A parameter that characterizes the ability of a material to absorb X-rays is the attenuation coefficient, .  The higher the value of  the thinner a part can be and still produce an acceptable fluoroscopic image.   For example, the attenuation coefficient for iron is 9.5 (1/cm) while that of tantalum is over six times as great at 59.4.  Iron is the primary component of stainless steel which is commonly used for medical implants because of its mechanical properties and resistance to corrosion.  Another material that is commonly used for peripheral stents and other vascular devices is the shape memory alloy Nitinol.  Nitinol consists of roughly equal amounts of nickel and titanium.  The attenuation coefficients for these materials are 13.4 and 3.5, respectively.  Because of the significantly higher attenuation coefficient of tantalum, medical devices made out of stainless steel and Nitinol can be made much more radiopaque by applying a coating of tantalum.

Isoflux VisTa® Coating
The Isoflux VisTa®# radiopaque coating was developed specifically for medical devices that are made out of poorly absorbing X-ray materials such as Nitinol.  Our VisTa® coating consists of tantalum and is made by Isoflux’ proprietary sputter deposition process#.  Because this sputter deposition process produces a uniform coating even on complex shaped parts (largely due to our use of cylindrical sputtering cathodes#), the entire device is seen in the X-ray image.  This is a great advantage compared to the common approach of attaching to the device radiopaque markers that show up on the fluoroscope as tiny moving dots.  Medical devices such as coronary stents, peripheral stents, vena cava filters, LAP anchors and guidewires can all benefit greatly from the VisTa® coating.

Structure
The VisTa® coating is deposited in such a way that it consists of individual columns of tantalum that adhere extremely well to the medical device.  Figure 1 shows SEM images of the VisTa® coating.  This unique structure allows the device to be flexed without risk of delamination of the tantalum.  This is extremely important for vascular stents since they undergo high strains during implantation and also need to be able to flex freely as long as they are in the body.  The porous columnar structure completely prevents the development of tensile stress since the columns are free to move independently of each other.   In contrast, any radiopaque coating that is does not have porous columnar structure like VisTa® is likely to crack and delaminate when the device is flexed.

In addition to producing a flexible and durable coating, the VisTa® sputter deposition process also preserves all of the important thermal and mechanical properties of the substrate. For instance, the highly sensitive austenitic and martensitic phase transition temperatures, Af and Mf, for Nitinol are not changed by the process. Other PVD and CVD coating processes cause the temperature of the substrates to rise to levels above which the thermal properties are destroyed.

Other Benefits
The nanoporous structure of the VisTa® coating provides another highly valuable benefit. The fully open and connected pore space can be used to deliver drugs (anti-restenosis, anti-inflammatory, anti-microbial, and others) from the surface of the implanted device without the need for polymer coatings. This eliminates the major medical concern about the long term presence of polymers in the body and greatly simplifies the process for designing drug delivery capability for the device#. Yet another benefit of the VisTa® coating is that the nanosize surface features may enhance the rate of cell growth. Fast reendothelialization of vascular implant surfaces is highly desirable because it minimizes the time the implant is exposed to blood flow and makes it less likely that biocompatibility problems will arise.
Although the VisTa® coating was developed for Nitinol devices it has been demonstrated successfully on a wide variety of other substrate materials such as stainless steel, cobalt-chromium and even polymers such as PEEK (polyether ether ketone).

For more information on the VisTa® radiopaque coating for medical devices, please see:

• Isoflux VisTa Brochure
• Tantalum Radiopaque Coatings for Stents
• Redacted 180 Day Animal Study

Cathodes – Isoflux is recognized as the world’s leading manufacturer of inverted cylindrical magnetron sputtering cathodes. We offer several standard cathode designs and can also deliver customized designs to fit specific coating needs.

Complete Systems – Isoflux can provide turnkey coating systems or work with your equipment manufacturer to integrate our cathodes into your system.

Coating Development

Isoflux has the expertise and tools to develop a wide variety of coatings for specific applications.  We interact with you as an extension of your R&D department to quickly achieve results that satisfying the most demanding requirements.

