The development of devices with active areas in the nanoscale as well as the understanding of their fundamental electronic transport properties makes necessary the development of new tools and measurement protocols. One of the tools that are currently being adopted for these purposes is the Atomic Force Microscopy (AFM). AFM has nanometric spatial resolution, it is able to work under liquid physiological environment, it can be adapted to perform a variety of electrical and electrochemical measurements and allowing to control the force applied onto sample it is able to access also biosamples.
The research group is contributing to extend the current state of the art of AFM instrumentation in order to perform electrical DC and AC electrical measurements on nanosamples in both spectroscopic mode (in a single point) and in imaging mode. To perform the measurements we have mounted into a commercial Atomic Force Microscopy a full custom low noise wide bandwidth current preamplifier. The new set up allows measuring simultaneously the sample topography and a variety of electrical signals (DC current and AC small signal impedance) with nanometric spatial resolution. Moreover, specific protocols combining contact, dynamic and jumping modes have been implemented in order to avoid sample damage during the measurements. Test measurements have been performed in ultra-thin oxides, in purple membrane and nano-liposomes formed from yeast cells expressing olfactory receptors, showing that the electrical characterization of nano-bio samples with nanometric spatial resolution is feasible.