Researchers develop a new technique for producing three-dimensional circuits

A research team from the National University of Singapore (NUS) has developed a cutting-edge technique – known as voltage-controlled CHARM3D – to fabricate three-dimensional (3D), self-healing electronic circuits, pushing the boundaries of 3D printing technology.

Led by Associate Professor Benjamin Tee of the Department of Materials Science and Engineering, the team used Field’s metal to demonstrate how CHARM3D can fabricate a variety of electronic components. This provides more compact designs for devices such as wearable sensors, wireless communication systems and electromagnetic metamaterials. In healthcare in particular, CHARM3D enables the development of contactless vital signs monitoring devices, increasing patient comfort and enabling continuous monitoring.

“By offering a faster and simpler approach to 3D metal printing as a solution for advanced electronic circuit manufacturing, CHARM3D holds immense promise for the industrial-scale production and widespread adoption of intricate 3D electronic circuits,” said Assoc Prof Tee.

The production of 3D circuits is playing an increasingly important role in modern electronics, from battery technology to robotics and sensors, enabling further miniaturization. However, direct inkjet printing (DIW), a promising 3D printing technique, has significant drawbacks, particularly the use of composite inks with low electrical conductivity and the need for support materials. Here, Field’s metal offers an attractive alternative, as it melts at low temperatures of 62 degrees Celsius and has high electrical conductivity. These properties enable fast printing without support materials and external pressure.

CHARM3D utilizes the low melting temperature of Field’s metal and the tension between the liquid metal in the nozzle and the leading edge of the printed part to create uniform, smooth micro-cable structures with adjustable widths from 100 to 300 microns. Compared to conventional DIW, CHARM3D offers faster print speeds of up to 100 millimeters per second and higher resolutions, resulting in more detailed and precise circuits.

These 3D architectures exhibit excellent structural properties and are self-healing, meaning they can recover from mechanical damage and are recyclable. Prof. Tee emphasizes that CHARM3D offers a faster and simpler approach to 3D metal printing and thus has great potential for industrial mass production and widespread use of complex 3D electronic circuits.

The team has successfully printed a 3D circuit for a wearable, battery-free temperature sensor system, highlighting the versatile applications of CHARM3D in healthcare. This technique could also optimize signal processing and acquisition, leading to better signal-to-noise ratios and higher bandwidths. This opens up the possibility of creating specialized antennas for targeted communications, enabling more accurate medical imaging and advanced safety applications.

In future steps, the team plans to extend the technique to other metals and structural applications and is looking for opportunities to commercialize this unique approach to metal printing.