Northwestern's DIAL process prints a lattice in 30 minutes versus 124 for direct ink writing
Researchers at Northwestern University have built a hybrid printing process called direct ink additive lithography (DIAL) that prints thick, particle-filled extrusion inks at speeds and resolutions closer to light-based processes. The work, led by Pranav Kaarthik, was published in Science Advances.
Digital light processing needs low-viscosity, weakly scattering resins. Direct ink writing handles functional yield-stress inks but is slowed by filament deposition and capped in resolution by nozzle diameter. DIAL sidesteps both limits by extruding a slot-die layer, scraping it into a thin sheet with a doctor blade, then curing selected regions with a 405-nanometer projector while uncured ink stays put as its own support.
| Metric | Value |
|---|---|
| Minimum sheet thickness | 25 microns |
| Projector pixel pitch (planar resolution) | 50 microns |
| Log pile structure (60 x 40 mm) print time, DIAL | 30 minutes |
| Same structure, direct ink writing | 124 minutes |
| Thinnest printed fins | ~150 microns |
| Chain mail strut thickness | ~250 microns |
| Gyroid electrolyte lattice batch | 15 parts in one 15-minute run |
| Hydrogel culture insert feature depth | 0.5 mm inverted pyramids |
Because light only passes through a thin sheet rather than a full vat, opaque, heavily filled inks stay printable, which is the main trick DIAL uses to beat DLP’s material ceiling. Rastering the projector over overlaid ink sheets let the team build a multimaterial lattice four times the projector’s native illumination area. The test ink was a polyurethane-based resin thickened with fumed silica; the ionogel used for the electrolyte lattices is a separate formulation.
The authors call their print times conservative, since tool-change steps weren’t tuned for speed, and argue that without the suction and peel forces of vat-based printing, scaling build area and volume should be easier. Kaarthik and professor Ryan Truby are listed as coinventors on a US provisional patent. Funding came from the National Science Foundation, the Air Force Office of Scientific Research, and Northwestern’s McCormick School of Engineering.