Simultaneous measurement of subsurface properties using AFM by indentation and vibration

Abstract

Non-destructive, nanoscale characterization techniques are necessary to understand both synthetic and biological materials. The atomic force microscopy uses a force-sensing cantilever with probe to measure the topography and other properties of surfaces. The AFM based nanorobot in combination with other nanomechanical sensors is developed to study the material mechanical properties, the adhesion, and cell signalling pathways which would provide high spatial resolution in imaging and extends it to manipulation of the nano scaled samples. The multiple input coupling control system was designed and implemented to solve the issues of nanomanipulation of materials, feedback, response frequency and nonlinearity. As the subsurface information become emerging challenge to overcome using AFM, an indentation-vibration-based AFM system is designed to simultaneously measure the the mechanical properties of materials including mass, elasticity, viscosity, based on principle of forced vibration stimulated by harmonic force using AFM probe integrated with a piezoelectric transducer (PZT) as the vibrator to provide the sample with periodic vibration signal. Multiple high precision, wide frequency band sensors have been implanted to the system including the piezoceramic sensors and piezoelectric polyvinylidene fluoride (PVDF) film. The multiple input and multiple output coupling with the mathematical model analysis provide the approach to reveal the morphological and compositional substructure of materials and living matters. The implemented indentation-vibration-based AFM system would further implant into biological research. Focal adhesions lie between the cell and the extracellular matrix where integrin and proteoglycan link the actin cytoskeleton to extra microenvironment that functionalize as signalling pathway that regulate the cell morphologies, proliferation and migration. Use the indentation-vibration-based system combine with the cellular incubator establishment to study the distribution and mechanical properties of the focal adhesion complex would further enhance the understanding of cellular behaviour in cancer therapy.