A transistor fiber for use in wearable electronics has been developed by researchers at the Korea Institute of Science and Technology (KIST). The transistor, which has the characteristics of a textile, can be inserted into clothing and retain an adequate level of functionality even after multiple washings. A new electronic textile developed by KIST’s research team can activate LEDs that are on top of fabric. Courtesy of Korea Institute of Science and Technology (KIST). The semiconductor channel of the fiber transistor is made of a twist assembly of the source and drain electrode microfibers, which are coated with an organic semiconductor. This architecture allows the researchers to control the thickness of the semiconductor layer and the twisted length of the two electrode microfibers. It also passivates the device without affecting its connections with other electrical components. The researchers were able to adjust the length of the threads and thickness of the semiconductor to obtain currents over 1000x higher than those possible using existing transistors. The new transistor demonstrated a high output current of over −5 mA at a low operation voltage of −1.3 V. The electronic textiles can be activated by an LED of an RGB color even if the transistor is bent. Courtesy of Korea Institute of Science and Technology (KIST). The team activated an LED device with the transistor inserted between the threads of clothing and measured electrocardiogram signals through signal amplification. Even after bending the transistor or winding it multiple times around a cylindrical object, the researchers found that it maintained a performance level of over 80%. This level remained adequate even after washing the transistor in water containing detergent. “The results of this study point to a new device structure that can overcome the limitations of current electronic textiles, including low current, high activation voltage, and low resilience to washing,” professor Jung-ah Lim said. The team believes that its study could contribute to the development of smarter wearable products, including next-generation wearable computers and smart clothing that could monitor vital signs. The research was published in Advanced Materials (https://doi.org/10.1002/adma.201900564).