These advantages have limitations, however. Silicone jacketing tolerates autoclaves and other forms of sterilization to a point, but will break down after several hundred cycles at best. The material is very sturdy and stable when faced with temperature extremes, but its durability is greatly decreased with abrasion and tear—and silicone is especially vulnerable to this type of external damage. In a fast-paced hospital or clinic, repetitive motion and heavy rolling equipment create ample opportunity for silicone cables to be damaged in this way. (See Figure 2)
Durability can be improved by thickening the cable jacket, but this compromises flexibility. Silicone-coated cable is soft and supple, but generally requires an additional coating to support these features. With this coating, it does not catch on patients, but measures must be taken to ensure that it does not catch on itself or become irreparably tangled when subjected to continuous motion or torque.
The procurement of medical-grade silicone for wire and cable applications also presents significant hurdles.
Silicone is a thermoset material, requiring a curing process to support biocompatibility and application-based specifications. Once cured, it cannot be changed. The curing process requires a careful balance of temperature, pressure, and time, as well as additional equipment and various curing catalysts. As a result, leading OEMs for silicone brands typically offer lead times of at least 8 to 12 weeks in the United States. The curing process can also involve substantial added expenses, and there are typically opportunity costs related to the lengthy development time.
Looking Ahead to Future Innovation
With today’s life science technology evolving and changing at one of the most rapid paces in history, source materials used in medical devices and critical system components must progress as well. Product designers, engineers, and research and development teams have risen to this call by developing effective and original substitutes to silicone-based cable assemblies. Many of these inventive solutions have successfully retained the comprehensive biocompatibility silicone enjoys and improved on the traditional material’s strength, resilience, flexibility, and versatility. Moreover, these materials can often be made without additional curing or coating processes, supporting faster paths to market and saving manufacturers money.
In laboratory tests, innovative silicone cable alternatives surpassed conventional components in a number of trials. In one example, a silicone cable assembly was subjected to rollover cycles by a 200-pound hospital gurney. The silicone assembly failed in fewer than 10,000 cycles, whereas the alternative product exceeded 186,000 cycles.
A similar test examined autoclave sterilization. In this situation, the silicone alternative also outperformed traditional silicone, retaining full tensile strength, elongation, and color clarity in more than 500 steam autoclave cycles. Other areas where alternatives overtook traditional materials included continuous motion and flex, retractability, fungal resistance, and chemical resistance. (See Figure 3)
To ensure quality and the long life span of these original silicone alternatives, interested buyers should be sure to conduct thorough research into the supplier, their quality management systems, and manufacturing processes. Unlike silicone, whose history affords it a well-defined process, the emerging market of silicone substitutes represents an assortment of different approaches. When conducting supplier evaluation, be sure to ask:
- What is the manufacturing methodology?
- What standards of biocompatibility does the material meet?
- Does it adhere to FDA regulations, USP Class VI, RoHS2, and ISO-10993?
- What are the supplier’s certified quality management systems?
- Has the material been fully tested in a third-party laboratory?
- Has the material been tested for resistance to sterilization, cut, tear, abrasion, and chemical interaction? If so, what were the results of these tests?
- What are typical lead times and cost investments for the material?