Northwestern University MRSEC IRG-2 has realized ultra-high-density and mechanically flexible vertical organic electrochemical transistor (vOECT) arrays and complementary circuits through electron-beam patterning of the conjugated organic semiconductors by electron-beam exposure. The high energy electron-beam disrupts the conjugation in the exposed organic semiconductor area, creating an electronic insulator while retaining ionic conductivity and topological continuity with the redox-active unexposed areas. Applying this spatially selective electron-beam exposure strategy to organic mixed ionic/electronic conductors in the vOECT array fabrication process provides ultra-high-resolution patterning and modulation of the charge transport. The resulting p-type and n-type vOECTs enable active-matrix arrays with superlative electronic switching characteristics. In this manner, this work opens new possibilities to expand the application of vOECTs to the fields of neuromorphic computing, stretchable electronics, wearable electronics, and bioelectronic sensing.