Ranica Arrowsmith, Associate Editor10.09.14
While “smaller and smaller” seems to be the push for many medical device sectors, such as electronics and surgical instrumentation, tubing is experiencing a unique push: lubricity. Lubricious additives is a demand almost every tubing manufacturer is seeing from its OEM clients, as end use cardiology and neurology applications demand increased sensitivity of movement and “pushability.”
PEEK (polyetheretherketone) has become something of a wonder material in recent years because of its strength and high temperature tolerances. It has very good pushability, or longitudinal stiffness capabilities—which basically means it can be pushed a long way before kinking. This makes it ideal for applications in tortuous in-patient applications, especially in catheters that go through long arteries or small, complex vascular systems. It is lubricious—but other plastics, specifically fluoropolymers are more so. Elevating PEEK’s lubricity to the level of fluoropolymers is a desirable achievement because of all its other benefits, and new science and engineering is making this a reality. New additives and technology now enables increased surface lubricity of PEEK, which minimizes patient trauma as catheters made of the material pass through tissue. There is now the potential for more and more advanced procedures and applications.
Earlier this year, engineers at Zeus Inc., an Orangeburg, S.C.-based company that develops PEEK fibers for minimally invasive applications, found that properties in lotus leaves could lend themselves well to increasing lubricity in the polymer. According to staff material scientist Irina Roof, Ph.D., Zeus customers have reported a tremendous decrease in drag force with the PEEK Engineered Surface tubing. “Imagine the pushability of PEEK with the lubricity of a fluoropolymer,” she said. “In addition, what we’re offering is 100 percent PEEK with no fillers, so customers won’t need to qualify product through the FDA (U.S. Food and Drug Administration). Zeus’ new Engineered Surface PEEK tubing simply uses enhanced PEEK properties and is therefore ideal for use as introducers and minimally invasive delivery therapy aids… The next step is for our customers to take these surface-engineered tubes into their environments for testing. After that, the possibilities are endless.”
Outside lubricity, smaller sizing is a demand that is never going to go away (for details, read the nanotechnology feature in the September issue of MPO). Larger inner diameters (ID) and smaller outer diameters (OD) call for ever-thinning walls, which pushes material sciences to greater heights. Participants in this feature, listed below, detail what demands and trends their companies are experiencing in terms of tubing technology.
Mike Badera, president of Precision Extrusion Inc., a manufacturer of medical custom thermoplastic tubing based in Glens Falls, N.Y.
Ken Koen, vice president of extrusion for AdvancedCath Inc., a catheter manufacturing services company headquartered in San Jose, Calif.
Apur Lathiya, executive vice president of sales and marketing for Vesta Inc., a Franklin, Wis.-based contract manufacturer for the medical device industry that provides thermoplastic and silicone extrusion.
Tim Lynch, vice president of operations at Tampa, Fla.-based MicroLumen Inc., which makes medical tubing from high-performance polyimide and other materials.
Sean Lynn, engineering manager for Teleflex Medical OEM, the original equipment manufacturing side of Teleflex Inc. The company provides medical product development and production services, and is based in Research Triangle Park, N.C.
Chris Mazelin, marketing manager for Paso Robles, Calif.-based Specialty Silicone Fabricators Inc. The company makes custom silicone components for the medical device industry.
Josh Ridley, business development manager of Biomaterials for Zeus Inc.
Howard Rowe, co-owner of CleanCut Technologies based in Anaheim, Calif. The company’s expertise is in medical device packaging, but it also now makes clipless catheter and guidewire dispensers to eliminate the excess waste and packaging issues encountered with clips.
Kevin Shutes, business development manager for K-Tube Technologies, which makes miniature stainless steel tubing such as the type used in hypodermic needles. The company is based in Poway, Calif.
Three participants from Interface Catheter Solutions, which provides balloon catheter development and production solutions for catheter manufacturers: Mark Geiger, vice president of sales and marketing; Kenny Mazzarese, director of advanced technologies, and Clarence Williams, director of extrusion. The company is headquartered in Laguna Niguel, Calif.
(Editor’s note: For a list of acronyms and definitions, turn to the end of the article.)
MPO: What materials do you use, and how is each material suited for the various end-use products? Have there been any new materials emerging in recent years that you work with?
Mike Badera: Thermoplastic polymers such as PA, PEBA, PUR, PVC, PP, PE, PEEK, PEI. These materials can be combined with different fillers to provide increased lubricity or radiopacity as required in the end product. The different grades within each family of polymers are used to provide flexibility or, vice versa, rigidity as required. In some cases the materials are selected for their inherent barrier properties or ease of assembly. Different materials are combined in some designs to provide an even greater range or combinations of physical properties.
The new materials we are testing have new or improved additives that affect strength and flexibility (e.g., nanoparticles). Also, new radiopaque compounds are coming into the market as well as different additives to change the surface properties (lubricity or ability to provide for surface coating).
Ken Koen: We extrude various durometers of polyamides, polyurethanes, polyolefins and polyethelenes. We extrude barium and bismuth loaded materials as well as various FDA-approved colors. Lately customers have been experimenting with lubricious additives. We have been working closely with polymer scientists to compound commonly used materials with these lubricious additives.
