Subcellular-Scale Stimulation Electrode Arrays (3SEA) Enabled by Diffusion-Tuned PEDOT:PSS Galvanostatic Deposition

Area of Science:

• Bioelectronics
• Neurotechnology
• Materials Science

Background:

• Neuromodulation at subcellular scales demands advanced stimulation electrodes with micrometer footprints and high spatial density.
• Efficient and reliable charge delivery is critical for precise neural interface applications.

Purpose of the Study:

• To introduce a novel fabrication method for Subcellular-Scale Stimulation Electrode Arrays (3SEA).
• To demonstrate the electrochemical performance and functional capabilities of these arrays for subcellular neuromodulation.

Main Methods:

• Utilized a diffusion-tuned galvanostatic deposition strategy with mass transport mediation.
• Coated densely packed microelectrodes (3-10 μm diameters) with PEDOT:PSS.
• Validated performance using calcium imaging of HT-22 neurons during neurostimulation.

Main Results:

• Achieved uniform PEDOT:PSS coating on microelectrodes.
• Demonstrated robust electrochemical performance: impedance of tens to hundreds of kilohms at 1 kHz.
• Exhibited high charge-storage (22.1-54.1 mC/cm²) and charge-injection capacities (2.31-10.1 mC/cm²).
• Confirmed reliable stimulus-evoked Ca²+ transients in neurons with low-charge biphasic pulses (1 nC/phase).

Conclusions:

• Established a scalable framework for fabricating high-performance subcellular-scale stimulating bioelectronics.
• 3SEA technology offers efficient stimulation capability for high-precision neural interfaces.
• The developed method enables precise neuromodulation at the subcellular level.