Extruded hoses and tubes are extensively used within the healthcare and medical industry in a wide variety of applications, from wound drains to catheters, from drug delivery to feeding tubes. Technology has moved far beyond the production of single, hollow tubes to multilumen ones that may incorporate stops, bumps, and varying thicknesses in one design.
Significant benefits can be achieved by taking advantage of innovative processes and the latest material options to reduce device manufacturers’ total cost of ownership while increasing component integrity. At the same time, the processes can improve patients’ quality of life by facilitating reduction in device size and weight, as well as incorporating multi-faceted geometries, multiple substrates, and active pharmaceutical ingredients (APIs). This enhances in-hospital treatment in terms of safety and comfort and makes wearable medical device options more feasible.
Global Market Trends
According to The Business Research Company, the global medical device market reached a value of nearly $456.9 billion in 2019, having increased at a compound annual growth rate (CAGR) of 4.4 percent since 2015. The market is expected to grow to $603.5 billion by 2023.
The growth in the medical device market is causing an increase in demand for medical tubing. According to Grand View Research, the global medical tubing market was estimated at $6.4 billion in 2018 and has an expected CAGR of 9.2 percent through 2025 when it is expected to reach $11.9 billion.
This growth can be attributed to the availability of cost-competitive, medical-grade plastics, a surge in demand for single-use, disposable devices (due to growing awareness of hospital-acquired infections and concerns with spreading them), and developing countries having increased access to healthcare supplies.
Factors and Material Considerations in Tubing and Hoses
Before designing tubing and hoses for medical devices, engineers should consider factors such as size, hardness, tear strength, elongation, surface friction, transparency, and visibility.
Depending on the application, medical hoses and tubing are produced in a variety of materials. These include plastics, such as fluorinated ethylene propylene (FEP), nylon, PVC, polyetheretherketone (PEEK), polytetrafluoroethylene (PTFE), and thermoplastic elastomers (TPE), as well as elastomers, in particular, silicone.
Silicone is a key material for tubing in medical devices, making it attractive for healthcare applications, especially for implants. The unique characteristics of high consistency rubber (HCR) silicones offer an uncured, “green” strength that allows for a variety of custom processing techniques. Additionally, silicone is non-reactive with other elements, odorless, tasteless, and nontoxic, and it has good tensile strength.
Recent innovations and techniques in medical tubing manufacturing are allowing medical device manufacturers to meet patients’ needs more effectively. Tubing technologies include the following:
High-precision, microextrusion, and thin-walled tubing for minimally invasive surgical devices.
Platinum-cured silicone for use in implants.
Multicomponent extrusion featuring radiopaque stripes for visibility in an x-ray or fluoroscope.
Reinforced and kink-resistant tubing used to keep fluid paths open.
Extruded ribbon and film used in diaphragms to support seals in devices such as pacemaker generator housings.
Jacketed wires and cables used to power implantable heart pumps.
Twisted extrusions for applications in which implanted power or sensing cables require strain relief from repeated flexing and bending, as with pacemaker leads.
Custom profiles used to seal housing assemblies and repair heart valves.
Bump tubing applied to plastics and elastomers, including silicone.
Bonded or overmolded stops typically added to peristaltic pumps for infusion, internal feeding, laboratory equipment, diagnostic equipment, and fluid transfer.
Formed extrusions used to fit tortuous anatomy or spiral shapes that might be used to soften contact within the bladder.
Multilumen extrusion for catheters, electric medical devices, analytical equipment, fluid transfer, drug delivery, and medical instrumentation.
Geometric transitioning extrusion applied to custom applications with precision tolerances.
Geometric transitioning single lumen for custom-end assemblies, such as accommodation of connectors, fittings, and peristaltic pumps.
Drug-eluting silicone extrusions that help prevent infection.
Foam extrusion that provide additional cushion space.
Applications and Advancements
Different processing options have led to groundbreaking ways of producing tubing. When customers partner with medical device component manufactures that utilize the latest capabilities and technologies, they can create solutions that optimize the performance and usability of medical devices.
For example, in cardiac catheterization, wider, thinner tubes make the procedure less invasive. Inserting a narrow micro-extruded catheter into a large blood vessel that leads to the heart enables doctors to examine how well the heart is working.
These more advanced new tubing technologies can potentially meet medical device manufacturers’ goals in areas such as miniaturization, wearability, and patient care. Multilumen extrusion allows for intricate design, more complex shapes, and better texture in the finished tubing. Filaments and rigid monofilaments within the walls of the product add reinforcement that provides the tubing with better kink- and crush-resistance.
The most accomplished tubing manufacturers are now pushing the limits of tubing size in terms of miniaturization, individual lumen, overall cross section, and wall thickness. Tubing with controlled texture can eliminate the risk and cost of additional coating processing in some cases. Silicone is inherently sticky, and inducing a texture on extruded silicone can address the unwanted tackiness of the material.
HCR silicone’s strength in its unvulcanized state allows for highly complex geometries in continuous extrusion processes. For example, GeoTrans™, a Trelleborg Healthcare & Medical process, enables tool components to be moved during extrusion to substantially change cross sections. It leverages the green strength of HCR silicone and eliminates assembled joints that can be weak and cause failure modes and internal misalignments, increasing component strength, longevity, and robustness.
Silicone is one of the most successful materials in the design and production of combination products, in particular, implantable devices. Due to the material’s favorable porous nature, an API can be integrated into a silicone matrix, enabling drugs to be eluted into the human body at specific doses over time.
Two methods exist for adding APIs to silicone for drug-delivery devices. The established method is the addition of an API to raw silicone. An alternative and more recent development is the impregnation of an API into vulcanized silicone by immersion. The advantages of this method are twofold: the API does not interfere with the cure chemistry of the silicone, and the API is uniformly impregnated throughout the component.
Responding to rapid growth in the medical device market, medical device manufacturers are looking to new and innovative processes, including miniaturization and wearability, to enhance their products and meet patients’ needs.
Advances in hose and tubing manufacturing techniques are helping to support these new developments and improve patients’ quality of life with better function and integrity, and by enabling the incorporation of APIs.
To facilitate the specification of these seemingly uncomplicated yet complex extrusions, it is important to work with an expert in hoses and tubing who will consider the key factors relevant to the application and can employ progressive technologies and processes to revolutionize the medical device design.
This article was written by Dan Sanchez, Product Manager Manufacturing, Trelleborg Healthcare & Medical, Fort Wayne, IN. For more information, visit here . For more information on tubing technologies and application examples, download the Advanced Extrusion Techniques whitepaper by Trelleborg Healthcare & Medical here .