Frequency modulation atomic force microscopy in ambient environments utilizing robust feedback tuning
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|Title:||Frequency modulation atomic force microscopy in ambient environments utilizing robust feedback tuning||Authors:||Kilpatrick, J. I.
Cleveland, J. P.
|Permanent link:||http://hdl.handle.net/10197/4241||Date:||2-Feb-2009||Abstract:||Frequency modulation atomic force microscopy (FM-AFM) is rapidly evolving as the technique of choice in the pursuit of high resolution imaging of biological samples in ambient environments. The enhanced stability afforded by this dynamic AFM mode combined with quantitative analysis enables the study of complex biological systems, at the nanoscale, in their native physiological environment. The operational bandwidth and accuracy of constant amplitude FM-AFM in low Q environments is heavily dependent on the cantilever dynamics and the performance of the demodulation and feedback loops employed to oscillate the cantilever at its resonant frequency with a constant amplitude. Often researchers use ad hoc feedback gains or instrument default values that can result in an inability to quantify experimental data. Poor choice of gains or exceeding the operational bandwidth can result in imaging artifacts and damage to the tip and/or sample. To alleviate this situation we present here a methodology to determine feedback gains for the amplitude and frequency loops that are specific to the cantilever and its environment, which can serve as a reasonable "first guess", thus making quantitative FM-AFM in low Q environments more accessible to the nonexpert. This technique is successfully demonstrated for the low Q systems of air (Q∼40) and water (Q∼1). In addition, we present FM-AFM images of MC3T3-E1 preosteoblast cells acquired using the gains calculated by this methodology demonstrating the effectiveness of this technique.||Type of material:||Journal Article||Publisher:||American Institute of Physics||Journal:||Review of Scientific Instruments||Volume:||80||Issue:||2||Start page:||023701||End page:||023701-6||Copyright (published version):||2009 American Institute of Physics||Keywords:||Atomic force microscopy; Biological techniques; Cantilevers; Cellular biophysics; Demodulation; Feedback; Frequency modulation||DOI:||10.1063/1.3073964||Language:||en||Status of Item:||Not peer reviewed|
|Appears in Collections:||Conway Institute Research Collection|
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