Scientists developed stretchable metal composites and 3D printed them on soft substrates at room temperature
It seems the days are gone when just tossing a smart watch on your wrist makes you look cool. The wearable biotech industry has recently revealed its insatiable hunger for futuristic items. Pain relief goggles that monitor brain waves, vital sign monitoring stickers, and even mind reading glasses.
Schematic illustration of 3D printing system of stretchable metal composite. The printing system consists of a pointed nozzle connected to an ink reservoir filled with stretchable metal composite, a pressure controller, and five-axis movement stage with automatic movements in x, y, z axes and two tilting axes in the xy plane.
Figure 3-1 Stereoscopic micrographs of stretchable metal composites printed on an electronic chip-like 3D structure of soft material (silicone rubber). Scale bars are 100 μm. Figure 3-2 Schematic illustrations (left) and scanning-electron microscopic images (right) of various 3D structures of printed stretchable metal composites. 3D interconnection can overlap Scale bars are 100 μm.
They are just few of the latest items discussed at the 2019 Wearable Tech, Digital Health, and Neurotech Silicon Valley conferences. Not to be sure whether all of these wearable prototypes can catch on, but one thing is clear: there are more to come in the field of wearable technology.
This great potential has been, however, held back by a technical restraint: these wearables have never really felt "wearable" to their users.
Though they were supposed to feel like a second skin of the wearer, it has been technically impossible to devise "wearable" devices that are comfortable to bend and stretch and also keep good data recording capabilities on soft and curved skin. Wearable smart devices gather a person's bio measurements by connecting electrodes to the surface of the skin.
Inside the device are 3D-shaped electrode wirings (i.e. interconnects) that transmit electrical signals. To date, not only can the wirings only be formed on a hard surface, but also the components of such interconnects delicate and hardly-stretchable metals such as gold, copper, and aluminum.
In a paper published today in the journal Nano Letters, the joint research team led by Prof. Jang-Ung Park at the Center for Nanomedicine within the Institute for Basic Science (IBS) in Daejeon, South Korea, and Prof. Chang Young Lee at the Ulsan National Institute of Science and Technology (UNIST) in Ulsan, South Korea reported fully-transformable electrode materials that also feature a high electric conductivity.
Notably, this novel composite is super-thin, 5 micrometers in diameter, which is half of the width of conventional wire bonding. By enabling ever-slimmer 3D interconnects, this study can help to revolutionize the physical appearance of smart gadgets, in addition to reinforcing their technical functions.
The research team used liquid metals (LM) as the main substrate since LMs are highly stretchable and have relatively high conductivities similar to solid metals. To improve the mechanical stability of the metal liquid, carbon nanotubes (CNT) were dispersed uniformly.
"To have a uniform and homogeneous dispersion of CNTs in liquid metal, we selected platinum (Pt), for having a strong affinity to both CNT and LM, as the mixer and it worked," said Young-Geun Park, the first author of the study.
This study also demonstrated a new interconnection technology that can form a highly conductive 3D structure at room temperature: For having a high conductivity, the new system does not require any heating or compressing process. Also the soft and stretchable nature of the new electrode makes it easy to come through the nozzle in a fine diameter. The research team used a nozzle for the direct printing of various 3D patterning structure as shown in Figure 3. Park explains, "Forming high-conductivity 3D interconnections at room temperature is an essential technology that enables the use of various flexible electronic materials.
The wire bonding technology used in existing electronic devices forms interconnects using heat, pressure, or ultrasonic waves that can damage soft, skin-like devices. They have been a great challenge in the manufacturing process of high-performance electronic devices." He noted that the pointed nozzle also allows reshaping of the preprinted pattern into various 3D structure, thus having an electrode work like a "switch" to turn on and off power.
Using the direct printing method, the high-resolution 3D printing of this composite forms free-standing, wire-like interconnects. This new stretchable 3D electrical interconnections specifically consist of super-thin wires, as fine as 5 micrometers. Previous studies on stretchable metals have only been able to present wire lines of several hundred micrometers in diameter.
The new system is even thinner than the interconnect of conventional wire bonding. Professor Jang-Ung Park, the corresponding author of the study noted, "We may soon be able to say goodbye to those bulky skin-based interfaces as this freely-transformable, super-thin 3D interconnection technology will come as a big breakthrough to the industry's efforts to produce ever compact and slim gadgets."
Blurring the boundary between the human body and electric devices, this new technology will facilitate the production of more integrated and higher-performing semiconductor components for use in existing computers and smartphones, as well as for flexible and stretchable electronic devices."
Dahee Carol Kim | EurekAlert!
Rewriting the periodic table at high pressure
15.08.2019 | Chalmers University of Technology
The first metal-organic coordination polymers were synthesized at the Samara Polytech
13.08.2019 | Samara Polytech (Samara State Technical University)
Soft robots have a distinct advantage over their rigid forebears: they can adapt to complex environments, handle fragile objects and interact safely with humans. Made from silicone, rubber or other stretchable polymers, they are ideal for use in rehabilitation exoskeletons and robotic clothing. Soft bio-inspired robots could one day be deployed to explore remote or dangerous environments.
Most soft robots are actuated by rigid, noisy pumps that push fluids into the machines' moving parts. Because they are connected to these bulky pumps by tubes,...
Researchers at TU Graz are working together with European partners on new possibilities of measuring vehicle emissions.
Today, air pollution is one of the biggest challenges facing European cities. As part of the Horizon 2020 research project CARES (City Air Remote Emission...
Over the next three years, researchers from the Vrije Universiteit Brussel, University of Cambridge, École Supérieure de Physique et de Chimie Industrielles de la ville de Paris (ESPCI-Paris) and Empa will be working together with the Dutch Polymer manufacturer SupraPolix on the next generation of robots: (soft) robots that ‘feel pain’ and heal themselves. The partners can count on 3 million Euro in support from the European Commission.
Soon robots will not only be found in factories and laboratories, but will be assisting us in our immediate environment. They will help us in the household, to...
Scientists at the University of Leeds have created a new form of gold which is just two atoms thick - the thinnest unsupported gold ever created.
The researchers measured the thickness of the gold to be 0.47 nanometres - that is one million times thinner than a human finger nail. The material is regarded...
An international team of scientists involving the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) in Hamburg has unraveled the light-induced electron-localization dynamics in transition metals at the attosecond timescale. The team investigated for the first time the many-body electron dynamics in transition metals before thermalization sets in. Their work has now appeared in Nature Physics.
The researchers from ETH Zurich (Switzerland), the MPSD (Germany), the Center for Computational Sciences of University of Tsukuba (Japan) and the Center for...
16.08.2019 | Event News
14.08.2019 | Event News
12.08.2019 | Event News
16.08.2019 | Life Sciences
16.08.2019 | Physics and Astronomy
16.08.2019 | Medical Engineering