Choosing the Right Polymer for Your Medical Device Component

Let’s start with the first series of questions we’ll need to ask and discuss with you. What is the intended application for the device you are creating? There are three areas in particular we need to know.

Will the device be something implanted within a patient’s body? There are very crucial parameters that go into creating components or a full device meant to be implanted. Only certain polymers are approved for use within the human body. Will the device need to be implanted for less than 29 days or more than 29 days? Will it need to be a permanent implant? These questions determine the steps down the road.

Non-Implantable Devices

If the device is not meant to be implanted, the compound landscape changes and might even expand. These devices may come into contact with the skin, but are not used within the body.

Non-Body Contact

If your medical device is not meant to be in contact with a patient at all, again, the nature and types of materials used changes.

These factors include:

• Is the device meant to be hard or soft?
• Will the end product need to be stiff or flexible?
• What is the intended lubricity?
• Are there harsh environmental concerns?

Key environmental factors include:

• Will the area where the device is used be hot, cold or somewhere in the middle?
• Chemical exposure. Is there risk of chemicals encountering the device?
• UV exposure. Will the application risk ultra-violet light exposure?

These questions and the answers given will help determine the next step and a recommendation about which compound to use.

The category of thermoplastics covers a range of compounds including:

• ABS
• Acrylic
• Nylon
• Polycarbonate
• Polyethylene
• Polypropylene
• Vinyl
• Thermoplastic Elastomers

Thermoplastics are plastic polymers which become pliable or moldable when high temperatures are applied to them. They have a high molecular weight, but the polymer chains weaken as temperatures increase. This turns the thermoplastics into a highly viscous fluid which can then be molded and shaped. They are used most often with injection molding, compression molding, extrusion and calendering.

Implantable thermoplastic devices

Some thermoplastic polymers will work well within the body. They can be used on implantable devices such as:

• Electromechanical devices
• Cardiac rhythm management devices
• Opthalmic devices
• Catheters
• Endoscopic tubing

Non-implantable thermoplastic devices

These include:

• Medicinal delivery devices such as inhalers
• Non-absorbable sutures
• Tracheal tubes

Non-body thermoplastic applications

Anything that should be durable, but not come into contact with the patient such as:

• Petri dishes
• IV bags
• Lab equipment

Elastomers are natural or synthetic polymers and the common materials used include:

• Silicone
• FKM
• Neoprene
• Nitrile
• Rubber
• Butyl

Elastomers are used when you need durability, flexibility, and reliability. Elastomers such as silicone can be easily cleaned and sterilized and have high biocompatibility. One of the key components is the strength of elastomers, because they hold up for a long time and many can be stretched only to return to their original shape many times over. In other industries seals and adhesives are made from elastomers. Their versatility is also wide, as they have been used in everything from medical devices to the soles of shoes.

Implantable Elastomers

One of the most commonly used elastomers in the medical field is silicone, which has properties that make them ideal for human body usage. Some implantable applications using elastomers include:

• Long term implanted applications
• Joint arthroplasty
• Catheters
• Drains
• Hydrocephalus shunts
• Implanted defibrillators
• Heart pumps

Non-implantable Elastomers

There are also many applications for elastomers within medical applications that touch a patient’s skin but are not approved for internal use. These include:

• Pharmaceutical manufacturing
• Diagnostic instruments
• Surgical instruments
• Gloves
• Hearing aid components

Non-Body Contact Elastomers

If you need a medical component within a device that should be resilient and durable but does not need to come in contact with a body, then elastomers may be the right solution. Some examples of non-body contact elastomer devices include:

• Rings
• Gaskets
• Stoppers
• Hoses

Flexan’s engineering team are experts with polymer materials. We understand that determining the right compound to use can be a complex process, but we can help you make the right determination. If you want to start the decision process, then contact the experts at Flexan today.