Application of carbon fiber composite materials in medical devices

Carbon fiber composite materials are increasingly used in diagnosis, treatment, healthcare, and related medical devices. With the growing demand in the medical market, the applications and forms of carbon fiber medical materials are constantly expanding and innovating.

Carbon fiber composite materials are increasingly used in diagnosis, healthcare, and related medical devices. With the growing demand in the medical market, the applications and forms of carbon fiber medical materials are constantly expanding and innovating.

Research on medical carbon fiber materials began in the 1960s, when the excellent anti-coagulation properties of carbon fiber materials were discovered in the study of anti-coagulation materials for artificial blood vessels. After 1970, Bokros proposed using carbon fiber materials as biomedical devices. Modern scientific research shows that carbon fiber materials have good biocompatibility, low irritation to biological tissues, non-toxicity, non-carcinogenicity, low specific gravity, and an elastic modulus similar to human bone, making them a potential advantage as a fourth-generation implant material.

Advantages of Carbon Fiber Composite Materials in Medical Applications

1. Anisotropy and Designability Carbon fiber composite materials are anisotropic materials, with different properties along and perpendicular to the fiber direction, giving great design freedom. By changing the lamination method (e.g., lamination angle, lamination sequence), the elasticity and strength of the product can be changed to meet specific requirements. Medical device components often act on different parts of the human body, and the specific performance requirements of different components are different.

2. High X-ray Transmittance The transmittance of X-rays is related to the elemental composition, atomic number, density, and thickness of the substance being penetrated. The main elements of carbon fiber composite materials are C, H, and O, with low atomic numbers, and the X-ray mass absorption coefficient is much lower than that of general materials. The X-ray transmittance of a 1 mm thick aluminum plate and a carbon fiber composite plate is 78% and 96%, respectively. The scattering and absorption consumption of the aluminum plate is 22%, while that of the carbon fiber plate is only 4%.

3. Good Fatigue Resistance Carbon fiber composite materials contain countless fiber/resin interfaces. When excessive external force causes cracks, these interfaces can effectively prevent further crack propagation and delay fatigue failure. Medical devices are used repeatedly every day, and the good fatigue resistance of carbon fiber composite materials ensures the service life of the instruments. In the field of medical devices, carbon fiber composite materials are used to manufacture mobile platforms for X-ray inspection instruments due to their X-ray full transmission; due to the excellent mechanical properties of CFRP, they are used to manufacture medical devices for orthopedics and organ transplantation, as well as prosthetics and orthoses.

Used in CT bed plates, X-ray examination equipment and auxiliary equipment

This is currently the most widely used application of carbon fiber medical materials in China. Representative examples include X-ray, CT, and ultrasound examination bed panels, headrests for diagnostic beds, panels for high-definition DR flat-panel detectors, and supports.

Medical CT bed plates mostly use insulating plates, but their X-ray transmittance is low, mechanical properties are poor, and imaging clarity is poor. The absorption and scattering rates of carbon fiber composite materials are much smaller compared to them. During diagnosis, the X-ray dose can be reduced accordingly, the power of the X-ray machine can be reduced, the service life of the instrument can be extended, and energy can be saved.

More importantly, due to its excellent X-ray transmission performance, carbon fiber composite materials allow X-rays to irradiate the bed plate at any angle without refraction. Only a small dose of X-rays is needed to obtain clear imaging, thus reducing the harm to patients and medical personnel.

Previously, at the Japan Medical Device Design and Manufacturing Exhibition, Teijin Group showcased its carbon fiber composite materials in medical applications—a carbon fiber support for neurosurgery.

Carbon Fiber for Artificial Bones and Joints

Currently, carbon fiber composite materials are widely used in intramedullary fixation plates, bone fillers, hip stems, artificial dental roots, cranial repair materials, and artificial heart materials, etc. The bending strength of human bones is around 100 MPa, the bending modulus is 7-20 GPa, the tensile strength is about 150 MPa, and the tensile modulus is about 20 GPa. The bending strength of carbon fiber composite materials is around 89 MPa, the bending modulus is 27 GPa, the tensile strength is about 43 MPa, and the tensile modulus is about 24 GPa. In comparison, it is close to or exceeds the strength of human bones.

