Medical biomaterials are also called biomedical materials, or biological materials and medical materials. Plastic surgery also calls this material artificial tissue substitute. Medical materials are a type of materials with special properties and special functions that are used in medical and health care fields such as artificial organs, surgical repair, physiotherapy and rehabilitation, diagnosis, and treatment of diseases, without causing adverse effects on human tissues and blood.

Biomedical materials are new high-tech materials used to diagnose, treat, repair or replace damaged tissues and organs of organisms or improve their functions. It is the basis for the study of artificial organs and medical devices, and has become an important branch of the materials discipline. Especially with the rapid development and major breakthroughs in biotechnology, biomaterials have become a hot spot for scientists from all over the world to conduct research and development. Contemporary biomaterials are on the verge of achieving major breakthroughs. In the near future, scientists may use biomaterials to design and manufacture entire human organs. The biomedical materials and products industry will develop into a pillar industry of the world economy in this century.

Biological materials are composed of biomolecules, and then biological components are composed of biomaterials. Various materials and components in living organisms have their own biological functions. They are "alive" and controlled by the whole organism. Some of the biomaterials are structural materials, including hard tissue materials such as bones and teeth, and soft tissues such as muscles, tendons, and skin. There are also functional components composed of many functional materials. For example, the eye lens is made of crystalline protein wrapped in a thin film composed of epithelial cells. The resulting wide-angle lens has no scattering, no absorption, and can be continuously zoomed. Materials and components with different functions grow in living organisms. One of the development directions of materials science is to simulate these biological materials to create artificial materials. They can be used as artificial substitutes for biological parts and can also be used in non-medical fields. The former includes artificial valves, artificial joints, etc.; the latter includes simulated biological adhesives, simulated enzymes, simulated biofilms, etc.

Biomedical materials are used directly in the human body or are closely related to human health. There are strict requirements. First, biomedical materials should have good blood compatibility and tissue compatibility. Secondly, it is required to be resistant to biological aging. That is, for long-term implanted materials, the biological stability should be good; for temporarily implanted materials, it is required to degrade into non-toxic monomers or fragments that can be absorbed or metabolized by the human body within a certain period of time. It also requires stable physical and mechanical properties, easy processing and molding, and appropriate price. Convenient disinfection and bacteria elimination, non-toxic and non-pyrogenic, non-carcinogenic and non-teratogenic must also be considered. Materials for different uses have different requirements.

The main research contents include: ① The study of the uniqueness and personality of special functions and properties, that is, the study of comprehensive physical and chemical properties; ② The physiological environment of organisms, tissue structure, and physiological functions of organs Research on the sterilization, disinfection, safety evaluation standards and methods and management of materials.

Medical materials can be classified according to the following aspects: ① Classification according to the source of the material; ② Classification according to the properties of the material; ③ Classification according to the application site of the material on the human body; ④ Classification according to the use requirements of the material; ⑤ According to Classification of contact time between materials and human body.

(1) Classification by source of materials

1. Human body's own tissue - autologous tissue transplantation technology.

2. Homologous organs and tissues - allogeneic tissue and organ transplantation technology.

3. Xenogeneic organs and tissues of the same kind - xenogeneic tissue and organ transplantation technology.

4． Natural biological materials: such as artificial kidneys and artificial livers made of biological sutures, chitin, cellulose, etc.

5. Synthetic materials: such as silicone and other polymers, ceramics, metals, etc.

(2) Classification according to material properties

1. Polymer materials: silica gel, polymer, etc.

2. Metal materials: such as various titanium alloy products, etc.

3. Inorganic non-metallic materials: such as hydroxyapatite, etc.

4． Natural biological materials: such as artificial heart valves made from cow pericardium.

(3) Classification by material application parts

1. Hard tissue materials: including bone, cartilage, tooth materials, etc.

2. Soft tissue materials: Various soft tissue fillers, including liquid fillers.

3. Cardiovascular materials: including artificial blood vessels, cardiovascular catheters, etc.

4． Blood substitute materials: including substitute plasma and artificial red blood cells.

5. Separation, filtration, and dialysis membrane materials: including membrane materials for blood purification, plasma separation, etc.

(4) Classification according to requirements for use of medical materials

1. Non-implantable materials and products: various syringes, infusion sets, blood transfusion sets, etc.

2. Implantable materials and products: such as porous polyethylene, expanded polytetrafluoroethylene, polyacrylamide hydrogel, etc.

3. Blood contact materials and products: such as cardiac counterpulsation balloons, etc.

4． Degradable and absorbable materials and products: absorbable sutures made from polylactic acid or collagen.

5. Others: such as immobilized enzyme carriers for diagnosis made of polyacrylamide, etc.

(5) Classification according to the contact time between materials and human body

1. Short-term exposure: Those exposed within 24 hours are called Class A materials.

2. Long-term contact: Those whose contact time is within 24 hours to 30 days are called Class B materials.

3. Permanent contact: Materials that are in contact for more than 30 days or even lifelong implants are called Class C materials.