ResearchNorthwestern's DIAL process cures paste inks with light and needs no support structures
Researchers at Northwestern University have described direct ink additive lithography (DIAL), a process that spreads paste inks in thin layers and hardens them selectively with projected light. The paste holds the part in place, so no separate supports are needed. The work appeared in Science Advances and targets materials such as battery electrolytes and hydrogels.
Key facts- Published in Science Advances by Northwestern University's Robotic Matter Lab
- Layers of 50 microns, light source is a DLP head
- Silica-doped polyurethane-based resins let the paste act as its own support
- Lattices with 150-micron walls, electrolyte and hydrogel structures shown
Context Yield-stress fluids are pastes that hold their shape at rest and flow only under force, which is why the ink can carry unhardened regions of a part.
How does DIAL build a part?
A slot-die nozzle deposits paste onto the print bed, and a recoater smooths it into layers of 50 microns. A Wintech PRO 4500 DLP projection head then hardens selected areas with light. Unhardened ink stays in place as support and is washed off afterwards.
Which inks and parts were shown?
The inks are photocurable polyurethane-based resins doped with silica nanoparticles, which let each layer keep its shape after recoating. Early tests produced lattices with 150-micron walls, porous structures from a structural electrolyte, and a hydrogel shaped like a cell culture scaffold. Moving the projection head allows parts larger than the build volume, and different inks can be used per layer.
What do the researchers plan next?
The group says it is working on structures for extreme environments in space, flexible robot body parts, medical devices and tissue culture environments. In some cases the process could be faster than material extrusion and Direct Ink Write while offering finer detail, similar to vat polymerization.
What it means
DIAL is a laboratory result, with no machine, price or production data yet. For European manufacturers its relevance lies in materials that current processes handle poorly, such as pastes, hydrogels and electrolytes, and in removing support structures. Until repeatability, throughput and material qualification are shown outside the lab, it remains a development to watch rather than a planning basis for production.
Frequently asked questions
What is DIAL 3D printing?
Direct ink additive lithography spreads paste inks in layers and hardens chosen areas with projected light. It combines traits of direct ink writing and vat polymerization.
Why are no supports needed?
Silica nanoparticles make the paste hold its shape, so unhardened ink supports the part and is washed away after printing.
Which materials were tested?
Photocurable polyurethane-based resins, a structural electrolyte for porous lattices and a hydrogel shaped like a cell culture structure.