Polytetrafluoroethylene (PTFE) is one of the most widely used fluoropolymers in the world. It has been used in medicine since the 1960s and now plays a major role in the design of catheters and other minimally invasive devices. Its widespread use is mostly due to its core properties, such as a very low coefficient of friction (COF) of around 0.04 and strong resistance to chemicals. It is also biocompatible and non-toxic under normal conditions, making it ideal for devices in contact with body fluids or tissues.
PTFE is primarily used in two key catheter components: the outer assembly (as heat-shrink tubing) and as liners.
This article provides a comprehensive exploration of PTFE heat shrink tubing vs PTFE liners. We will use Hydromer®’s 40+ years of material expertise to overview what each component is, how they are made, where they are used, and the differences between them.
Importance of PTFE Material in the Medical Device Industry
PTFE was discovered by chemist Dr. Roy J. Plunkett on April 6th of 1938. The carbon and fluorine backbone of PTFE gives it properties that most commercial-grade plastics cannot match.
Common medical materials such as nylon, PVC, polyurethane, and silicone are easy to process and lower in cost. However, they soften, swell, or react when pushed to their limits.
PTFE sits in a different class, with a very low coefficient of friction (CoF) around 0.04, near-complete chemical inertness, and a stable thermal performance range from -200°C to +260°C.
PTFE’s unique properties make it a reliable choice for interventional devices. Therefore, it is commonly used in neurovascular, cardiovascular, and urology procedures. It is one of the most commonly used materials in catheter manufacturing. Companies such as Hydromer® (alongside their partner jMedtech) manufacture a comprehensive range of PTFE tubing and liner products for medical device manufacturers worldwide. These include liners, mini tubing, multi-lumen tubing, as well as PTFE (and FEP) heat shrink tubing.
We give an overview of both heat-shrink tubing and PTFE liners below.
What is Medical-Grade PTFE Heat Shrink Tubing?
A PTFE heat shrink is also known as PTFE cladding. This type of PTFE tubing shrinks to a smaller diameter when heat is applied. They are always supplied in an expanded state and recover to their original shape in the presence of heat.
They are helpful in encapsulating, insulating, or joining components into a single, clean assembly.
Hydromer® PTFE heat-shrink tubing is produced with smooth, uniform walls. It is also offered as a Zebra (spiral) version with colored spiral stripes for better visibility under imaging.
Key Applications of PTFE Heat Shrink in Catheter Manufacturing
In catheter manufacturing, PTFE heat shrink is mostly used for the following:
- encapsulation and cladding
- joining and reinforcing components
- insulating electrodes in energy-based devices.
It is able to stay on the device as a permanent protective layer because of its low friction and chemical stability.
Shrink Ratio and Operating Temperatures
The shrink ratio is the ratio between the expanded inner diameter and the final recovered inner diameter. It describes how much the tubing contracts (shrinks) when heated.
Hydromer® PTFE heat-shrink tubing is available in ratios such as 2:1, 3:1, 4:1, 5:1, and 6:1. It simply means our PTFE heat shrink tubes can recover to one-sixth of their expanded state.
A typical PTFE heat-shrink tubing can safely withstand temperatures ranging from -200°C to 260°C. This means it is fully compatible with a variety of sterilization processes. The tubing shrinks at higher temperatures, generally between 330°C and 350°C. This means it stays stable in normal use and only shrinks during controlled heating.
PTFE Heat Shrink Tubing Dimensions and Tolerances
Hydromer® PTFE heat-shrink tubing is available in a range of sizes to ensure compatibility with various medical devices.
In the expanded state, our PTFE heat shrink tubing has an inner diameter ranging from approximately 0.25 mm to 10 mm (0.0098″ to 0.3937″). After shrinking, the inner diameter is typically 0.15 mm to 6 mm (0.0059″ to 0.2362″). The wall thickness can be as low as 0.01 mm, minimizing the added profile on the device.
Benefits of PTFE Heat Shrink Tubing
Key factors that make PTFE heat-shrink tubing a preferred choice for cladding and component protection include:
- Precise Shrinkage: Advanced heat shrink tubing products shrink evenly with a smooth, wrinkle-free finish, even at the maximum 6:1 ratio. This gives a clean, tight fit that encapsulates medical devices without gaps.
- Ultra-Thin Wall: The wall thickness can be as low as 0.01 mm, which adds very little to the outer profile of the device. This helps keep catheters and instruments slim enough for minimally invasive procedures.
- Lubricity: PTFE heat-shrink provides a low-friction outer surface, allowing devices such as catheters to glide smoothly through complex anatomical pathways and ensuring easy insertion.
- Electrical Insulation: PTFE’s strong dielectric properties support stable performance in medical devices such as RF and electrosurgical instruments. PTFE heat shrink tubing is commonly used to insulate electrodes and energy-based components.
