A high-bandwidth amplitude estimation technique for dynamic mode atomic force microscopy.

While often overlooked, one of the prerequisites for high-speed amplitude modulation atomic force microscopy is a high-bandwidth amplitude estimation technique. Conventional techniques, such as RMS to DC conversion and the lock-in amplifier, have proven useful, but offer limited measurement bandwidth and are not suitable for high-speed imaging. Several groups have developed techniques, but many of these are either difficult to implement or lack robustness. In this contribution, we briefly outline existing amplitude estimation methods and propose a new high-bandwidth estimation technique, inspired by techniques employed in microwave and RF circuit design, which utilizes phase cancellation to significantly improve the performance of the lock-in amplifier. We conclude with the design and implementation of a custom circuit to experimentally demonstrate the improvements and discuss its application in high-speed and multifrequency atomic force microscopy.

[1]  Toshio Ando,et al.  Video imaging of walking myosin V by high-speed atomic force microscopy , 2010, Nature.

[2]  Hideki Kandori,et al.  High-speed atomic force microscopy shows dynamic molecular processes in photoactivated bacteriorhodopsin. , 2010, Nature nanotechnology.

[3]  Ricardo Garcia,et al.  Theory of Q control in atomic force microscopy , 2003 .

[4]  Graham C. Goodwin,et al.  Design of modulated and demodulated controllers for flexible structures , 2007 .

[5]  D. Rugar,et al.  Frequency modulation detection using high‐Q cantilevers for enhanced force microscope sensitivity , 1991 .

[6]  P. Heszler,et al.  Novel amplitude and frequency demodulation algorithm for a virtual dynamic atomic force microscope , 2006, Nanotechnology.

[7]  Ricardo Garcia,et al.  The emergence of multifrequency force microscopy. , 2012, Nature nanotechnology.

[8]  Hiroyuki Noji,et al.  High-Speed Atomic Force Microscopy Reveals Rotary Catalysis of Rotorless F1-ATPase , 2011, Science.

[9]  S. Solares,et al.  Bimodal atomic force microscopy driving the higher eigenmode in frequency-modulation mode: Implementation, advantages, disadvantages and comparison to the open-loop case , 2013, Beilstein journal of nanotechnology.

[10]  S. Solares,et al.  Triple-frequency intermittent contact atomic force microscopy characterization: Simultaneous topographical, phase, and frequency shift contrast in ambient air , 2010 .

[11]  Hemantha K. Wickramasinghe,et al.  Atomic force microscope–force mapping and profiling on a sub 100‐Å scale , 1987 .

[12]  T. Ando,et al.  A high-speed atomic force microscope for studying biological macromolecules , 2001, Proceedings of the National Academy of Sciences of the United States of America.

[13]  T. Ando,et al.  High-speed atomic force microscopy for nano-visualization of dynamic biomolecular processes , 2008 .

[14]  Ricardo Garcia,et al.  Theory of multifrequency atomic force microscopy. , 2008, Physical review letters.

[15]  Toshio Ando,et al.  High-speed atomic force microscopy coming of age , 2012, Nanotechnology.

[16]  Roger Proksch,et al.  Multifrequency, repulsive-mode amplitude-modulated atomic force microscopy , 2006 .

[17]  Dan Wang,et al.  Cantilever dynamics and quality factor control in AC mode AFM height measurements. , 2007, Ultramicroscopy.