Silicone, a highly versatile synthetic polymer, seems to show up everywhere from cooking utensils and adhesives to sealants and cosmetics. Its unique properties have contributed to silicone’s traditional appeal in more complex fields as well; for decades, the material has been an integral ingredient in medical technology. Valued by original equipment manufacturers (OEMs) and product designers for its adaptability, silicone lends itself to intense applications in implantable medical devices, reusable and single-use components, and other health care technologies involving hospital equipment and surgical tools that demand reliability and trustworthy performance. (See Figure 1)
Until recently, few materials filled the same requirements as silicone for these applications, making it the default choice in many instances. Medical-grade silicone is one of the most common materials in jackets and coatings for wire and cable assemblies utilized for medical devices, largely due to a lack of adequate alternatives. Although silicone offers advantages in biocompatibility and versatility, there are still challenges in integrating the ingredient into medical cable components. Lack of availability of supply, long lead times, and multiple curing processes often result in high initial investments with hidden long-term costs. Silicone products also tend to be vulnerable to abrasion damage, extensive sterilization, and repetitive motion, decreasing their overall life span.
To combat these difficulties without sacrificing biocompatibility or utility, medical device designers and manufacturers have developed field-proven silicone substitutes. Innovative silicone alternatives build on the foundation and history of silicone’s successes in medical applications while paving the way forward for improved performance.
The History of Silicone in Medical Applications
Chemists first discovered silicon, the naturally occurring element that forms the basis for silicone, in the early 1800s. Just over a century later, in the 1940s, silicone materials became commercialized and companies such as Dow Corning and General Electric were discovering the full extent of their properties. Resistance to temperature extremes, environmental factors, and electricity were noted, and silicone materials quickly gained acceptance and adoption.
A key factor in silicone’s rise to popularity was its ability to adapt and succeed in a highly diverse range of applications. Silicone has been used in life sciences, aerospace/defense, electrical, and industrial applications since the 1960s. In medical manufacturing, the material is suitable for use in a broad variety of components, from valves and tubing to long- and short-term implantable devices, and far beyond. It is often used as the external jacketing on medical wire and cable for hospital equipment, surgical tools, patient monitoring systems, imaging and diagnostic instruments, and other medical devices.
Although additional processing and potential costly reapplication of parylene is required for silicone to meet stringent FDA and biocompatibility requirements, the core ingredients are abundant and easy to manipulate. This accessibility, combined with silicone’s adaptability, makes it an obvious choice for use in medical manufacturing. When the material is processed to medical-grade standards, it results in silicone cable products that are biocompatible, hypoallergenic, flexible, and durable—all necessary characteristics for use in health care environments.
Advantages of Silicone-Jacketed Medical Cable
Silicone has proven its worth in medical manufacturing over the past several decades by achieving reliable high performance across a number of complex requirements. For siliconejacketed cable assemblies, these include biocompatibility and tolerance to sterilization, flexibility and durability, and userfriendly appearance and feel.
Biocompatibility is critical for components that interact with, or are implanted into, the human body. Medical-grade silicone can adhere to meticulous and comprehensive biocompatibility standards, such as USP Class VI, the most demanding standard in its category, and ISO 10993, often considered even more intensive than USP Class VI. To further enhance its safety to patients, silicone jacketing satisfactorily tolerates severe hospital sterilization in autoclaves and other forms of sterilization. This allows silicone-coated cable to operate in both single-use and reusable applications.
Beyond sterilization, silicone cables stand up to day-to-day wear that typically occurs in hospital environments. From resistance to common cleaning solutions to exceptional stability in temperature extremes, durability is often listed as a top advantage of silicone materials. Similarly, silicone-jacketed cable products afford a high level of flexibility and elongation, particularly useful in medical device cable involving cameras, power tools, robotic surgery, and other electrosurgical instruments.
In addition to excelling in these prominent requirements for life science cable components, silicone allows for a look and feel that is supportive of both patients and medical professionals. Silicone-jacketed cables are soft and supple to prevent irritation or tearing of skin or tissue and make it easier for medical staff to apply wound dressings.