Most lubricious additives are proprietary but the purpose would be to increase catheter movement or tracking in the vascular anatomy. Most soft materials tend to be tacking on the surface which can be a problem. With the introduction of these additives to these materials we can maintain the same performance and decrease surface friction.
Apur Lathiya: Silicones are used for implants such as ICDs (implantable cardioverter defibrillators) or pacemakers because they have good biostability. Silcones used for both short and long term applications, in wound drainage for surgeries and in intracranial pressure catheters. Where you want biostability and relative softness, it works well. For thermoplastics, depending on where they are used because there’s such a variety, a lot of it is used in vascular applications because they provide good pushability, torquability and flexibility. Polyurethane has great durability so it’s also used in long term implant applications. It softens in the body so it’s used for dialysis products. What material you choose is really application-specific.
Tim Lynch: Polyimide is the material on which our business began in 1987. Polyimide is a top-of-the-line plastic in terms of strength, and our process enables us to produce very small, thin wall tubing to very tight tolerances. Since that time, braiding and coiling have been added for the purpose of reinforcing the tubing in specific ways. Coiling can add kink resistance, crush resistance and flexibility. Braiding offers column strength and torque and can also vary the flexibility of a tube. Plastics are generally chosen for one of three reasons in a catheter; lubricity, flexibility or compatibility. Most recently, customers have been using additives in an effort to improve lubricity of many plastics. MicroLumen offers tubing in polyimide, PTFE, pebax, urethane, nylon and many other materials. MicroLumen’s PTFE liners seem to be gaining acceptance in the marketplace for their thin, yet lubricious, nature.
Sean Lynn: Demand for minimally invasive procedures has increased the need for specialized tubing for catheters that deliver stents, stent grafts, and other medical devices in the body. Gone are the days when the standard catheter process was to jacket a coiled wire. Designers and manufacturers of modern interventional catheters, like Teleflex Medical OEM, are challenged with a demand to achieve what seem like contradictory performance characteristics simultaneously. This can include performance characteristics such as strength, and flexibility or trackability, pushability and maneuverability. Generally these conflicting performance requirements can be achieved by employing extrusion based on continuous extruded reinforced composite designs.
These types of catheter designs can also use continuous extrusion processes to help provide the most economic catheter solution.
An important first step in achieving optimal performance characteristics is choosing the right tubing materials. Fluoropolymers, such as PTFE and FEP, are good choices because of their desirable properties of lubricity, chemical inertness, and biocompatibility.
PTFE is the most lubricious polymer available today. Both polymers can be extruded in an extensive array of diameters and shapes with single- and multi-lumens, and readily accept secondary finishing operations such as etching, cutting, and printing.
Modern OEM extrusion for catheter type applications is a complex blend of materials, knowledge, reinforcement techniques and in-house knowledge required to combine a number of techniques or capabilities to provide a solution truly tailored to the custom need. Most often the most economical and efficient solutions are offered by companies who invest both capital and time in developing unique solutions that build on improving existing processes to provide a unique solution.
Kenny Mazzarese: Almost all the materials we use are thermoplastics. Initially, it was thought that hitting the ID and OD and hitting an ultimate percent strain on the material was very important for balloon extrusions. We spent a good three to four years on trying to understand everything about the characteristics of what is required of tubing characteristics to make quality balloons—everything, including the elongation, crystallinity and expansion ratios of these materials. Making sure that we could achieve lot to lot consistency was something that took us quite some time to figure out. But the different material types used in balloons and tubing is all dependent on the application of the catheter itself. So when it comes to a standard PTA catheter, you’re looking at a semi- to non-compliant material, which usually consists of your nylons or PET-type materials. When it comes to occlusions, having to simply occlude or conform to anatomy, you’re looking at softer urethanes and things of that nature. Those are just a few of many different types of applications that require specialized material characteristics.
Chris Mazelin: Silicone is the gold standard among implantable elastomers. Because of its unique biocompatibility silicone rubber has been used in applications around, on, and in the human body for well over 50 years. Medical- and implant-grade silicone rubbers are the primary material types we work with. Some variations of these types of materials we have experimented with are a hybrid material blending silicone with a polyurethane. Changes are related to how the material is cured, we have experimented with UV (ultraviolet) curing technology as well.
Josh Ridley: High performance, engineered resins like PTFE and FEP are often the best candidates for a number of medical devices due to their inherently low coefficient of friction, chemical inertness, biocompatibility, and predicate use. The push for novel therapies and devices in minimally invasive surgery is stronger than it’s ever been. Reducing patient trauma, hospitalization time, and improving clinical outcomes is of paramount importance to device OEMs and clinicians.
