Soft on tissue, strong on signal: Enabling tissue compatible pressure sensing conductive hydrogels via oxidative chemical vapor deposition
Adrivit Mukherjee, Julien Es Sayed, Beatrice Corci, Jessie Suyanto, Aaltje van der Molen, Amalia M. Dolga, Ajay Giri Prakash Kottapalli, Marleen Kamperman, Ranjita K. Bose
Abstract
Electrically conductive hydrogels provide a unique platform for tissue-compatible electronics, enabling seamless integration between soft biological tissues and electronic devices. Here, we present a fabrication strategy using oxidative chemical vapor deposition (oCVD) to deposit nanometer-scale polypyrrole (PPy) coatings within a hybrid PAAm-PSS/PDADMA hydrogel network. Our approach can be leveraged to fabricate electrically conductive hydrogels with ultra-low weight fraction of conductive reinforcements, that preserves the intrinsic properties of the underlying hydrogel, including high water content (up to 90 %) and exceptional stretchability (>200 %). The combination of a covalently crosslinked PAAm network with an interpenetrating, physically crosslinked polyelectrolyte complex network allows precise tuning of mechanical properties (elastic modulus 75–900 kPa), facilitating modulus matching with soft biological tissues. The resulting hydrogels function as sensitive, durable pressure sensors, exhibiting high linearity, stability over repeated cycles, and reliable responses under dynamic mechanical loading over a broad detection range. Biocompatibility studies with human dopaminergic neurons demonstrate preserved morphology, viability, and electrical activity on PPy-coated surfaces. This work establishes a versatile platform for soft, viscoelastic, pressure-sensing bioelectronics that bridges the biomechanical gap between tissues and devices. The combination of high electrical conductivity, tunable mechanical properties, and excellent biocompatibility enables advanced applications in neural tissue engineering, implantable bioelectronics, and wearable sensor technologies. • Vapor-phase oxidative CVD enables fabrication of electrically conductive hydrogels. • High conductivity, tissue-like softness, viscoelasticity bridges biomechanical gap. • Ultra-low conductive reinforcement preserves inherent properties of the hydrogel. • Highly sensitive, linear, and stable pressure sensing over a broad detection range. • Electrically conductive oCVD polypyrrole coatings are biocompatible with neurons.