Researchers in South Korea have developed a flexible electronic device that can switch between different jobs simply by changing the salt concentration around it.
The breakthrough could lead to smarter wearable health monitors, electronic skin, and medical devices that can both process and store information without needing multiple electronic components.
Wearable technology has advanced rapidly in recent years.
Devices such as fitness trackers and health monitors can already measure heart rate, body temperature, and other vital signs. However, most wearable electronics are still built from separate components, with one part collecting information, another processing it, and another storing data.
This makes the devices larger, more complex, and more power-hungry.
A research team led by Assistant Professor Hyunseok Shim at Pusan National University wanted to simplify this design by creating a single soft electronic device capable of performing multiple functions.
Their work was published in the journal ACS Nano.
The researchers built a stretchable organic electrochemical transistor, or OECT. Unlike traditional electronic transistors that rely only on moving electrons, this type of transistor also moves charged particles called ions through a special conducting polymer. Because it is soft and flexible, it is well suited for wearable electronics that need to bend and stretch with the human body.
Rather than inventing a completely new material, the team improved an existing conducting polymer called PEDOT:PSS by adding two special ingredients. These additives increased the material’s electrical performance while also allowing it to stretch repeatedly without losing its function.
The most remarkable feature of the new device is its ability to change how it works depending on the amount of sodium chloride, or common salt, in the surrounding liquid.
When the salt concentration is high, ions move quickly through the transistor, allowing it to operate like a digital logic circuit that rapidly switches on and off to perform computing tasks. When the salt concentration is lower, ion movement slows down, giving the device memory-like behavior that resembles the way connections between brain cells, known as synapses, transmit and store information.
The researchers also gave the device an easy-to-read visual indicator. As it changes between operating modes, its color shifts from light blue to dark blue. This means users can tell what mode the device is in simply by looking at it.
To demonstrate the technology, the team created a wearable patch that monitors signs of inflammatory swelling and skin temperature. Based on the information it collects, the patch automatically adjusts the tightness of a compression bandage, making it tighter or looser as needed. This could help reduce the risk of tissue damage while improving comfort during treatment.
The researchers believe the technology could eventually support a wide range of advanced medical and wearable applications. Future electronic skin could detect injuries and respond automatically, while adaptive prosthetic devices and soft robots could learn from their surroundings and adjust their behavior in real time.
By combining sensing, computing, and memory into a single stretchable device, the new technology offers a promising step toward wearable electronics that are smarter, simpler, and more responsive to the needs of the human body.