An emerging area for Zeus and the medical device industry in general involves a number of different biomaterials. Zeus’s biomaterials product line includes Absorb bioabsorbable polymers, Aeos expanded PTFE (ePTFE), and Bioweb electrospun nonwovens. There is a tremendous amount of activity and interest in bioabsorbable polymers that can behave and perform like traditional metallic components or otherwise durable polymers, perform a function for a given amount of time, and ultimately disappear, allowing the body to return to a state of normalcy without a permanent implant being left behind. This is most predominately seen today in the work being done in bioabsorbable vascular scaffolds, but the potential applications and areas of use is seemingly unlimited, with exploration in areas such as GI (gastro intestinal)/endoscopy, ENT (ear, nose and throat), brachytherapy, targeted drug delivery, and cosmetics, just to name a few.
Howard Rowe: Our Clipless Dispenser is manufactured from high-density polyethylene (HDPE) or polypropylene. Both materials have common uses in the medical device industry. The Clipless Dispenser typically ranges from 20 to 187 inches in length and is used for packaging guidewires and catheters. All designs are custom made to the end device user’s specifications. Materials have not changed much, although there have been additives developed to enhance lubricity that allows the guidewires and catheters to advance through the tubing with minimal friction. In addition, materials have become more compatible to the various sterilization methods e.g., EtO, gamma and E-beam.
Kevin Shutes: While the majority of K-Tube’s business remains 300 series stainless steel due to its excellent corrosion resistance and predictable physical properties across a broad range of applications, we’ve seen a shift towards more exotic alloys (i.e., MP35N and L605) as device engineers design catheters needing higher strength and stiffness properties for thinner walls. For biopsy applications, demand is increasing for precipitation-hardened alloys (i.e., 17-7) designed to reduce puncture forces and increase edge retention on cutting surfaces. For high temperature applications like heat exchangers we’ve seen traditional alloys like stabilized 300 series (347, 321) or precipitation hardened Ni-based alloys (I-718) being used in much smaller diameters.
MPO: What emerging technologies have you see in terms of end-uses for tubing, and what demands have those technologies placed on your business?
Badera: The new products coming into the market tend to be either smaller diameter, with increased performance, or products that maintain the same sizes, but provide more functionality. These product designs generally require tighter control of our internal processing in order to provide thinner walled tubing with very minimal tolerance ranges, allowing the finished device manufacturer to “go where they’ve never gone before.”
Lynch: My dad always used to say, “You are trying to put 10 pounds of stuff into a five-pound bag.” The principle for the catheter industry is the same. Engineers are trying to get more and more technology into the body through smaller and smaller holes. Whether it is ablation of some sort, delivery of some device or medicine, or temporary use of some mechanical apparatus, the need for our tubing is generally the same: Smaller entry wounds heal faster and lead to fewer complications. The smaller the better. Our business is perfectly suited to making tubing smaller for the catheter industry; smaller, stronger, more capable.
Rowe: Tubing has been used for years in the medical device industry for IV (intravenous) drip sets, perfusion sets, custom packs and packaging of devices. CleanCut Technologies (CCT), through the use of its patented technology, took the use of HDPE and PPE to a new level. The CCT Clipless Dispenser cannot be compared to a Clipped Dispenser as in “apples to apples.” This new technology has provided the customer with a more uniform design and shape, reduced material from the elimination of clips and has stabilized the packaging of our customers’ critical and delicate devices. Our dispensers provide a robust and reliable packaging system that ensures retention and protection.
Shutes: K-Tube is celebrating its 40th anniversary this year and for the first 30 years of our history we primarily sold from a catalog of standard industry sizes. Most of our customers were designing and selling hypodermic needles. Today, however, more than 93 percent of our business is custom and supports a wide range of applications in the medical device industry.
We design a tube to meet the specific medical device application and collaborate with device design engineers before the device is released to contract manufacturing houses for production. As a result, we’ve invested in application engineers and a dedicated manufacturing line we call K-Tube Discover. When our material science and application engineers collaborate with device engineers directly, the potential for failures or issues downstream is dramatically reduced.
Ridley: Staying out in front of the device innovation curve is always a challenge. At Zeus, we find it extremely important and beneficial to attend conferences like Transcatheter Cardiovascular Therapeutics meeting, the International Symposium on Endovascular Therapy, the American College of Cardiology meeting, Digestive Disease Week and others to stay abreast of the latest trends and unmet needs from a clinical standpoint. This affords us a unique perspective and helps us relate and align more closely with some of the world-leading multinational OEMs to again help foster device innovation through polymer science. We often hear about companies looking for their suppliers to bring or enable innovation through their various product offerings and that’s exactly what we’re trying to do. The extensive work we’re doing in the bioabsorbable space, especially related to coronary stenting, is a perfect example, and a direct result of Zeus taking a proactive approach in attending industry conferences to try and understand what’s next. Working on what’s now is undoubtedly important, but if you’re not vertically integrating and positioning for three to five years down the road you’re missing the boat.
MPO: What types of recent demands have you seen from OEM clients?
