[Editor's Note] David Pike of Mouser Electronics discusses the need for disposable connectors in the medical field.



There has been a lot of discussion about plastics in recent years. In the public perception, plastics are associated with cheap or disposable products, and there is a growing perception that they are a source of pollution.

According to recent reports, huge amounts of plastic waste are flowing into the ocean every year. These floating plastics enter the food chain and threaten wildlife.

Therefore, concerns about the environmental impact of plastics have highlighted the need to reduce the consumption of plastic materials.

As a result, the use of plastics in industry has become a topic under scrutiny, and manufacturers continue to look for new alternatives.

However, plastics are still important in many fields, including medicine. Despite environmental concerns, disposable plastic connectors remain essential in medical settings.

This article explains why single-use is often necessary to meet safety and performance requirements.

■ Understanding Plastics

Plastics is a general term for a wide variety of materials with different properties.

Plastics are manufactured using polymers, mostly derived from fossil fuel-based chemicals, and are made into various shapes using techniques such as molding or extrusion.

Plastics are very attractive for large-scale industrial use because they can be easily formed into complex shapes.

Plastic materials have different properties that make them suitable for different applications, and not all plastics are the same.

Plastic components are widely used in the electronics market. The insulating properties of plastics make them an ideal choice for connector designers.

All connectors use insulators (also called inserts) to separate the electrical circuits. This insulation is essential to prevent unnecessary contact between the circuits and to protect the user. In addition to the insulating properties, plastics also offer other advantages.

■ Choosing the right plastic

Many connectors are required to operate in outdoor environments. They must withstand wind and rain, and many use metal shells to protect them from the elements.

To reduce the effects of oxidation, material selection is important. Materials such as stainless steel and marine grade bronze are highly resistant to corrosion, but add weight and cost. In these situations, high-performance plastics can be a smart, lightweight, and cost-effective alternative.

However, the choice of plastic material is very important. Some plastics are damaged when exposed to direct sunlight, including ultraviolet (UV) radiation. UV radiation breaks down the molecular bonds within the polymer, causing oxygen to react and causing the surface to turn chalky or discolored. Long-term exposure can weaken the parts and eventually break them under harsh conditions. In fact, this is one of the ways plastic waste enters the environment.

To create parts that provide long-term reliability, designers must understand the properties of different types of plastics.

This understanding must 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 rays.

On the other hand, other materials, such as polyetheretherketone (PEEK), are not suitable for exposed environments.

PEEK is strong, high temperature resistant, and biocompatible, but its performance degrades significantly when exposed to UV light. There are many trade-offs when incorporating plastic materials into designs, and it is clear that selecting the right material is key to long-term reliability.

■ Disposable Plastics in the Medical Field

Even in a world where long-term reliability is valued, there is one industry that must maintain single-use plastics in connectors.

In the medical field, connectors are the link between patients and equipment.

Medical professionals rely on its reliability because their lives depend on its performance. This must be balanced with the need to protect patients.

In the medical field, many instruments must be cleaned and sterilized before use to ensure patient safety and prevent the spread of infection.

Most surgical instruments are cleaned in autoclaves, which use high-pressure saturated steam for sterilization.

It is essential to select the right plastic for these extreme environments. Parts made from the wrong material can melt or deform under high temperatures and pressures, and even the right plastic can deteriorate over time with repeated exposure.

Additionally, electronic devices are often not suitable for exposure to vapors that can penetrate sensitive areas.

Alternatively, chemical or radiation methods may be used to provide the sterilization needed for surgical instruments.

However, both methods carry significant risks. The chemicals used to clean surgical instruments can be irritating and dangerous. The ionizing radiation used for sterilization is also dangerous.

These harsh conditions are further complicated by the requirements of medical devices. Many medical devices must prevent the patient from touching conductive parts. In the event of a short circuit, the patient must be protected when the metal parts become energized.

For this reason, many medical connectors use plastic casings instead of metal to ensure the insulation needed by the patient.

Medical connector design can be viewed as a compromise between the need to keep patients safe and the need to enable sterilization of devices or components.

The problem is that materials like PEEK and polyethylene terephthalate (PEI, also known as Ultem®) aren't cheap. They provide the necessary performance, but come with a correspondingly high price tag.

One solution is to discard the connectors after use. This may be contrary to the public perception that single-use plastics should be avoided, but preventing cross-contamination is an important consideration.

If the need to withstand repeated sterilization is eliminated, lower performance plastics can be used. There are many high-performance connectors specifically designed for repeated use in the medical field, but in this case, disposable connectors offer a clear advantage.

■ Conclusion

Plastics still play a central role in many industries. They are still widely used because they offer strength, flexibility, and economy, and despite growing concerns about their environmental impact, they are very valuable when used correctly and in the right way.

In the medical field, where safety and hygiene are absolutely essential, single-use plastics may be the most practical solution. Future designs must balance practicality and sustainability to ensure that plastics remain a viable option.

※ About the contributor
David Pike is well known throughout the connector industry for his enthusiasm and general 'geek' nature. His online moniker is Connector Geek.