Micro Coaxial Cable factory

What are the specifications for medical-grade micro coaxial cables?

Medical-grade micro coaxial cables are specialized components critical to the function of life-saving and diagnostic equipment like endoscopes, catheters, ultrasound probes, imaging systems, and patient monitoring devices. Unlike standard industrial coaxial cables, they must meet stringent specifications to ensure patient safety, device reliability, and consistent performance in demanding medical environments. Here are the key specifications:

1. ​Electrical Performance:
   • ​Impedance: Strictly controlled impedance, almost universally ​50 Ohms. This ensures minimal signal reflection and maximum power transfer for accurate data transmission of high-frequency signals (like video or ultrasound echoes).
   • ​Attenuation: Very low signal loss (attenuation) per unit length, especially critical for high-frequency applications (>1 GHz). Measured in dB/meter or dB/100 feet at specific frequencies. Lower attenuation allows longer cable runs or lower transmission power.
   • ​Velocity of Propagation (Vp): Consistent signal speed, usually expressed as a percentage of the speed of light (e.g., 70%). Important for timing-critical signals and impedance matching.
   • ​Shielding Effectiveness: Excellent shielding (typically multiple layers: braid + foil) is crucial to prevent external electromagnetic interference (EMI) from disrupting sensitive signals and to prevent signals from the cable interfering with other equipment. Critical in EMI-heavy hospital settings. Often specified by dB reduction at specific frequencies.
2. ​Mechanical Reliability & Flexibility:
   • ​Size: Extremely small outer diameters (OD), often ranging from ​0.40 mm (AWG 50) to 1.78 mm (AWG 36) or similar micro sizes. Essential for minimally invasive procedures and integration into compact devices.
   • ​Flex Life: Exceptional resistance to fatigue from repeated bending, flexing, twisting, and articulation. Must withstand tens of thousands or even hundreds of thousands of dynamic cycles without performance degradation. Crucial for cables inside articulating endoscopes or catheters.
   • ​Conductor: Typically high-quality copper alloy (like silver-coated copper, tin-coated copper, or bare copper) for conductivity and flexibility. Stranded designs are common for dynamic applications.
   • ​Dielectric: High-performance insulating material (e.g., specialized fluoropolymers like PTFE, FEP, or ETFE) ensuring low signal loss, stable impedance, and resistance to crushing and abrasion. Material choice heavily impacts flexibility and electrical properties.
   • ​Jacket: Biocompatible material that must withstand sterilization and environmental exposure while being flexible and offering protection. Common materials include specialized polyurethanes, silicones, and fluoropolymers.
3. ​Biocompatibility & Safety:
   • ​Material Safety: All cable materials in direct or potential contact with the patient must meet rigorous biocompatibility standards, primarily ​ISO 10993 (Biological evaluation of medical devices). This involves cytotoxicity, sensitization, and irritation testing. Materials also meet ​USP Class VI (highest plastic purity standard) for implantable or fluid-contacting applications.
   • ​Low Particulates: Minimal shedding of particles from cable materials is essential, especially in sterile fields or implantable devices.
4. ​Sterilization Resistance & Environmental Durability:
   • ​Compatibility: Must withstand repeated exposure to medical sterilization methods without degrading electrical or mechanical properties: ​Autoclaving (steam), Ethylene Oxide (EtO), Gamma Radiation, and Chemical Disinfectants (like isopropyl alcohol, bleach solutions – check specific compatibility).
   • ​Environmental Stability: Resistance to temperature extremes (both high sterilization temps and low storage/operating temps), humidity, bodily fluids, and cleaning agents.
5. ​Regulatory Compliance & Traceability:
   • ​Manufacturing Standards: Produced under stringent quality management systems like ​ISO 13485, specifically designed for medical device manufacturing.
   • ​Traceability: Full material traceability (Lot/Batch numbers) is essential for safety recalls and quality control.
   • ​End Device Approval: While the cable itself isn’t FDA-approved as a device, it must be manufactured to standards acceptable for integration into FDA-cleared or CE-marked medical devices. The OEM validates the entire assembly.

In Summary:

Medical-grade micro coax isn’t defined by a single “magic number” spec. Instead, it’s a ​comprehensive set of demanding requirements focusing on:

• ​Consistent, High-Fidelity Signal Transmission: (Impedance, Attenuation, Shielding)
• ​Ultra-Reliability in Motion: (Flex Life, Small Size, Durability)
• ​Patient Safety: (Biocompatibility, Low Particulates)
• ​Withstanding Medical Processes: (Sterilization Compatibility)
• ​Traceable, Controlled Manufacturing: (ISO 13485, Material Traceability)

Choosing the right medical-grade micro coaxial cable means verifying all these specifications align with the specific performance, environmental, safety, and regulatory needs of the medical device application. Always work with cable manufacturers experienced in and dedicated to the medical market.