Cables are long wire strands covered by a protective shielding material (jacket) and an insulation material. Cable assemblies are a small grouping of individual cables or wires bound together to increase the wires’ efficiency, protect them from external contaminants, and help them fit more efficiently in a given application. Protective coverings for cables and cable assemblies vary greatly, depending on the application environment. They can be made of polyvinyl chloride (PVC), polyethylene (PE), ethylene-vinyl acetate (EVA), thermoplastic elastomer (TPE), perfluoroalkoxy alkane (PFA), and more. The internal wires (conductors) are made mostly of copper and occasionally aluminum.
In medical device applications, cables are used with nearly all electrically operated devices. As such, cables can be found in everything from medical robotics and medical imaging devices to wearable electronics. This diversity of uses leads to an immeasurable amount of differing conditions to consider when selecting the right cable and cable assembly for a device.
For example, many medical device cables must be reused and therefore must undergo repeated sterilizations. Electron-beam sterilization is a common method, but can compromise the plastic jacket at a molecular level. The branched-chain polymers in the plastic can bond with each other, making the cable brittle. The cable might also be subjected to chemicals and heat, leading to additional wear. These elements can all affect the flexibility of the cable, which must flex freely and repeatedly to be efficient. This performance element is another consideration when choosing the type of cable for a medtech device.
Lastly, to ensure that cables can meet the demands of the conditions listed above, cables are subjected to many requirements and certifications. It is important to always refer to a manufacturer’s specifications for a cable when not having the cable specifically customized for your individual application.