Title- 4D Printable Electroactive and Biodegradable PEDOT:ĸ-Carrageenan inks for (Bio)electronics
Rajat Rai a, Antonio Dominguez-Alfaro b, Salim El Hadwe b, Amy T Jin b, George G. Malliaras b, Daniele Mantione a,c, Miryam Criado-Gonzalez a,d
aPOLYMAT - University of the Basque Country UPV/EHU, Donostia / San Sebastian, Spain
bElectrical Engineering Division, Department of Engineering, University of Cambridge, 9 JJ Thomson Ave, Cambridge, CB3 0FA, UK
cIKERBASQUE, Basque Foundation for Science, 48009, Bilbao, Spain
dInstitute of Polymer Science and Technology (ICTP-CSIC), C/Juan de la Cierva 3, 28006 Madrid, Spain
Abstract- Over the past decade, conducting polymers (CPs) have gained significant attention as electroactive inks for additive manufacturing of (bio)electronic devices, particularly through high-resolution light-based 3D printing methods such as digital light processing (DLP) and two-photon polymerization (2PP). Poly(3,4-ethylenedioxythiophene) (PEDOT), known for its excellent biocompatibility and conductivity, is often paired with non-degradable polystyrene sulfonate (PSS) in the form of PEDOT:PSS dispersions, that also need to be mixed with photocurable polymers to be processed through light-based 3D printing. Thus, developing polymer-based inks with high electronic conductivity for printing disposable devices presents difficulties in degradability and sustainability. To address these challenges, we developed biodegradable PEDOT: Biopolymer dispersions by oxidative polymerization of EDOT using biopolymers with varying anionic groups: ĸ-carrageenan (CAR, sulfate), Alginate (ALG, carboxylic), and Inulin (INU, hydroxyl). PEDOT:CAR exhibited the highest conductivity (0.1 S/cm). CAR was further modified with methacrylate (MA) groups to yield photopolymerizable PEDOT:CAR-MA inks, enabling direct DLP printing of shape-defined, conductive hydrogels. These 4D-printed hydrogels demonstrated electrical conductivity, swelling/deswelling shape memory, degradability, and cytocompatibility with human induced pluripotent stem cell (iPSC)-neurons, supporting cell viability. The resulting materials show promise as sustainable, disposable sensors for in-vivo pressure sensing for brain and Electrocorticography (ECoG) applications.