As medical technologies improve, the role of surface engineering is becoming more important. This is especially true when it comes to caring for patients. One major advancement in this area is the application of lubricious coatings on medical device surfaces. These special polymer coatings help reduce friction between the device and the patient. This improves the performance and durability of the devices. It also makes them safer and increases patient comfort. In this article we introduce what these coatings are, what they are used for, and their benefits.
Why Lubricity Matters in Medical Device Applications1
Medical devices are often used in and around delicate parts of the human body. This happens in a wide range of procedures. Examples include treating blood vessels, using catheters, performing eye surgeries, or doing minimally invasive surgeries. Devices like catheters, guidewires, stents, and endoscopic instruments must move through complicated pathways in the body. And they must do it without hurting tissues or causing pain or trauma.
However, many common materials used to make medical devices, such as silicone, latex, polyurethane, stainless steel, and polycarbonate, are naturally repellent to water (hydrophobic). This can create a lot of friction (and pain). This can make it difficult for the devices to work smoothly and safely inside the body.
Friction can cause several problems. Examples include difficulty inserting devices, irritation to body tissues, longer procedure times, and even tiny tears that raise the risk of infection. To address these issues, lubricious polymer coatings are used. These coatings help decrease surface resistance, making the devices safer, more comfortable, and more efficient.
Understanding Lubricity & Lubricious Coatings
Lubricious coatings work by reducing the coefficient of friction (µ). This tells us how easily one surface can slide while in contact with another. A lower µ means that movement is smoother and there is less resistance when parts move against each other. It is divided into two types:
- Static coefficient of friction: The force needed to initiate movement.
- Dynamic coefficient of friction: The force needed to maintain movement.
An ideal medical coating exhibits minimal difference between these two values.
Friction can severely compromise the performance and safety of medical devices. Excessive resistance can damage tissues, increase procedural time, and lead to device failure (due to durability issues). In turn, low-friction coatings are essential for patient comfort, procedural efficiency, and long-term safety.
Types of Lubricious Polymer Coatings2: Hydrophilic vs. Hydrophobic
Lubricious polymer coatings can be divided into two main types based on their chemical properties. These two types are hydrophilic coatings and hydrophobic coatings.
Hydrophilic Lubricious Coatings
Hydrophilic lubricious coatings attract water and can help reduce friction in wet conditions. These slippery-when-wet coatings absorb water or bodily fluids to create a slippery surface.
These coatings are made from materials like polyvinylpyrrolidone (PVP), polyethylene glycol (PEG), or hyaluronic acid, etc. They are extremely effective in wet conditions. They can lower the friction coefficient (µ) to about 0.01, which is as slippery as ice.
Hydrophilic lubricious coatings are commonly used for medical applications, such as:
- Catheters and guidewires: they are used for smoother insertion and maneuverability. Learn more about Hydrophilic Catheter Coatings For Reduced Friction.
- Intraocular lenses: hydrophilic coatings reduce the risk of irritation during eye surgery.
- Urethral and vascular devices: these coatings are used to prevent trauma during insertion and removal of urethral and vascular devices.
Here are some key benefits of hydrophilic lubricious coatings:
- Reduced Friction: Hydrophilic medical coatings are lubricious. They create a slippery surface that minimizes friction between a medical device and the surrounding tissue.
- Enhanced biocompatibility: Hydrophilic coatings are biocompatible. They are safer and do not react with the body tissues.
- Patient Comfort: These lubricious coatings improve patient comfort by allowing smoother insertion and less trauma.
- Anti-fouling: The smooth, water-attracting surface also helps to prevent bacterial adhesion, reducing the risk of infection.
- Thromboresistance: Hydromer® Thromboresistant Coatings are “slippery-when-wet” and are non-leaching. These lubricious polymer coatings reduce the adherence of blood to the surface of the device. This can reduce blood clotting when coming in contact with medical devices. The result is improved patient safety and clinical outcomes as well as longer lifetimes of the products.
Learn more about Hydromer Medical Device Coatings.
Hydrophobic Coatings:
Hydrophobic lubricious coatings repel water, instead of absorbing it. They help reduce friction without needing to absorb water. As such, they are suitable in dry conditions. These coatings, such as Parylene coatings, are dry films. Similar to hydrophilic coatings, hydrophobic lubricious coatings provide lubrication and are durable.
