An Overview of Medical Cable Assemblies

Medical equipment

Medical cable assemblies are vital in the healthcare sector, serving as critical links in the functionality and reliability of many devices and equipment. These specialized cables are essential for transmitting power and data, and are extensively used in diagnostic imaging systems like MRI and CT scanners and patient monitoring equipment like ECG and EEG machines.

Because medical cables directly impact diagnostic accuracy and patient care, there are stringent industry standards engineers and manufacturers must follow to ensure safety and reliability.

Cable Assembly Applications in the Medical Industry

A cable harness assembly used in medical visual equipment

Several types of cable assemblies are frequently used in the medical industry, including coaxial, ribbon, and shielded.

  1. Coaxial Cables: Typically found in MRI and CT scanners due to their exceptional ability to carry high-frequency signals with minimal loss. They provide excellent electromagnetic interference shielding, which is crucial for maintaining the integrity of the sensitive imaging data.
  2. Ribbon Cables: Used in medical device applications where space is limited and multiple data channels need to be consolidated neatly, like in patient monitoring systems. Their flat, thin design helps organize connections within compact devices, making maintenance and assembly much easier.
  3. Shielded Cables: This cable type is essential in nearly all medical systems to prevent interference that could distort signal clarity and produce inaccurate readings.

Customization Process

Coaxial cables plugged into patient monitoring equipment

Customizing cable assemblies for the medical industry is a meticulous process that involves assessing several critical factors, including biocompatibility, sterilization requirements, flexibility, size and weight, chemical resistance, and overall design.

Biocompatibility

Medical cable assemblies must be safe for patient contact, particularly those used in surgical or diagnostic applications that involve direct skin contact. Materials used in the cables, such as the outer jacket and insulation, must be non-toxic, hypoallergenic, and free from latex to prevent adverse reactions. Additionally, compliance with standards like ISO 10993 or IEC 60601 is common.

Sterilization

Cables used in surgical rooms (or any room that requires frequent cleaning to prevent infection) must withstand various sterilization processes. Manufacturers will use materials capable of enduring high temperatures, radiation, or chemical sterilants when developing these cable assemblies. Some of these materials include PTFE (Teflon®), which can withstand autoclaving, and polyurethane, which is resistant to most chemical sterilization methods.

Flexibility

The physical design of the cable must allow for easy handling and manipulation without damage. Flexibility is particularly important for cables used in dynamic applications like endoscopy or portable diagnostic equipment. Manufacturers typically use flexible conductive cores and elastic insulations and jackets to ensure the cable maintains performance, even when repeatedly bent or twisted.

Size & Weight

Size and weight are crucial for handheld or wearable devices because lightweight and compact cables ensure patient comfort and device usability.

Chemical Resistance

Most medical applications require components resistant to chemicals, especially cleaning agents and disinfectants, to ensure longevity and reliability. In cable assembly, silicone and fluoropolymers are often used because they have excellent chemical resistance properties.

Overall Design

The specific requirements of the medical device (or equipment) also influence the design/construction of the cable assembly, including the number of conductors, the configuration, connector types, and color coding. Some devices may even require specialized features like strain reliefs, shielding, and locking mechanisms.

Manufacturing Challenges

Multiple cables plugged into an ECG

Public Safety

The direct impact of cable assemblies on public/patient safety shouldn’t be understated. Any variance in the specifications, however minor, can lead to malfunctions or failures. For example, a failure in cable assembly used in a heart monitor could delay critical decisions, potentially resulting in death. So, manufacturing processes must maintain extremely tight tolerances and undergo rigorous quality control checks to ensure each cable assembly performs consistently and reliably.

Industry Compliance

To ensure safety, the medical industry has rigorous standards that manufacturers must adhere to. For medical cable assemblies, these standards include ISO 13485, IEC 60601-1 and 2, IEC 60512, AAMI EC53, and UL 544.

  • ISO 13485: This standard outlines quality management system requirements for designing and manufacturing medical devices, including cable assemblies.
  • ISO 10993: This ISO standard provides a general framework for assessing the biocompatibility of medical device materials and covers tests for cytotoxicity, sensitization, irritation, acute toxicity, and other biological hazards.
  • IEC 60601-1: 60601-1 includes important provisions for the safety and performance of medical electrical systems, which affect cable assemblies. It covers general safety requirements, testing for electrical hazards, and mechanical integrity.
  • IEC 60601-2: 60601-2 specifically deals with electromagnetic compatibility of medical electrical equipment, ensuring that cable assemblies do not emit excessive electromagnetic interference and are resistant to it.
  • IEC 60512: This standard is focused on the connectors used within cable assemblies and provides requirements for testing their reliability under electrical continuity, mechanical operation, and environmental exposure.
  • AAMI EC53: This standard was developed by the Association for the Advancement of Medical Instrumentation. It specifies performance and safety requirements for electrocardiography monitoring cables and lead wires, and addresses issues like biocompatibility.
  • UL 544: This standard, developed by Underwriters Laboratories, applies to medical and dental equipment, focusing on the safety of electrically powered devices. It helps ensure that cable assemblies used in this type of equipment meet specific insulation and performance standards to prevent electrical and fire hazards.

Learn More About Cable Assemblies

PGF Technology is an electronic manufacturer specializing in assemblies, including cable, PCB, box build, and wire harness. Since our founding over 50 years ago, we’ve helped clients in the medical sector develop safe, reliable, and compliant ribbon, coaxial, and shielded cable assemblies.

Our cable assembly services include cable preparation, conductor termination, connector attachment, shielding termination, testing, insulation and strain relief, and labeling and identification. To ensure quality, we hold several certifications, including ISO 9001:2015, ISO 13485:2016, and are ITAR compliant. All cable assemblies are made in-house in the United States and thoroughly tested to meet the stringent medical industry standards.

Please contact us today to learn more about our capabilities or visit our website for more cable assembly resources.