Development of modified lateral force microscopy technique

Yen-Kai Hseu, Purdue University


The scanning probe microscope (SPM) is a high precision measurement research equipment that enables one to obtain images of a sample’s surface topography at the nano-level using atomic force microscopy (AFM) techniques. In addition to its imaging capabilities, the SPM can also be used to obtain sample properties such as surface electrical charges, magnetic properties, pliability/elasticity, and friction. Past researches in similar areas have shown that a direct correlation exists between a cell’s surface forces and its mechanical properties. Changes in the cell membrane’s properties and performance caused by internal or external stimuli may cause degradation of the cell. Surface force data, represented through force curves, can be generated by different methods of approaching the SPM tip to the artificial membrane interactions. The data in past research were primarily based on force curves obtained in the vertical direction. The focus of this thesis is the development of a new lateral force curve technique using a SPM nanomanipulation software; the new technique will be used to measure direct lateral forces in addition to surface frictional forces. It was concluded that the SPM nanomanipulation software provided enough versatility for the author to control the movement of the SPM probe to create the Modified LFM (MLFM) technique. The results from the experiments validated the consistency of the new Modified LFM technique in air. Further validation of the technique must be performed in a fluid medium. The results also indicated that the properties of the artificial membranes were too dynamic and a better understanding of the artificial membranes was required. Overall, the research was successful in the development of the new Modified LFM technique but the application of the technique to the artificial membrane was unsuccessful.




McNally, Purdue University.

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