Materials’ surfaces of vital medical devices, such as silicon (Si) microchip (artificial retina) implanted on human retina, restoring partial vision to people blinded by genetically induced photoreceptors degeneration, and metallic dental implants, are attacked chemically by eyes’ fluids or oral fluids respectively.
Metallic stents/artificial heart valves, inside human blood vessels, activate blood enzymes, inducing coagulation, and fibrinolytic, leading to thrombus formation (i.e., blood clot in blood vessels, obstructing blood flow or loosed clot getting stuck in arteries/veins’ walls, causing life-threatening stroke/heart attack. A34 USB Digital
Polytetrafluoroethylene (PTFE) and Diamond-like Coating (DLC) are investigated to protect metallic implants/ surfaces. However, PTFE exhibits nonuniformity/instability/poor adhesion on metals, resulting in delamination. DLC coating provides lubricity/biocompatibility but degrades in fluids.
The problems described above are solved by using a transformational ultrananocrystalline diamond (UNCD™) coating, developed by Auciello et al., grown by microwave plasma and hot filament chemical vapor deposition, using patented Ar/CH4 gases, with CH4 cracked into C atoms, linking chemically to each other, with diamond-type bonds, on substrates’ surfaces. The (UNCDTM) coating exhibits unique combined physical/chemical/mechanical/electrical /biological properties, the latter promoted by UNCDTM exhibiting the best biocompatibility because it is made of C-atoms (element of life in human DNA/cells/molecules).
Key materials problems in critical medical devices/prostheses, implantable in humans, replacing degraded natural body parts to improve quality of life, include:
Polytetrafluoroethylene (PTFE)/Diamond-like Coating (DLC) coatings are investigated to improve the mechanical/chemical performance of the metals’ surfaces of prostheses. However, PTFE exhibits nonuniformity/instability/poor adhesion on metals. DLC coating exhibits a wide range of C atomic bonds, potentially responsible for high stress/coating degradation in fluids (see review of metal prostheses problems (2)).
Materials problems described above are solved using a UNCD™ coating, described in Section 2.
The transformational UNCD™ coating, developed (Ch. 1 in (1), (3)) and patented (4) by Auciello et al., is grown by microwave plasma and hot filament chemical vapor deposition, using a patented Ar/CH4 gas chemistry flown into an air evacuated system. Where CH4 molecules crack, releasing C atoms, linking to each other, with diamond-type C atoms bonds, on substrate surfaces, producing UNCD™ films (3-5 nm grains (Fig. 1 (a)-smallest of polycrystalline diamond coatings).
UNCD™ films exhibit unique combined physical/chemical/mechanical/ electrical/biological properties, namely: 1) Hardness (98 GPa)/Young modulus (1000 GPs), like diamond gem; 2) lowest friction coefficient (≤ 0.04) than other materials (≥ 0.5) used in prostheses; 3) resistant to corrosion by eye’s fluid, oral fluid, joint fluids; 4) best biocompatibility (because made of C-atoms-element of life in human DNA/cells/molecules); 5) super-hydrophobic surface, eliminating blood cell adhesion in cardiovascular stent and heart valves.
The transformational UNCD™ coating enables new generations of superior implantable medical devices/prostheses, improving people’s quality of life worldwide.
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