3D Printing of PEDOT:PSS-PU-PAA Hydrogels with Excellent Mechanical and Electrical Performance for EMG Electrodes

Abstract

Bioelectronics has been developed for recording the electrophysiological activity of diagnostic and therapeutic devices. However, current bioelectrodes still imperfectly comply with tissues, which results in high interfacial impedance and even mechanical detachment. Herein, we report a simple yet effective approach to overcome such hurdles by designing a highly conductive, adhesive hydrogel composite based on freeze-dried poly(3,4-ethylenedioxythiophene):poly (styrene sulfonate) (PEDOT:PSS), polyurethane (PU), and poly(acrylic acid) (PAA). With the continuous phase-separation of PEDOT:PSS, PU, and PAA, the resultant composite hydrogels can simultaneously achieve high adhesion (lap-shear strength > 8 kPa), stretchability (fracture strain > 1100%), and electrical conductivity (conductivity > 2 S/m) by overcoming the traditional trade-off between mechanical and electrical properties in conducting polymer hydrogels. Moreover, such hydrogels are readily applicable to advanced manufacturing techniques such as 3D printing. We further fabricated skin electrodes and achieved high quality and high signal-to-noise ratio EMG signal recording of the forearm.