Korean researchers have developed a next-generation high-performance communication semiconductor switch that is as thin and flexible as vinyl yet can withstand extreme heat, a breakthrough that could enable stable 5G and 6G communications in wearable devices and autonomous vehicles operating in harsh environments.
A research team led by Professor Kim Myung-soo from the Department of Electrical and Electronic Engineering at Ulsan National Institute of Science and Technology (UNIST) announced Wednesday that they jointly developed a high-performance flexible RF switch with Professor Kim Min-ju's team at Dankook University.
RF switches are communication components that prevent signal interference and efficiently distribute power. Commercially available RF switches are based on rigid inorganic materials that crack easily when bent. This is why foldable phones can be made by placing RF switches in non-bending areas, but fully rollable or wearable communication devices have remained impossible to produce.
The RF switch developed by the research team is based on polymers as thin and flexible as vinyl, yet features excellent heat resistance and communication performance comparable to inorganic RF switches. Conventional organic polymer RF devices have the advantage of flexibility but melt easily under heat and have inferior communication performance compared to inorganic RF devices, particularly showing significant performance degradation in 5G and 6G bands.
In laboratory tests, the RF switch demonstrated stability capable of retaining data for more than 10 years even in high-temperature environments of 128.7°C. In communication performance verification experiments, the switch could stably transmit and block signals up to 5.38 terahertz (THz), including the millimeter wave (mmWave) band that serves as a key frequency range for 5G and 6G communications. The 5.38 THz represents the widest frequency range that polymer-based switches can process, marking the highest performance level among existing organic polymer switches. The device also demonstrated exceptional flexibility by operating normally without performance degradation after being bent more than 3,600 times.
The research team was able to develop this RF switch using a special polymer material called "pV3D3." This material has a three-dimensional mesh structure that makes it resistant to heat. The researchers created the RF switch by layering this material between gold foils thinner than a human hair. When voltage is applied, ions released from the gold foil move to create an electrical pathway, and when the voltage direction changes, this pathway is severed to block current flow. This is a memristor method that turns current flow on and off without mechanical switching.
UNIST researchers Park Sung-moon and Pyo Chang-woo, along with Dankook University researcher Yoo Ji-ho, participated as first authors in this research. The research team explained that "this is significant in that it simultaneously overcomes the thermal instability and high-frequency performance limitations of existing electronic devices."
"This research breaks the stereotype that flexible devices are weak to heat and have poor performance," Professor Kim Myung-soo said. "We expect it to be widely applied to next-generation wearable communication devices, IoT sensors, and autonomous vehicle communication systems that must operate in high-temperature or curved environments."
The research was supported by the National Research Foundation of Korea's Individual Basic Research (Early Career Research) program and the Institute of Information & Communications Technology Planning & Evaluation's (IITP) Regional Intelligence Innovation Human Resources Development Project. The findings were published on December 12 in Advanced Functional Materials (IF: 19.0), a world-renowned journal in materials science.