Extrusion of Low Friction and Low Stiction Microstructured Surfaces On Silicone Rubber

The purpose of this work is to create low friction and low stiction silicone surfaces without addition of coatings or lubricants but through alteration of the physical structure of the silicone surface.  Low friction  silicone is desirable in medical catheters where sliding polymer surfaces affect how well a surgeon can perform surgery.  Low stiction is desirable in peristaltic pump tubing where stiction of the inner portion of the tube causes pumping performance degradation and eventual failure.

We have micromachined an existing extrusion die and mandrel with microscopic grooves so that the extruded silicone tube has microscopic ridges on the outer diameter and inner diameter.  The microscopic ridges reduce the contact area of the silicone tube and reduce the sliding friction.  Our paper will present

• Metrology of the tubing surface
• Coefficient of Friction data showing friction reduction due to surface micro ridges

Our presentation will include video of

• Mock catheter, tube-in-tube demonstration comparing conventional silicone surface friction versus Hoowaki microstructured silicone surface friction
• Demonstration comparing conventional silicone surface stiction vs Hoowaki microstructured silicone surface stiction to thin plastic film