- Chemical Inertness: PTFE does not react with solvents, body fluids, or cleaning agents under normal operating conditions.
- Thermal Stability: PTFE heat shrink tubing is designed to withstand a wide temperature range, supporting both standard and advanced sterilization methods.
Now that we understand PTFE heat-shrink tubing we will dive into PTFE liners.
What is a PTFE Catheter Liner?
A PTFE liner is a thin tube that forms the innermost layer of medical devices, such as catheters. Its primary function is to line or create a lubricious inner channel, ensuring safe, smooth passage for other devices and fluids like medications.
Hydromer PTFE liners are manufactured through three main processes:
- Free Extrusion
- Over-The-Wire (OTW) Extrusion
- Casted OTW, also known as dip coating.
Hydromer® and jMedtech produce these under their MatrixLiner® and MorphoLiner® product lines, with strength and elasticity options such as ToughFlex® and ElastiFlex®.
Etched PTFE liners are where the outer surface of the liner is etched. This allows braids, coils, and outer jackets bond firmly to it during catheter assembly. Each process is selected based on the size, strength, and flexibility your catheter design needs.
Typical Dimensions and Tolerances
PTFE liners for medical applications require high manufacturing precision. Modern PTFE liners are available with diameters ranging from approximately 0.10 mm to 11 mm (0.0039″ to 0.433″). Wall thickness can be as low as 0.00635 mm (0.00025″), preserving maximum lumen space.
Tolerances are where PTFE liner manufacturers show their precision. At Hydromer®, we offer liners with inner diameter tolerance as tight as ±0.0051 mm (±0.0002″), and the wall thickness tolerance between ±0.0038 mm (±0.00015″).
Such tolerances become highly critical while ensuring a consistent lumen. This is important when a device like a guidewire or other instrument needs to pass through without resistance or play.
Benefits of PTFE Liners
Below are the biggest benefits of PTFE liners:
- Lubricious Inner Surface: PTFE has one of the lowest coefficients of friction of any solid material, at around 0.04. This lets guidewires, instruments, and fluids pass through the lumen smoothly, with very little resistance.
- Flow Efficiency: It plays a critical role in accurate dosing and reliable fluid or medication transport. PTFE liners create a smooth inner surface, which reduces turbulence and drag as fluids pass through. This improves flow efficiency in drug delivery systems, infusion lines, and diagnostic tools.
- Biocompatibility: PTFE is non-toxic and non-carcinogenic. It does not trigger immune or inflammatory responses when in contact with human tissue.
- Low-Particulate Generation: PTFE liners do not shed particles under normal operating conditions. This is critical for devices used in sensitive environments such as neurovascular procedures or drug delivery, where even small particulates can cause complications.
- Long-Term Durability: Advanced Hydromer® PTFE tubing resists degradation, cracking, and performance loss under normal operating conditions, even with repeated use.
PTFE Heat Shrink vs PTFE Liners: Quick Comparison
Although PTFE heat shrink and PTFE liners are made from the same material, they serve distinct functions within a device. The following table compares their key differences to help determine which is best suited for your specific application.
| PTFE Heat Shrink Tubing | PTFE Liners | |
|---|---|---|
| Purpose | Cladding that encapsulates, insulates, and joins components | Lining that reduces friction inside the lumen |
| Placement | Outer surface of the assembly | Innermost layer of devices like catheters |
| Lubricious Surface | Smooth, low-friction outer surface of medical devices | Smooth, low-friction inner surface for guidewires, instruments, and fluids |
| How It Works | Shrinks tightly when heated and creates a protective layer over the device surface | Bonded into the inner wall through its etched outer surface |
| Critical Dimensions | Shrink ratio from 2:1 to 6:1 | Inner diameter tolerance as tight as ±0.0002″ |
| Thickness | As low as 0.01 mm | As low as 0.00635 mm |
| Inner Diameter | Shrinks to about 0.15 mm to 6 mm | About 0.10 mm to 11 mm |
| Uses | Electrode insulation, component joining, encapsulation and protection | Smooth inner lining for catheters, guidewires, or instrument passage |
How to Choose Between PTFE Heat Shrink and PTFE Liners?
These two products may seem similar, but they differ mainly in their placement and purpose (how they are used). PTFE heat-shrink tubing acts as an outer cladding to protect, insulate, and join components on the exterior of a medical device, such as a guidewire. PTFE liners form the inner layer of a catheter lumen to create a smooth, low-friction channel for guidewires and fluids.
When it comes to PTFE heat shrink versus a PTFE liner, people are mostly confused about where each component sits and what job it does. Many are sure that they need PTFE, but they are not always sure which form fits their design. This is mostly because both products share the same material and the same core properties, including low friction and chemical stability.
