Fig. 1.

Schematic illustration of a soft conductive hydrogel micropillar array for electrophysiological recording and its fabrication process. (A) Soft MEA with ECH micropillar electrode for electrophysiological recording of cardiomyocytes. The platinum interconnects were passivated by chemical-vapor-deposited (CVD) silicon oxide and wire-bonded to a printed circuit board (PCB). Hydrogel micropillars bend with engulfing cardiomyocytes, reducing perturbations to the beating of the cardiomyocytes. (B) Fabrication process: Platinum was photolithographically patterned on a glass wafer (feedlines 3 μm wide, 50 nm thick) (B, i), followed by deposition and patterning of silicon dioxide as a passivation layer (0.8 μm thick) (B, ii). An aqueous solution of PEDOT:PSS and IL was then drop casted (1.8 μm) (B, iii) and patterned by electron beam lithography and reactive-ion etching (B, iv) to give diameter of 3 μm. Finally, the conductive hydrogel micropillar was formed by soaking in water for 4 h (B, v).