Additive manufacturing by digital light processing: a review

Abstract

Additive manufacturing is a layer-by-layer strategy enabling the advanced design and fabrication of complex 3D objects and structures, overcoming geometry limitations and reducing waste production compared to conventional technologies. Among various additive manufacturing technologies, digital light processing (DLP), is an additive manufacturing technology used to print photopolymer parts, using a projected light source to cure an entire layer at once. Initially developed for pure resins, recent advances have demonstrated the potential of DLP in the polymerization of ceramic and metal-loaded suspensions, enabling the fabrication of ceramic and metal components after proper debinding and sintering. Such flexibility increases the potential of DLP for different applications, ranging from dental implants and bone scaffolds to smart biomaterials for soft robotics, smart wearables, and microfluidic devices. The review provides an overview of DLP technology and its recent advances; specifically, the review covers the photopolymer properties, the ceramic and metallic feedstock preparation, and the light-matter interaction mechanism underpinning the printing and post-processing steps. Finally, a description of the current application is provided and complemented with future perspectives.

Vat photopolymerization-based 3D printing of polymer nanocomposites: current trends and applications

“…68 More comprehensive details about photopolymer resins can be found in ref. 23, 24, 26, 27, 69 and 70…”

Combining 3D Printing and Microfluidic Techniques: A Powerful Synergy for Nanomedicine

“…Although SLA and DLP employ the same working principle as rapid prototyping, in DLP the photoinitiator is represented by a digital projector [ 93 ]. The light path in DLP is direct, allowing for complete LbL photopolymerization at once, making this process quicker and slightly higher in resolution than similar SLA, in which the process is point-to-point laser-depended [ 79 , 94 ]. Despite several DLP printer machineries, all operate with the same fundamental set-up, which includes a building stage (or head), a resin container (vat), and a photoinitiator [ 26 ] ( Figure 5 ).…”

“…After curing the first layer, the head travels lower, allowing fresh resin to be deposited on the plate’s surface for polymerizing the next layer. Both arrangements ensure the movement of the head in the vat, so that the amount of resin between the building stage and the photoinitiator is identical to the desired layer thickness [ 78 , 79 ].…”

Rational Design and Characterization of Materials for Optimized Additive Manufacturing by Digital Light Processing

“…When compared to stereolithography (SLA) [ 9 ], which is based on a laser source for voxel-by-voxel polymerization, one of the major advantages of DLP is the use of a high-resolution source [ 10 ], curing an entire layer with one projection at each step, thus reducing the overall printing time. Initially developed for producing prototypes using pure photopolymers (resins), the technology has been recently tested to print ceramic and metal suspensions [ 11 ]. One of the earliest introductions of suspensions was in the form of ceramic powder, such as alumina and zirconia, in freeform fabrication using SLA [ 12 ].…”