Coating Services

Isoflux provides coating services to save your company the time and cost of implementing your own in-house manufacturing operation.

Licensing

Isoflux licenses coatings for a number of applications.  If you have a specific coating need, ask us what we have to offer.

Aluminum, Bismuth, Chromium, Copper, Gold, Iridium, Molybdenum, Palladium, Platinum, Silicon, Silver, Tantalum, Titanium, Tungsten, Zirconium
[/grid5] [grid7]

Oxides of

Aluminum, Chromium, Indium-tin, Iridium, Silicon, Tantalum, Tin, Titanium, Tungsten, Zirconium
[/grid7] [grid5]

Nitrides of

Aluminum, Iridium, Tungsten, Silicon, Tantalum, Titanium, Zirconium
[/grid5] [grid7]

Alloys

Cobalt-Chromium, Nickel-Chromium, Stainless Steel
[/grid7] ]]> http://isofluxinc.com/case-studies/feed/ 0 http://isofluxinc.com/contact/ http://isofluxinc.com/contact/#comments Tue, 31 May 2011 13:06:26 +0000 admin http://isofluxinc.mymoxie.com/?p=18

Candy Obourn, CEO

cobourn@isofluxinc.com

585-349-0640, x109

Dave Glocker, CTO

dglocker@isofluxinc.com

585-349-0640, x106

Mark Romach, Production Manager

mromach@isofluxinc.com

585-349-0640, x107

Brent Bell, New Technology Manager

bbell@isofluxinc.com

585-349-0640, x110

We are actively engaged in the biomedical, aerospace, electronics, energy, and industrial tools and equipment industries.
[/grid4] [grid4] [gear]biomedical[/gear]

• Coating for Radiopacity and Drug Delivery
• Stents
• Guide wires
• Othopedic Applications/ implants
• Dental Applications
• Antibacterial/Antimicrobial
• Protein/antibody storage/release
• Catheters
• Pacemaker Electrodes

• Absorber Coatings for Solar Tubes
• Exterior Metal Coatings for Superconducting ribbons
• Solar collectors and getters
• Optical absorbers, stray light control
• Optical Coatings
• Sensors
• Thermal Insulators
• Catalytic devices
• Batteries/Fuel Cells
• EMI Shielding
• Efficiency Improvement with Lighting
• Thermal Barrier
• Thermal Control

• Thermal Conduction/Insulation
• Electrical Conduction/Insulation
• Catalytic Enhancement

The Isoflux team is an accomplished group of specialists who hold numerous patents in surfaceengineering technology. With decades of combined experience in the development of coating processesand equipment, we deliver the surface functionality you need to bring your product to market – so youcan offer your customers the valuable features and reliable outcomes they demand.

Isoflux is a world leader in commercializing innovative surface engineering technology. We developcustomized inorganic coatings and plasma surface treatments for a wide variety of applications, and ourproprietary equipment and processes are attracting the attention of leading innovators world-wide.

What we Coat

Our cylindrical cathodes are ideal for uniformly coating the surfaces of many different three dimensional parts including stents, guidewires, orthopedic implants, pacemaker leads, and cutting tools. Cables, ribbon and wire can also be coated in a roll-to-roll operation.  A wide variety of metals, alloys, oxides and nitrides can be coated with precise control over all important film properties.  Our sputtering processes also provide the most efficient use of target materials possible, making them highly attractive for applications involving high cost precious metals.

Our Advantage

Our coatings offer advantages such as flexibility, wear resistance, corrosion resistance, electrical insulation, thermal insulation, diffusion resistance, radiopacity, drug delivery, biocompatibility, and antimicrobial properties.

In particular, Isoflux’s VisTa™ tantalum coating renders medical devices completely radiopaque, providing doctors with the ability to easily see both position and orientation of the device during and after implantation. The porous microstructure of our VisTa coating allows it to survive the extremely high strains experienced on flexible devices such as stents without cracking or delaminating and also provides a polymer-free platform for local drug delivery.