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A Cover Story of Medical Device Surface Treatments & Coatings

Nearly a dozen surface treatment and coatings experts discuss their business trends and challenges for medical device manufacturing.

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By: Sam Brusco

Associate Editor

Powdered calcium phosphate (CaP) biomaterials for medical implant coatings. Photo: Himed

Surface treatments and coatings are crucial to medical device performance, safety, and longevity. Devices are becoming more sophisticated and are expected to reliably operate in complex biological environments.

As such, manufacturers must carefully design both the bulk material and the surface that interacts with tissue, blood, and other parts of the body. Surface technologies are often necessary to meet clinical and regulatory demands by improving biocompatibility, reducing friction, bolstering corrosion resistance, and preventing infection.

Coating materials can include polymers, thin-film ceramics, antimicrobial layers, and nanostructured surfaces. Every approach matches specific device requirements for either implants, surgical instruments, or diagnostic tools. The growth of implantable electronics further fuels the need for precision-engineered surfaces that can perform consistently over long periods of time.

As regulatory scrutiny escalates and medical device innovation quickens, understanding surface treatments is crucial for manufacturers to stay competitive and ensure safety and accuracy. That’s why Medical Product Outsourcing spoke to nearly a dozen experts in surface treatment and coating services and technologies for medical device manufacturing.

Brusco: Which design features can cause surface treatment/coating issues? How can these be addressed?

Dr. Julia Calvet: Material selection is one of the most important factors. Freudenberg Medical can coat virtually all approved materials used in medical devices through a single‑step process, but some substrates inherently pose greater challenges. Silicone, for example, has a chemically inert, naturally hydrophobic, low‑surface‑energy surface, which makes adhesion more difficult and typically requires a two‑step process for optimal results. Even with these more complex materials, our chemistry team can tailor the formulation to achieve strong, reliable coating performance.

Device geometry such as different shapes, diameters, or design features can also play a significant role. Ensuring complete and uniform UV curing is essential for strong covalent cross‑linking within the coating and between the coating and the substrate. When the geometry and curing process are properly aligned, the coating consistently delivers the expected lubricity, durability, and low particulate performance.

For the most intricate device designs, a customized coating program may be required to fine‑tune both the coating chemistry and the application process. We offer a range of pre‑treatment methods and coating processes that allow us to address challenging surfaces, flexible materials, and unique geometries.

We take a customer‑centric approach, supporting partners from early feasibility through to mass production to ensure the coating solution is fully optimized for the device design and clinical use.

Eric Guire: Open design features such as fenestrations, slots, grooves, or integrated sensors can create coating “bridging,” where the coating occludes the opening and creates non-uniformity during dipcoating. This can affect drainage, torque, and sensor response, or create stressed weak points in the coating that become initiation sites for delamination if not properly managed. Balloon segments are another common challenge: sometimes they need coating, sometimes not, and sometimes a separate coating, such as drug-eluting coating is applied. This can involve distinct manufacturing steps involving masking and/or separate coating steps depending on the balloon features, so those regions often require a tailored strategy.

Material selection matters just as much as geometry. Fully fluorinated materials like PTFE and FEP are essentially inert to most commercial coating chemistries, making them poor candidates for coating. Silicone presents a different issue: hydrophobic recovery, where migrating oligomers bloom to the surface and interfere with the coated surface performance over time can reduce shelf life or affect coating manufacturing if not mitigated. Similar issues may be observed with softer resins that contain low molecular weight hydrophobic additives to reduce tack and facilitate processing, or wire drawing agents used in guidewire manufacturing. Here it is especially important to remove these mobile additives from the substrate by thoroughly cleaning the surface just prior to application of a hydrophilic coating chemistry. Even with more conventional medical device substrates like PEBAX or nylons, higher-durometer segments are typically harder to coat effectively than softer ones using the same chemistry.

