Fig. 3: Different formats of PEDOT: PSS-based electrodes.

a–c PEDOT:PSS-ionic liquid colloidal (PILC) ink for 3D-printed hydrogel⁴⁵. Copyright 2024, Springer Nature (Fig. S1). a: Images of a 3D array with a high aspect ratio (top) and high resolution (~50 µm) (bottom) fabricated via direct ink writing. b Impedance stability of PILC electronic devices incubated in PBS solution at 37 °C over 30 days. c Mechanical properties of printed PILC hydrogel, exhibiting a low Young’s modulus (750 kPa), comparable to biological tissues. d–f PEDOT:PSS/pHEMA film deposited on a rigid metal substrate (Au electrode) via electrochemical deposition for microelectrode array (MEA) fabrication¹⁶⁵. Copyright 2022, John Wiley and Sons (Fig. S2). d Images of the MEA shank (top) and a zoomed-in view of the pattern at the MEA tip (bottom). Gold: Au electrode; Black: PEDOT:PSS/pHEMA film. e Electrochemical impedance spectroscopy (EIS) measurement from 1 Hz to 100 kHz of bare gold MEAs (green), PEDOT/PSS (red), and PEDOT/PSS/pHEMA-coated (blue) MEAs. f EIS measurement of PEDOT/PSS (red) and PEDOT/PSS/pHEMA-coated (blue) during ageing test in PBS solution at 60 C for 7 days. g–i: PEDOT:PSS film deposited on a flexible substrate (PET) via spin coating¹⁷⁹. Copyright 2023, John Wiley and Sons (Fig. S3). g Images of a transparent PEDOT:PSS-based ECoG grid wrapped around a cylindrical glass rod (5 mm diameter) (top) and a zoomed-in view of the electrode array (bottom). h EIS of the 30-channel ECoG grid. i Mechanical stability test of the ECoG grid, showing stable EIS values across 30 channels in four different states: original, kinked, folded, and sulcus