High-Speed Atomic Force Microscopy
it before engaging. Finally, the overall data acquisition workflow including tip load- ing and setup, sample loading, navigation, engaging, capturing data, final analysis, and image processing need to be streamlined to improve ease of use and to maximize user productivity.
Figure 5: The challenge in Z scanner design is to increase resonant frequency while maintaining Z range, linearity/ orthogonality, and easy probe loading. The Z scanner is waterproof, enabling easy fluid imaging, and the measured frequency response is over 10× faster than older designs. A finite-element-model illustration of the motion of the Z scanner is shown.
can move between multiple samples via a motorized sample stage, and exhibits AFM performance unaffected by sample mass. As a result, tip-scanning high-speed AFMs enable a significant increase in user productivity.
Other Requirements for High-Speed AFM Additional properties for a high-bandwidth AFM include
both a high-speed servo controller and a high-performance piezo amplifier that drives the Z piezo at high bandwidth and high-slew rates. Te XY flexure scanner should offer flat scanning motion at high speeds while suppressing any inertial coupling from the fast Z axis. AFMs are typically combined with a light-microscopy capability to find a sample region of interest and position the AFM cantilever above
High-Speed AFM Example An example of the results
that can be achieved with the new generation of scanners is an image of a Celgard®
polypropylene battery separator membrane (Figure 6). Te sample is challenging to image because of the combination of nanometer filaments supported only at their ends with deep trenches in between. Te high-speed AFM that was used to capture the image in Figure 6 exhibits good force control at a scan rate of over 20 scan lines per second (~22 seconds per 512-line image), which is consistent with a gain in imaging bandwidth of 10–20× when compared to a standard AFM.
Conclusion Te AFM community has spent considerable effort
over the past decade to address the speed and productivity limitations of AFM. Although many fundamental technological challenges have been addressed in academic settings, the latest generation of commercially available high-speed AFMs is the first to marry large scan sizes, large sample capacity, and enhanced productivity with high scan speed, while simultaneously preserving data quality, force control, and operating costs. Tis new generation of instruments allows researchers to quickly and efficiently perform nanoscale imaging using the full breadth and content richness of the AFM technique, thus enabling both increased productivity and new applications.
References [1] G Binnig, CF Quate, C Gerber, Phys Rev Lett 56 (1986) 930–33.
[2] T Ando, N Kodera, E Takai, D Maruyama, K Saito, and A Toda, Proc Natl Acad Sci 98 (2001) 12468–72.
[3] SR Manalis, SC Minne, and CF Quate, App Phys Lett 68 (1996) 871–73.
[4] G Schitter, G Fantner, J Kindt, P Turner, and PK Hansma, Proc of 2005 IEEE/ASME (2005).
[5] ME Lauer, O Grassman, M Siam, J Tardio, L Jacob, S Page, JH Kindt, A Engel, and J Alsenz, Pharmaceut Res 28 (2011) 572–84.
Figure 6: High-speed AFM image of Celgard® polypropylene battery separator membrane. These data were collected simultaneously for topography (upper left) and phase (lower right). The sharp, undisturbed structures of the topography image show excellent tracking qualities of the AFM, and the phase image structure clarity is evidence of the high bandwidth to support high scan rates of the AFM system.
2011 November •
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[6] YL Lyubchenko and LS Shylakhtenko, Methods March (2009) 206–13.
[7] J Hobbs, J McMaster, M Miles, and P Barham, Polymer 39 (1998) 2437.
[8] Bruker SPM Training 004-130-000 or
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