BIOCOMPATIBLE CARBON NANOLAYERS FOR COATING LENSES
At a Glance
Section titled âAt a Glanceâ| Metadata | Details |
|---|---|
| Publication Date | 2022-06-30 |
| Journal | LĂ©kaĆ a technika - Clinician and Technology |
| Authors | Petr PĂsaĆĂk |
| Institutions | Czech Technical University in Prague |
| Citations | 1 |
| Analysis | Full AI Review Included |
Technical Documentation & Analysis: Biocompatible Carbon Nanolayers for Coating Lenses
Section titled âTechnical Documentation & Analysis: Biocompatible Carbon Nanolayers for Coating LensesâThis document analyzes the research paper âBIOCOMPATIBLE CARBON NANOLAYERS FOR COATING LENSES,â focusing on the application of diamond-like carbon (DLC) in ophthalmic optics. The analysis highlights the critical role of diamond materials in achieving superior wear resistance and biocompatibility, directly connecting the research requirements to 6CCVDâs advanced MPCVD Single Crystal Diamond (SCD) and Polycrystalline Diamond (PCD) capabilities.
Executive Summary
Section titled âExecutive Summaryâ- Application Focus: The study validates the use of DLC nanolayers for enhancing the durability and biocompatibility of ophthalmic lenses, including spectacle, contact, and intraocular lenses (IOLs).
- Superior Wear Resistance: DLC coatings demonstrated tribological performance equal to or better than leading commercial surface modifications (e.g., HMC, SHMC).
- Exceptional Hardness: The optimized DLC-3 layer (40 nm thickness) remained completely undamaged after tribological testing (1 N load, 10 m path), while the Chromium steel testing ball showed visible damage, confirming the extreme hardness of the carbon layer.
- Low Friction Coefficient: The DLC-3 layer achieved the lowest final friction coefficient (0.099), attributed to the formation of a graphitic slip layer during friction.
- Methodology: DLC films were prepared using Pulsed Laser Deposition (PLD) from a high-purity graphite target, with optimal results achieved at an energy density of 10 J·cm-2.
- Key Trade-off: The primary drawback noted was a 15% reduction in visible light transmittance compared to uncoated lenses, a factor directly linked to the control of sp3 bond content in the carbon layer.
Technical Specifications
Section titled âTechnical SpecificationsâThe following table summarizes the critical parameters and performance metrics extracted from the study, focusing on the optimal DLC-3 sample.
| Parameter | Value | Unit | Context |
|---|---|---|---|
| Substrate Material | CR39 | - | Spectacle lenses (Polymer) |
| Deposition Method | PLD | - | Pulsed Laser Deposition |
| Laser Wavelength | 248 | nm | KrF Excimer Laser |
| Laser Pulse Duration | 20 | ns | KrF Excimer Laser |
| Optimal Energy Density (DLC-3) | 10 | J·cm-2 | Highest stability and transmittance |
| Optimal Layer Thickness (DLC-3) | 40 | nm | Undamaged layer after testing |
| Base Vacuum | 5Ă10-4 | Pa | Coating system environment |
| Ambient Pressure | 0.25 | Pa | Argon gas |
| Tribology Test Load | 1 | N | Pin-on-Disk (Dry conditions) |
| Testing Ball Material | Chromium Steel (Ac 100 Cr6) | - | 6 mm diameter |
| Final Friction Coefficient (DLC-3) | 0.099 (0.100) | - | Lowest value observed, layer intact |
| Transmittance Reduction | 15 | % | Lower than commercial lenses (at 570 nm) |
| Highest UV Cut-off Wavelength | 422.0 | nm | Observed in specialized commercial lens (UV+420 BlueCut 1.5 SHMC) |
Key Methodologies
Section titled âKey MethodologiesâThe DLC films were prepared using Pulsed Laser Deposition (PLD) to achieve the desired nanolayer structure on CR39 substrates.
- Substrate Cleaning: CR39 spectacle lenses were cleaned ultrasonically in ethanol and dried in air.
- Vacuum Setup: Substrates were placed in a chamber achieving a high base vacuum (5Ă10-4 Pa).
- Target & Laser Source: A high-purity graphite target was ablated using a KrF excimer laser (λ = 248 nm, Ï = 20 ns).
- Deposition Parameters: Films were grown at room temperature under an Argon ambient pressure of 0.25 Pa.
