The First "Rubber CMOS" Electronics Could Lead to a Much More Flexible Future
Medical implants, wearables, and soft robotics could all take a leap forward with the creation of the first p- and n-type soft transistors.
Researchers from the University of Houston, King Abdullah University of Science and Technology, the Ulsan National Institute of Science and Technology, Pusan National University, Pennsylvania State University, the University of Illinois Urbana-Champaign, and Southeast University have developed what they say is the first rubber-like stretchable electronic device to provide the same functionality as conventional complementary metal-oxide semiconductors (CMOS) — and aim to make use of it in soft robots, medical implants, and more.
"The field has been demonstrating primarily p-type materials, which transport positively charged electrical carriers," project lead and senior author Cunjiang Yu explains of his team's work. "We've never before demonstrated true CMOS behavior in rubber electronics. For rubber electronics, you don't use any metal, don't use oxides, and don’t use conventional semiconductors. It's still a transistor, but it doesn’t rely on conventional MOS materials."
CMOS technology is at the heart of everything from high-performance servers to digital watches, but its materials — being based on metal oxides — are rigid and unyeilding. "Rubber electronics," by contrast, are soft and stretchy, but haven't been able to match the elasticity of pure rubber nor the performance of CMOS components. That is, until now.
The team's research focuses on the creation of fully-stretchable complementary integrated circuits which combine elastic p-type and n-type transistors. These, the researchers say, retained stable electrical performance even when stretched by up to 50% — and prototype digital logic gates constructed using the soft transistors were able to keep running even when under heavy mechanical strain.
To prove the concept, the researchers built a "sensory skin" prototype — a wearable which can adhere to the skin, confirm to the shape of the body, and provide sensing capabilities. "Soft robotics and human–machine interfaces are natural next steps," Yu says of the technology's future potential. "Imagine a wearable glove made of integrated circuits that can both sense and process information directly within the glove!"
The team's work has been published in the journal Science Advances under open-access terms.