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Liquid metal printer could enable development of personal electronics

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Posted December 19, 2013

3D printing becomes very popular in a wide range of applications, although the manufacture of electronic equipment using spatial printing techniques is still rather limited and restricted to a narrow selection of suitable materials and production methods. However, a team of engineers from the Chinese Academy of Sciences and the Tsinghua University (Beijing, China) are working to make this technology available for personal use.

Pictures illustrating the mechanical structure of liquid metal printer and examples of printed patterns of electronic tracks.

Pictures illustrating the mechanical structure of liquid metal printer and examples of printed patterns of electronic tracks. Image courtesy of the researchers.

According to a recently published paper (available at arXiv.org), there is a huge need for equipment, which will be suitable for personal electronic devices production, as the traditional industrial machinery and manufacturing processes are suitable only for mass-production and usually do not provide high economy of resources, like time, materials, water or energy. The authors claim that it is possible to adapt 3D printing technologies by including relatively simple modifications to overcome the main technical obstacles.

Diagrams showing how external factors (printer head contact angle and pressure, head movement speed and substrate selection) influence the liquid metal ink droplet shape and printing resolution.

Diagrams showing how external factors (printer head contact angle and pressure, head movement speed and substrate selection) influence the liquid metal ink droplet shape and printing resolution. Image courtesy of the researchers.

The development described in the current paper clearly shows that this is not a  theoretical idea. The team not only offered to use composite liquid metal ink with customized ink delivery and printing mechanism, paired with regular personal computer and automated control software, but also developed a working prototype, which is suitable to print quite complex conductive structures that can be integrated into electronic equipment dedicated for various purposes. Complete electronic circuit patterns can be produced in a matter of ten or twenty minutes.

Unfortunately, the current version of the device works in 2D-mode only, although the developers vaguely mention that 3D printing should be possible by adding a third axis of printer head movement. Probably, this would also mean a significant reduction in printing speed.

The team explains that their developed personal liquid metal printer includes an automatic printing driver, ink cartridge, mechanical part that moves the printer head and a notebook computer with installed software. The printing driver is hardware-based with a built-in control sensor that detects pre-patterned electronic tracks to avoid destroying them. Printing is performed using vector-based graphical images processed by the printer control software.

Examples of printed functional patterns of electronic tracks. Image courtesy of the researchers.

Examples of printed functional patterns of electronic tracks. Image courtesy of the researchers.

The currently available prototype model is suitable to print patterns at a resolution of 100 μm, which is not so far from the modern hard-wiring electronic technologies. The engineers hope to increase the resolution further, although they admit this task is difficult to accomplish due to intricacies of liquid metal flow dynamics. For example, the latest version of rolling-transfer printing head uses a 700 μm roller-bead, which rhythmically taps the substrate to allow ink outflow, which is then transferred onto the surface with the assistance of roller-bead rotation, similarly as in ballpoint pens. According to the authors, it is difficult to remove structural metal impurities and maintain a smooth flow with smaller-sized roller-bead.

In any case, the members of the team are certain that further advancements of the designed prototype are possible through precise control of printer head movement and speed, selection and real-time feedback-based control of head tapping mode, and selection of proper ink and substrate composition.

Let’s hope that the 3D version of new prototype will be also developed and tested soon.

By Alius Noreika, Source: www.technology.org

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