Currently, some companies have developed artificial bones and joints using carbon fiber composite materials. The bending strength of this artificial bone is closer to that of real bone than artificial bones made of other biomaterials, which is of great significance to orthopedics. The wear resistance of artificial joints made from it at the moving connection is also higher than that of ultra-high molecular weight polyethylene and metal products.

Invibio, a well-known medical device supplier, has developed a short-cut carbon fiber reinforced polyetheretherketone (PEEK) with excellent mechanical strength and tensile creep resistance. It can bear the load required by bones, blood, and human tissues, and has good biocompatibility with the human body. The bending strength of this artificial bone is closer to that of real bone than artificial bones made of other biomaterials, which is of great significance to orthopedics. The wear resistance of artificial joints made from it at the moving connection is also higher than that of ultra-high molecular weight polyethylene and metal products.

Another company has developed continuous carbon fiber or felt-reinforced plastics for bone repair. The resin matrix uses polymethyl methacrylate, and the mass fraction of carbon fiber is 20%-60%. Because this material is lightweight, does not interfere with magnetic resonance imaging, and has good biocompatibility, long-term implantation in the body has no adverse reactions to biological tissues, blood, and cerebrospinal fluid, and no rejection reaction. Therefore, it is suitable for use as a fixation material for fractures, intramedullary fixation, or bone repair material.

Dental Restoration

In Western countries, non-metal restoration—prefabricated fiber post systems—are increasingly used in clinical practice and are gradually considered to be an effective replacement for traditional metal post core systems for repairing damaged teeth. Studies on the physical and chemical properties and biological properties of carbon fiber posts show that carbon fiber posts have mechanical properties that are more compatible with dental tissues. Their elastic modulus, similar to that of dentin, allows stress to be distributed more evenly along the post, which is beneficial for protecting the root. At the same time, they have good biocompatibility and corrosion resistance, are easy to remove, and are convenient for secondary repair, among other advantages.

Carbon Fiber Prosthetics

The connecting portion between the prosthesis and the human body is called the socket, which mainly encases the residual limb and transmits force. This part has high load-bearing requirements and cannot be too heavy; carbon fiber material can also be used to make this part. The part that encases the residual limb can use polyethylene plates, and the support can use a carbon fiber frame structure to achieve easy support and force transmission.

The articulation between the human ankle and foot plays a key role in body balance and support. A carbon fiber ankle joint can achieve the human jumping function. In addition, the connecting part between the ankle and lower leg prosthesis can also be made of carbon fiber. The resulting product is very exquisite and shows excellent performance in terms of damage safety.

Carbon Fiber Wheelchair

The density of carbon fiber is only 1.7g/cm3, and accessories of the same specifications are more than half lighter than those made of aluminum alloy, but the strength is much greater. In addition, carbon fiber also has strong corrosion resistance. A considerable proportion of wheelchair users face incontinence and frequent contact with injections and medicinal solutions. In this case, carbon fiber composite material accessories demonstrate durability that is unmatched by ordinary metal materials.

Currently, carbon fiber composite materials are mainly used in accessories such as armrests, arm supports, footrests, leg rests, backrests, skirt guards, and frame tubes. Most of these accessories can be adjusted in height. Carbon fiber composite materials are easy to assemble with the wheelchair as a whole through mechanical connections. Most importantly, after using carbon fiber composite materials for these accessories, the overall weight of the wheelchair is significantly reduced, and as parts with high usage frequency, they have also become more durable.

Carbon fiber composite materials have reliable performance and have been widely used in daily civilian life. They have also been verified through decades of application, and they are safe and reliable for the environment and human health.

With the continuous advancement of medical technology, medical equipment is also constantly innovating and developing. The application of carbon fiber in medical devices represents a new trend and direction, and it will surely usher in a broader application prospect in the future.