24/7 Space News
CHIP TECH
MIT engineers develop a soft, printable, metal-free electrode
illustration only
MIT engineers develop a soft, printable, metal-free electrode
by Jennifer Chu for MIT News
Boston MA (SPX) Jun 16, 2023

Do an image search for "electronic implants," and you'll draw up a wide assortment of devices, from traditional pacemakers and cochlear implants to more futuristic brain and retinal microchips aimed at augmenting vision, treating depression, and restoring mobility.

Some implants are hard and bulky, while others are flexible and thin. But no matter their form and function, nearly all implants incorporate electrodes - small conductive elements that attach directly to target tissues to electrically stimulate muscles and nerves.

Implantable electrodes are predominantly made from rigid metals that are electrically conductive by nature. But over time, metals can aggravate tissues, causing scarring and inflammation that in turn can degrade an implant's performance.

Now, MIT engineers have developed a metal-free, Jell-O-like material that is as soft and tough as biological tissue and can conduct electricity similarly to conventional metals. The material can be made into a printable ink, which the researchers patterned into flexible, rubbery electrodes. The new material, which is a type of high-performance conducting polymer hydrogel, may one day replace metals as functional, gel-based electrodes, with the look and feel of biological tissue.

"This material operates like metal electrodes but is made from gels that are similar to our bodies, and with similar water content," says Hyunwoo Yuk SM '16, PhD '21, co-founder of SanaHeal, a medical device startup. "It's like an artificial tissue or nerve."

"We believe that for the first time, we have a tough, robust, Jell-O-like electrode that can potentially replace metal to stimulate nerves and interface with the heart, brain, and other organs in the body," adds Xuanhe Zhao, professor of mechanical engineering and of civil and environmental engineering at MIT.

Zhao, Yuk, and others at MIT and elsewhere report their results in Nature Materials. The study's co-authors include first author and former MIT postdoc Tao Zhou, who is now an assistant professor at Penn State University, and colleagues at Jiangxi Science and Technology Normal University and Shanghai Jiao Tong University.

A true challenge
The vast majority of polymers are insulating by nature, meaning that electricity does not pass easily through them. But there exists a small and special class of polymers that can in fact pass electrons through their bulk. Some conductive polymers were first shown to exhibit high electrical conductivity in the 1970s - work that was later awarded a Nobel Prize in Chemistry.

Recently, researchers including those in Zhao's lab have tried using conductive polymers to fabricate soft, metal-free electrodes for use in bioelectronic implants and other medical devices. These efforts have aimed to make soft yet tough, electrically conductive films and patches, primarily by mixing particles of conductive polymers, with hydrogel - a type of soft and spongy water-rich polymer.

Researchers hoped the combination of conductive polymer and hydrogel would yield a flexible, biocompatible, and electrically conductive gel. But the materials made to date were either too weak and brittle, or they exhibited poor electrical performance.

"In gel materials, the electrical and mechanical properties always fight each other," Yuk says. "If you improve a gel's electrical properties, you have to sacrifice mechanical properties, and vice versa. But in reality, we need both: A material should be conductive, and also stretchy and robust. That was the true challenge and the reason why people could not make conductive polymers into reliable devices entirely made out of gel."

Electric spaghetti
In their new study, Yuk and his colleagues found they needed a new recipe to mix conductive polymers with hydrogels in a way that enhanced both the electrical and mechanical properties of the respective ingredients.

"People previously relied on homogenous, random mixing of the two materials," Yuk says.

Such mixtures produced gels made of randomly dispersed polymer particles. The group realized that to preserve the electrical and mechanical strengths of the conductive polymer and the hydrogel respectively, both ingredients should be mixed in a way that they slightly repel - a state known as phase separation. In this slightly separated state, each ingredient could then link its respective polymers to form long, microscopic strands, while also mixing as a whole.

"Imagine we are making electrical and mechanical spaghetti," Zhao offers. "The electrical spaghetti is the conductive polymer, which can now transmit electricity across the material because it is continuous. And the mechanical spaghetti is the hydrogel, which can transmit mechanical forces and be tough and stretchy because it is also continuous."

The researchers then tweaked the recipe to cook the spaghettified gel into an ink, which they fed through a 3D printer, and printed onto films of pure hydrogel, in patterns similar to conventional metal electrodes.

"Because this gel is 3D-printable, we can customize geometries and shapes, which makes it easy to fabricate electrical interfaces for all kinds of organs," says first-author Zhou.

The researchers then implanted the printed, Jell-O-like electrodes onto the heart, sciatic nerve, and spinal cord of rats. The team tested the electrodes' electrical and mechanical performance in the animals for up to two months and found the devices remained stable throughout, with little inflammation or scarring to the surrounding tissues. The electrodes also were able to relay electrical pulses from the heart to an external monitor, as well as deliver small pulses to the sciatic nerve and spinal cord, which in turn stimulated motor activity in the associated muscles and limbs.

