Injectable conductive hydrogel electrodes for minimally invasive neural interfaces.

Area of Science:

• Biomaterials Science
• Neuroscience
• Materials Engineering

Background:

• Soft bioelectronic neural interfaces are promising alternatives to traditional metal electrodes.
• Conductive hydrogels (CHs) offer tissue compliance and necessary electrochemical properties.
• Injectable CHs enable minimally invasive implantation but often lack control over particle size and packing.

Purpose of the Study:

• To develop an injectable PEDOT:PSS/acetic acid-based hydrogel with independently tunable mechanical and electrochemical properties.
• To improve particle size control and packing for enhanced injectability and stability.
• To evaluate the material's performance in neural interfacing applications.

Main Methods:

• Fabrication of a PEDOT:PSS/acetic acid-based hydrogel.
• Independent tuning of mechanical and electrochemical properties via acetic acid composition.
• Utilizing batch emulsion to control particle size and packing.
• Assessment of material stability, injectability, and electrochemical performance in vitro and ex vivo.
• Evaluation of safety through non-cytotoxicity testing and biphasic current stimulation.

Main Results:

• The PEDOT:PSS/acetic acid hydrogel demonstrated independently tuneable mechanical and electrochemical properties.
• Batch emulsion resulted in decreased particle sizes and tighter packing.
• The hydrogel exhibited stability and anatomical compactness upon injection in tissue phantom and ex vivo.
• Favorable electrochemical properties were maintained in both contexts.
• Biphasic current stimulation showed voltage transients below the charge injection limit.
• The material proved to be non-cytotoxic.

Conclusions:

• The developed injectable hydrogel offers a mechanically favorable and tuneable platform for neural interfaces.
• The material demonstrates stability, injectability, and favorable electrochemical performance for safe and effective neural interfacing.
• This work advances the development of minimally invasive soft bioelectronic devices.