Here are some benefits:
- Biocompatibility: Parylene is safe for use in the body. It does not react with body fluids, making it suitable for long-term medical implants.
- Uniform Thickness: Parylene can coat complex shapes evenly, even at very small sizes, thanks to its unique vapor-phase deposition process.
- Chemical Resistance: It can resist damage from body fluids, sterilization agents, and other strong chemicals.
These characteristics make dry-film lubricious coatings suitable for implanted devices, sensors, surgical tools, and implants.
5 Properties of Effective Lubricious Polymer Coatings
Effective low-friction coatings are designed to reduce friction and enhance wear resistance. These coatings must demonstrate several fundamental properties. These include:
- Low coefficient of friction
- High load-bearing capacity
- Exceptional durability under demanding conditions
- Thermal and chemical stability
- Biocompatibility (in medical device applications)
Biomedical Applications for Lubricious Coatings
Lubricious coatings are used for many biomedical applications. Some common biomedical applications of these coatings are discussed in more detail below.
Intravascular Device Coatings
One of the prominent biomedical applications of lubricious coatings is for intravascular devices. Examples include catheters, sheaths, and guidewires. Lubricious polymer coatings on these devices are essential for facilitating smoother navigation through tortuous blood vessels.3,4
Hydrogel Microspheres
Super-lubricious polyethylene glycol (PEG) hydrogel microspheres have demonstrated promising friction-lowering properties. These have shown promise in potentially reducing the progression of osteoarthritis and delaying the need for invasive surgical interventions, such as joint replacements.5 PEG coatings are biocompatible, biodegradable, and can be custom formulated to meet specific product requirements. Learn more about contract R&D and custom formulation of hydrophilic coatings.
Endovascular Procedures
Chitosan derivative coatings have contributed valuable in vitro evidence around the friction behavior of hydrophilic lubricious layers. They have demonstrated potential in reducing mechanical trauma during endovascular procedures.1 Hydrophilic lubricious coatings are commonly applied on devices used in these procedures, such as catheters, guidewires, balloons, stents, and more.
Sustainability and Biocompatibility Considerations
The selection of the proper medical coating is becoming more important. This is especially true regarding environmental regulations and concerns. Lubricious coatings need to work well, but they also have to be safe for people (and the environment).
This means they should not be toxic, cause cancer, or harm the environment if at all possible. Additionally, companies are trying to improve their manufacturing processes in order to reduce waste and save energy.
Companies like Hydromer, Inc. are taking the lead in creating customizable and eco-friendly hydrophilic coatings solutions to meet these challenges. These coatings are used in many different medical applications.
Conclusion
Lubricious polymer coatings are essential in the design of advanced medical devices. They play a crucial role in ensuring patient safety, comfort and outcomes. They also are important in making procedures more efficient, and increasing the lifespan of medical devices. Lubricious coatings can be hydrophilic (water-loving) or hydrophobic (water-repelling) depending on the purpose. They are important for reducing friction during delicate medical procedures.
As material science improves, we can expect to see even more advanced and versatile coatings. These new coatings will help create a new wave of high-performance medical devices that are safer for patients and more effective for medical professionals.
Need a custom lubricious coating for your medical device? Our team can custom formulate a coating to meet your specific product requirements. Contact the coating experts at Hydromer to get started.
References
Click to see references for this article
1. Niemczyk A, El Fray M, Franklin SE. Friction behaviour of hydrophilic lubricious coatings for medical device applications. Tribology International. 2015/09/01/ 2015;89:54-61. doi:https://doi.org/10.1016/j.triboint.2015.02.003
2. Uyama Y. Lubricating polymer surfaces. CRC Press; 1998.
3. Lin C, Wan H, Kaper H, Sharma P. A hyaluronic acid based lubricious coating for cardiovascular catheters. Tribology International. 06/01 2020;151:106495. doi:10.1016/j.triboint.2020.106495
4. Edwards PA, Price M, Nimchuk N, Mahon J. Novel Water Loving Coatings (WLC) Lubricious and Durable Guidewires. 2017; Accessed 2/1/2025. https://doi.org/10.1115/DMD2017-3434 2017 Design of Medical Devices Conference
5. Stealey S, Dharmesh E, Bhagat M, et al. Super-lubricous polyethylene glycol hydrogel microspheres for use in knee osteoarthritis treatments. NPJ biomedical innovations. 2025;2(1):11. doi:10.1038/s44385-025-00011-3