Lathiya: On the technical side, what you’re seeing is a trend that has been around for years—the push to go smaller and thinner. As device companies try to develop devices that go into the small arteries in the brain or heart—areas they couldn’t go before—they are looking for ways to get there. They have to have smaller diameters to get there, but they also need to have enough working area. So they need the largest ID with the smallest OD. That trend has been around for approximately the past five years and we continue to see that. The other trend we’re seeing more from a supply chain side is our customers are asking us to do more. Historically, we have done the tubing, and now they’re asking for more secondary operations. We’re being asked to print, flare and tip the tubing. We’re also seeing more requests for braided tubing: As companies go into torturous anatomy and try to make those tight turns in the vasculature they need braided tubing so they don’t kink the catheter as they navigate through the anatomy. On the quality side we are seeing our customers push more and more for quality agreements in which they define all the terms up front, whereas historically some of that was not in written format.
Lynch: The complexity of tubing is increasing. Tubing itself, in the traditional sense of the word, sounds very simple, and, in fact, used to be very simple. Today’s market demands much more sophisticated tubing; tubing that is constructed in layers of different materials where each material lends a different property to the tubing or to the device. Tubing can contain lubricious inner layers, reinforcing layers that add strength, flexible outer layers that may even vary in flexibility along the length of the tube, geometric features (holes, slots, etc.) with purpose, coatings, and so on. Any combination of potential materials is a possible solution to an engineer’s problem.
Lynn: In the medical industry, the trend for minimally invasive surgical techniques has created demand for extrusion with smaller diameters, tighter tolerances, and more varied functions. While some designers tend to focus on specific resins to achieve performance characteristics, Teleflex Medical OEM believes it is just as important to take note of the advances in extrusion technologies that impact medical device development. For example, multi-layer or co-extrusion tubing—extrusion of multiple layers simultaneously—gives designers a catalog of options for developing specific performance characteristics that cannot be achieved with a single material. Co-extrusion permits the creation of composite tubing with different interior and exterior properties. This effective synergy allows the achievement of unique properties that are not possible with any single material.
Mazzarese: We’ve been called upon to make very thin-walled, tri-layer extrusion. We’ve seen the demand for the ability to have a lubricious inner layer for tractability over the guide wire and then the thermoplastic layer on the outside to be able to thermally adhere a balloon tube, and then an adhesive layer to bond two dissimilar material types together. Say we want to go into the body and deliver a drug using a drug eluting balloon. At Interface, we’d provide a solution for understanding what the characteristics of the bursts, the compliance needs to be, where its going in the body, and we’ll recommend material types based on the application and based on where it needs to go in the body. We’ll also post-process these extrusions and we could apply other applications to be able to dispense a drug better in that location.
Mark Geiger: Interface gets the full spectrum of opportunities from customers large and small. There are some customers who know exactly what they want because they have the internal expertise to specify every single detail, and we can deliver that. But equally as often, we have customers that submit their dream specifications. They don’t know exactly what’s possible but they know what their ideal is. Because of not just the extrusion expertise that we have, but the catheter expertise— the actual, finished device expertise that we have internally— we can help customers take their dream specifications, doing all of the natural and necessary back and forth with the customer to help them understand what the trade-offs are to help identify the right material. An example of that is you might have a customer who wants a dual lumen tube to go through a very small French size. With our expertise, we’ll be able to say, “well if you want a lumen that large inside a tube that small, you’re running out of real estate because the wall thickness is going to be too small and the catheter’s going to kink, collapse or burst under pressure.” So I either need my lumen smaller to allow wall thickness to be larger, or I need to increase the OD of the shaft to accommodate the lumen size that I need. It’s easy to say we’re a CMO (contract manufacturing organization) and we just extrude the print that somebody sends us, but what really happens at least half the time is this trading of expertise to help educate our customers on what’s possible with the materials, the shaft size and the lumen size that the customer needs, going back and forth to help them identify what’s possible and what’s repeatedly manufacturable.
Ridley: Again, supplier-enabled innovation. Bringing new ideas, processes, products, novel polymer species, and availing those to our customers to help foster innovation from raw material to component to finished device. Of course, being cost conscientious is always important, but it’s also important that we help educate our customers and paint a bigger picture with respect to the true cost associated with innovation. For example, it may seem counterintuitive to pay an exorbitant amount of money for a polymeric component as part of a device, but if that component helps reduce hospitalization time, reduces the incidence of re-intervention, and improves clinical outcomes, there’s a bigger story to tell there as far as what that particular component may cost, or save perhaps.
Rowe: Cost is always an issue for any material. Flared tubing can be a cost saving process when used to secure a luer or fitting in place instead of an injection molded retention element.
Shutes: Speed to market and traceability have always been important to our OEM clients, but increased scrutiny by the FDA over raw material supply chains is starting to make device firms dig deeper. A simple certificate of compliance isn’t enough anymore.
Many of our customers are shocked to learn that some of their stainless steel tubing suppliers don’t even manufacture their stainless steel tubing, let alone understand the metallurgical complexity and risks associated with a fragmented and murky supply chain. Device companies should be asking their contract manufacturing partners exactly where and how their raw materials were manufactured and demand change notifications whenever a new raw material supplier is used. Everyone understands there is pricing pressure on device companies against the backdrop of rising costs, but cutting corners on material compliance and sourcing material from distributors only focused on profit could expose them to regulatory risk that far outweighs any short-term cost savings.
