Heat shrink tubes and bellows are widely used in medical devices, mainly due to their excellent physical and chemical properties and flexible design adaptability. The following are their specific applications, advantages and related precautions in medical devices:
1. Application of heat shrink tube in medical devices
Heat Shrink Tubing is a type of polymer tubing that has been shrunk by heat and is often used for insulation, protection, and fixation.
Typical application scenario
Insulation and protection of wires and conductors
Used to insulate internal cables in medical devices such as monitors, endoscopes, and ultrasound devices to prevent short circuits or signal interference.
Provides mechanical protection to prevent cable damage due to bending or friction.
Marking and enhancement of catheters and interventional instruments
Mark specific sites (such as length scales or functional areas) on vascular catheters and minimally invasive surgical instruments.
Enhance the rigidity of the catheter end and facilitate operation (such as local reinforcement of the heat shrink tube).
Sterile barrier and seal
Used to seal the packaging of disposable devices to ensure sterility (subject to ISO 11607).
Seal sensor or electrode connections to prevent liquid penetration (such as ECG electrode leads).
Biocompatibility requirements
Heat shrink tubes that come into contact with human body or body fluids must comply with USP Class VI, ISO 10993 biocompatibility standards (such as silicone heat shrink tubes).
Material selection
Polyolefin (PO) : versatile, low cost, suitable for non-implantable devices.
Fluoropolymers (e.g. PTFE, FEP) : high temperature resistant, chemically inert, used in high-precision equipment.
Silicone: Good flexibility, high biocompatibility, suitable for long-term implantation or contact with the skin.
2. Application of bellows in medical devices
Corrugated Tube (Corrugated Tube) has the characteristics of being flexible, compressive and anti-crease, and is often used for fluid transmission or mechanical protection.
Typical application scenario
Breathing line and anesthesia equipment
Bellows are used as ventilation pipes for ventilators to avoid airflow obstruction due to folding (according to ISO 5367).
Flexibility reduces mechanical stress at patient connections.
Drainage system and fluid delivery
The corrugated structure of thoracic drainage tube and urinary system catheter prevents negative pressure from sucking up.
For peristaltic pump conveying line, extrusion resistance and long life.
Sheath for endoscopes and minimally invasive instruments
Protects the optical fiber or wire inside the endoscope while allowing bending operation (such as a gastroenteroscope).
The corrugated design enhances the torsional flexibility of the device.
Antistatic and clean environment requirements
An antistatic agent may be added to the bellows for operating room equipment to prevent dust adsorption.
Material selection
PVC: Economical, for disposable drainage tube (need to pay attention to plasticizer migration problem).
Silicone: resistant to high temperature disinfection (such as high-pressure steam sterilization), good biological compatibility.
Polyurethane (PU) : strong wear resistance, suitable for repeated bending scenarios.
3. Key strengths
Safety and reliability: Heat shrink tubes provide insulation and seal, and bellows ensure smooth flow.
Lightweight and miniaturization: suitable for portable medical devices (such as wearable monitoring devices).
Customized design: Diameter, wall thickness, and material can be adjusted to meet specific device requirements (e.g. no metal components required for MRI compatibility).
