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Abstract Poly(3,4‐ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) is a promising material because of its favorable electrical and mechanical properties, stability in ambient environments, and biocompatibility. It finds broad application in energy storage, flexible electronics, and bioelectronics. Additive manufacturing opens a plethora of new avenues to form and shape PEDOT:PSS, allowing for the rapid construction of customized geometries. However, there are difficulties in printing PEDOT:PSS while maintaining its attractive properties. A 3D printing method for PEDOT:PSS using a room‐temperature coagulation bath‐based direct ink writing technique is reported. This technique enables fabrication of PEDOT:PSS into parts that are of high resolution and high conductivity, while maintaining stable electrochemical properties. The coagulation bath can be further modified to improve the mechanical properties of the resultant printed part via a one‐step reaction. Furthermore, it is demonstrated that a simple post‐processing step allows the printed electrodes to strongly adhere to several substrates under aqueous conditions, broadening their use in bioelectronics. Employing 3D printing of PEDOT:PSS, a cortex‐wide neural interface is fabricated, and intracranial electrical stimulation and simultaneous optical monitoring of mice brain activity with wide field calcium imaging are demonstrated. This reported 3D‐printing technique eliminates the need for cumbersome experimental setups while offering desired material properties. 

Abstract Electrohydrodynamic jet (e‐jet) printing is a high‐resolution printed electronics technique that uses an electric field to generate droplets. It has great application potential with the rapid development of flexible and wearable electronics. Triboelectric nanogenerators (TENG), which can convert mechanical motions into electricity, have found many high‐voltage applications with unique merits of portability, controllability, safety, and cost‐effectiveness. In this work, the application of a TENG is extended to printed electronics by employing it to drive e‐jet printing. A rotary freestanding TENG is applied as the high‐voltage power source for generating stable ink droplet ejection. The TENG‐driven droplet generation and ejection process and printed features with varied operation parameters are investigated. Results reveal that the jetting frequency could be controlled by the TENG's operation frequency, and high‐resolution printing with feature size smaller than nozzle size is achieved using the setup. Notably, TENG as the power source for e‐jet printing supplies a limited amount of current, which leads to better safety for both equipment and personnel compared to conventional high‐voltage power supplies. With the superiority of TENG in the sense of safety and cost, the work presents a promising solution for the next‐generation of high‐resolution printed electronics and broadens the scope of TENG application.