Title: Versatile High-Speed and Large-Range Atomic Force Microscope Design
Bio:
Fangzhou Xia received his M.S. and Ph.D. degrees in Mechanical Engineering from Massachusetts Institute of Technology (MIT), US, in 2017 and 2020. He obtained his dual Bachelor's degrees in Mechanical engineering from University of Michigan, Ann Arbor, US, and in Electrical and Computer Engineering from Shanghai Jiao Tong University, China, in 2015. He is currently a postdoctoral associate researcher in the Mechatronics Research Lab at MIT. His is interested in the field of control, robotics and instrumentation with application to intelligent mechatronic systems, precision instrumentation and learning-based motion control.
Abstract:
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 interaction. 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.
In the Mechatronics Research Lab, we develop AFM systems to remove such AFM restrictions and enable advanced visualization capabilities. Example applications include visualizing chemical reactions and biological responses in their native environments. We design new generation nano-positioners to address the low imaging throughput limitation and enabled high-speed video-rate AFM imaging. To resolve the transparency limitation, active cantilever probes with embedded piezoresistive sensing and thermomechanical actuation are developed with nano-fabrication techniques. We apply coating to protect the functional structures to enable AFM imaging in chemically harsh opaque liquid enabled. This allows observation of samples in their native environment such as non-transparent acid, crude oil, cells in blood, etc. Using our expertise in AFM design, we have also developed a modular low-cost AFM platform for precision instrumentation and mechatronics education.
In this talk, the development of high-bandwidth nano-positioning systems, active cantilever probes and other enabling technologies will be presented. We will show AFM images and videos to demonstrate the new capabilities. The high-speed imaging capability is used to capture videos for calcite etching process and electrochemical deposition of copper on gold substrate. Images taken in opaque acidic liquid and crude oil are used to verify the functionality of the coated active cantilever probes. We conclude by discussing related applications and broader impacts of the development on both the AFM user and instrument designer communities.
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