Precise, high-quality silicone is increasingly important for devices such as catheters, surgical instruments, prosthetics and long-term implants. Medical-grade silicone is biocompatible and breathable, making it ideal for sealing, bonding and making elastic parts. In fact, it can be a versatile and effective tool in the medical designer's toolkit. But medical-grade silicone must meet the most stringent purity standards before it can be used in life-critical devices.
Learn about medical silicone
Silicone medical device raw materials are currently manufactured by a variety of suppliers. NuSil, DuPont, Wacker, and Elkem are just a few examples of leading raw material suppliers, many of which have FDA and ISO 10993 certifications to support their use in medical device applications.
From these raw materials, suppliers can produce a wide variety of medical devices, many of which use silicone films and sheets. The resulting material can be cut and formed to fit nearly any need. Precision cutting is accomplished by die cutting and laser cutting. There are also multi-layer options, usually with two or three layers of silicone, which adds another dimension of versatility.
Equipment developers also have many options when it comes to thickness and configuration. With calendaring, thicknesses range from 0.005 to 0.125 inches, while extrusion and doctoring can create ultra-thin films as thin as 0.0005 inches. This means it can be as soft as chewing gum or as hard as the sole of a dress shoe, depending on the need. It can also be reinforced with mesh for added strength or foam for added softness. And with matte or glossy finishes and a wide range of colors available, engineers can deploy a highly customizable material for their specific needs.
Silicone also has unique functional properties that make it the material of choice for improving patient outcomes, especially in challenging applications.
Silicone films are particularly good in wound care because they are both breathable and liquid-proof, preventing bacterial growth while ensuring breathability. For example, silicone gel sheets used for scar healing are usually worn for a week or more, which can keep the skin moisturized while venting water vapor to prevent problems such as skin over-softening. And because medical-grade silicone is chemically inert, it will not cause irritation or allergies.
Silicone is frequently used as a primary wound dressing in direct contact with wounds. Perforated silicone film dressings can remain in place for longer periods of time, so secondary wound dressings used to absorb wound exudate can be changed without disturbing the delicate healing skin. In addition, the transparency of the film means that you can inspect the wound without removing the dressing, which is a great benefit for undisturbed healing and reduced number of dressing changes.
How silicones overcome design challenges in critical applications
Reinforced sheets take silicone to the next level by embedding materials such as polyester or nylon mesh. Depending on the application, mesh can be incorporated in varying thicknesses and pore sizes (percent open area). Reinforced sheets are ideal for devices and components that need to remain flexible but not overstretch or tear.
A common use for reinforcement tabs is in sutures. Without reinforcement, the sutures can cut through the silicone, causing it to tear. Proper reinforcement can make the sutures stronger than the sutures themselves. For example, tissue expanders used in breast reconstruction or skin repairs use suture tabs made of reinforcement tabs to ensure they stay in place.
Devices implanted in the brain, such as shunts and electrodes, can also rely on reinforced membranes to handle physical stress while keeping nearby tissue safe. Silicone encapsulation prevents tissue from growing into the mesh and minimizes trauma to surrounding tissue if the device moves or must be removed.
Most importantly, silicone is a material that OEMs can trust because it is tough when needed, yet soft enough for delicate uses.
