Custom system for single molecule force spectroscopy

Atomic Force Microscopy (AFM) is nowadays a widely distributed imaging technique, able to achieve nanometric resolution on a broad range of samples, from innovative materials to living biological systems. The physical principle underlying the AFM technology is based on the measurement of the interaction force between a sharp tip and the sample, with picoNewton sensitivity. This aspect of AFM was more recently exploited to perform force spectroscopy experiments on single molecules, paving the way for the study of mechanical properties of single proteins and peptides [1]. This type of measurement has two major requirements: great stability and precision in terms of vertical displacement and force sensing, and the ability to acquire a large, statistically relevant, set of repeated measurements. Apart from the stability and precision point, with commercial systems it is not always easy to gather the needed amount of curves for the analysis, since this ideally requires the instrument to be able to perform multiple curves on a number of different spots on the sample surface. To overcome this limitation, researchers have to customize their instruments and/or the control software that comes with them, spending time and also money on already expensive systems. By tailoring the hardware and using an open source software architecture that could allow easy and fast modifications and also a complete redesign of the control software, we managed to create a system that addresses the problem cited above, without losses on the performance side. Materials and Methods