As one of conducting polymers, PEDOT:PSS, is commonly used in organic electronics, especially for bioelectronics due to its advantages such as high electrical and ionic conductivity, solution-processability and biocompatibility. Creating bioelectronics with the PEDOT:PSS requires advanced techniques to obtain physical/chemical modification of the PEDOT:PSS for improved performance and various applications. To satisfy these demands, fibrillary gelation of PEDOT:PSS by injection to choline acetate, an ionic liquid, with a constant flow rate was used in this study to make a conductive fiber and improve characteristics of PEDOT:PSS. Conductive fibers by fibrillary gelation showed enhanced electrical conductivity of about 400 S cm−1 and volumetric capacitance of about 154 F cm−3 which would be strongly beneficial to be utilized for organic electrochemical transistors (OECTs), resulting in a high transconductance of 19 mS in a depletion-mode. Moreover, dedoping of the conductive fibers by PEI (polyethyleneimine) enabled the creation of enhancement-mode OECTs. Interdigitated inverters were then fabricated by connecting depletion and enhancement-mode OECTs. These results demonstrate that these conductive fibers and electronic-textiles are suitable candidates for applications in bio-integrated electronics.

The miniaturization and flexibility of wearable and implantable devices allow humans to carry them directly on or in their bodies, thus enabling these devices to measure biometric signals in real-time anywhere. However, as they are embedded or implanted into an actively moving human interface, motion artifact noise inevitably occurs. Typically, devices are laminated or implanted on body surfaces, but the positions of such devices cannot be designed without any discussion of the noise. Thus, this paper investigates an approach that minimizes the noise to achieve negligible motion artifacts in implantable micro-devices that have a specific angle on the surface of the body, while maintaining the function of sensor. The device with a specific angle successfully detects the target signal, while motion artifacts-such as tension, compression, and bending-disturb the measurement. The pulse signal on a wrist is well measured while the hand is rotating, and artificial skin implanted on a rat can distinguish external pressure from the movement noise. A thermometer sensor that follows the same rule is further examined. Therefore, this approach is expected to be useful in numerous areas including human interface-based medical devices, virtual reality, and health aids to improve quality of life.