Modern catheters often combine multiple resins and durometers, creating transition zones where adhesion and durability can change. When delamination occurs, it frequently starts at these interfaces. We encourage teams to design and validate for the most difficult segment, and to test friction and adhesion at multiple points along the shaft. Simplifying to a single coating solution across multiple substrates and durometers—such as using more robust chemistries that perform well without primers—can reduce masking, documentation burden, and the risk of process errors on the manufacturing floor.

Dr. David Kissel: Sharp edges from flush cuts, threads, or complex geometries can create thin coating areas or localized stress points, which may increase the risk of wear or adhesion issues. Adding a small edge break or radius to transition areas helps improve coating uniformity and durability.

Surface finish and material preparation also play a critical role. Poor surface finishes, contamination, or inadequate cleaning can reduce coating adhesion and consistency. Proper surface preparation, including thorough cleaning and, when required, additional surface treatments, is essential to ensure coating systems perform as intended.

Components exposed to repeated friction or high mechanical loads may experience accelerated wear. Selecting an application-specific coating designed for the device’s mechanical demands helps maintain durability and performance.

Most potential issues can be avoided by incorporating design-for-coating principles early in device development and collaborating with coating SMEs during R&D. Early review of component geometry, tolerances, materials, and application requirements helps ensure the selected PTFE Natural coating performs reliably throughout manufacturing and clinical use.

Lincotek Medical: When having a hard coating on any articulating surface against polyethylene, it is crucial to minimize roughness of the final part. We ask our customers to take great care in polishing the joint surface, ensuring that it is free of scratches and residue. We have internal specifications for parts ready for coating to ensure expected performance of the DLC coating. Of course, we can manage this surface preparation for customers as well.

Margy Lydon: Sharp edges, complex geometries, and internal lumens can create challenges that lead to cracking, thinning, or delamination. Material selection is equally important: low‑surface‑energy materials such as PTFE present adhesion challenges for hydrophilic coatings.

To address these risks, surface preparation steps—such as gas plasma treatment, chemical etching, or the use of primers—can be employed to enhance adhesion. Early collaboration between the OEM and coating partner helps ensure the device geometry and material choices are compatible with the intended coating system.

James Morris: Edges, corners, and abrupt transitions cause problems. Coatings, especially liquid and powder coatings, naturally become thin around sharp edges. Furthermore, getting a coating to propagate and adhere to a tight inside corner can be difficult. Modifying these features early in the design process often results in a more robust coating and a better performing medical device. Even breaking sharp edges with a small radius can result in vastly superior coating performance.

Todd Paulsen: With almost 25 years of coating experience, there isn’t much that Formacoat hasn’t coated. We are known as the place to go for those difficult, out-of-the-box product designs that many folks don’t like to touch. Almost anyone can coat a catheter, but one with multiple substrates? Odd features or controls? Only a certain section of it requires coating? What about an odd geometric shape? We have built our proprietary coating technology from the needs and demands of our customers so we can avoid any of the issues that other coating houses might have.

Katie Schindler: “Multiple substrate materials (e.g., metals, silicones, other polymers) can reduce adhesion unless the coating is engineered for broad compatibility. Complex geometries—including sharp edges, tight radii, inner surfaces, and cavities—may hinder uniform coating deposition. Thin‑wall structures can create stress points that impact coating durability.

In high flex applications such as catheters or lead insulation, repeated bending can cause premature coating wear. Coatings for devices requiring both strength and flexibility (e.g., stents) must maintain structural integrity. Materials such as HydroMed help address complex design challenges by enabling both inner and outer surface coating while minimizing the risk of leaching unreacted components.

Greg Teh: Device geometry, material selection, and processing conditions can significantly influence coating performance and durability. Complex geometries such as multilumen shafts, tight bends, step transitions, textured surfaces, or very thin-walled components can make it difficult to achieve uniform coating coverage and consistent thickness.

