A nanopore cell includes a conductive layer and a working electrode disposed above the conductive layer and at the bottom of a well into which an electrolyte may be contained, such that at least a portion of a top base surface area of the working electrode is exposed to the electrolyte. The nanopore cell further includes a first insulating wall disposed above the working electrode and surrounding a lower section of a well, and a second insulating wall disposed above the first insulating wall and surrounding an upper section of the well, forming an overhang above the lower section of the well. The upper section of the well includes an opening that a membrane may span across, and wherein a base surface area of the opening is smaller than the at least a portion of the top base surface area of the working electrode that is exposed to the electrolyte.