Rubbery CMOS

Researchers at University of Illinois Urbana-Champaign, University of Houston, Ulsan National Institute of Science and Technology, Pusan National University, and Southeast University designed fully stretchable complementary integrated circuits composed of both elastic n-type and p-type transistors that provide the same functionality as conventional CMOS while retaining stable electrical performance even when stretched by up to 50 percent.

The device uses a layered elastomer-semiconductor-elastomer architecture. Digital logic gates, including inverters, NAND, and NOR, maintained robust function under large mechanical strains.

“For rubber electronics, you don’t use any metal, don’t use oxides, and don’t use conventional semiconductors,” said Cunjiang Yu, a founder professor of engineering in the Department of Electrical and Computer Engineering at the University of Illinois Urbana-Champaign, in a press release. “It’s still a transistor, but it doesn’t rely on conventional MOS materials.”

Photos of a sample stretchable tactile sensing skin created by Yu’s team, before (left) and during (right) stretching. (Credit: Authors of “Stretchable complementary integrated electronics based on elastic dual-type transistors” published in Science Advances. [1])

To demonstrate this rubbery CMOS, the researchers created a stretchable tactile sensing skin comprised of a complementary inverter active matrix integrated with a single-electrode triboelectric nanogenerator array that can adhere to human skin for medical and health-monitoring applications. [1]

Self-healing polymer conductor

Researchers from RIKEN created a self-healing polymer that can repair itself after being damaged by modifying polyolefins, a common polymer, with sulfur-containing thioether. The resulting polymer is suitable for use as a flexible conductor in wearable devices and robots.

“Polyolefins are ubiquitous in daily life and account for the largest production volume among all polymers. They combine several desirable properties, including low cost, robust mechanical strength, ease of processing, and excellent chemical and environmental stability, making them promising candidates for conductor applications,” said Zhaomin Hou of the RIKEN Center for Sustainable Resource Science, in a statement.

Hou noted that the natural affinity between sulfur and gold ensured a strong bond between the self-healing polymer and gold coatings. “The durability of the gold coating on the thioether-functionalized polymer far exceeded our expectations. It was resistant to more than 50 cycles of a tape-peeling test.”

The team plans to test different building blocks for polyolefins to develop a family of self-healing polymers for flexible conductors with greater durability. [2]

Kiri-origami

Researchers from Waseda University propose using a hybrid kirigami and origami technique for creating stretchable electronics using non-stretchable materials.

The kiri-origami design features a mutual orthogonal cutting line pattern, in which triangular joint panels consisting of two folding lines act as hinges and connect two square panels formed by the cutting lines. When stretched from a flat state, the square panels rise and rotate. This opens slits between the panels, ultimately resulting in a Z-shape around the hinges. This structure allows simultaneous mounting of rigid components and stretching to a target shape, while also supporting large-area and large-number-of-unit structures.

“This structure enables large-number-of-unit, large area electronic devices, allowing rigid electronic components to be folded by stretching,” said Eiji Iwase, a professor in the Department of Applied Mechanics and Aerospace Engineering at Waseda University, in a press release. “Our approach makes it possible to develop stretchable electronic devices that can accommodate complex shapes and do not compromise on performance, including next-generation high-performance wearable sensors, curved displays, and flexible sensors and actuators for human assistance robots.”

To demonstrate the kiri-origami structure, the researchers fabricated a stretchable display with more than 500 hinges and 145 LEDs. All hinges could fold up simultaneously, and the device’s performance was maintained before and after folding. [3]

References

[1] Y. Zhang, K. Sim, H. Shim, et al. Stretchable complementary integrated electronics based on elastic dual-type transistors. Sci. Adv. 11, eaea1867 (2025). https://doi.org/10.1126/sciadv.aea1867

[2] M. Chi, L. Sun, M. Nishiura, et al. Thioether-functionalized self-healing polyolefins for flexible conductors. Journal of the American Chemical Society 147 23128−23135 (2025). https://doi.org/10.1021/jacs.5c06579

[3] N. Nakamura, E. Iwase. Stretch-based kirigami structure with folding lines for stretchable electronics. npj Flex Electron 9, 51 (2025). https://doi.org/10.1038/s41528-025-00409-4

Jesse Allen

(all posts) Jesse Allen is the Knowledge Center administrator and a senior editor at Semiconductor Engineering.