Development and Characterisation of PEDOT:PSS Based Conductive Hydrogels for Bioelectronic Neural Interfaces
N. Konstantinou (TU Delft - Mechanical Engineering)
Achilleas Savva – Mentor (TU Delft - Electrical Engineering, Mathematics and Computer Science)
More Info
expand_more
Other than for strictly personal use, it is not permitted to download, forward or distribute the text or part of it, without the consent of the author(s) and/or copyright holder(s), unless the work is under an open content license such as Creative Commons.
Abstract
Bioelectronic neural interfaces require materials that can bridge the gap between soft, hydrated biological tissue and conventional electronic systems. Conductive hydrogels are promising candidates because they combine the mechanical softness and hydration of hydrogels with electrical functionality.
In this thesis, PEDOT:PSS-based conductive hydrogels were developed and characterised as soft material candidates for bioelectronic neural interface applications. Three formulations were investigated: PEDOT:PSS-DBSA, PEDOT:PSS-PAA, and PEDOT:PSS-PEGPACHI. PEDOT:PSS-DBSA was used as a literature-based additive-induced hydrogel formulation, while PEDOT:PSS-PAA represented a polymer-network-based approach involving redox polymerisation, post-treatment, annealing, and rehydration. PEDOT:PSS-PEGPACHI was developed in this thesis as a new formulation based on PEDOT:PSS, phytic acid, chitosan, and PEGDE. The hydrogels were evaluated through physical observation, electrochemical impedance spectroscopy, cyclic voltammetry, nanoindentation, biological compatibility assessment, and preliminary device integration. The results showed that the gelation strategy and additive system strongly influenced the final material behaviour.
PEDOT:PSS-DBSA showed the strongest electrochemical response and the most uniform local mechanical behaviour, but was fragile during handling. PEDOT:PSS-PAA was more robust and easier to handle, but showed a weaker electrochemical response and greater local variability. PEDOT:PSS-PEGPACHI showed an intermediate electrochemical response, soft hydrogel-like mechanical behaviour, and favourable preliminary biological compatibility. Based on the combined material and biological assessments, PEDOT:PSS-PEGPACHI was selected for preliminary integration into a PDMS hydrogel array device. The formulation could be patterned into hydrogel tracks and electrically accessed after gelation and hydration, demonstrating its potential for future soft bioelectronic platforms.
Overall, this thesis demonstrates that PEDOT:PSS-based conductive hydrogels are promising materials for neural interface applications and identifies PEDOT:PSS-PEGPACHI as a strong candidate for further optimisation and biological validation.