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Ten Surface Treatments that Improve the Performance of Biomedical Components

Thu, 09/02/2010 - 11:49am
Surface Solutions Group

Surface treatments are available to improve function, ease of use, service life, and patient comfort of medical devices and products. Surface Solutions Group of Chicago specializes in solving a wide range of functional problems at the surface of devices, from guide wires to needles to tubing to cannulas. Here is an overview of successes using coatings to improve the surface function of devices.

SlickSil
Slick Sil:
0% Elongation                                                           25% Elongation

Parylene
Parylene:
0% Elongation                                                          25% Elongation

1. Taking the “sticky” out of silicone rubber

Untreated, silicone rubber is almost as tacky as chewed gum. To get around this problem and give parts a measure of “slip,” OEMs used to coat parts with Parylene. But Parylene does not elongate to the degree that silicone does and cracks and flakes off when parts are flexed. Also, Parylene is applied by vapor deposition which is a line-of-sight process; the film cannot reach interior surfaces or recesses.

Slick Sil has none of the shortcomings of Parylene and it halves of the surface friction—on both inside and outside surfaces and recesses. This includes lowering the friction of tubing of any length. Also Slick Sil elongates to the same degree that silicone products do. So, when a silicone tube or other part is stretched to three or four times its length, the Slick Sil coating does not crack or flake off as does Parylene.

2. Keeping electrosurgical blades non-stick

Historically, electrosurgical blades have been coated with PTFE and other coatings to prevent the buildup of burnt tissue (eschar) on blades. This has been only partially successful because PTFE is soft and porous and soon allows

Electrosurgical Blades

eschar to cling to the blades.

Surface Solutions developed a thin, very high temperature eschar release coating— ElectroBondSM —that is eight times harder than PTFE and silicone coatings. Plus, it eliminates the porosity and subsequent sticking problem with eschar. Porosity of PTFE is not an issue with ElectroBond. Another bonus is that ElectroBond will withstand gamma radiation of 110 kgy for verification and 25 kgy for production. PTFE will decompose if exposed to gamma radiation.

There are several formulations of ElectroBond that actually will allow electrosurgical procedures as low as 1 watt of power.

3. Making permanent marks on PTFE coated surfaces without cuts, grinding, or ink.
Graduated Marks

The standard technique for marking graduations on PTFE coated cannulas, needles, probes, and similar instruments is to notch them with lasers or cut notches into them by grinding the surface. This results in a saw tooth edge on the surface that can tear flesh and resist the motion for which the part is intended. Also, because notches are almost indistinguishable from the remainder of the coating, particularly in bright light conditions, graduations made with notches are hard to read.

 

PTFE Markings

Pure PTFE markings on wires or other surfaces can be
of almost any shape, spacing, or color. Even logos can
be included.

 The VisiMarkSM process uses color-shifting pigments in a PTFE coating to create easy-to-read graduations—or almost any other type of mark, including logos, numbers, bar codes, etc. Now, different sizes of components can be color coded for easy identification.

AquaGlide
4. Making parts as “slippery as a fish” in water, saline, or most fluids.

Hydrophilic coatings become extremely slippery in the presence of water, saline, or body fluids. When near-zero friction is important—as is the case with some probes or insertable objects—a coating of AquaGlideSM will ease the passage. Metals, plastics and flexible products can be coated with AquaGlide to provide friction reduction of up to 95%.

5. New low-temperature cure , low-friction coatings that don’t get “cooked” during gamma sterilization

PlastiGlide

Gamma radiation is the most intense sterilization process known, destroying microbes throughout almost any object. Only problem is, it does pretty much the same to a long list of plastics that are commonly used for biomedical implements. It’s particularly destructive to the best-known low-friction polymers, PTFE and FEP. Gamma literally turns PTFE into wax.

Surface Solution’s PlastiGlide can withstand gamma radiation of 110 kgy for verification and 25+ kgy for production. PlastiGlide is a coating that is based on near nano-sized particles of polyethylene. Unlike the more exotic polymers, PE becomes stronger when exposed to gamma. Friction values are good, too, almost the same as PTFE and FEP. It can be applied inside and outside of parts, including long lengths of tubing, to give them low-friction surfaces on both rigid plastic and flexible polymers.

FluoroBond
6. Bonded films that make rubber parts work smoothly.

For so many biomedical applications, the wide family of elastomers is an ideal material for sealing, positioning, damping vibration, or flexing. But the extreme high friction properties of rubber can inhibit its use, or even be dangerous. For instance, inserting glass tubes into an untreated rubber grommet or seal can cause the glass to break.

FluoroBond-R is a low-cure flexible fluoropolymer coating that can be applied to the exterior and interior of rubber parts to give them a surface that is permanently bonded and wax-like.

7. Protect glass parts from shattering
FluoroGlass

Drop a beaker or glass tube onto a hard floor and it shatters. But not if it is coated with FluoroGlassSM. This optically clear fluoropolymer that is almost invisible on the surface of glass parts. When they are accidentally dropped and break, the coating contains the dangerous shards and keeps them from scattering. Unlike standard coatings, FluoroGlass bonds to the glass, containing shards inside the protective coating. High temperature capable, the coating can protect incandescent and infrared heater bulbs.

8. Add fail-safe anti-microbial protection to implements

 

FluoroMed Antimicrobial

The size and universal dispersion of microbes means that sterilized parts can become unsterile at almost any point during their lifetime.

To give parts fail-safe protection from microbes, OEMs can specify FluoroMed Antimicrobial additives to be included in all coatings that are applied to improve slip or wear properties.

FluoroMed Antimicrobial is based on a combination of inorganic materials that destroy over 99% of known pathogens by eliminating their ability to reproduce.

The antimicrobial material can be added to almost any functional coating to increase the margin of safety of the components.

FluoroWire
9. Eliminate binding and sticking in wire products

Coiled or straight guide wires, made of corrosion resistant stainless steel and Nitinol, have a naturally high friction. FluoroWire coatings are bonded to finished devices or even reel-to-reel single continuous lengths wire and small diameter tubing. This coating greatly reduces intervascular friction, helps deliver devices like catheter, stents, balloons and the like. Any wire can be provided with a low friction surface.. The coating can be applied to discrete lengths of guide wire or to continuous rolls. PFOA-free formulations are now in production.

10. Lubricated cutting edges cut better

 

Surgical Knife

Lubricated cutting edges simply cut easier than unlubricated ones. FluoroPlate-N is a micron-thin coating that bonds to the edge of scalpels, razors, and other cutting edges to reduce cutting forces. Cuts are made smoother, faster and with less friction. The film is deposited at 0.0001 in. (2.5µ) without altering the temper of the blade.

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