By stacking and connecting layers of stretchable circuits on top of one another, engineers have developed an approach to build soft, pliable “3D stretchable electronics” that can pack a lot of functions while staying thin and small in size.
The work is published in the Aug. 13 issue of Nature Electronics.
As a proof of concept, a team led by the University of California San Diego has built a stretchable electronic patch that can be worn on the skin like a bandage and used to wirelessly monitor a variety of physical and electrical signals, from respiration, to body motion, to temperature, to eye movement, to heart and brain activity. The device, which is as small and thick as a U.S. dollar coin, can also be used to wirelessly control a robotic arm.
“Our vision is to make 3D stretchable electronics that are as multifunctional and high-performing as today’s rigid electronics,” said senior author Sheng Xu, a professor in the Department of NanoEngineering and the Center for Wearable Sensors, both at the UC San Diego Jacobs School of Engineering.
Xu was named among MIT Technology Review’s 35 Innovators Under 35 list in 2018 for his work in this area.
To take stretchable electronics to the next level, Xu and his colleagues are building upwards rather than outwards. “Rigid electronics can offer a lot of functionality on a small footprint—they can easily be manufactured with as many as 50 layers of circuits that are all intricately connected, with a lot of chips and components packed densely inside. Our goal is to achieve that with stretchable electronics,” said Xu.
The new device developed in this study consists of four layers of interconnected stretchable, flexible circuit boards. Each layer is built on a silicone elastomer substrate patterned with what’s called an “island-bridge” design. Each “island” is a small, rigid electronic part (sensor, antenna, Bluetooth chip, amplifier, accelerometer, resistor, capacitor, inductor, etc.) that’s attached to the elastomer. The islands are connected by stretchy “bridges” made of thin, spring-shaped copper wires, allowing the circuits to stretch, bend and twist without compromising electronic function.
This work overcomes a technological roadblock to building stretchable electronics in 3D. “The problem isn’t stacking the layers. It’s creating electrical connections between them so they can communicate with each other,” said Xu. These electrical connections, known as vertical interconnect accesses or VIAs, are essentially small conductive holes that go through different layers on a circuit. VIAs are traditionally made using lithography and etching. While these methods work fine on rigid electronic substrates, they don’t work on stretchable elastomers.
So Xu and his colleagues turned to lasers. They first mixed silicone elastomer with a black organic dye so that it could absorb energy from a laser beam. Then they fashioned circuits onto each layer of elastomer, stacked them, and then hit certain spots with a laser beam to create the VIAs. Afterward, the researchers filled in the VIAs with conductive materials to electrically connect the layers to one another. And a benefit of using lasers, notes Xu, is that they are widely used in industry, so the barrier to transfer this technology is low.
Multifunctional ‘smart bandage’
The team built a proof-of-concept 3D stretchable electronic device, which they’ve dubbed a “smart bandage.” A user can stick it on different parts of the body to wirelessly monitor different electrical signals. When worn on the chest or stomach, it records heart signals like an electrocardiogram (ECG). On the forehead, it records brain signals like a mini EEG sensor, and when placed on the side of the head, it records eyeball movements. When worn on the forearm, it records muscle activity and can also be used to remotely control a robotic arm. The smart bandage also monitors respiration, skin temperature and body motion.
“We didn’t have a specific end use for all these functions combined together, but the point is that we can integrate all these different sensing capabilities on the same small bandage,” said co-first author Zhenlong Huang, who conducted this work as a visiting Ph.D. student in Xu’s research group.
And the researchers did not sacrifice quality for quantity. “This device is like a ‘master of all trades.’ We picked high quality, robust subcomponents—the best strain sensor we could find on the market, the most sensitive accelerometer, the most reliable ECG sensor, high quality Bluetooth, etc.—and developed a clever way to integrate all these into one stretchable device,” added co-first author Yang Li, a nanoengineering graduate student at UC San Diego in Xu’s research group.
So far, the smart bandage can last for more than six months without any drop in performance, stretchability or flexibility. It can communicate wirelessly with a smartphone or laptop up to 10 meters away. The device runs on a total of about 35.6 milliwatts, which is equivalent to the power from 7 laser pointers.
The team will be working with industrial partners to optimize and refine this technology. They hope to test it in clinical settings in the future.
The Latest on: 3D stretchable electronics
via Google News
The Latest on: 3D stretchable electronics
A transparent stretchable sensor for distinguishable detection of touch and pressure by capacitive and piezoresistive signal transduction
on May 23, 2019 at 3:19 pm
Fabrication of the 3D micropatterned elastomeric substrate A ... In this respect, the proposed sensor has great potential for future wearable electronics. Trung, T. Q. et al. An omnidirectionally ... […]
Extremely stretchable and self-healing conductor based on thermoplastic elastomer for all-three-dimensional printed triboelectric nanogenerator
on May 14, 2019 at 2:13 am
Advances in next-generation soft electronic devices rely on the development of highly deformable, healable, and printable energy generators to power these electronics ... extremely stretchable, and ... […]
Crumpled carbon nanotube forests to power wearables
on May 6, 2019 at 5:06 pm
In the medical field, stretchable/wearable electronics are being developed that are capable ... the CNT forest forms impressive stretchable patterns, like a blanket. The 3D interconnected CNT forest ... […]
3d printed electronics
on April 17, 2019 at 5:00 pm
Stretchable electronics have a lot of potential for applications ... using a 3D printer to print... When you think of 3D printed electronics, what’s the first company that comes to mind? Chances are ... […]
Nanoscale "supersoap" allows liquid 3D structures to be printed within other liquids
on March 30, 2019 at 5:00 pm
This new form of 3D printing could give rise to flexible and stretchable liquid electronics, aid chemical synthesis, or serve as a transport and delivery system for nanoscale particles. The team of ... […]
Using a Combined 3D Printing Method to Create Stretchable Electronics
on October 4, 2018 at 1:52 pm
Stretchable electronics have a lot of potential for applications in wearable devices, soft robotics, artificial skin and more. To create stretchable electronics, 3D printing is a fast, accurate ... […]
Scientists stack elastic circuits to build 3D stretchable electronics
on August 13, 2018 at 12:50 pm
Aug. 13 (UPI) --Scientists at the University of California, San Diego have built a stretchable electronic patch capable of measuring a variety of biological activities, including respiration, ... […]
'Building up' stretchable electronics to be as multipurpose as your smartphone
on August 13, 2018 at 9:42 am
"Our vision is to make 3D stretchable electronics that are as multifunctional and high-performing as today's rigid electronics," said senior author Sheng Xu, a professor in the Department of ... […]
Extremely Stretchable Hydrogels for Use in UV Curing Based 3D Printing Methods
on June 1, 2018 at 7:24 am
Overall, we believe the highly stretchable and UV curable hydrogels, together with the UV curing based 3D printing techniques, will significantly enhance the capability of fabricating biostructures ... […]
via Bing News