Single and Multi-lumens
Lumens provide working channels within minimally invasive devices through which fluids or other devices pass. These can be extremely small lumens used in neurovascular devices, or relatively large passageways for laparoscopy devices. Dunn is capable of producing single lumen tubes with diameters as small as 0.008 inches and as large as 0.480 inches.
Multiple lumens are commonly used in interventional devices to allow for multiple fluid channels, accommodate multiple devices, or both. These lumens come in a wide variety of shapes, from circular channels for guide wires to ‘D’ configurations used in peripherally inserted central catheters (PICC lines). Dunn has produced small catheters with more than 17 lumens.
Over the past 30 years of extruding medical tubing, Dunn has established a library of mandrels and dies. These have proven to be invaluable for creating rapid prototypes to accelerate time-to-market for medical device marketers.
Simultaneous extrusion of multiple materials, with unique property profiles, improves the functionality of tubing and reduces secondary manufacturing operations. Minimally invasive catheters often require discrete physical properties on the inner and outer surfaces. For example, passage of guide wires and other instruments through the lumens requires low friction polymers on the inner surface of the tube. Atraumatic requirements of the outer catheter surface often require soft, flexible polymers. Coextrusion of different materials for the inner and outer layers allows designers to achieve both outcomes.
Minimally invasive device tubes frequently require radiopaque fillers added to the polymer to provide visibility under X-ray or fluoroscopy. However, these compounds can be substantially more costly than unmodified polymers. Coextrusion of longitudinal radiopaque stripes with unmodified polymers can be an economical alternative.
Dunn offers a wide array of coextrusion combinations that include multiple materials, colors, layers, stripes and more.
Tapered Tubing (Bump)
Precision controlled pullers and die head technologies allow for the variation of extrusion cross sections along the length of a tube. This is often advantageous for offering greater access to multiple lumens at the larger, proximal end. This is commonly referred to as bump tubing.
Variation in diameter can also enhance structural performance and feel of the tube. Larger diameters at the proximal end provide clinicians with greater rigidity and control. Smaller diameters at the distal end provide more flexibility for navigation.
Dunn offers tapered tubing for single lumen, multi-lumen and coextruded extrusions.
Longitudinal Wires and Jacketing
Wires or fibers can be incorporated into extruded tube walls along the length. These inclusions provide specific benefits, such as tensile strength, flexural control or electrical transmission. Jacketing often refers to a wire placed in the center of the extrusion, surrounded by polymer.
Dunn offers a wide range of options for incorporating longitudinal wire and fibers with custom extrusions for medical device components.
The term “microextrusion” refers to extremely small diameter extrusions. With regards to catheters, these are generally 2 to 3 French size or less and used to reach extremely small blood vessels. Neurovascular procedures frequently require catheters of this size.
The metric measurement for catheter diameter (mm) can be determined by dividing the French size (Fr) by 3 (i.e., D (mm) = Fr/3). For example, a 3 Fr micro catheter has a diameter of 1 mm. Increasing French sizes correspond to a larger diameters (note: this is the opposite ofs, where the diameter is 1/gauge, and larger gauge sizes represent increasingly narrow needle bores).
Dunn has the ability to extrude medical tubing with outside diameters as small as 0.008 inches; less than 1 French size.
|French Gauge||Diameter (mm)||Diameter (inches)|