• Starts: 3:00 pm on Tuesday, December 3, 2024
  • Ends: 5:00 pm on Tuesday, December 3, 2024

ECE PhD Thesis Defense: Hongli Ni

Title: Advanced Vibrational Microscopy for Clinical Translation

Presenter: Hongli Ni

Advisor: Professor Ji-Xin Cheng

Chair: Professor Selim Unlu

Committee: Professor Ji-Xin Cheng, Professor Darren Roblyer, Professor Jerome Mertz, Professor Siddharth Ramachandran.

Google Scholar Link: https://scholar.google.com/citations?user=1kfxnwcAAAAJ&hl=en

Abstract: The label-free chemical imaging capability of vibrational microscopy overcomes the limitations of fluorescence microscopy, which arise from the use of exogenous fluorescent dyes. Advanced vibrational microscopy techniques, including mid-infrared photothermal and coherent Raman scattering, have found broad applications in life sciences and showed great potential for clinical applications. However, clinical translation of vibrational microscopy faces challenges including the lack of clinical-compatible imaging systems and the limited imaging depth.

My dissertation addresses these translational challenges by developing novel vibrational microscopy techniques. Utilizing a rapid widely-tunable fiber laser, we developed a clinical-compatible stimulated Raman scattering microscopy with multi-window chemical imaging capability. As a focused clinical application, we demonstrated label-free breast cancer histology using this system. Through the integration of a regularized spectral unmixing algorithm and a spectral selective sampling method, high-speed, high-content mapping of tissue components is achieved. To overcome the challenge of limited imaging depth, we invented the short-wave infrared photothermal microscopy (SWIP) to bridge the gap for a micron-resolution millimeter-deep chemical imaging method. By pumping the overtone transition of carbon–hydrogen bonds and probing the subsequent photothermal lens with shortwave infrared light, SWIP can obtain chemical contrast from 1 μm polymer particles located at 800 μm depth in a highly scattering phantom. We further demonstrated that SWIP can resolve intracellular lipids across an intact tumor spheroid and the layered structure in thick liver, skin, brain and breast tissues.

Together, my dissertation advances vibrational microscopy by developing a clinical-compatible system and establishing a new approach for micron-resolution millimeter-deep chemical imaging. These contributions bring vibrational microscopy closer to clinical translation and open new possibilities for a broad range of biomedical applications.

Location:
PHO 428