Acronym Key
PEEK (polyetheretherketone) has become something of a wonder material in recent years because of its strength and high temperature tolerances. It has very good pushability, or longitudinal stiffness capabilities—which basically means it can be pushed a long way before kinking. This makes it ideal for applications in tortuous in-patient applications, especially in catheters that go through long arteries or small, complex vascular systems. It is lubricious—but other plastics, specifically fluoropolymers are more so. Elevating PEEK’s lubricity to the level of fluoropolymers is a desirable achievement because of all its other benefits, and new science and engineering is making this a reality. New additives and technology now enables increased surface lubricity of PEEK, which minimizes patient trauma as catheters made of the material pass through tissue. There is now the potential for more and more advanced procedures and applications.
Earlier this year, engineers at Zeus Inc., an Orangeburg, S.C.-based company that develops PEEK fibers for minimally invasive applications, found that properties in lotus leaves could lend themselves well to increasing lubricity in the polymer. According to staff material scientist Irina Roof, Ph.D., Zeus customers have reported a tremendous decrease in drag force with the PEEK Engineered Surface tubing. “Imagine the pushability of PEEK with the lubricity of a fluoropolymer,” she said. “In addition, what we’re offering is 100 percent PEEK with no fillers, so customers won’t need to qualify product through the FDA (U.S. Food and Drug Administration). Zeus’ new Engineered Surface PEEK tubing simply uses enhanced PEEK properties and is therefore ideal for use as introducers and minimally invasive delivery therapy aids… The next step is for our customers to take these surface-engineered tubes into their environments for testing. After that, the possibilities are endless.”
Outside lubricity, smaller sizing is a demand that is never going to go away (for details, read the nanotechnology feature in the September issue of MPO). Larger inner diameters (ID) and smaller outer diameters (OD) call for ever-thinning walls, which pushes material sciences to greater heights. Participants in this feature, listed below, detail what demands and trends their companies are experiencing in terms of tubing technology.
Mike Badera, president of Precision Extrusion Inc., a manufacturer of medical custom thermoplastic tubing based in Glens Falls, N.Y.
Ken Koen, vice president of extrusion for AdvancedCath Inc., a catheter manufacturing services company headquartered in San Jose, Calif.
Apur Lathiya, executive vice president of sales and marketing for Vesta Inc., a Franklin, Wis.-based contract manufacturer for the medical device industry that provides thermoplastic and silicone extrusion.
Tim Lynch, vice president of operations at Tampa, Fla.-based MicroLumen Inc., which makes medical tubing from high-performance polyimide and other materials.
Sean Lynn, engineering manager for Teleflex Medical OEM, the original equipment manufacturing side of Teleflex Inc. The company provides medical product development and production services, and is based in Research Triangle Park, N.C.
Chris Mazelin, marketing manager for Paso Robles, Calif.-based Specialty Silicone Fabricators Inc. The company makes custom silicone components for the medical device industry.
Josh Ridley, business development manager of Biomaterials for Zeus Inc.
Howard Rowe, co-owner of CleanCut Technologies based in Anaheim, Calif. The company’s expertise is in medical device packaging, but it also now makes clipless catheter and guidewire dispensers to eliminate the excess waste and packaging issues encountered with clips.
Kevin Shutes, business development manager for K-Tube Technologies, which makes miniature stainless steel tubing such as the type used in hypodermic needles. The company is based in Poway, Calif.
Three participants from Interface Catheter Solutions, which provides balloon catheter development and production solutions for catheter manufacturers: Mark Geiger, vice president of sales and marketing; Kenny Mazzarese, director of advanced technologies, and Clarence Williams, director of extrusion. The company is headquartered in Laguna Niguel, Calif.
(Editor’s note: For a list of acronyms and definitions, turn to the end of the article.)
MPO: What materials do you use, and how is each material suited for the various end-use products? Have there been any new materials emerging in recent years that you work with?
Mike Badera: Thermoplastic polymers such as PA, PEBA, PUR, PVC, PP, PE, PEEK, PEI. These materials can be combined with different fillers to provide increased lubricity or radiopacity as required in the end product. The different grades within each family of polymers are used to provide flexibility or, vice versa, rigidity as required. In some cases the materials are selected for their inherent barrier properties or ease of assembly. Different materials are combined in some designs to provide an even greater range or combinations of physical properties.
The new materials we are testing have new or improved additives that affect strength and flexibility (e.g., nanoparticles). Also, new radiopaque compounds are coming into the market as well as different additives to change the surface properties (lubricity or ability to provide for surface coating).
Ken Koen: We extrude various durometers of polyamides, polyurethanes, polyolefins and polyethelenes. We extrude barium and bismuth loaded materials as well as various FDA-approved colors. Lately customers have been experimenting with lubricious additives. We have been working closely with polymer scientists to compound commonly used materials with these lubricious additives.
Most lubricious additives are proprietary but the purpose would be to increase catheter movement or tracking in the vascular anatomy. Most soft materials tend to be tacking on the surface which can be a problem. With the introduction of these additives to these materials we can maintain the same performance and decrease surface friction.
