3D Printed Ultrasoft and Adhesive PEDOT:PSS-Based Hydrogel for Bioelectronics

Conducting polymer-based bioadhesive conductive hydrogel (CP-BCH) is widely used in bioelectronics for electronic devices and signal monitoring due to its good flexibility, biocompatibility, and electromechanical properties, making it a very promising bioelectronic material. However, the existing conducting bioadhesive hydrogels are commonly processed by inkjet printing, screen printing, and lithography, which have a series of defects such as low resolution, low aspect ratio, and complex procedures that hinder the rapid development of conducting polymers in the field of bioelectronics. 3D printing has significant applications in bioelectronic interfaces due to its unique and excellent processing methods (high operability, flexibility, recognition, and high operating accuracy). On the other hand, in signal monitoring, it is also necessary to solve the obstacles to achieving high-precision, accurate, and lasting signal detection due to the mismatch with low Young’s modulus adhesion substrates such as skin. The present study has developed a poly(3,4-ethylenedioxythiophene): polystyrenesulfonate (PEDOT:PSS)–poly(vinyl alcohol) (PVA)–poly(acrylic acid) (PAA) hydrogel based on the conducting polymer PEDOT:PSS, through a physical cross-link method. This hydrogel exhibits high resolution (∼60 μm) for various printed patterns. It possesses a high elongation at break (267%), a low Young’s modulus (∼12.79 kPa), a high electrical conductivity (4.43 S m^–1), and strong adhesive capability to a variety of materials (over 28 kPa). This ultrasoft and universally strong adhesion could significantly improve the printing and application of bioelectronics such as high-resolution electrodes and high-precision biological signal monitoring.