Discrete and Process Automation

New Method Can 3D Print Fully Functional Electronic Circuits

09 November 2017

Researchers from the University of Nottingham have pioneered a breakthrough method to rapidly 3D print fully functional electronic circuits.

The circuits, which contain electrically conductive metallic inks and insulating polymeric inks, can now be produced in a single inkjet printing process where a UV light rapidly solidifies the inks.

The technique paves the way for the electronics manufacturing industry to produce fully 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. Source: University of NottinghamA 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. Source: University of Nottingham

The new method combines 2D printed electronics with additive manufacturing (AM) or 3D printing, which is based on layer-by-layer deposition of materials to create 3D products. This expands the impact of multifunctional additive manufacturing (MFAM) — printing multiple materials in a single additive manufacturing system to create components with broader functionalities.

The new method overcomes some of the challenges in manufacturing fully functional devices that contain plastic and metal components in complex structures, where different methods are required to solidify each material.

Existing systems typically use one material, which limits the functionality of the printed structures. Using two materials — like a conductor and an insulator — expands functionality. For example, a wristband that includes a pressure sensor and wireless communication circuitry could be 3D printed and customized for the wearer in a single process.

The breakthrough speeds up with the solidification process of the conductive inks to less than a minute per layer. Previously this process took much longer using conventional heat sources, like ovens and hot plates, making it impractical when hundreds of layers are needed to form an object. In addition, the production of electronic circuits and devices is limited by current manufacturing methods that restrict the form and potentially the performance of these systems.

Professor Chris Tuck, Professor of Materials Engineering and lead investigator of the study, highlighted the potential of the breakthrough.

“Being able to 3D print conductive and dielectric materials (electrical insulators) in a single structure with the high precision that inkjet printing offers will enable the fabrication of fully customized electronic components. You don't have to select standard values for capacitors when you design a circuit, you just set the value and the printer will produce the component for you,” said Tuck.

Professor Richard Hauge, Director of the Centre for Additive Manufacturing (CfAM), added: “Printing fully functional devices that contain multiple materials in complex, 3D structures is now a reality. 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.”

Dr. Ehab Saleh and members of the team from CfAM found that silver nanoparticles in conductive inks are capable of absorbing UV light efficiently. The absorbed UV energy is then converted into heat, which evaporates the solvents of the conductive ink and fuses the silver nanoparticles. This process affects only the conductive ink and doesn’t damage any adjacently 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 multi-material 3D structures.

With advancements in technology, inkjet printing can deposit a wide range of functional inks with a spectrum of properties. It is used in biology, tissue bioprinting, multi-enzyme inkjet printing and various types of cell printing where the ink can be made of living cells.

The breakthrough established an underpinning technology with the potential for growth in academia and industry. The project has led to several collaborations intended to develop medical devices, radio frequency shielding surfaces and a novel structure for harvesting solar energy.

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