Soft Printable Electrode Coating for Neural Interfaces.

Area of Science:

• Biomaterials Science
• Neurotechnology
• Polymer Chemistry

Background:

• Mechanical mismatch between rigid implants and soft neural tissue causes damage and limits device longevity.
• Soft polymeric materials offer a potential solution to improve biocompatibility and performance of neural interfaces.

Purpose of the Study:

• To develop and characterize a screen-printable, soft conductive hydrogel coating for neural interfacing devices.
• To evaluate the adhesion, mechanical properties, electrochemical performance, and biocompatibility of the novel hydrogel coating.
• To integrate the hydrogel into a microelectrode array for neural recording applications.

Main Methods:

• Formulation of a conducting hydrogel using polyacrylamide and poly(3,4-ethylenedioxythiophene) polystyrene sulfonate.
• Screen-printing technique for patterning the hydrogel onto polydimethylsiloxane substrates.
• Characterization of mechanical properties (elastic modulus), electrochemical performance, and in vitro neural cell attachment/proliferation.
• Integration into a 4x4 microelectrode array for electrocorticography and acute neural recordings.

Main Results:

• The hydrogel coating demonstrated tunable elastic modulus (10-100 kPa) and excellent adhesion to polydimethylsiloxane.
• Electrochemical properties were comparable to stiff conductive inks.
• The coating supported neural cell attachment and proliferation in vitro.
• Stable acute recordings of cortical local field potentials were achieved with the integrated microelectrode array.

Conclusions:

• The developed soft, screen-printable conducting hydrogel is a promising material for reducing mechanical mismatch in neural interfaces.
• The material exhibits favorable mechanical, electrochemical, and biocompatibility properties for implantable bioelectronic devices.
• This approach offers a robust and scalable method for fabricating advanced neural recording technologies.