Material selection is another important factor. Many medical polymers used in catheter construction (TPU, Pebax, or PVC) may contain plasticizers or additives that can migrate to the surface over time. These additives, such as processing aids, slip agents, or residual low-molecular-weight species, can reduce surface energy or interfere with coating adhesion, leading to potential issues with coatability, delamination, or durability during device use. Early collaboration between device designers, material suppliers and coating specialists helps identify compatible materials and appropriate surface preparation methods.

Curing technology is also an important consideration. Different coating chemistries require different curing approaches, including thermal or UV curing. Each method has practical constraints depending on device geometry and coating location. For example, UV curing provides rapid crosslinking but requires direct line-of-sight exposure, making it less suitable for internal lumens or shadowed areas. On the other hand, thermal curing can provide uniform curing across complex substrate geometries but must be compatible with the thermal limits of the underlying polymer substrate.

Addressing these factors early in the design phase through proper material selection, surface preparation strategies, and curing method optimization can significantly improve coating reliability and manufacturability.

Colin Weightman: When trying to improve the strength or life of a device, adding mass isn’t usually a desirable option. Changing the design, materials, or other aspects of the manufacturing process is needed. Medical devices are getting smaller, yet they still need appropriate strength to do their job. They also need to last longer. These smaller, more intricate designs benefit from precision shot peening as a surface treatment to improve strength and life. 

A compressive layer is created during peening by bombarding a metal surface with spherical media, creating tiny overlapping surface dimples and forcing the molecules to become more tightly packed together. The underlying, unaffected material resists this, placing the surface in a state of high-magnitude residual compressive stress. Creating a compressive surface layer helps by actively counteracting tensile stresses, which inhibits the initiation and growth of cracks, thereby significantly increasing material fatigue life and strength.

Brusco: When a surface treatment/coating process changes, how is regulatory impact assessed?

Dr. Calvet: A change to a surface treatment or coating typically requires regulatory resubmission to demonstrate that the new coating is safe, effective, and equivalent to the previous version. A change in coating begins with an initial assessment to define the scope of work—such as coating‑characterization testing, biocompatibility evaluation, and shelf‑life studies. Some of these assessments are performed at the full‑device level to confirm overall system safety and performance.

Dr. Kissel: When any of our coatings undergo a process change, the regulatory and performance impacts are assessed through a structured change-control and risk-based evaluation to determine whether the change could affect device safety, performance, or biocompatibility.

We first document the change and evaluate it through a risk analysis and an engineering verification procedure under our quality management system (QMS) to determine whether the coating’s critical attributes—such as thickness, lubricity, adhesion, durability, or material composition—are affected. If there is potential impact, additional verification testing, biocompatibility review, and process validation may be required to confirm equivalence.

We then notify any customer affected by the change so they can assess whether it triggers regulatory notifications or submissions (e.g., FDA 510(k) change evaluation or EU MDR change assessment) or any internal quality or manufacturing changes.

Lincotek Medical: Any coating on an implantable device, be it TiN or TiNbN or DLC or any other, requires risk analysis. ISO 13485 is clear in this regard: “The organization shall determine the significance of the change to function, performance, usability, safety, and applicable regulatory requirements for the medical device and its intended use. Before implementation, the changes shall be reviewed, verified, validated, and finally approved”. We can offer assistance with this evaluation.

Lydon: We treat any coating formulation or process change as a formal design change. Early communication with the OEM is essential, as they are ultimately responsible for determining regulatory impact. Our role is to support their risk assessment by providing data, technical rationale, and guidance on how the change may affect coating performance, biocompatibility, or device safety. This collaborative approach helps ensure a smooth transition and a clear regulatory pathway.

Morris: There is no easy way to say this, except to state that changes late in the design process, and especially coating changes, can be very costly. The evaluation of the regulatory impact of changes must take into account the performance of the entire device, including manufacturing processes. Maintaining regulatory requirements when a coating has been changed often requires more than just repeating biocompatibility testing. Process validation for the coating application processes, as well as device performance validation, will most likely need to be repeated. This is why a defined, formal process for selecting an appropriate coating, implemented early in the design process, is so critical.

