3D printing is a generalized term that encompasses the printing of various materials such as polymers, plastics, ceramics, metals, and composites. Bioprinting refers specifically to the printing of live cellular material, usually mixed in with a polymer (i.e. biomaterial) of choice. This allows researchers to develop tissue constructs with a high degree of complexity that mimics the observed structure and composition within the body. Such cellular tissue constructs can be applied towards research (such as investigation of cell biology) or in preclinical research (such as implantation in animal models). The ultimate goal of such approaches is to engineer 3D-printed constructs that are repaid, regenerate, or replace damaged tissue in the body.
3D printing, also referred to commonly as ‘additive manufacturing,’ refers to the layer-by-layer deposition of a material of choice through a computer-aided and controlled machine to create three-dimension (3D) objects. The design to be printed is supplied to the computer as a computer-aided-design (CAD) model. There are several different types of 3D printing technologies, each differing in the way material is deposited and the layers fused for creating the 3D object. Learn more about this technology below.
There are extensive reviews in literature on various kinds of technologies used for 3D printing and bioprinting. Two main techniques commonly used are vat photopolymerization (where a light-sensitive polymer is printed using lasers) and material extrusion (where the desired material is extruded from a syringe-needle combination).
Within vat photopolymerization, Stereolithography (SLA) utilizes a laser to map out the design fed into the computer (the CAD model) on the vat containing the resin to be printed linearly. It prints the design one layer at a time, and as the stage moves upon completion of each layer. In the Digital Light Processing (DLP) technique, the entire layer design is shone on the vat resin. While very fine features (~20 µm) can be obtained, the process takes a long time (hours depending on the design) and is not conducive to cells.
Material extrusion on the other hand allows the inclusion of desired cells or other biological components in the ‘bioink’ that is to be printed, provided it does not damage the components during the printing process. Some polymers (e.g. gelatin, alginate, collagen) can be printed at room temperatures while others (e.g. polycaprolactone, polystyrene, etc.) require much higher temperatures (up to 100 °C) for printing. Researchers often use a combination of materials to 3D print their biological constructs. Several factors such as temperature, pressure, printing speed, etc. need to be optimized for obtaining the ideal prints. Fused Deposition Modeling (FDM) is another form of extrusion printing where the desired material (usually plastics such as acetyl butyl styrene) is passed through a heating tool as a filament in solid form. The heating tool melts the plastic which can then be deposited in a layer-by-layer fashion per the CAD model.
Finally, several other printing techniques such as inkjet printing, binder jetting, powder bed fusion, etc. can be utilized depending on the application and material of choice.
The center boasts of a wide range of different printer types, which can be found in our Resource section, that utilize one or more of these technologies for 3D printing and bioprinting purposes. We also recognize that this is a highly dynamic field with new technologies and modifications being constantly made. We aim to be on top of the technology curve to provide our collaborators and research partners the latest in 3D printing technologies that aid their research efforts.
Image courtesy of UMD.