- Parameter Optimization: Laser energy density (ED) was varied (4 to 12 J·cm-2) and pulse counts (NO) adjusted to control the resulting layer thickness (40 nm to 150 nm).
- Optical Characterization: Transmittance was measured using UV-VIS spectrophotometry from 200 nm to 1100 nm to assess UV protection and visible light clarity.
- Tribological Testing: Wear resistance was quantified using a Pin-on-Disk Tribometer with a 6 mm Chromium steel ball under 1 N load over a 10 m path length to determine friction coefficient and surface damage.
6CCVD Solutions & Capabilities
Section titled â6CCVD Solutions & CapabilitiesâThe research confirms that diamond-based coatings are essential for achieving next-generation durability and biocompatibility in ophthalmic and precision optical systems. 6CCVDâs expertise in MPCVD diamond growth provides the necessary material control to replicate and significantly extend the performance achieved in this study, particularly by optimizing the sp3 content for maximum optical transmittance.
Applicable Materials
Section titled âApplicable MaterialsâTo replicate the superior wear resistance while minimizing the transmittance trade-off, 6CCVD recommends the following materials:
- Optical Grade SCD (Single Crystal Diamond): Ideal for high-end applications requiring maximum transparency, minimal scattering, and ultra-low surface roughness (Ra < 1 nm). SCD offers the highest purity and controlled sp3 bonding, crucial for optimizing UV/Visible transmission.
- High-Durability PCD (Polycrystalline Diamond) Thin Films: Suitable for large-area coating applications. 6CCVD can grow PCD films with precise thickness control (0.1 ”m to 500 ”m) on various substrates, providing exceptional hardness and chemical inertness for biocompatible surfaces.
- Boron-Doped Diamond (BDD): While not the primary focus of this optical study, BDD is available for researchers exploring electrochemically active or antibacterial coatings (as suggested in the paperâs introduction regarding silver-doped DLC).
Customization Potential
Section titled âCustomization Potentialâ6CCVDâs in-house engineering and manufacturing capabilities directly address the needs of advanced optical research and manufacturing:
| Research Requirement | 6CCVD Customization Service | Specification Range |
|---|---|---|
| Large-Scale Coating/Substrates | Custom PCD Plate Manufacturing | Plates/wafers up to 125 mm diameter |
| Precise Layer Thickness | SCD and PCD Film Growth | SCD (0.1 ”m - 500 ”m), PCD (0.1 ”m - 500 ”m) |
| Surface Finish for Optics | Precision Polishing Services | Ra < 1 nm (SCD), Ra < 5 nm (Inch-size PCD) |
| Integration & Sensorization | Custom Metalization | Au, Pt, Pd, Ti, W, Cu deposition capability |
| Substrate Flexibility | Custom Substrate Dimensions | Substrates available up to 10 mm thickness |
Engineering Support
Section titled âEngineering SupportâThe successful implementation of diamond coatings requires precise control over material properties, especially the sp3/sp2 ratio, which dictates both hardness and optical transparency.
- Tribology and Wear: 6CCVDâs in-house PhD team specializes in material selection for extreme tribological environments, ensuring the diamond layer provides maximum protection against abrasion and chemical degradation, critical for IOL and contact lens longevity.
- Optical Optimization: We provide consultation on achieving optimal UV/Visible transmittance by controlling the crystalline quality and purity of the MPCVD diamond, directly addressing the 15% transmittance reduction noted in the DLC study.
- Biocompatibility Projects: We offer material consultation for similar ophthalmic optics, medical device, and high-durability coating projects, leveraging the inherent biocompatibility and chemical inertness of high-purity CVD diamond.
For custom specifications or material consultation, visit 6ccvd.com or contact our engineering team directly.
View Original Abstract
As previous studies indicated, diamond-like carbon (DLC) layers exhibit outstanding biocompatible properties. Additionally, due to high hardness and high transmittance in infrared and visible parts of spectra it is possible to utilize for application ophthalmic optics. DLC layers are suitable for coating of spectacle lenses, contact lenses and even intraocular lenses. In this paper, we focused on transmittance and wear resistance of different commercially available spectacle lenses with surface modification and lenses with DLC layer. The lens transmittance depends on base material and its surface modification. Commercially manufactured lenses exhibit usual transmittance of 90±5%, while transmittance of DLC coated lenses was lower by 15%. Wear resistance is strongly dependent on surface modification. The results of DLC layers were similar or better than commercially manufactured lenses with surface modification.