By Melbourne Centre for Nanofabrication
Atomic force microscopy (AFM) is an ultra-high resolution imaging technology and it is one of the most versatile characterisation methods. AFM performs scanning probe microscopy at a very high resolution scale, probing the surface of a material with a nanoscale cantilever, either through direct contact or through oscillating the cantilever just above the surface. When the cantilever is positioned in close proximity to the surface, forces between the tip and the sample lead to deflection of the cantilever, which is then measured with a laser signal reflected to a photodiode detector. The properties of the material surface such as topography, mechanical properties and tip-surface interaction forces can then be generated leading to an understanding of the material surface at the nanoscale. AFM has a wide range of applications including nanoscale materials and surface characterisation, electrical materials characterisation, interaction forces and mechanical properties mapping. Bio AFM is useful for pharmaceutical studies, immunology studies, biosensing applications, antibody/antigen binding studies, as well as intra-molecular studies such as protein folding. MCN has two AFM instruments – the Dimension Icon AFM which resides in the class 10,000 cleanroom and the NanoWizard II Bio AFM which resides in the Microscopy Lab. The Dimension Icon AFM is designed with a large sample platform, providing the highest level of functionality, accessibility and performance, with ultra-low drift. It features a number of application modules such as ScanAsyst TM, Peak Force QNM TM (PFQNM), electrical materials characterisation and heating and cooling studies. The ScanAsyst TM imaging mode performs automatic image optimisation by controlling the tip-sample interaction force for easier, faster and more consistent imaging results. The PFQNM mode analyses tip-sample interaction forces and generates quantitative nanoscale maps of mechanical properties, including modulus, adhesion, deformation, and dissipation. PFQNM operates over an extremely wide range to characterise a large variety of sample types. The AFM executes temperature control and thermal analysis on samples from -35°C to 250°C while scanning in various AFM modes. The Nanowizard II Bio AFM is designed for imaging fixed and live cells in air or biological or chemical fluids. It can be used to understand surface chemistry of cells and measure force spectroscopy of surfaces. It is able to take measurements at variable temperatures with the possibility of perfusion. The system features stand-alone tip scanning, allowing for flexibility in applications whilst maintaining high resolutions as well as a large scan field of 100x100x15µm. It can also be integrated with the laser scanning confocal microscope.
