Wet etching of the protective Cr layer resulted in significant undercutting near the micropore region, leading to observable device shrinkage (Scheme 1(V), Figure ) at the micropore boundary leaving unaffected the pore area with the exposed active Au-electrode. This phenomenon occurs because the voids created by the removal of the Cr layer are rapidly filled by ALD-grown alumina, which collapses on and strongly adheres to the underlying Au layer. The alumina fragments demonstrated robust adhesion on the area exposed by device shrinkage, remaining intact even after 30 minutes of ultrasonic bath sonication (before base-piranha treatment). Atomic force microscopy (AFM) images distinctly revealed the shrinkage effect around the micropore area (Figure ).