Throughout the past century, the military has always been at the forefront of technological innovation, so its hardly surprising they have fully adopted 3D printing technology as well. While several military innovations have already been revealed, yesterday the US Air Force and the American Chemical Society unveiled a very interesting development that could have farther reaching applications than the military. They have used 3D printing technology to develop flexible hybrid electronic materials that are small, compact, powerful and above all able to withstand extreme external pressures – thus perfect for use on aircraft and even on bombs. However, the rest of the making world can obviously also benefit from these next-gen replacements of the PCB.
This fascinating development was unveiled at a press conference by the American Chemical Society in the Boston Convention & Exhibition Center yesterday, a video of which can be seen below. A subsequent press conference is scheduled for Wednesday. The American Chemical Society, to explain, is government-backed scientific society and the global leader in providing access to chemistry-related research. The ACS is also expected to unveil more at their 250th national meeting on Thursday.
However, the press release and conference yesterday already revealed a lot of interesting information. As Benjamin J. Leever, of the Air Force Research Laboratory at Wright-Patterson Air Force Base, explained, they are working towards the next generation of flexible, bendable and stretchable electronics to replace the rigid printed circuit board and the vulnerable electronics we are currently limited to. Over the last few years, they have therefore been developing electronic equipment suitable for use on aircraft, bombs, and even on military personnel themselves to monitor health and so on.
And with the help of 3D printing, they have succeeded. ‘Basically, we are using a hybrid technology that mixes traditional electronics with flexible, high-performance electronics and new 3-D printing technologies,’ Leever, Ph.D. explained. ‘In some cases, we incorporate ‘inks,’ which are based on metals, polymers and organic materials, to tie the system together electronically. With our technology, we can take a razor-thin silicon integrated circuit, a few hundred nanometers thick, and place it on a flexible, bendable or even foldable, plastic-like substrate material.’
These Flexible Hybrid Electronics, or FHEs, are based on inorganic semiconductors with 3D printed components and connectors. Together, Leever explains that they offer significant size, weight, and power (also known as SWaP) benefits without sacrificing on performance. Among the current range of applications they are thinking of, you can find: wearable electronics and sensors to monitor health, space efficient electronics and antennas with an eye on reducing aerodynamic drag and more generally electronics capable of withstanding the rigors of military use. Especially the biomedical application is interesting, and would involve sensors that measure heartbeat, hydration, temperature and more. In short, a high-tech nicotine patch, that can also be used by athletes and medical personnel.
So how do you create that highly flexible effect? As Leever explains, the key are liquid gallium alloys which they use as interconnecting material. ‘While these liquid alloys typically oxidize within minutes and become essentially useless, the team has been able to dramatically reduce the effects of the oxidation through the use of ionic species confined to the walls of microvascular channels within the flexible substrates.’ Essentially, this approach has enabled them to create circuitry in extremely tight spaces and even integrate them in a person skin or in the curved surfaces of aircraft.
What’s more, their tests have already progressed very far. Among the tests used, they have fabricated photovoltaic devices on PET and polymer surfaces. ‘We have also fabricated Li-ion batteries based on structurally resilient carbon nanotube-based electrodes that have survived thousands of flexing cycles,’ they add. Systems for monitoring the conditions of bridges and other types of infrastructure are also possible.
But of course, there’s a clear military application too. The same system can be applied to bunker busting bombs that detonate upon penetration. In this case, the toughness of the circuitry would survive the impact and can still detonate. ‘Overall, the military has the advantage of being able to move ahead with potentially higher risk research,’ Leever explains. ‘Commercial investors want a clear demonstration before making an investment. The military can pursue possibly transformational applications at earlier stages if we see a promising approach to realize and advance a technology’s revolutionary potential.