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
- Stretchable wireless sensor could monitor healing of cerebral aneurysm | IDTechEx Research Articleon September 4, 2019 at 7:24 pm
For more information see the IDTechEx report on Flexible, Printed and Organic Electronics 2019-2029. To reduce costs and accelerate manufacturing, fabrication of the stretchable sensors uses aerosol ...
- Stretchable Wireless Sensor Could Monitor Healing of Cerebral Aneurysmson August 28, 2019 at 3:58 pm
Use of the aerosol jet 3D printing technique was essential to producing the stretchable and flexible electronics necessary for the sensor. The technique uses a spray of aerosol particles to create ...
- 3D Printed Wireless Biosystems for Monitoring Cerebral Aneurysms in Real Timeon August 21, 2019 at 2:25 am
Continuing to further the progress between 3D printing and electronics within the medical field, authors Robert Herbert, Saswat Mishra, Hyo-Ryoung Lim, Hyoungsuk Yoo, and Woon-Hong Yeo explore a new ...
- A transparent stretchable sensor for distinguishable detection of touch and pressure by capacitive and piezoresistive signal transductionon May 23, 2019 at 5:00 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 ...
- ‘Building up’ stretchable electronics to be as multipurpose as your smartphoneon April 29, 2019 at 5:00 pm
“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 ...
- Using a Combined 3D Printing Method to Create Stretchable Electronicson October 4, 2018 at 1:52 pm
To create stretchable electronics, 3D printing is a fast, accurate technology that can built circuits and structures from liquid metal. Recently, researchers have been interested in stretchable ...
- Scientists stack elastic circuits to build 3D stretchable electronicson August 13, 2018 at 1:41 pm
"Our vision is to make 3D stretchable electronics that are as multifunctional and high-performing as today's rigid electronics," Sheng Xu, a professor of nanoengineering at the UCSD Center for ...
- 3D printing breakthrough has potential in stretchable electronicson March 6, 2018 at 4:32 am
Galinstan 3D prints According to researchers at Oregon State University ... The gallium alloy paste is said to demonstrate several features new to the field of flexible, stretchable electronics, added ...
via Bing News