible doping elements is stabilized at 0.5%–8%.

[0032] The biocompatible nanodiamond composite diaphragm prepared by this invention consists of a medical titanium alloy substrate (thickness 20μm~100μm) and a porous diamond layer and a biocompatible element doping layer formed sequentially. It achieves efficient electrical signal transmission with biological tissue through the piezoelectric effect.

[0033] The composite diaphragm obtained by this invention is particularly suitable for biomedical applications such as implantable ultrasound transducer diaphragms, neurophysiological recording electrodes, or electrical stimulation electrodes. It has a working resonant frequency range of 1MHz to 20MHz, excellent biocompatibility, stable electrical properties, and good mechanical properties. It can significantly reduce electrode-tissue interface impedance and inhibit glial scar formation, providing an ideal functional material solution for biomedical implantable devices.

[0034] The contents not described in detail in this specification are existing technologies known to those skilled in the art.

[0035] The working principle of this invention: The composite diaphragm of this invention is prepared by CVD process, and nanodiamond grains are deposited after substrate pretreatment. Dynamic control of temperature, gas pressure, and carbon source concentration forms a gradient porous structure, promoting biocompatibility.

[0036] The key step involves in-situ doping with nitrogen, silicon, or boron to optimize cell affinity and electrical properties. The composite diaphragm consists of a porous diamond layer and a doped layer, utilizing the piezoelectric effect to conduct electrical signals. The porosity reduces interfacial impedance, and the doping elements inhibit tissue reactions. Suitable for implantable devices, it ensures biocompatibility and efficient signal transmission, combining mechanical strength with bioactivity.

[0037] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0038] The present invention and its embodiments have been described above. This description is not restrictive, and the accompanying drawings are only one embodiment of the present invention; the actual structure is not limited thereto. In conclusion, if those skilled in the art are inspired by this description and design similar structures and embodiments without departing from the spirit of the invention, such designs should fall within the protection scope of the present invention.

Claims

1. A CVD coating process for a biocompatible nanodiamond composite diaphragm, characterized in that: Includes the following steps: S1: Pretreatment of the substrate for surface activation and nucleation enhancement; S2: Microwave plasma chemical vapor deposition is used to deposit nanodiamond grains on the substrate surface in a reaction atmosphere containing carbon source gas and hydrogen. S3: Monitor deposition environment parameters and dynamically adjust deposition temperature, gas pressure and carbon source concentration to enable nanodiamond grains to accumulate and form a porous diamond layer with controllable porosity. S4: Biocompatible dopant elements are introduced in situ during the growth of porous diamond layers, and biocompatible nanodiamond composite diaphragms are obtained through co-deposition.

2. The CVD coating process for a biocompatible nanodiamond composite diaphragm according to claim 1, characterized in that: The substrate is a titanium alloy substrate, and the pretreatment is a bias-enhanced nucleation treatment.

3. The CVD coating process for a biocompatible nanodiamond composite diaphragm according to claim 1, characterized in that: The carbon source gas is methane, and the flow ratio of hydrogen to carbon source gas in the reaction atmosphere is 50:1 to 200:

1. The deposition temperature is 600℃~900℃, and the deposition time is 2h~8h.

4. The CVD coating process for a biocompatible nanodiamond composite diaphragm according to claim 1, characterized in that: The biocompatible doping element includes at least one of nitrogen, silicon, or boron, and its doping concentration is adjusted by regulating the flow rate of the doping source gas.

5. The CVD coating process for a biocompatible nanodiamond composite diaphragm according to claim 1, characterized in that: The nanodiamond grains have a particle size of 5nm to 100nm, the porous diamond layer has a porosity of 15% to 45%, and a thickness of 0.5μm to 10μm.

6. The CVD coating process for a biocompatible nanodiamond composite diaphragm according to claim 1, characterized in that: The surface roughness Ra of the biocompatible nanodiamond composite diaphragm is less than 50 nm, and the atomic percentage content of the biocompatible dopant element is 0.5% to 8%.

7. A biocompatible nanodiamond composite diaphragm, prepared by the process described in any one of claims 1-6, characterized in that: It includes a substrate and a porous diamond layer and a biocompatible element doping layer formed sequentially on its surface, which achieves electrical signal transmission with biological tissue through the piezoelectric effect.

8. The biocompatible nanodiamond composite diaphragm according to claim 7, characterized in that: The substrate is a medical titanium alloy substrate with a thickness of 20μm to 100μm.

9. The biocompatible nanodiamond composite diaphragm according to claim 7, characterized in that: The composite diaphragm is an implantable ultrasound transducer diaphragm, a functional diaphragm for neurophysiological recording electrodes or electrical stimulation electrodes, and its working resonant frequency is 1MHz to 20MHz.

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