Paulsen: Regulatory impact is evaluated per our risk management process, in cooperation with our customers’ requirements and QMS systems. What this means is when a change is going to or needs to occur, this is discussed in advance with our customer and put through the paces of against the requirements and QMS systems already in place. As with any partnership, we work side by side to make sure we are in compliance with all regulatory issues our customers might face.

Schindler: Regulatory readiness begins with a comprehensive review aligned with FDA and ISO quality system requirements. Changes to additives, curing chemistry, or coating thickness may trigger the need for a renewed biocompatibility evaluation in accordance with ISO 10993. Equally important is performance reverification, including adhesion, lubricity, durability, extractables and leachables, as well as sterilization and aging studies.

Dr. Kristin Taton: Any change to a coating or its process ultimately becomes part of the device manufacturer’s regulatory narrative. It begins with a formal risk assessment and flows into impact analysis documentation, validation, and testing. Whether the change involves the coating itself or how it is applied, it must be reflected in regulatory filings—updates to Device Master Files—and supported by data showing that device performance and safety has not been compromised.

Changes to coating chemistry carry the greatest regulatory burden. Switching formulations or suppliers can trigger repeat biocompatibility testing, chemical characterization/extractables and leachables studies, and performance testing. For blood-contacting or long-term devices, this work can be extensive, costly, and time-consuming—sometimes reaching into the “half-million dollars or more” range in complex scenarios.

Process-only changes that adjust coating parameters, equipment, production scale, or line layout while maintaining the same chemistry are generally more manageable, but they are not insignificant. Manufacturers must still complete process validation and risk analyses to confirm there are no unintended impacts.  Changing only the process may avoid repeating full biocompatibility testing because the underlying chemistry remains unchanged.

Teh: Any change to a coating formulation, process parameter, or manufacturing location can have regulatory implications. Under both U.S. FDA regulations (such as 21 CFR Part 820 design control and change management requirements) and EU Medical Device Regulation (MDR) requirements for CE-marked devices, manufacturers must evaluate whether the change could affect device safety, performance, or biocompatibility.

A risk-based assessment typically considers whether the change may influence coating adhesion or durability, lubricity and device performance, shelf-life impact, sterilization compatibility, extractables and leachables profiles, biocompatibility outcomes under ISO 10993, and particulate generation or coating integrity.

Depending on the magnitude of the change, manufacturers may need to perform comparative testing, revalidation, or regulatory submissions to demonstrate continued equivalence and compliance.

Industry experience has shown that coating failures can lead to device recalls if coating delamination or particulate generation affects patient safety. As a result, robust process validation and long-term manufacturing consistency are critical. Organizations with extensive coating experience and a strong regulatory track record, such as Hydromer, maintain rigorous quality systems and validated processes. A clear history without coating-related recalls reflects the importance of process control, materials expertise, and collaborative development with device manufacturers, particularly when supporting coating transitions or process updates.

Brusco: How do cost-reduction efforts affect surface treatment/coating selection or thickness?

Dr. Calvet: One of the most impactful considerations is whether a primer layer is required. Many traditional hydrophilic coatings use a multi‑step process—applying a primer, curing, then applying and curing the topcoat. Each step adds time, labor, energy use, and handling risk. Freudenberg Medical’s LUBRITEQ platform is designed as a single‑step coating system for most standard substrates, eliminating the primer layer and effectively cutting the coating and curing process in half compared to conventional multi‑layer chemistries.

Curing methodology is another important factor. Thermal curing can require 30-90 minutes or longer per cycle, creating batch‑processing bottlenecks in otherwise lean production environments. LUBRITEQ, as a UV‑cured system, can achieve full cure in as little as 10 seconds, enabling true in‑line processing, supporting lean flow, and improving line balancing—all of which contribute directly to lower per‑unit manufacturing costs.

