Current voltage characteristics within an AFM technique on a monolayer of bacteriorhodopsin. Measured I-V characteristics of the native state of bR are compared with theoretical calculations carried out using the 2NTU structure at the reported different indentations of the AFM tip. The AFM technique is sketched in the inset. The thick continuous lines show experimental data  and the symbols numerical simulations obtained with extended contacts including a leakage current .
Reggiani et al. Nanoscale Research Letters 2012 7:340 doi:10.1186/1556-276X-7-340