LED-Based UV Light Can Rapidly Convert 3D Printing Polymeric Inks Into Solids

A breakthrough in rapid additive manufacturing that involves UV light solidifying the inks used could pave the way for fully functional 3D-printed electronic circuits.

Researchers at the University of Nottingham have pioneered the breakthrough and hope to produce functional components such as 3D antennae and fully printed sensors from multiple materials including metals and plastics.

A schematic diagram showing how UV irradiation heats and solidifies conductive and dielectric inks to form the letter N with silver tracks that connect a green LED to a power source. Courtesy of University of Nottingham.

The new method combines 2D-printed electronics with additive manufacturing, expanding the impact of multifunctional additive manufacturing (MFAM), which involves printing multiple materials in a single additive manufacturing system to create components that have broader functionalities.

Existing systems typically use just one material, which limits the functionality of the printed structures. Having two materials such as a conductor and an insulator expands the range of functions in electronics.

The Nottingham researchers were able to speed up the solidification process of the conductive inks to less than a minute per layer. Previously, this process took much longer to be completed using conventional heat sources such as ovens and hot plates, making it impractical when hundreds of layers are needed to form an object.

The researchers found that silver nanoparticles in conductive inks are capable of absorbing UV light efficiently. The absorbed UV energy is converted into heat, which evaporates the solvents of the conductive ink and fuses the silver nanoparticles. This process affects only the conductive ink and does not damage any adjacent printed polymers. The researchers used the same compact, low-cost LED-based UV light to convert polymeric inks into solids in the same printing process to form multimaterial 3D structures.

“Printing fully functional devices that contain multiple materials in complex, 3D structures is now a reality,” said Richard Hague, director of the Centre for Additive Manufacturing. “This breakthrough has significant potential to be the enabling manufacturing technique for 21st century products and devices that will have the potential to create a significant impact on both the industry and the public."

The project has led to several collaborations to develop medical devices, radio frequency shielding surfaces and structures for harvesting solar energy.