Mechanical Engineering Seminar: Mechanics of Stretchable Electronics

Abstract
Although buckling has historically been viewed as a mechanism for structural failure, pioneering work in the late 1990’s showed that buckling can be controlled in micro and nanoscale systems to generate interesting structures with well defined geometries and dimensions in the 100 nm – 100 mm range. These observations created renewed interest in this area which persists today, with many active research groups currently exploring basic scientific aspects as well as applications in stretchable electronics, micro and nanoelectromechanical systems, tunable phase optics, force spectroscopy in cells, biocompatible topographic matrices for cell alignment, high precision micro and nano-metrology methods, and pattern formation for micro/nano-fabrication. In these systems, controlled buckling is realized in thin films deposited, typically by vapor phase or physical transfer processes, onto prestrained elastomeric substrates. Depositing a film on this stretched substrate and then releasing the prestrain can create ‘wavy’ structures.

Mechanics plays a key role in this development. Our recent papers on the following mechanics problems related to stretchable electronics will be discussed: wavelength and amplitude of stretchable silicon film [Science 311, p 208, 2006], controlled buckling mode [Nature Nanotechnology 1, p 201, 2006], finite deformation effect [PNAS 104, p 15607, 2007], and 2D herringbone pattern [Nano Letters 7, p 1655, 2007]. We have applied this technology to stretchable, foldable and twistable circuits [Science 320, p 507, 2008; PNAS 105, p 18675, 2008 (cover article)], electronic-eye camera [Nature 454, p 748, 2008 (cover article)], flexible LED display [Science 325, p 977, 2009], transfer printing [Nature Materials 5, p 33, 2006], flexible silicon solar microcell [Nature Materials 7, p 907, 2008 (cover article)], and curvilinear electronics [PNAS 106, p 10875, 2009]

Bio of Prof. Yonggang Huang
Yonggang Huang is the Joseph Cumming Professor of Mechanical Engineering, and also Civil and Environmental Engineering, at Northwestern University. He is interested in establishing mechanics models for advanced technology, such as stretchable electronics, flexible silicon solar cell, and transfer printing. Mechanics plays a critical role in the development of scientific and engineering foundations for these advanced technologies. He has published 1 book, 25 book chapters, and 300 papers in journals, including multi-disciplinary journals Science, Nature, Nature Materials, Nature Nanotechnology, and PNAS; physics journals PRL, PRB, and APL; materials journals Advanced Materials, Advanced Functional Materials, Acta Materialia, and JMR; nano journals Nano Letters, Small, and Nanotechnology; chemistry journals Langmuir, and Angewandte Chemie; and mechanics journals JMPS. Four of his papers published in 1999, 2000, 2002 and 2004 have become the most cited ones among more than 9000 papers published annually in all 110 mechanics journals listed in ISI Web of Science in the corresponding years. These are also the most cited papers among more than 8700 papers published annually in all 104 mechanical engineering journals in the corresponding years. His recent work has been reported by many popular media such as ABC, BBC, Boston Globe, Chicago Tribune, Discover, MSNBC, New York Times, Newsweek, Reuters, United Press International, and US News & World Report.

His recent awards include the Larson Memorial Award in 2003 and Melville Medal in 2004, both from ASME; Young Investigator Medal from the Society of Engineering Sciences in 2006; International Journal of Plasticity Medal in 2007; Guggenheim Fellowship from the John Simon Guggenheim Foundation in 2008; ISI Highly Cited Researcher (Engineering) in 2009. He held the Grayce Wicall Gauthier Professorship (2003-04), Shao Lee Soo Professorship (2004-07) at the University of Illinois at Urbana-Champaign, the Visiting Clark Millikan Professorship (2005-06) at Caltech, and Honorary Professor at Nanjing University of Posts and Telecommunications.