| Summary: | Microscopy instruments are important in nano-technology research for imaging of nanoscale phenomena. Among such tools is the atomic force microscope (AFM) for nanoscale imaging and surface characterization. An AFM scans a micro-cantilever over the sample surface to measure various quantities from the probe-sample inter- action. With high-speed imaging, dynamic processes can be visualized to improve fundamental understanding of microscopic interactions. Scientists can use videos, in addition to images, to observe and compare experimental data with theoretical predictions, and verify models without speculating about intermediate dynamics. However, conventional AFMs have limited throughput that allow for static imaging only and require transparent working environments.
The contributions of this thesis remove such AFM restrictions and enable advanced visualization capabilities. Example applications include visualizing chemical reactions and biological responses in their native environments. To this end, the thesis addresses four main AFM limitations. These are (i) increase the low imaging throughput to be compatible for higher temporal resolution imaging, (ii) remove the transparency requirement, for AFMs that use optical beam deflection sensing, and enable imaging in harsh opaque liquids, (iii) establish automation algorithms to reduce operational overheads associated with experiment setup and controller tuning, and (iv) introduce custom design modifications resulting in affordable AFMs for engineering education.
These new capabilities are primarily enabled with the development of new sub- systems. The key components include nano-positioners, cantilever probes, and control algorithms. New generation AFM nano-positioners are designed with high-speed, large-range or low-cost characteristics for different scanning needs. Coated active cantilever probes are developed for AFM imaging in specialized opaque environments. Multiple algorithms for scanner control, automatic tuning, and image formation are investigated to improve AFM imaging performance. Additional developments to sup- port AFM imaging include high-bandwidth driver electronics, optical systems with vision-based automation, and software implementation for AFM big data processing. Three AFM systems are integrated using these new subsystems for different applications. They include a versatile sample scan AFM for overview-and-zoom imaging in air and liquids, a multi-layer stacked scanner AFM for high-speed and large-range imaging in air, and a low-cost active probe AFM for engineering education. AFM im- ages and videos at 20 frames per second are taken in various environments to verify the new capabilities. These developments have broader impacts in the fields of precision instrumentation, nano-fabrication, and nano-scale process video-rate visualization.
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