The primary types of bio-inks used in 3D printing include:

• Hydrogels: Synthetic polymers with the ability to swell. They are especially used in drug delivery applications, with swelling controlled by factors such as polymer material, viscosity, and shear stress.
• Ceramic-Based Inks: These provide high stiffness and a surface for bone tissue development. Common materials like hydroxyapatite and tricalcium phosphate enhance scaffold strength.
• Polymer-Based Inks: Materials like polylactic acid (PLA) and acrylonitrile butadiene styrene (ABS) are extensively used for engineering applications, prototyping, and assisting in bone formation and regeneration.
• Composite Inks: Combinations of different inks (e.g., hydrogels and polymers) that enhance mechanical properties and bioactivity. They accelerate healing and are primarily used in tissue engineering applications.