When developing implantable medical devices for soft tissue applications (vascular, gastrointestinal, urology, and more), one of the earliest and most critical decisions is selecting the right polymer material. The polymer you choose directly impacts biocompatibility, mechanical performance, and even regulatory approval timelines. And in many designs, the polymer needs to work in tandem with metallic components like nitinol or stainless-steel stents and frames to deliver the right balance of structure, flexibility, and the ability to be deployed through a catheter.
At Medical Murray, we’ve helped bring many implantable devices to market, and we know material selection is never one-size-fits-all. Here’s a look at the most common implantable polymers used for soft tissue devices, how they’re applied, and when they make sense, especially when paired with metal.
Expanded Polytetrafluoroethylene (ePTFE)
- Where it’s used: Vascular grafts, covered stents, surgical patches
- Why it works:
- Long-term chemical and biological stability
- Can be made incredibly thin while still having incredible strength
- Can have microporous structure to promote tissue ingrowth or densified to prevent tissue ingrowth
- Flexible and conformable for soft tissue anatomy
- Available as sheets, tubes, or membrane
- Metal pairings: Often laminated to metal frames in endovascular devices
- Watch-outs: Limited elasticity, commonly degrades from radiation sterilization
Polyethylene Terephthalate (PET / Polyester)
- Where it’s used: Vascular grafts, heart valve cuffs, surgical meshes
- Why it works:
- Excellent tensile strength and suture retention
- Long clinical track record in cardiovascular implants
- Customizable porosity via woven or knitted construction can promote tissue ingrowth
- Metal pairings: Often sewn to metal frames in endovascular devices
- Watch-outs: Less compliant than some other polymer options
Polyurethanes
- Where it’s used: Ureteral stents, vascular access ports, long-term catheters
- Why it works:
- Tunable flexibility, hardness, and other characteristics
- High abrasion and fatigue resistance in dynamic environments
- Strong kink resistance in small-diameter designs
- Metal pairings: Can be overmolded onto metallic hypotubes or wire frames for hybrid flexibility and durability
- Watch-outs: Certain grades may degrade over time, stabilized formulations are preferred
Silicone Elastomers
- Where it’s used: Gastrostomy tubes, shunts, urology implants
- Why it works:
- Soft, compliant, and inert in the body
- Excellent long-term fatigue resistance
- Flexible without added plasticizers
- Metal pairings: Molded over metal reinforcements for shape retention
- Watch-outs: Lower tear strength than some thermoplastics, high gas permeability in some applications
Bioresorbable Polymers (PLA, PLGA, PCL, PDO)
- Where it’s used: Temporary scaffolds, drug delivery systems, absorbable stents
- Why it works:
- Gradually degrades into safe byproducts
- Eliminates need for removal procedures
- Can be engineered for precise degradation timelines
- Metal pairings: Often integrated with metallic markers for radiopacity, even in fully bioresorbable designs; magnesium is emerging trend for resorbable material choice
- Watch-outs: More lot-by-lot variation than other polymers, potential for acidic degradation byproducts, packaging needs special attention to maximize shelf life
What to Consider When Choosing a Polymer
Whether your design is all-polymer or a hybrid metal-polymer construct, keep these factors in mind:
- Compliance: Match modulus to tissue to reduce trauma
- Fatigue Resistance: Handle long-term dynamic loading
- Surface Properties: Minimize thrombosis and biofilm formation
- Processing Needs: Can the polymer be extruded, molded, knitted, or cast?
- Sterilization Compatibility: Will it withstand EtO, gamma, or e-beam without performance loss?
- Integration with Metals: How will it bond, laminate, or mechanically attach to frames or supports?
The Bottom Line
The right polymer can make or break your implant design, and the right polymer-metal combination can take performance to the next level. At Medical Murray, we help device developers make these decisions early, so their implants meet both clinical needs and regulatory requirements without costly redesigns later.
If you’re designing a vascular, GI, or urology implant and want to explore material options, including how they integrate with metallic frames, our engineering and materials team is ready to help. Contact us to discuss your project!