Direct ink writing PEDOT:PSS-based interfaces with high stretchability and strong adhesion for flexible electronics

Conducting polymer-based bioadhesive conductive interface (CP-BCI) are widely used in bioelectronics, strain sensors due to their ease of processing and fabrication, excellent electrical, and biocompatibility. However, CP-BCI is conventionally fabricated using techniques such as cast molding, screen printing, electrochemical patterning, and photolithography. These traditional methodologies often encounter challenges in achieving precise control and the generation of intricate patterns, thus limiting the widespread application and evolution of these materials. Direct ink writing has become an emerging research hotspot for processing CP-BCI due to its high degree of programmability, precision, and process stability. Herein, biointerface inks with enhanced electrical conductivity and high adhesion have been specifically developed for direct ink printing. The development of this novel ink involves the incorporation of PAM into the PVA matrix to promote composite cross-linking, coupled with the integration of PEDOT:PSS conductive nanofibers within the matrix, thereby yielding the PEDOT:PSS-PAM-PVA biointerface ink. The innovative ink showcases exceptional printability, high electrical conductivity (0.24 ± 0.053 S m −1 ), high adhesion (54 ± 2.7 kPa), and a well-balanced mechanical profile, featuring a maximum stress of 51 kPa and an elongation at break of 369%. This research introduces the novel direct writing ink, promoting advancements in the manufacturing of flexible electronics. Graphical abstract