Wet‐Printed Stretchable and Strain‐Insensitive Conducting Polymer Electrodes: Facilitating In Vivo Gastric Slow Wave Mapping

Wearable and implantable devices play a crucial role in clinical diagnosis, disease treatment, and fundamental research on the body's electrophysiology and biochemical processes. Conducting polymers are emerging as promising solutions to surpass the limitations of traditional metal‐based electrodes, offering enhanced conformability, and stretchability. However, current microfabrication techniques of CP electrodes have a number of limitations. In this study, a novel wet‐printing technique is developed for the fabrication of highly stretchable poly(3,4‐ethylenedioxythiophene): polystyrene sulfonate (PEDOT:PSS) microelectrodes. The wet‐printing, conducted in a liquid coagulation bath, has the advantages of being non‐contact, easy and fast to perform, and capable of printing low‐viscosity inks. Wet‐printing of PEDOT:PSS lines with a width of ≈20 µm is demonstrated. By adding D‐sorbitol as a plasticizer, an ultra‐high stretchability of PEDOT:PSS electrodes, of more than 720% is achieved while the electrodes remained conductive and strain‐insensitive up to high strains. The use of PEDOT:PSS wet‐printed electrode arrays for the electrophysiological recording from the stomach is demonstrated. The stretchable electrodes conformed swell to the tissue and recorded comparable electrophysiological signals to Au‐plated electrodes in porcine and rodent animal models. The wet‐printing approach to fabricating flexible and stretchable electrode arrays using low‐viscosity, conducting inks holds promise for applications in conformable electronics.