Engineers at Northwestern University published a study on November 4 in Science Advances introducing a new 3D printing method called DIAL — Direct Ink Additive Lithography. The method combines features of extrusion and light-based printing, aiming to preserve speed and precision while printing a wider range of functional materials, and can print complex structures without additional scaffolding.
According to Northwestern's news release, DIAL deposits thick, paste-like ink through a long slot-die nozzle onto a flat surface, then a blade sweeps the material into a uniform sheet about 50 microns thick — thinner than a human hair. A projector then shines patterned light onto the sheet, hardening selected areas into a precise design. The process repeats layer by layer. Resolution depends primarily on the projector's pixel size and each ink layer's thickness rather than nozzle size, enabling fine features.
A key advantage is that the ink itself serves as support. The team mixed light-curable resin with fumed silica nanoparticles to give the ink a yield stress, so it regains stiffness after the blade passes and holds overhanging structures. After printing, unhardened ink can be washed away and the excess collected and reused, reducing waste. In side-by-side tests, DIAL printed porous grid structures in 30 minutes versus 124 minutes for conventional extrusion — more than four times faster. The team also printed lattices with walls as thin as 150 microns, interlocking chainmail, and a honeycomb spanning nearly four times the projector's illumination area.
To demonstrate material compatibility, the team printed samples with two functional inks: a structural electrolyte made from a polymerizable ionic liquid, producing 15 porous lattices the size of small coin-cell batteries in a single 15-minute run; and a hydrogel ink, printing microstructured containers modeled after cell culture inserts for tissue engineering. The study was led by the group of Assistant Professor Ryan Truby, with Ph.D. candidate Pranav Kaarthik as lead author.