Medical tubing is an essential component of countless healthcare applications, from intravenous (IV) and oxygen lines to catheters and diagnostic equipment. These tubes, often made of clear flexible polymers, must be produced to exacting standards: free of contaminants, strong under pressure, and biocompatible. However, the joining process to connect these tubes can introduce significant manufacturing challenges.
While some tubing, such as polyvinyl chloride (PVC), can be solvent bonded, more flexible medical tubing made from fluoropolymers like polytetrafluoroethylene (PTFE) cannot and are typically joined using adhesives instead. However, for applications involving drug delivery, IV lines, working with blood or other bodily fluids, etc., it can be difficult to find solvents or adhesives that are FDA approved for these types of uses.
To address these issues, engineers at EWI have developed a new laser-based welding technique that enables the clean, reliable joining of clear-to-clear polymer tubing without the need for adhesives, solvents, colorants, or any chemical surface treatment. This innovation opens up new opportunities for medical device designers and manufacturers to meet demanding cleanliness and performance requirements while making it easier to abide by regulatory standards in joining these materials.
Overcoming Longstanding Limitations in Polymer Joining
The challenge of welding clear medical tubing is both geometric and materials based. From a geometric perspective, tubes are small, round, and must be joined completely around their circumference to form a hermetic seal, while still keeping the interior of the tubes open to allow for medications, oxygen, and other material to flow through it. Unlike welds on flat surfaces, tube joints require precision alignment and uniform energy delivery around a curved surface. Traditional welding methods such as ultrasonic welding or hot plate welding often struggle to meet these requirements without introducing deformation into the finished product.
Material compatibility is an even greater hurdle. Many medical-grade polymers are chosen for their transparency, a property that also makes them a poor candidate for traditional laser welding, which typically uses a 1-μm wavelength laser. At this wavelength, the laser energy simply passes through the polymer without being absorbed, making welding impossible unless a colorant or additive is introduced, which could then disqualify a component from use. For example, IV lines or blood-handling systems must often be fully transparent and free from additives that could interact with a drug, interfere with sensors, or compromise biocompatibility.
EWI’s new process addresses this by using a 2-μm wavelength laser, which is partially absorbed by many unfilled, transparent polymers. This small but critical change in wavelength opens the door to laser welding without the need for any colorants or additives. The laser can pass through the outer surface of the first tube and is absorbed just enough by the second layer to create a controlled melt layer, forming a strong bond as the material cools.
Full Circumferential Welds Without Residue or Deformation
To ensure a uniform weld around the entire tube, EWI has developed a process using angled mirrors that reflect and guide the 2-μm laser beam around the joint. This approach allows the beam to reach all sides of the tube evenly, forming a 360° weld without needing to rotate the part or reposition the beam. The fixture design is flexible, allowing for the use of mandrels to preserve internal geometry or operating without one when the application permits.
Internal testing has shown that joints produced using this method are leaktight up to at least 100 psi, with the true strength likely exceeding that benchmark. The welds are smooth, uniform, and visually clean, with no signs of scorching or distortion. Most importantly, the internal passage of the tubing remains unobstructed, allowing for clear flow and visual inspection.
This process is especially beneficial for medical applications where leak prevention and sterility are critical, and any excess adhesive or surface defect can compromise function or safety. Since laser welding is a noncontact, heat-focused process, it avoids many of the complications associated with mechanical or chemical joining, including cure times, solvent handling, and storage requirements, as well as post-processing cleanup processes.
Tunable Wavelengths for Broader Material Compatibility
While the 2-μm wavelength used in the current system works well for a wide range of clear polymers, EWI’s platform is designed to be flexible. For polymers that do not absorb the 2-μm wavelength well, the laser source can be tuned to a different wavelength to match the specific absorption characteristics of the material.
This wavelength agility makes the system suitable for use with an expanding portfolio of medical-grade polymers, giving device manufacturers more freedom to select materials based on end-use performance, not just joinability. Whether the application requires chemical resistance, transparency, thermal performance, or specific mechanical properties, this welding system can be adapted to meet those needs.
A Cleanroom-Ready Process for Modern Manufacturing
In addition to solving longstanding bonding issues, this welding process is inherently well-suited for cleanroom environments. It produces no particulates, requires no consumables, and operates in a fast, precise, and repeatable manner. Unlike adhesive bonding or having to incorporate additives, it eliminates the risk of contamination from foreign chemicals. Additionally, it does not create the airborne particles or microvibrations other welding processes can cause that can damage sensitive components.
These advantages also support automation. The laser welding process can be integrated into existing assembly lines or custom manufacturing cells. Because it relies on optical control rather than mechanical force or complex fixturing, it offers high repeatability and minimal variation from part to part. That makes it ideal for scaling production of high-volume medical disposables, wearable devices, and next-generation fluid handling systems.
Supporting Innovation in an Expanding Market
The demand for medical tubing systems continues to grow, driven by expanding healthcare markets and the increasing use of minimally invasive and wearable technologies. As devices get smaller, more complex, and more integrated, traditional bonding methods are falling short — limited by the need for adhesives, additives, or geometries that restrict design flexibility.
This laser-based welding solution addresses these challenges directly. By leveraging a previously underutilized portion of the laser spectrum, this process enables clear-to-clear polymer tube welding without adhesives, solvents, or colorants. It delivers precise, leak-tight joints while preserving material performance and abiding by regulatory requirements. Beyond its immediate technical advantages, this method supports broader manufacturing goals. It simplifies assembly, reduces waste, and improves compatibility with cleanroom environments and automated production lines. It also gives engineers greater freedom to design for performance rather than process constraints.
As medical device design and manufacturing continues to push boundaries in miniaturization, automation, and material complexity, scalable joining technologies like this will be essential. This adaptable laser welding approach not only meets today’s requirements, but opens the door for the design of safer and more efficient medical products for the future.
This article was written by Dr. Miranda Marcus, Senior Engineer and Technical Lead for plastic and composite welding technologies at EWI, Columbus, OH. EWI is an independent engineering and technology consultancy that helps manufacturers develop, validate, and implement advanced manufacturing processes and innovations. For more information, contact Miranda Marcus at
