Due to the excellent properties of silicone tubing and the characteristics of environmental protection, non-toxic, harmless and tasteless, in recent years, silicone tubing get more wide applications.

Silicone tubing is also widely used in medical support. Generally speaking, ordinary food-grade silicone tubing will slowly turn yellow after a period of use, and physiological inertia will be weakened under long-term use. In terms of medical treatment, the requirements for silicone tubing are very strict and must ensure that it will not hurt the human body. So the general food-grade silicone tube is far from reaching this requirement.

Medical silicone tubing belongs to platinum vulcanization, using imported gas phase adhesive as raw material and forming vulcanization agents at high temperatures rapid vulcanization. The medical silicone tubing produced in this way typically has the characteristics of environmental protection, high efficiency and odorless, high transparency, yellow resistance, long service life, excellent physiological inertia, aging resistance, and so on. With an inner diameter of at least 0.3mm, it passes the biocompatibility test rigorously. There will be no adverse reactions after implantation. So it is more and more widely used in medical care.

• High transparency, high hygiene level, environmental protection, efficient and odorless, can be high-temperature disinfection and autoclave sterilization;

• Medical silicone tubing has good physiological inertia and will not cause harm to human tissues. It will not cause body reaction after entering human tissues, and will not cause inflammation to surround tissues;

• High tensile strength, high tear resistance, low shrinkage, good resilience;

• Strong resistance to high and low temperatures, no deformation at high temperatures, no decomposition of harmful substances, physiological inertia, strong resistance to biological aging;

• High sanitation and environmental protection level, and get the approval of FDA, LFGB;

The process of selecting medical silicone tubing is complex. Medical device designers need to consider mechanical properties such as size and hardness, visibility or streaks that require no radiation penetration, and advanced designs such as kink resistance. In addition, material purity, chemical and biological compatibility, size, and durability need to be considered when selecting implantable silicone tubing, as these factors play a key role in product performance.

So how to choose the correct medical silicone tubing for medical equipment?

• Size is the main mechanical property to consider when selecting medical silicone tubing, especially as medical device designs move toward smaller devices and drug delivery devices. Currently, implantable silicone tubing is available in sizes of 0.007×0.014 inches.

• Hardness. Generally speaking, silicone from Shore A20 to Shore A80 hardness can be formed by the extrusion process. Tensile strength decreases with increasing hardness. This is an important factor in evaluating devices such as wound drainage tubing, which is subject to significant stress when removed from the body.

• Tear strength and tensile elongation are also two keys. If there is a small crack trace in the silicone tubing, then the tear strength will seriously affect its size. This is especially important if the silicone tubing is likely to come into contact with parts with sharp edges. The elongation is related to the elasticity of the tubing, and it is a mechanical property that needs to be considered.

• The quality of the surface treatment of the tubing must be carefully evaluated. In general, low friction on the surface of silicone tubing is very important for practical applications. While it is possible to reduce the viscosity of the silicone itself with surface coatings, these coatings must be bio-compatible, especially where the devices have the potential to contact and enter human tissue.

• Visibility is important for certain types of medical devices, such as drug delivery devices that deliver fluids to the body, or devices that drain from the body to the outside. Although silicone itself is transparent, some silicone fillers added to increase hardness, barium sulfate (BaSO4) for development, and titanium dioxide (TiO2) for modification can reduce or eliminate transparency, which can affect the clinician’s ability to see if the liquid flows in the desired path.

• In some cases, designers want to make the tubing more visible inside the body, such as when they are needed to guide medical devices through the body for X-ray or fluoroscopic observations. Barium can be added to the silicone tube so that it is not only visible in the soft tissue, but can still observe the liquid state to verify the flow. In addition, a higher percentage of the barium additive can be used to ensure that the tube is visible even as it passes through the bone to help the surgeon place the catheter in the spine.

• When the guide wire is insulated in a silicone tube and subjected to repeated dynamic loads, such as where the cardiac pacemaker leads are connected to the pacemaker housing, designers may consider using multi-chamber tubes produced by continuous kink to minimize strain hardening, thereby reducing or eliminating the possibility of wire breakage.

As the market for medical tubing continues to grow, designers should consider mechanical properties, surface finish, bio-compatibility, permeability, and advanced extrusion capacity when evaluating product needs and suppliers.