81 BIOMATERIALS, NANOMATERIALS, AND SMART MATERIALS Atom Molecule Virus Bacteria Cell Period Tennis ball 1 1 nm 100 nm 0,001 mm 0,01 mm 1 mm 10cm Nanomaterials Biomaterials, nanomaterials, and smart materials represent the new frontier of materials science, with potential applications across multiple industries. Even though they have specific applications and properties, they often overlap in certain fields such as medicine, engineering, and technology. Nanomaterials are able to cross biological membranes and access cells, tissues, and organs that larger-sized particles normally cannot. They can gain access to the blood stream via inhalation or ingestion, for this reason they might be dangerous for health if not properly treated. Biomaterials Biomaterials are synthetic or natural materials used in medical devices or in contact with biological systems. Their main range of applications includes implants, prothesis, limbs replacement, artificial arteries, and much more. They can be divided into three main categories: Nanosilver, for example, consists of many silver atoms or ions clustered together to form a particle between 1 and 100nm in size. It is contained in a range of products, including washing machines, food packaging, and wound dressings. ONLINE RESOURCES Nanomaterials in aerospace engineering fabric: tessuto joint: articolazione lasting: duraturo limb: arto to overlap: sovrapporre rod: barra surgical: chirurgico wettability: bagnabilit wound dressing: medicazione per ferita 192 MeCHaNiCs metallic biomaterials are generally used for load bearing applications such as bone implants because they guarantee an excellent resistance to long lasting activities such as walking and arm lifting. They are inert because they produce no or minimal tissue response; ceramic biomaterials are generally used in joints replacements, teeth implants, and cartilage regeneration in orthopedics because they are extremely hard and resistant. They can be both inert or active, when they encourage bonding to the surrounding tissue; polymeric biomaterials are flexible, elastic, and deformation resistant. For their properties, they are typically used in implants, tissue repairing, and for surgical sutures. They can be both inert or degradable, when they dissolve completely once incorporated into the surrounding tissue. Nanomaterials Nanomaterials are classified as such when their external or internal dimension measures 100 nanometres or less. They may be in the form of particles, tubes, rods, or fibres, and have very versatile physicochemical characteristics such as melting point, wettability, electrical and thermal conductivity, and light absorption. Current applications include healthcare (for example in regenerative medicine and diagnostics), electronics, cosmetics, textiles, information technology, and environmental protection. We also find nanomaterials in stain-repellent fabrics, self-cleaning windows, and ceramic coatings for solar cells, and their applications are increasing. Smart materials Smart materials are materials engineered to react predictably and reversibly to external stimuli, such as specific mechanical stress or temperature changes, by altering some of their properties. Because of their response they are also referred to as reactive materials. Nowadays, there are different types of smart materials and new ones arise every day, thanks to investment in research. Some of them are: piezoelectric materials, which generate an electric charge when mechanically deformed or which change shape when subjected to an electric field. They are commonly used in telecommunications, construction, and renewable energy; chromoactive materials, which change colour when subjected to a certain variation in temperature, light, pressure, etc. They are used in sectors such as optics; magnetorheological materials, which change their properties when exposed to a magnetic field. For example, they are used in shock absorbers to prevent seismic vibrations in bridges or skyscrapers.