Bench Talk

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There has been much discussion in recent years about plastic. The public perception is that plastic is associated with cheap or disposable products, and there is a growing awareness of its role in pollution. Recent revelations have highlighted the enormous volume of plastic waste that finds its way into the ocean every year. Once suspended in the water, these plastics enter the food chain and threaten wildlife.

Concern about plastics’ environmental impact has, therefore, highlighted a need to reduce the consumption of plastic materials. As a result, the use of plastic in industry has become the subject of some scrutiny, and manufacturers continue to look for new alternatives. However, plastic remains important in many applications, including medical. Despite environmental concerns, disposable plastic connectors remain essential in medical settings. This blog explains why disposability is often necessary to meet safety and performance demands.

Understanding Plastics

Plastics represent a wide variety of different materials, each with its own characteristics. They are manufactured from polymers derived mainly from fossil fuel-based chemicals, then formed into different shapes using techniques such as molding and extruding. The ease with which it creates complex shapes makes plastic highly attractive for large-scale industrial use. The differing characteristics of plastic materials are useful in different applications and not all plastics are created equal.

The electronics market makes extensive use of plastic components. For connector designers, the insulating property of plastic makes it an ideal choice. Every connector uses an insulator—sometimes referred to as an insert—to keep electrical circuits separate. This isolation is essential, both to prevent unwanted contact between circuits and to protect users from harm. Beyond its insulating qualities, plastic offers other advantages.

Choosing the Right Plastic

Many connectors must function in outdoor environments. They must withstand wind and rain, and many use a metal shell to protect against the elements. To reduce the effects of oxidization, material choice is important. Materials like stainless steel and marine-grade bronze resist corrosion well but come with added weight and cost. In these situations, high-performance plastics can be the smart, lightweight, and cost-effective alternative.

However, the choice of plastic material is vital. Exposure to direct sunlight, which contains ultraviolet (UV) radiation, has detrimental effects on some plastics. UV radiation can degrade the molecular bonds in polymers, allowing oxygen to interact and cause the surface to become chalky or discolored. Prolonged exposure may weaken the component to the point of failure under harsh conditions. In fact, this is one of the ways plastic wastes enter the environment.

Creating components that deliver long-term reliability requires designers to understand the attributes of different types of plastic. This must then be balanced with the needs of the design. High-performance plastic materials, such as polyamide, are ideal for outdoor use due to their excellent resistance to UV radiation. In contrast, other materials, such as Polyether ether ketone (PEEK), would be less suitable for exposed applications. PEEK is strong, resistant to high temperatures, and biocompatible, but it performs poorly when exposed to UV. With an array of trade-offs involved in designing with plastic materials, it is clear that the key to long-term reliability is choosing the right material.

Single-Use Plastics in Medical Applications

Even in a world where long-term reliability is valued, there is one industry where it may be necessary to retain single-use plastic for connectors. In medicine, connectors are the link between patients and equipment. Medical professionals depend on their reliability as lives may depend on their performance. This must be balanced with the need to protect the patient.

In medical applications, many instruments must be cleaned and sterilized before each use to ensure patient safety and prevent the spread of infections. Most surgical instruments are cleaned in an autoclave that uses pressurized saturated steam to kill bacteria and other biohazards. The correct choice of plastic for this extreme environment is essential. High pressure and temperature can melt or deform components made from the wrong materials, and even compatible plastics can degrade with repeated exposure to these conditions.

In addition, electronic devices are often unsuitable for exposure to steam, which can penetrate sensitive areas. Alternatives use chemical or radiation methods to provide the necessary sterilization for use with surgical instruments. However, both carry significant hazards. To clean equipment for use in surgery, the chemicals themselves can be harsh and even dangerous. The ionizing radiation used in sterilization is no less hazardous.

These tough conditions are complicated by the requirements of medical devices. Many medical instruments must ensure that the patient is unable to touch a conductive element. In the event of a short circuit, the patient needs to be protected from metal parts that might be accidentally live. That is why many medical connectors use plastic outer shells instead of metal to ensure the necessary isolation for the patient.

Medical connector design can be viewed as a compromise between the need to keep the patient safe and the need to ensure that the device or component can be sterilized. The problem is that materials like PEEK or Polyetherimide (PEI), sometimes known as Ultem^®, are not cheap. They deliver the required performance but have a price tag to match their extensive abilities.

One solution is to dispose of the connector after use. While this may contradict public opinion that says single-use plastics should be avoided, the prevention of cross-contamination is a crucial consideration. Removing the requirement to withstand repeated exposure to sterilization means that lower-performance plastics can be used. While there are many highly capable connectors designed specifically for repeated use in the medical arena, in this case, a disposable connector offers clear advantages.

Conclusion

Plastic continues to play a pivotal role across industries. It offers strength, flexibility, and affordability, which keeps it popular, and despite growing concerns over its environmental impact, the right plastic, used in the right way, can be very valuable.

In the medical sector, where safety and hygiene are non-negotiable, single-use plastics may offer the most practical solution. Future designs must blend practicality with sustainability to ensure plastics remain a viable option.