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Mechanics-Guided 3D Assembly of Complex Mesostructures and Functional Devices

Abstract: A rapidly expanding research area involves the development of routes to complex 3D structures with feature sizes in the mesoscopic range (that is, between tens of nanometres and hundreds of micrometres).  A goal is to establish methods to controll the properties of materials systems and the function of devices constructed with them, not only through chemistry and morphology, but also through 3D architectures.  Hwever, existing approaches of 3D assembly/fabrication are only compatible with a narrow class of materials and/or 3D geometries.  In this talk, I will introduce a mechanics-guided assembly approach that exploits controlled buckling for constructing complex 3D micro/nanostructures from patterned 2D micro/nanoscale precursors that can be easily formed using established semiconductor technologies.  This approach applies to a very broad set of materials (e.g., semiconductors, polymers, metals, and ceramics) and even their heterogeneous integration, over a wide range of length scales (e.g., from 100 nm to 10 cm).  To enrich the class of 3D geometries accessible to the proposed assembly approach, we devised a set of mechanics-driven design strategies, such as kirigami/origami designs of 2D precursors, heterogeneous substrate designs and loading-path controlled shape morphing strategies.  I will also introduce a series of mechanics models for the direct postbuckling analysis, as well as inverse design methods that map target 3D topologies onto unknown 2D precursor patterns, which could provide an important theoretical foundation of the rational 3D assembly.  The compatibility of the approach with the state-of-the-art fabrication/processing techniques, along with the versatile capabilities, allow transformation of diverse existing 2D microsystems into 3D configurations, providing unusual design options in the development of novel functional devices. 

Bio: Yonggang Huang is the Achenbach Professor of Mechanical Engineering, Civil and Environmental Engineering, and Materials Science and Engineering at Northwestern University.  He is interested in mechanics of stretchable and flexible electronics, and mechanically guided deterministic 3D assembly.  He is a Highly Cited Researcher in Engineering (2009), in Materials Science (since 2014), and in Physics (2018).  He is a member of the National Academy of Engineering, National Academy of Sciences, and a fellow of American Academy of Arts and Sciences.  He received the Guggenheim Fellowship in 2008, and his research awards in the last few years include the Nadai Medal (2016), Thurston Lecture Award (2019) and Honorary Membership (2021) from the American Society of Mechanical Engineers (ASME); Prager Medal (2017) from the Society of Engineering Sciences; and Bazant Medal (2018) and von Karman Medal (2019) from the American Society of Civil Engineers.  He has received awards for undergraduate teaching and advising from University of Arizona (1993); University of Illinois at Urbana-Champaign (2003, 2004, 2005, 2006, and 2007); and Northwestern University (2016, 2018, 2020). 

All seminars are held on Wednesdays from 12:00 noon-1:00 p.m. in the Bowen Hall Auditorium Room 222. A light lunch is provided at 11:30 a.m. in the Bowen Hall Atrium immediately prior to the seminar.