How to reasonably choose silicone tube in the process of medical equipment design

According to data from Marketsand Markets Research, the global medical tubing market continues to grow at a significant rate and is expected to reach US$9.4 billion by 2022. Within the forecast range, in terms of volume, silica gel is recognized as the material with the largest use and the fastest growth rate in the global medical tubing field.

The process of selecting silicone tubing is complicated, and medical device designers need to consider mechanical properties such as size and hardness, visibility or fringes that require radiopaque, and advanced designs such as kink resistance.

In addition, when choosing an implantable silicone tube, you need to consider the purity of the material, chemical and biological compatibility, size and durability, because these factors play a key role in product performance.

However, in order to provide a successful solution for the development of medical devices, designers need to understand not only the mechanical properties of silicone, but also biocompatibility, permeability and advanced extrusion processes. In this article, we will discuss all the important factors of silicone tubing, regardless of whether these silicone tubings are implanted or non-implanted components.

When choosing a silicone tube, especially when the design of medical equipment tends to be small and drug delivery devices, the main mechanical property that needs to be considered is the size. Currently, the size of implantable silicone tube that can be produced is 0.007 x 0.014 inches. However, not all suppliers have the ability to bring products to the market in a timely manner, so this should be kept in mind in the supplier selection process.

Another consideration is hardness. Generally speaking, silica gel with hardness from Shore A 20 to Shore A 80 can be molded by extrusion process. As the hardness increases, the tensile strength decreases. This is an important factor in the evaluation of devices such as wound drainage tubes, because they are subject to a lot of pressure when they are removed from the body.

Two other mechanical factors that need to be considered are tear strength and tensile elongation. If there are tiny traces of cracks in the silicone tube, the tear strength will seriously affect its degree of increase. Especially when the silicone tube is likely to come into contact with parts with sharp edges, this is especially important to consider. The elongation is related to the elasticity of the tube, and it is a mechanical property that needs to be considered for balloon catheters.

Finally, the surface treatment quality of the pipe must be carefully evaluated. Under normal circumstances, low friction on the surface of the silicone tube is very important for practical applications. Although surface coatings can be used to reduce the viscosity of silica gel itself, these coatings must meet biocompatibility, especially when these devices may contact and enter human tissues.

In the process of silicone tube extrusion, adjusting tool design and processing parameters, such as extrusion pressure, can also have a positive impact on the surface texture of the final tube.

Although the pipe has a high degree of biocompatibility, it is still necessary to choose the grade of silicone and additives according to the application. According to specific circumstances, in some occasions with high volatility requirements, it is necessary to consider 350ºF (176.67ºC) high temperature leaching test and secondary vulcanization process for silica gel.

Visibility is important for certain types of medical devices, such as drug delivery devices that deliver fluids into the body, or devices that drain from the body to the outside of the body. Although silica gel itself is transparent, some silica fillers added to increase hardness, barium sulfate (BaSO4) added for development and titanium dioxide (TiO2) added for modification will reduce or eliminate transparency, thereby Affect the clinician to observe whether the fluid flows according to the desired trajectory.

In some cases, the designer wants to make the silicone tube more visible in the body. For example, when using X-ray or fluoroscopy, the silicone tube is required to guide the medical device through the body. You can add barium to the silicone tube to not only make it visible in the soft tissues, but also to observe the liquid state to verify the flow. In addition, a higher percentage of barium additives can be used to ensure that the tube is visible as it passes through the bone to help the surgeon place the catheter in the spine.

Kink-resistant silicone tubing and multi-lumen silicone tubing are very important in the design of certain medical devices. Several types of reinforcement materials (including some with biocompatibility) can reduce the tendency of the pipe to kink and reduce the risk of liquid leakage. This is particularly important in implanted medical devices, because fluid delivery is very critical, and the implanted catheter must be kept open during the movement of the human body.

Similarly, when the guide wire is insulated in a silicone tube and subjected to repeated dynamic loads, such as where a cardiac pacing lead is connected to a pacemaker housing, designers can consider using a multi-lumen tube produced by continuous twisting to maximize Reduce strain hardening, thereby reducing or eliminating the possibility of wire breakage.

Finally, the inherent permeability of silicone can be used to control the release of additives. For example, the antibacterial ingredients added to the catheter can reduce the risk of infection, and the anti-inflammatory ingredients added to the pacing lead can help healing after implantation.

With the continuous growth of the medical tubing market, designers should fully consider the mechanical properties, surface finish, biocompatibility, permeability and advanced extrusion capabilities of the tubing when evaluating product requirements and suppliers. When a supplier becomes a member of your design team, it can simplify the development process and speed up the time to market for medical devices. The innovation, engineering, and manufacturing advice provided by suppliers can help you gain a competitive advantage by significantly improving total cost of ownership, quality, and overall product performance.