Inspection requirements also influence cost. Traditional dye‑based uniformity testing relies on hazardous chemicals, requires controlled lab environments, specialist operator training, and is inherently destructive—resulting in product scrap. LUBRITEQ coatings can instead be evaluated using fluorescence‑based optical inspection, which is non‑destructive, compatible with in‑line integration, and eliminates the environmental, safety, and yield burdens associated with dye testing.

Ultimately, coating selection should be viewed not just as a materials decision but as a process‑level decision. When evaluated holistically—including process steps, curing time, inspection methods, and line integration—the right hydrophilic coating platform can deliver meaningful operational efficiencies while maintaining high standards of clinical performance and regulatory compliance.

Guire: The most effective cost optimization happens early, during coating selection and initial process design, rather than after a device is already commercialized. Once a device has cleared a 510(k) or PMA, the regulatory cost of switching coatings is often prohibitive. As a result, teams tend to focus on commercial levers such as tiered pricing, volume discounts, or eliminating royalties rather than changing chemistries.

Manufacturability is one of the biggest cost drivers. Pretreatment steps like plasma treatment require batch processing with the resultant workflow interruptions, as well as potentially higher capital investment or outsourcing. Choosing a coating that does not require significant pretreatment eliminates these unnecessary costs, as does consolidating to a single coating composition that can perform well across a wide variety of substrates. Decreasing the number of coating steps and solutions can significantly reduce per-device cost while also simplifying quality systems and lowering the risk of line-level mix-ups.

Coating thickness is another important variable. Thinner coatings are typically less expensive and often lower risk of particulate generation.  Many devices have tight tolerances that require very thin coatings. These thin coatings typically have as good or better performance vs. thicker coatings on lubricity and durability testing. Thicker is not inherently better; the goal is to identify the thinnest coating that reliably delivers the required clinical performance.

Chemistry price per liter is only a small part of the total cost equation. True cost depends on yield, surface area, geometry, parts per liter, labor, and process time. That’s why we advocate for involving coatings early and evaluating the entire manufacturing ecosystem when making cost-reduction decisions.

Dr. Kissel: We understand our customers’ need to reduce costs over a product’s lifecycle. The PTFE Natural family of coatings provides consistent, robust PTFE coatings across a wide range of applications, materials, and substrates while meeting device performance requirements. We work with customers early to review cost initiatives through engineering and quality change-control processes. When regulatory requirements limit any change, we collaborate to evaluate alternatives and verify performance through testing and process validation. This approach helps ensure cost improvements do not compromise coating reliability, quality, or device functionality.

Lydon: Cost‑reduction initiatives must be balanced against coating performance and regulatory implications. Switching to a lower‑cost coating or reducing coating thickness may appear attractive, but such changes can trigger additional testing, regulatory submissions, or performance trade‑offs. Because coatings are integral to device function, even small modifications can have outsized downstream costs. Thoughtful evaluation is essential before implementing any cost‑driven changes.

Morris: Cost vs. performance, like in most markets, is a very real thing in the coatings industry. High-performance coatings such as ETFE and PEEK are incredibly robust, especially with regard to dielectric strength and holding up to many re-sterilizations. But they come at a high cost, often approaching an order of magnitude higher than some other commonly used coatings. While some medical devices absolutely require these high-performance coatings in order to achieve their operational performance goals, many do not. By starting with defining the user needs of a device, and then having this drive into the product performance specifications, including the coating performance specifications, an appropriate coating can be identified, often at a lower cost. In other words, we strive to select a coating that is appropriate for the device, but not a coating that is complete overkill from a cost and performance perspective.

Paulsen: We have never been about maximizing price points or using pricing models that continually take money out of the hands of customers. We know more about surface modification and treatment than anyone else out on the market, and have all the bells and whistles to make it happen. It is why we have over 90 different coatings to choose from! This allows us to find the perfect coating solution for devices, applying at an appropriate thickness for functionality, durability, and cost from the beginning. We also understand that speed to market is of the essence, so we can plan develop pathways that ensure a cost reduction effort is continually sought after initial production.