Apur Lathiya: Silicones are used for implants such as ICDs (implantable cardioverter defibrillators) or pacemakers because they have good biostability. Silcones used for both short and long term applications, in wound drainage for surgeries and in intracranial pressure catheters. Where you want biostability and relative softness, it works well. For thermoplastics, depending on where they are used because there’s such a variety, a lot of it is used in vascular applications because they provide good pushability, torquability and flexibility. Polyurethane has great durability so it’s also used in long term implant applications. It softens in the body so it’s used for dialysis products. What material you choose is really application-specific.
Tim Lynch: Polyimide is the material on which our business began in 1987. Polyimide is a top-of-the-line plastic in terms of strength, and our process enables us to produce very small, thin wall tubing to very tight tolerances. Since that time, braiding and coiling have been added for the purpose of reinforcing the tubing in specific ways. Coiling can add kink resistance, crush resistance and flexibility. Braiding offers column strength and torque and can also vary the flexibility of a tube. Plastics are generally chosen for one of three reasons in a catheter; lubricity, flexibility or compatibility. Most recently, customers have been using additives in an effort to improve lubricity of many plastics. MicroLumen offers tubing in polyimide, PTFE, pebax, urethane, nylon and many other materials. MicroLumen’s PTFE liners seem to be gaining acceptance in the marketplace for their thin, yet lubricious, nature.
Sean Lynn: Demand for minimally invasive procedures has increased the need for specialized tubing for catheters that deliver stents, stent grafts, and other medical devices in the body. Gone are the days when the standard catheter process was to jacket a coiled wire. Designers and manufacturers of modern interventional catheters, like Teleflex Medical OEM, are challenged with a demand to achieve what seem like contradictory performance characteristics simultaneously. This can include performance characteristics such as strength, and flexibility or trackability, pushability and maneuverability. Generally these conflicting performance requirements can be achieved by employing extrusion based on continuous extruded reinforced composite designs.
These types of catheter designs can also use continuous extrusion processes to help provide the most economic catheter solution.
An important first step in achieving optimal performance characteristics is choosing the right tubing materials. Fluoropolymers, such as PTFE and FEP, are good choices because of their desirable properties of lubricity, chemical inertness, and biocompatibility.
PTFE is the most lubricious polymer available today. Both polymers can be extruded in an extensive array of diameters and shapes with single- and multi-lumens, and readily accept secondary finishing operations such as etching, cutting, and printing.
Modern OEM extrusion for catheter type applications is a complex blend of materials, knowledge, reinforcement techniques and in-house knowledge required to combine a number of techniques or capabilities to provide a solution truly tailored to the custom need. Most often the most economical and efficient solutions are offered by companies who invest both capital and time in developing unique solutions that build on improving existing processes to provide a unique solution.
Kenny Mazzarese: Almost all the materials we use are thermoplastics. Initially, it was thought that hitting the ID and OD and hitting an ultimate percent strain on the material was very important for balloon extrusions. We spent a good three to four years on trying to understand everything about the characteristics of what is required of tubing characteristics to make quality balloons—everything, including the elongation, crystallinity and expansion ratios of these materials. Making sure that we could achieve lot to lot consistency was something that took us quite some time to figure out. But the different material types used in balloons and tubing is all dependent on the application of the catheter itself. So when it comes to a standard PTA catheter, you’re looking at a semi- to non-compliant material, which usually consists of your nylons or PET-type materials. When it comes to occlusions, having to simply occlude or conform to anatomy, you’re looking at softer urethanes and things of that nature. Those are just a few of many different types of applications that require specialized material characteristics.
Chris Mazelin: Silicone is the gold standard among implantable elastomers. Because of its unique biocompatibility silicone rubber has been used in applications around, on, and in the human body for well over 50 years. Medical- and implant-grade silicone rubbers are the primary material types we work with. Some variations of these types of materials we have experimented with are a hybrid material blending silicone with a polyurethane. Changes are related to how the material is cured, we have experimented with UV (ultraviolet) curing technology as well.
Josh Ridley: High performance, engineered resins like PTFE and FEP are often the best candidates for a number of medical devices due to their inherently low coefficient of friction, chemical inertness, biocompatibility, and predicate use. The push for novel therapies and devices in minimally invasive surgery is stronger than it’s ever been. Reducing patient trauma, hospitalization time, and improving clinical outcomes is of paramount importance to device OEMs and clinicians.
An emerging area for Zeus and the medical device industry in general involves a number of different biomaterials. Zeus’s biomaterials product line includes Absorb bioabsorbable polymers, Aeos expanded PTFE (ePTFE), and Bioweb electrospun nonwovens. There is a tremendous amount of activity and interest in bioabsorbable polymers that can behave and perform like traditional metallic components or otherwise durable polymers, perform a function for a given amount of time, and ultimately disappear, allowing the body to return to a state of normalcy without a permanent implant being left behind. This is most predominately seen today in the work being done in bioabsorbable vascular scaffolds, but the potential applications and areas of use is seemingly unlimited, with exploration in areas such as GI (gastro intestinal)/endoscopy, ENT (ear, nose and throat), brachytherapy, targeted drug delivery, and cosmetics, just to name a few.
