An interpenetrating, microstructurable and covalently attached conducting polymer hydrogel for neural interfaces

Area of Science:

• Materials Science
• Biomedical Engineering
• Electrochemistry

Background:

• Conductive polymer hydrogels (CPHs) are promising for neural interfaces but suffer from delamination and lack patterning methods.
• Existing CPHs often fail to address both substrate adhesion and site-specific application challenges simultaneously.

Purpose of the Study:

• To develop a novel CPH system for neural interface surface modification.
• To create a material that covalently attaches to electrodes, can be patterned, and possesses excellent electronic properties.

Main Methods:

• Fabrication of a composite hydrogel: P(DMAA-co-5%MABP-co-2,5%SSNa) and poly(3,4-ethylenedioxythiophene) (PEDOT).
• Characterization using cyclic voltammetry (CV), impedance spectroscopy (EIS), and X-ray photoelectron spectroscopy (XPS).
• Evaluation of electrochemical stability, charge storage capacity (CSC), impedance, and non-toxicity via elution tests and cell lines.

Main Results:

• The CPH system demonstrated covalent attachment, interpenetrating network formation, and homogeneous PEDOT distribution.
• CPH exhibited a 2.5x higher CSC and reduced impedance compared to bare hydrogel.
• Material showed electrochemical stability over 1000 redox cycles and confirmed non-toxicity.

Conclusions:

• The new CPH material offers a unique combination of adhesion, patterning capability, and superior electrochemical performance.
• This hybrid material holds significant promise for advanced neural probe surface modification.
• It enables integration of hydrogel benefits with high-quality neural microelectrode requirements.