When designing a custom cable solution for a medical device, what considerations are needed?
There are many cable component and material choices to make. Which ones are the right ones for your medical device end-use application? Northwire cable design engineers will partner with you through the process. They will begin by asking questions to ensure your cable solution will meet the exact requirements of your project.
Below are common cable design healthcare application questions:
- What is the end application? What is the type of medical device?
- What is the expected cable life span?
- Is this a single-use cable?
- Is the product medical device going to be implanted?
- Yes (30+ days)
- Yes (up to 29 days)
- No
- Is sterilization required?
- Gamma
- Autoclave
- ETO
- Wipe Down
- What regulatory compliance expectations are needed?
- Are there any cable biocompatibility standards required?
- Will the cable come into contact with patients' skin?
- If so, for how long?
Answers to these questions help the cable design engineers better understand the cable requirements and materials needed for your project.
Popular Medical Device Material Options
BioCompatic® Silicone Cable Alternative Jacketed Material
Northwire developed this thermoplastic alternative to silicone cable where biocompatibility and resilience are vital. It also offers a shorter lead time that eliminates the lengthy curing process silicone requires.
BioCompatic Silicone Cable Alternative features:
- Flexible and soft to the touch as silicone cables
- Resistant to chemicals, sterilization, abrasion, cut, and crush
- Biocompatibility under USP Class VI
- Compliance to ISO 10993-5 cytotoxicity and ISO 10993-10 irritation and skin sensitization requirements
- Free of phthalates, halogens, and latex
- Compatible with steam autoclave, H2O2, gamma, and ETO sterilization
Compare BioCompatic® to Silicone and Santoprene.™
Download BioCompatic Data Sheet
Download BioCompatic Whitepaper
Santoprene™
Santoprene is a medical-grade TPE (thermoplastic elastomer) with the high-performance characteristics of rubber and the ease of processing of plastics.
- Soft to the touch feel
- Superior chemical resistance
- Compatible with various sterilization techniques
Northwire Enhanced PTFE
Northwire Enhanced PTFE offers the thinnest PTFE wall on the market and is well-suited for medical applications. It offers an advanced PTFE processing for high-volume production and will not suffer from length restrictions.
Northwire Enhanced PTFE features:
- High temperature rating up to 300°C
- High dielectric strength results in weight and space reduction
- Compatible with steam autoclave, H2O2, and ETO sterilization techniques
- Does not release any volatile components making it well-suited for clean room applications
Compare Northwire Enhanced PTFE to the most popular fluoropolymers.
Other Fluoropolymers
PFA
- Offers superior performance like PTFE
- One trade-off for the high-performance characteristics is the price
FEP
- A cost-effective alternative to PFA
- Lack chemical resistance
ETFE
- Cold flow resistance
- High tensile strength
- Abrasion resistance
- Maintains high-temperature performance
- Good electrical properties
- Good chemical inertness
Cable Components
Internal components of a cable include conductors such as tubing, strength members, and shielding. Each have a set of qualifying questions to identify the proper material for your medical device end application.
1 | What is the primary purpose of the cable component? What function will it provide?
For example, if a tube is needed, it will be important to know if the tube needs to supply, vacuum, or vent. If shielding is required, is it to reduce interference or provide structural integrity and protect the cable from wear and tear?
2 | What are the desired cable features?
If flexibility is determined to be a desired feature, then different durometers or ‘hardness’ will be specified accordingly when it comes to tubing. Or when considering a braid shield, a box weave braid will offer a higher flex life, but a spiral shield will be more flexible.
3 | What environment will the cable experience during the application lifecycle?
The environment has a significant influence on materials chosen to ensure the cable will hold up to the demands or stressors.
Flex Requirements
With healthcare applications, cable design engineers commonly receive requests for characteristics of flexibility or suppleness. Within the world of “flex,” flexibility and flex life may sound equivalent, but there are key differences. Some high-flex cables have short flex lives and some wires and cables with high-flex life are not flexible. Let's take a look.
Flexibility
Simply put, flexibility is a measure of how much movement a cable can tolerate at a given time. Flexibility types include: torsional, rolling, bending, and variable. Flexibility is tested when a cable is bent, twisted, or pulled into positions other than its original state. A flexible cable can bend significantly and stay bent for a large amount of time without being damaged.
Supple is another way to refer to flexibility. A flexible (or supple) cable is soft and easy to manipulate or bend back and forth. A flexible cable allows a surgeon to working effortlessly using an electrosurgical tool without hand fatigue since it prevents cable kinking, back twisting, and pulling on the surgeon’s hand.
Flex Life
Flex life deals less with how the cable moves, and more with how often it moves without damage. Many cables can bend for limited use (e.g., installation). A high-flex life cable can bend repeatedly and regularly without disrupting the cable’s intended use, such as power supply or data transfer.
If your cable will experience repeated movement for surgical applications, a cable with high-flex life may be needed.
Flexible and/or Flex Life?
Ultimately, the distinction comes down to use and application. If your cable needs to move well, it must be flexible. If your cable needs to move often, it must have a high-flex life. In many applications, such as electrophysiology or laparoscopic surgery, both flexibility and high-flex life are required.
From a cable design perspective, start your connectivity considerations early in your medical device design to save time and possible frustration at the end of your project.
Need help? Northwire cable designer engineers will partner with you to design and manufacture a quality cable connectivity solution for your end application.