Howard Rowe: Our Clipless Dispenser is manufactured from high-density polyethylene (HDPE) or polypropylene. Both materials have common uses in the medical device industry. The Clipless Dispenser typically ranges from 20 to 187 inches in length and is used for packaging guidewires and catheters. All designs are custom made to the end device user’s specifications. Materials have not changed much, although there have been additives developed to enhance lubricity that allows the guidewires and catheters to advance through the tubing with minimal friction. In addition, materials have become more compatible to the various sterilization methods e.g., EtO, gamma and E-beam.
Kevin Shutes: While the majority of K-Tube’s business remains 300 series stainless steel due to its excellent corrosion resistance and predictable physical properties across a broad range of applications, we’ve seen a shift towards more exotic alloys (i.e., MP35N and L605) as device engineers design catheters needing higher strength and stiffness properties for thinner walls. For biopsy applications, demand is increasing for precipitation-hardened alloys (i.e., 17-7) designed to reduce puncture forces and increase edge retention on cutting surfaces. For high temperature applications like heat exchangers we’ve seen traditional alloys like stabilized 300 series (347, 321) or precipitation hardened Ni-based alloys (I-718) being used in much smaller diameters.
MPO: What emerging technologies have you see in terms of end-uses for tubing, and what demands have those technologies placed on your business?
Badera: The new products coming into the market tend to be either smaller diameter, with increased performance, or products that maintain the same sizes, but provide more functionality. These product designs generally require tighter control of our internal processing in order to provide thinner walled tubing with very minimal tolerance ranges, allowing the finished device manufacturer to “go where they’ve never gone before.”
Lynch: My dad always used to say, “You are trying to put 10 pounds of stuff into a five-pound bag.” The principle for the catheter industry is the same. Engineers are trying to get more and more technology into the body through smaller and smaller holes. Whether it is ablation of some sort, delivery of some device or medicine, or temporary use of some mechanical apparatus, the need for our tubing is generally the same: Smaller entry wounds heal faster and lead to fewer complications. The smaller the better. Our business is perfectly suited to making tubing smaller for the catheter industry; smaller, stronger, more capable.
Rowe: Tubing has been used for years in the medical device industry for IV (intravenous) drip sets, perfusion sets, custom packs and packaging of devices. CleanCut Technologies (CCT), through the use of its patented technology, took the use of HDPE and PPE to a new level. The CCT Clipless Dispenser cannot be compared to a Clipped Dispenser as in “apples to apples.” This new technology has provided the customer with a more uniform design and shape, reduced material from the elimination of clips and has stabilized the packaging of our customers’ critical and delicate devices. Our dispensers provide a robust and reliable packaging system that ensures retention and protection.
Shutes: K-Tube is celebrating its 40th anniversary this year and for the first 30 years of our history we primarily sold from a catalog of standard industry sizes. Most of our customers were designing and selling hypodermic needles. Today, however, more than 93 percent of our business is custom and supports a wide range of applications in the medical device industry.
We design a tube to meet the specific medical device application and collaborate with device design engineers before the device is released to contract manufacturing houses for production. As a result, we’ve invested in application engineers and a dedicated manufacturing line we call K-Tube Discover. When our material science and application engineers collaborate with device engineers directly, the potential for failures or issues downstream is dramatically reduced.
Ridley: Staying out in front of the device innovation curve is always a challenge. At Zeus, we find it extremely important and beneficial to attend conferences like Transcatheter Cardiovascular Therapeutics meeting, the International Symposium on Endovascular Therapy, the American College of Cardiology meeting, Digestive Disease Week and others to stay abreast of the latest trends and unmet needs from a clinical standpoint. This affords us a unique perspective and helps us relate and align more closely with some of the world-leading multinational OEMs to again help foster device innovation through polymer science. We often hear about companies looking for their suppliers to bring or enable innovation through their various product offerings and that’s exactly what we’re trying to do. The extensive work we’re doing in the bioabsorbable space, especially related to coronary stenting, is a perfect example, and a direct result of Zeus taking a proactive approach in attending industry conferences to try and understand what’s next. Working on what’s now is undoubtedly important, but if you’re not vertically integrating and positioning for three to five years down the road you’re missing the boat.
MPO: What types of recent demands have you seen from OEM clients?
Lathiya: On the technical side, what you’re seeing is a trend that has been around for years—the push to go smaller and thinner. As device companies try to develop devices that go into the small arteries in the brain or heart—areas they couldn’t go before—they are looking for ways to get there. They have to have smaller diameters to get there, but they also need to have enough working area. So they need the largest ID with the smallest OD. That trend has been around for approximately the past five years and we continue to see that. The other trend we’re seeing more from a supply chain side is our customers are asking us to do more. Historically, we have done the tubing, and now they’re asking for more secondary operations. We’re being asked to print, flare and tip the tubing. We’re also seeing more requests for braided tubing: As companies go into torturous anatomy and try to make those tight turns in the vasculature they need braided tubing so they don’t kink the catheter as they navigate through the anatomy. On the quality side we are seeing our customers push more and more for quality agreements in which they define all the terms up front, whereas historically some of that was not in written format.
