Device fabrication and in situ monitoring were performed using optical/zeta microscopy and atomic force microscopy (AFM)-based imaging, primarily with the tapping mode, at various stages of device development. The quality of the immobilized protein layers was assessed, and their thicknesses determined by AFM scratching using a stiff AFM cantilever (spring constant ~2 N/m). AFM imaging was done with a Bruker Nanoscope V Multimode AFM system, and protein layer scratching was achieved by applying a 150-200 nN contact force. Detailed experimental procedures are given elsewhere. All AFM images were analyzed and processed using Gwyddion 2.65 software.