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Ended Mechanical Engineering Special Seminar

ME SPECIAL SEMINAR Date 2025.08.08(Fri.) 10:30-12:30 Speaker Prof. Cheng Sun (Department of Mechanical Engineering, Northwestern University) Prof. Hao F. Zhang (Department of Biomedical Engineering, Northwestern University) Place Room No. 108 at Sci. Bldg. 5 Room No. 108/110 at Sci. Bldg. 5 Host of a Seminar Prof. Junsuk Rho Optical Coherence Tomography (OCT) and 3D printing emerge from the opposite perspective in connecting physical objects with digital representations. OCT captures anatomical details and converts them into 3D digital images, whereas 3D printing transforms digital models into tangible 3D objects. The synergistic combination of these technologies holds promising potential in creating a bidirectional bridge to unify physical and virtual realms. In this talk, I will take customized contact lenses as a presentative example to illustrate this concept, employing visible- light optical coherence tomography (vis-OCT) and micro-continuous liquid interface production (µCLIP) 3D printing, both of which offer micron-scale resolution. We used vis-OCT to capture the topology of the corneal surface, which informs the posterior surface of the contact lens design, leaving its anterior surface with the freedom to achieve the desired optical power. The digital model is then materialized using µCLIP. We assess the dimensional accuracy of the 3D-printed contact lenses and their fit on the original physical object—the cornea—using vis-OCT. Finally, the performance of the assembled unit, consisting of the cornea and custom contact lens, is validated by vis-OCT imaging of the mouse retina. This work not only showcases the feasibility of creating personalized devices but also underscores the potential of enhancing the physical world through its integration with digital counterparts. My group focuses on two core technologies, spectroscopic single-molecule localization microscopy (sSMLM) and visible-light optical coherence tomography (vis-OCT), and their applications to vision and cancer imaging at the length scale ranging from single molecules to whole human eyes. While traditional OCT uses near-infrared light, vis-OCT leverages the significantly higher tissue contrast within the visible light spectral range to extract physiological and pathological information, in addition to ultra-high (1.3 µm) resolution anatomical imaging. Using vis-OCT in both patients and small animal models, we detected retinal ischemia well before the onset of angiogenesis, produced the first in vivo three-dimensional imaging of the entire ocular outflow pathway, and discovered new biomarkers of neuronal damage. In contrast, sSMLM offers multiplex super-resolution imaging with a spatial resolution of up to 1 nm by analyzing the spatial locations and full fluorescence emission spectra of stochastic single-molecule fluorescence emissions. Using sSMLM, we overcame the long-standing challenges of rejecting fluorescence impurities, investigated single-molecule fluorescence heterogeneities, and imaged molecular interactions with drastically different molecular concentrations. In this talk, I will describe the working principles of vis-OCT and sSMLM and how we combine them to investigate multiple blinding diseases, especially glaucoma, comprehensively.

2025-08-08 10:30 27031

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