Going forward, Yuk envisions that an immediate application for the new material may be for people recovering from heart surgery.

"These patients need a few weeks of electrical support to avoid heart attack as a side effect of surgery," Yuk says. "So, doctors stitch a metallic electrode on the surface of the heart and stimulate it over weeks. We may replace those metal electrodes with our gel to minimize complications and side effects that people currently just accept."

The team is working to extend the material's lifetime and performance. Then, the gel could be used as a soft electrical interface between organs and longer-term implants, including pacemakers and deep-brain stimulators.

"The goal of our group is to replace glass, ceramic, and metal inside the body, with something like Jell-O so it's more benign but better performance, and can last a long time," Zhao says. "That's our hope."

This research is supported, in part, by the National Institutes of Health.

Related Links
Department of Mechanical Engineering
Computer Chip Architecture, Technology and Manufacture
Nano Technology News From SpaceMart.com

Subscribe Free To Our Daily Newsletters
Tweet

RELATED CONTENT
The following news reports may link to other Space Media Network websites.
CHIP TECH
Ex-Samsung exec charged with stealing chip tech for China factory
Seoul (AFP) June 13, 2023
South Korea has charged a former Samsung executive accused of stealing company secrets worth hundreds of millions of dollars to set up a copycat chip factory in China, prosecutors told AFP on Tuesday. Semiconductors have become a flashpoint issue between the United States and China, which are locked in a fierce battle over access to chip-making technology and supplies. South Korean prosecutors said the 65-year-old former Samsung employee allegedly stole the company's factory blueprints and clean ... read more

CHIP TECH
Schools, museums, libraries can apply to receive artifacts from NASA

Catastrophic failure assessment of sealed cabin for ultra large manned spacecraft

Shenzhou-16 spaceship transports seeds for breeding experiments

Boeing's first crewed space launch delayed, again

CHIP TECH
China's parachute system makes controllable landing of rocket boosters

Arianespace's next Ariane 5 mission to support France and Germany's space ambitions

China launches rocket with record payload

Iran unveils homegrown defense shield-busting hypersonic missile

CHIP TECH
Up and Over - Curiosity Is Heading East: Sol 3857

How NASA gives a name to every spot it studies on Mars

Science and sampling attempts at the Onahu Outcrop

Time To Try a New Route: Sols 3853-3856

CHIP TECH
Tianzhou 5 reconnects with Tiangong space station

China questions whether there is a new moon race afoot

Three Chinese astronauts return safely to Earth

Scientific experimental samples brought back to Earth, delivered to scientists

CHIP TECH
CNES, E-Space complete next-generation low earth orbit constellation study

HawkEye 360's Cluster 7 begins operation in record time

York Space Systems acquires Emergent Space Technologies

How activity in outer space will affect regional inequalities in the future

CHIP TECH
Defense Department announces effort to increase Idaho cobalt extraction

US judge pauses Microsoft's Activision buy

Italy sets curbs on Pirelli's Chinese investor Sinochem

AFRL demonstrates new augmented reality capability to improve DAF Nondestructive Inspections

CHIP TECH
Photosynthesis, key to life on Earth, starts with a single photon

Phosphate, a key building block of life, found on Saturn's moon Enceladus

Plate tectonics not required for the emergence of life

Elusive planets play "hide and seek" with CHEOPS

CHIP TECH
Colorful Kuiper Belt puzzle solved by UH researchers

Juice deployments complete: final form for Jupiter

First observation of a Polar Cyclone on Uranus

Research 'solves' mystery of Jupiter's stunning colour changes

Subscribe Free To Our Daily Newsletters




The content herein, unless otherwise known to be public domain, are Copyright 1995-2024 - Space Media Network. All websites are published in Australia and are solely subject to Australian law and governed by Fair Use principals for news reporting and research purposes. AFP, UPI and IANS news wire stories are copyright Agence France-Presse, United Press International and Indo-Asia News Service. ESA news reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. All articles labeled "by Staff Writers" include reports supplied to Space Media Network by industry news wires, PR agencies, corporate press officers and the like. Such articles are individually curated and edited by Space Media Network staff on the basis of the report's information value to our industry and professional readership. Advertising does not imply endorsement, agreement or approval of any opinions, statements or information provided by Space Media Network on any Web page published or hosted by Space Media Network. General Data Protection Regulation (GDPR) Statement Our advertisers use various cookies and the like to deliver the best ad banner available at one time. All network advertising suppliers have GDPR policies (Legitimate Interest) that conform with EU regulations for data collection. By using our websites you consent to cookie based advertising. If you do not agree with this then you must stop using the websites from May 25, 2018. Privacy Statement. Additional information can be found here at About Us.