New Test Method for Printability of Bioinks and Material Inks Used in Laminar Flow Extrusion Bioprinting
1. Scope
1. Scope
1.1 This standard describes a procedure to assess the printability of bioinks used in laminar flow extrusion-based 3D bioprinting. Laminar flow extrusion-based 3D printing fundamentally differs from other types of additive manufacturing; such as, fused deposition modeling (FDM), stereolithography (SLA) and powder bed 3D printing techniques in that it involves extrusion of a gel rather than preformed filament or particulates as the feedstock. This standard may also be used to test printability of the pastes or slurries used in the more closely related direct-ink-writing 3D printing.
1.2 Bioprinting often involves the printing of lattice or porous designs. This three-part test method evaluates the fidelity of three bioprinted structures: lines with increasingly closer line spacing, a multi-layered lattice with varying line separation, and an upright cylinder. The consistency and fidelity of the printed lines and shapes to the computer design is assessed by measurements of the printed single and multi-layered structures.
1.3 Printability of bioinks is one of several important parameters for precision manufacturing of bioprinted parts. The effects of the 3D bioprinting extrusion process on viability and biological activity of cells or other biological or drug components that may be contained in the bioink are also important, but not addressed in this standard.
Keywords
additive manufacturing; laminar flow extrusion bioprinting; 3D printing of polymers; tissue engineering; bioprinting
Rationale
Bioprinting is a type of additive manufacturing used to synthesize pieces of living tissues for use in reconstructive surgeries and other tissue engineering medical product applications, including drug testing. The bioprinting process, also called laminar flow extrusion-based 3D printing, has similarities to Direct-Ink-Write or robocasting used for 3D printing ceramic materials. However, bioprinting differs fundamentally from fused deposition modeling (FDM), stereolithography (SLA) and powder bed 3D printing methodologies therefore this standard is being proposed. Laminar flow extrusion based bioprinters are the most commonly used 3D printers for building tissue engineered medical products that contain living cells and growth factors; thus, this standard focuses on that modality. This standard will provide a standardized way of measuring print fidelity of bioinks that has not been addressed in any of the ASTM or ISO additive manufacturing activities to date. This test method is a companion document to F3659 – 24 a Standard Guide for Bioinks Used in Bioprinting.