The real difference lies in their application:
- PTFE heat-shrink tubing protects, insulates, and joins parts on the outside.
- Whereas a PTFE liner creates a smooth, low-friction channel on the inside of medical device lumens.
Here are the typical applications of both a PTFE heat-shrink tubing and a PTFE liner.
Applications of PTFE Heat-Shrink Tubing
- Catheters: PTFE heat shrink insulates the electrodes and wiring along the catheter shaft. This keeps signal transmission clean and protects the surrounding components.
- Ablation and Electrosurgical Instruments: The tubing is used to insulate energy-based tips and components in RF devices to support safe and stable performance during use.
- Guidewires: Heat-shrink tubing commonly is used for guidewires. In addition, some companies like Hydromer® offer multi-colored, zebra heat-shrink tubes. They have colored spiral stripes that improve visibility under imaging. This helps with guidewire integration and accurate positioning during the procedure.
- Interventional Catheters: The tubing shrinks tightly to encapsulate, join, and reinforce catheter components. The goal is to hold the junctions and transition points together in the finished assembly.
Applications of PTFE Liners
There are numerous applications of PTFE liners. They play a silent but highly critical role across a wide range of minimally invasive procedures. Liners are the inner layer that makes it possible for instruments, fluids, and guidewires to move through devices safely and reliably.
- Catheters: PTFE liners line the lumen of many catheter types, such as guide catheters, neurovascular microcatheters, delivery catheters, steerable catheters, and balloon catheters. The liner gives a smooth, low-friction inner channel, so guidewires, instruments, and fluids pass through with little resistance. In the case of the steerable catheters, it also makes room for pull wires while keeping the channel smooth for precise tip control.
- Introducer Sheaths and Dilators: These are used for vascular access. The liner reduces friction inside the lumen. This allows instruments and guidewires to pass through safely and more easily.
- Coil and Stent Delivery Systems: The liner keeps a consistent, low-friction lumen for deploying coils and stents. This helps the implant move and release smoothly at the target site.
- Endoscopic Devices: PTFE liners form a smooth, lubricious layer across the inner lumen of endoscopic instruments. The goal is to let the tools and accessories pass through the channel with less resistance during the procedure.
- Urology and Stone Retrieval Devices: The liner provides a smooth lumen for ureteral catheters, access sheaths, and stone retrieval devices. This supports the easy passage of instruments through narrow anatomy.
Hydromer®: Advanced PTFE Heat-Shrink Tuning and Liners Manufacturer
Hydromer®, Inc. is a leading hydrophilic coatings manufacturer and supplier with over 40 years of experience. Through a strategic partnership with jMedtech, Hydromer® now also manufactures PTFE liners, PTFE tubing, and PTFE heat shrink tubing.
Our product portfolio now includes advanced PTFE liners, tubing, and heat shrink tubing, custom hydrophilic coatings, automated coating equipment, and a full range of contract coating services.
Through this partnership we now combine 40+ years of hydrophilic coating expertise with exceptional PTFE manufacturing processes to provide device manufacturers with a single-source solution. As such, we are able to support device manufacturers at every stage of the product development lifecycle.
Our PTFE Liner Products include:
- MatrixLiner® Free Extruded Liner
- MatrixLiner® Extruded OTW Liner
- MorphoLiner® Casted OTW Liner
Our PTFE Heat Shrink Products include:
- PTFE Heat-Shrink Tubing
- PTFE Zebra Heat-Shrink Tubing
5 Top Advantages of Hydromer® PTFE Liners and Tubings
Hydromer, Inc. manufactures ultra-thin-wall PTFE liners and heat shrink tubings through advanced production processes. We select the processes according to your device’s mechanical and dimensional requirements.
Below are the top five benefits of selecting Hydromer® PTFE Liners:
- Reliable Extrusion Lines: Our production lines deliver precise micro-dimensional extrusion, achieving wall thicknesses as low as 0.00635 mm and inner diameter tolerances of ±0.0051 mm, with advanced quality inspection throughout production.
- Scalable Output: Our extrusion lines ensure reliable dimensional accuracy and consistent performance from prototype to high-volume production.
- Accelerated Timelines: Rapid prototyping and dedicated production lines enable faster development cycles without compromising quality or precision.
- End-to-End Support: We provide engineering support, design for manufacturability, regulatory services, material formulation, prototyping, testing, validation, and full-scale manufacturing within a single partnership.
- Premium Fluoropolymers: We use high-grade fluoropolymers that meet biocompatibility, lubricity, and long-term reliability standards for medical device applications.
Get In Touch
Hydromer’s PTFE liners and tubing, hydrophilic coatings, coating equipment, and contract services can support your device from early development to full-scale production.
Contact Hydromer® to learn more about our PTFE liner products or to request samples.