Schindler: Cost‑driven engineering decisions often influence how coatings are selected and applied. Optimize coating thickness to ensure required performance while minimizing material use and waste. Optimize batch size of coating solutions to reduce costs and manufacturing inefficiencies. Process simplification, such as using TPUs (e.g., ChronoFlex grades) eliminates the need for adhesives, tie layers, or secondary materials—reducing both cost and complexity.

Teh: Cost pressures are a constant reality in medical device manufacturing, but coating optimization must be approached carefully. Attempts at reducing coating thickness or switching materials solely for cost reasons can negatively affect lubricity, durability, or particulate performance.

In practice, cost optimization often focuses on manufacturing efficiency, coating yield, and integration with device component design rather than simply minimizing coating thickness or coverage. By considering coatings together with component architecture, extrusion design, coating automation, and material compatibility, manufacturers can achieve both performance and cost efficiency.

Materials that Heal
Old Bethpage, N.Y.-based Himed creates and customizes bioactive calcium phosphate-based biomaterials and provides biocompatible surface treatments for orthopedic, spinal, and dental implants. The company also operates a 3D-print and biomaterials research center for rapid prototyping. Because of this unique position in the medical device industry, MPO spoke to the company’s president Craig Rosenblum to gain further insights.

What differentiates Himed’s biomaterials and surface treatments from competitors in the implant space?
Craig Rosenblum: We differentiate ourself through deep expertise in the calcium phosphate biomaterials and a unique ability to precisely control critical material properties such as composition, particle size and distribution, morphology, and surface area. Our capability to manufacture biomaterials to rigorous standards and optimize their performance through a variety of surface treatment processes enables the creation of customized solutions tailored to specific medical implant geometries and forms.

Spearheaded by our newly established Bioceramics Center of Excellence, a strong emphasis on R&D leads to continuous innovation and the introduction of novel materials and technologies that keeps us at the forefront of biomaterial technologies. 

With 35 years in the biomaterials industry, we have established a strong global presence and long-standing partnerships across the medical device sector. We have supplied biomaterials and surface treatment technologies to implant manufacturers, researchers, and healthcare providers all around the world. 

How is additive manufacturing changing your approach to biomaterials and implant surface engineering?
Rosenblum: With advancements in additive manufacturing, we can now create more complex implant surfaces, allowing for further optimization of biomaterials for stringent applications, such as biomceramic additive manufacturing and enhanced post-processing techniques. New technologies have inspired enhanced applications for existing biomaterial products. While technology plays a crucial role in these developments, maintaining the quality of materials remains paramount. 

What are the benefits of partnering with a business that develops their own biomaterials for surface treatment?
Rosenblum: As the direct manufacturer of biomaterials, we understand the importance of critical material parameters and their influence on developing custom implant surfaces. We maintain FDA Master Files for both the manufacturing of biomaterials and the associated surface treatments. 

Please describe the process of using Himed’s analytical lab services. Can you share any examples where your materials enabled a breakthrough in implant performance or patient outcomes?
Rosenblum: The process of working with our analytical lab is designed to be collaborative and straightforward. It typically begins with an initial discussion where our client discusses their material, implant, or processing challenge with our technical team. Based on the project goals, we can recommend the appropriate analytical techniques based on which material/surface characteristics are most critical. 

A typical example is when an implant manufacturer approaches us seeking to improve the performance of an existing medical device, such as a calcium phosphate used in a bone graft device. Leveraging our analytical laboratory, the biomaterial can be fully characterized—evaluating critical parameters such as composition, particle size and distribution, morphology, and surface area. Based on this characterization, our R&D team can optimize the calcium phosphate formulation and processing conditions to better match the desired conditions. When working closely with these device manufacturers, the improved material may demonstrate enhanced osteoconductivity and more predictable clinical behavior, ultimately helping the device achieve stronger bone integration and improved patient outcomes.

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