Events

Opportunities for All-Optical Assembly of 3D Structures Using Selective Tweezing and Immobilization of Colloids

Kimani C. Toussaint, Jr., Senior Professor and Director of the Brown University Center for Digital Health, Brown University

Presented in-person in Goergen 101 and on Zoom

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Abstract

The ability to assemble arbitrary 3D structures using nano‐ to micron‐scaled colloidal building blocks has several interesting potential applications, including photonic, electronic, and biological. To achieve this, the combination of optical tweezers (OT) with two‐photon polymerization (TPP), offers the advantage of complete 3D optical manipulation and immobilization of particles without the need for specialized functionalization of the constituent particles. Unlike previous approaches, we demonstrate that utilizing high‐repetition rate femtosecond‐laser pulses, rather than the traditional continuous‐wave (cw) laser source, permits optical tweezing with intensities below the threshold for TPP, and thus enables both OT and TPP using the same laser source. We apply this approach for selective tweezing and immobilization of colloids (STIC) to various particle types. As an all‐optical platform, STIC provides an opportunity to both freely manipulate and immobilize objects in three spatial dimensions using a single platform. This talk reviews the operational principle of STIC and provides proof‐of‐principle experiments that highlight its capabilities on a diverse array of materials including silica microparticles and bacterial cells, and select 2D materials. The current challenges and opportunities of this platform are also discussed.

Biography

 Kimani C. Toussaint, Jr., PhD, is the Thomas J. Watson, Sr. Professor of Science and Senior Associate Dean for Research and Strategic Initiatives in the School of Engineering at Brown University, and serves as Director of the Brown University Center for Digital Health. Dr. Toussaint also directs the Laboratory for Photonics Research of Bio/Nano Environments (PROBE Lab), a highly interdisciplinary research group working in the areas of quantitative nonlinear optical imaging techniques, structured light, nano‐optics, and optical health‐monitoring techniques that mitigate bias. He is a recipient of a 2010 NSF Career Award, the 2014‐2015 Dr. Martin Luther King, Jr. Visiting Associate Professor at MIT, the 2015 Illinois Dean’s Award for Excellence in Research, the 2017 Illinois Everitt Award for Teaching Excellence, the 2019 Distinguished Promotion Award, and the 2024 Innovator of the Year by Brown University’s Technology Innovations Office. Dr. Toussaint is also a Fellow of Optica, SPIE, AIMBE (American Institute for Medical and Biological Engineering), and AAS (African Academy of Sciences), as well as a Senior Member in the IEEE. In addition, he is a member of the Board of Reviewing Editors for Science, and has served as a Guest Editor for PNAS. Dr. Toussaint’s work on equitable pulse oximetry has appeared in popular press, including NPR, Politico, CNN, STAT+, and the Boston Globe.