Lynch: The complexity of tubing is increasing. Tubing itself, in the traditional sense of the word, sounds very simple, and, in fact, used to be very simple. Today’s market demands much more sophisticated tubing; tubing that is constructed in layers of different materials where each material lends a different property to the tubing or to the device. Tubing can contain lubricious inner layers, reinforcing layers that add strength, flexible outer layers that may even vary in flexibility along the length of the tube, geometric features (holes, slots, etc.) with purpose, coatings, and so on. Any combination of potential materials is a possible solution to an engineer’s problem.
Lynn: In the medical industry, the trend for minimally invasive surgical techniques has created demand for extrusion with smaller diameters, tighter tolerances, and more varied functions. While some designers tend to focus on specific resins to achieve performance characteristics, Teleflex Medical OEM believes it is just as important to take note of the advances in extrusion technologies that impact medical device development. For example, multi-layer or co-extrusion tubing—extrusion of multiple layers simultaneously—gives designers a catalog of options for developing specific performance characteristics that cannot be achieved with a single material. Co-extrusion permits the creation of composite tubing with different interior and exterior properties. This effective synergy allows the achievement of unique properties that are not possible with any single material.
Mazzarese: We’ve been called upon to make very thin-walled, tri-layer extrusion. We’ve seen the demand for the ability to have a lubricious inner layer for tractability over the guide wire and then the thermoplastic layer on the outside to be able to thermally adhere a balloon tube, and then an adhesive layer to bond two dissimilar material types together. Say we want to go into the body and deliver a drug using a drug eluting balloon. At Interface, we’d provide a solution for understanding what the characteristics of the bursts, the compliance needs to be, where its going in the body, and we’ll recommend material types based on the application and based on where it needs to go in the body. We’ll also post-process these extrusions and we could apply other applications to be able to dispense a drug better in that location.
Mark Geiger: Interface gets the full spectrum of opportunities from customers large and small. There are some customers who know exactly what they want because they have the internal expertise to specify every single detail, and we can deliver that. But equally as often, we have customers that submit their dream specifications. They don’t know exactly what’s possible but they know what their ideal is. Because of not just the extrusion expertise that we have, but the catheter expertise— the actual, finished device expertise that we have internally— we can help customers take their dream specifications, doing all of the natural and necessary back and forth with the customer to help them understand what the trade-offs are to help identify the right material. An example of that is you might have a customer who wants a dual lumen tube to go through a very small French size. With our expertise, we’ll be able to say, “well if you want a lumen that large inside a tube that small, you’re running out of real estate because the wall thickness is going to be too small and the catheter’s going to kink, collapse or burst under pressure.” So I either need my lumen smaller to allow wall thickness to be larger, or I need to increase the OD of the shaft to accommodate the lumen size that I need. It’s easy to say we’re a CMO (contract manufacturing organization) and we just extrude the print that somebody sends us, but what really happens at least half the time is this trading of expertise to help educate our customers on what’s possible with the materials, the shaft size and the lumen size that the customer needs, going back and forth to help them identify what’s possible and what’s repeatedly manufacturable.
Ridley: Again, supplier-enabled innovation. Bringing new ideas, processes, products, novel polymer species, and availing those to our customers to help foster innovation from raw material to component to finished device. Of course, being cost conscientious is always important, but it’s also important that we help educate our customers and paint a bigger picture with respect to the true cost associated with innovation. For example, it may seem counterintuitive to pay an exorbitant amount of money for a polymeric component as part of a device, but if that component helps reduce hospitalization time, reduces the incidence of re-intervention, and improves clinical outcomes, there’s a bigger story to tell there as far as what that particular component may cost, or save perhaps.
Rowe: Cost is always an issue for any material. Flared tubing can be a cost saving process when used to secure a luer or fitting in place instead of an injection molded retention element.
Shutes: Speed to market and traceability have always been important to our OEM clients, but increased scrutiny by the FDA over raw material supply chains is starting to make device firms dig deeper. A simple certificate of compliance isn’t enough anymore.
Many of our customers are shocked to learn that some of their stainless steel tubing suppliers don’t even manufacture their stainless steel tubing, let alone understand the metallurgical complexity and risks associated with a fragmented and murky supply chain. Device companies should be asking their contract manufacturing partners exactly where and how their raw materials were manufactured and demand change notifications whenever a new raw material supplier is used. Everyone understands there is pricing pressure on device companies against the backdrop of rising costs, but cutting corners on material compliance and sourcing material from distributors only focused on profit could expose them to regulatory risk that far outweighs any short-term cost savings.
Acronym Key
| FEP: Fluorinated ethylene propylene | PET: Polyethylene terephthalate |
| PA: Polyamide | PP: Polypropylene |
| PE: Polyethylene | PTA: Purified terephthalic acid |
| PEBA: Polyether block amide | PTFE: Polytetraflouroethylene |
| PEEK: Polyetheretherketone | PUR: Polyurethane |
| PEI: Polyethylenimine | PVC: Polyvinyl chloride |
