Blog Post from John Schmitz, President of Aberdeen Technologies
In 1983 I was contacted by an engineer at Baxter who was looking to manufacture a multi-lumen heart catheter using the insert molding process. At the time this had never been done before. All catheters were assembled using a pre-molded manifold and then gluing the extension lumens in place. The process was very time consuming with high reject levels and involved noxious chemical adhesives which were disagreeable to the workers who used them.
Our concept involved placing stainless steel wire mandrels through individual extension lumens, then positioning them into separate passageways in a multi-lumen extrusion. This assembly was then placed in a mold and polyurethane was insert molded in the shape of a manifold. Afterward the mandrels were removed, leaving unobstructed passageways in the plastic manifold connecting the extension lumens to the multi-lumen extrusion. The greatest challenge was insuring the channels were not touching one another, which would result in leakage between the passageways when fluids were introduced into the assembly during a surgical procedure.
The initial manifold incorporated a flat plane in the form of a Y shaped profile, however it became very difficult to keep the channels from crossing over into one another with this design because the mandrels would shift and touch one another when plastic was injected. An alternative design was formulated which separated the extension lumens into a circular pattern, allowing for more space between the mandrels and preventing them from touching during molding. This proved to be very effective and today it is often combined with insert molding when there are more than 3 lumens in a catheter assembly.
Aberdeen Technologies is often called upon to assist with other complex catheter designs being developed which offer smaller footprints and increasingly thinner lumen diameters.