Minimally Invasive
Precise mechanical properties are essential for polymers used in minimally invasive devices. Laparoscopic devices rely on the high tensile properties of engineering resins like PEEK, while gastrointestinal devices require highly elastic and low durometer resins like urethane to maintain flexibility in relatively large diameter devices. The desired mechanical properties can be dialed in with precision blends of two or more polymers. Reinforcing additives can be compounded into the polymer to maximize tensile and flexural properties for torque transmission and pushability.
As catheter diameters increase to the sizes used in natural orifice or single port procedures, it becomes increasingly difficult to maintain flexibility without buckling collapse of the lumens. One solution is to utilize a coaxial catheter shaft design with a mechanized articulation joint encapsulated in a thin walled polymer extrusion to provide a smooth external surface and to prevent tissue from being engaged in the articulation joint mechanism. Another solution is to reinforce the primary outer catheter shaft with a stainless steel coil to provide the hoop strength required to resist buckling with minimal increase in overall stiffness.
The distal end of an outer catheter frequently features an atraumatic soft tip which is welded onto the main catheter shaft. This is particularly valuable if coil reinforcement has been used as the distal wire ends must be encapsulated. Minimally invasive devices also frequently feature distal holes used for irrigation and aspiration. Insertion depth is monitored by pad printed features on the outer catheter shaft. Insert molded features on the proximal end of the component allow for the attachment of device handles.