IVUS

IVUS Catheter Manufacturing Notes: Process Practice and Process Control Based on Clinical Pain Points

In the production of IVUS (Intravascular Ultrasound) catheters, a classic trade-off exists:

Make the acoustic window thinner?

Image clarity soars, but the catheter is prone to kinking during pushability tests.

Increase wall thickness to ensure strength?

The catheter becomes “stiffer,” but ultrasound waves cannot penetrate effectively, leaving the far-field image completely blurred.

This is not merely a matter of parameter adjustment, but a “triple constraint” of acoustics, mechanics, and biocompatibility at the millimeter scale. The challenges are becoming increasingly severe, especially under the trend of >60MHz high frequency and multi-modal fusion (IVUS+OCT).

We tend to understand products from the perspective of “functional modules” rather than simple parts assembly.

• Drive Shaft Assembly:

Responsible for 360° rotational scanning. The process difficulty lies in the stiffness gradient design​ of the spring coil to ensure concentricity and signal stability during high-speed rotation.

• Distal Shaft Assembly:

Responsible for protecting the internal structure and distal encapsulation. The core lies in the extrusion control of tapered tubing to ensure the consistency of the acoustic window and trackability through complex paths.

• Connector Assembly:

Responsible for signal transmission. It involves the welding stability of ultra-fine coaxial cables​ and signal fidelity in tortuous environments.

02. Process Practice Based on Clinical Pain Points

We transform every “pain point” fed back from the clinic into controlled parameters and process indicators on the production line.

• Precision Extrusion & Modular Assembly

To reduce image flickering caused by fluctuations in the gap between the outer tube lumen and the transducer, we have changed the model of relying on experience for machine adjustment:

• Material Control:​ The Melt Flow Rate (MFR) is measured upon the arrival of raw materials for each batch, and the extrusion temperature (±2°C) and haul-off speed are automatically matched.
• Dimensional Accuracy:​ Cooperating with online laser diameter gauges, the outer diameter tolerance is controlled within ±0.01mm and the wall thickness within 0.07mm to ensure a constant inner lumen gap.
• Precision Assembly:​ We provide customized assembly services in a Class 10,000 (ISO 7) cleanroom environment. Through extreme micro-precision control, we strictly prevent the introduction of micron-sized foreign objects, eliminating the risk of acoustic interference at the source.
• Stiffness Gradient Optimization of Distal Assembly

Addressing the issues of poor guidewire trackability and sluggish push force transmission, we optimized the welding process of the RX port (Rapid Exchange port):

• Material Selection & Combination:​ Based on a deep understanding of the characteristics of polymer materials such as EVA and PE, we conduct scientific selection and combination design to improve the physical properties of the tubing from the underlying logic.
• Multi-segment Splicing & Staged Welding:​ Through structural analysis, tubes of different hardness are stacked and thermally welded in stages. This reduces the local hardness of the RX area, achieving a smooth gradient from the Tip head to the distal shaft, thereby improving the ability to cross tortuous lesions.
• Tensile Strength & Connection Reliability

To address the low connection strength between different materials and the challenge of aging resistance, we improve firmness through surface modification technology:

• Surface Activation Treatment:​ Adopting plasma special surface treatment technology, we alter surface roughness and wettability without damaging the material matrix, significantly increasing surface energy to solve the connection strength problem of difficult-to-bond materials such as PEEK and HDPE.
• Adhesive System Optimization:​ We have established a comprehensive adhesive selection library. Combined with surface activation processes to adapt to heterogeneous material connections, we ensure the long-term stability and aging resistance of the catheter in simulated human body environments.
  
  In comparative tests, thanks to the process optimization of the RX port, the push force of our catheter in simulated vascular paths is significantly better than domestic competitors and demonstrates comparable trackability to global competitors.

The push force of the AccuPath IVUS catheter distal assembly is 30% lower than that of domestic competitors.

03. Process Control & Mass Production Delivery

Some quality defects of IVUS catheters are “hysteretic”; for example, internal stress release causes image drift only months after leaving the factory. To this end, we have introduced Statistical Process Control (SPC):

• Process Fingerprint:​ Collecting key parameters during extrusion, welding, and dispensing processes.
• Early Warning Mechanism:​ Relying on a monitoring system to capture fluctuations in key parameters, triggering alerts and proactive intervention before defects occur.
• Quality Assurance:​ Relying on high-level process control capabilities, we have achieved extremely high batch consistency, helping customers move from “strict sampling inspection” to “reduced inspection,” thereby reducing costs and increasing efficiency with stable quality.

The industry is transitioning towards higher frequencies (>60MHz), the popularization of single-use devices, and multi-modal fusion, which poses new challenges to the manufacturing end. We are developing an automated assembly system based on machine vision. While strictly maintaining assembly accuracy, we aim to break through an annual production capacity of 100,000 units to provide customers with higher-quality service guarantees.

The birth of each IVUS catheter is an ultimate challenge to precision manufacturing. We are committed to providing you with higher-performance and more reliable solutions through systematic manufacturing logic.