To create a micropore, it is essential to coat the conductive electrode with an insulating layer. In this study, alumina was selected for several reasons. Alumina is highly suitable for atomic layer deposition (ALD), as its precursors are cost-effective and chemically stable over a wide pH range, and the resulting oxide layer is highly resistive (~10¹⁴ Ω•m). ALD-grown alumina ensures uniform layer coverage with minimal pinhole formation, in contrast to plasma-enhanced chemical vapor deposition (PECVD), or sputtering, E-beam-based physical vapor deposition, which can introduce defects. For this study, a 20 nm alumina layer was chosen, as it provides effective complete coverage of insulating coating over the conductive bottom electrodes without pinholes. This thickness suffices to study protein multilayers while ensuring complete electrical as no current can be measured during a ±1V voltage sweep.