3D printing advanced electronics

This new technique, known as CHARM3D (tension-driven Continuous High-resolution Autonomous Rapid Metal 3D printing), allows for the efficient printing of free-standing 3D structures with high electrical conductivity, self-healing capabilities, and recyclability.

A novel approach to 3D circuitry

Traditional printed circuit boards (PCBs) are flat, limiting the integration of components and requiring larger footprints for devices. However, 3D circuitry enables the stacking and vertical integration of components, dramatically reducing the space needed. CHARM3D takes this a step further by enabling the creation of intricate 3D structures without the need for support materials or external pressure, overcoming some of the significant limitations of current 3D printing techniques.

The research, led by Associate Professor Benjamin Tee from the Department of Materials Science and Engineering at NUS, utilised Field’s metal, a eutectic alloy composed of indium, bismuth, and tin. This alloy melts at a low temperature of 62°C, has high electrical conductivity, and is non-toxic, making it an ideal candidate for 3D printing applications. The team’s findings were published in Nature Electronics.

Addressing the limitations of current methods

Current 3D printing techniques like Direct Ink Writing (DIW) use composite inks that suffer from low electrical conductivity and require support materials to maintain structure during printing. These inks are also highly viscous, which slows down the printing process. CHARM3D leverages the unique properties of Field’s metal to overcome these issues.

The technique exploits the tension between the molten metal in a nozzle and the leading edge of the printed part, allowing the creation of uniform and smooth microwire structures with adjustable widths ranging from 100 to 300 microns – comparable to the width of one to three strands of human hair. Unlike DIW, CHARM3D does not suffer from phenomena such as beading and uneven surfaces, and it supports faster printing speeds of up to 100 millimetres per second.

Benefits and applications of CHARM3D

CHARM3D’s ability to create free-standing 3D structures without additional post-treatment steps opens up numerous possibilities for advanced electronic devices. For example, in healthcare, it enables the development of contactless vital sign monitoring devices that enhance patient comfort and allow continuous monitoring without skin contact, reducing the risk of infections. This can be particularly beneficial in smart clothing and wearable devices used in hospitals, assisted-living facilities, and home settings.

In communications, the technique can be used to fabricate 3D antennas, improving signal sensing and processing applications. Arrays of 3D antennas created through CHARM3D can offer higher bandwidths and better signal-to-noise ratios, which are essential for applications like wireless vital sign monitoring and advanced security systems. These antennas can also be tailored for specific electromagnetic wave manipulation, leading to more accurate medical imaging and the detection of hidden devices or contraband.

Future prospects and commercialisation

The successful demonstration of CHARM3D by the NUS team, including the printing of 3D circuits for wearable battery-free temperature sensors and antennas, highlights the diversity of its potential applications. The team envisions extending this technique to other metals and structural applications, broadening the scope of its impact.

Associate Professor Tee remarked: “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.”

The research collaboration included Dr Zhuangjian Liu from the Agency for Science, Technology and Research’s Institute of High Performance Computing and Professor Michael Dickey from North Carolina State University’s Department of Chemical and Biomolecular Engineering. The team is actively seeking opportunities to commercialise this unique metal printing approach, which could herald a new era in the manufacturing of advanced electronics.

The development of CHARM3D is a significant advancement in the field of 3D printed electronics, and by utilising Field’s metal and a tension-driven process, the NUS research team has addressed key limitations of existing 3D printing techniques, enabling the creation of high-resolution, self-healing, and recyclable 3D circuits.

The potential applications of this technology span healthcare, communications, and security, and it promises to pave the way for more compact, efficient, and versatile electronic devices in the future.