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Geometry is concerned with the properties of configurations of points, lines, and circles, while topology is concerned with space, dimension, and transformation. Geometry is also materials independent and scale invariant. By introducing holes and cuts in 2D sheets, we demonstrate dramatic shape change and super-conformability via expanding or collapsing of the hole arrays without deforming individual lattice units. When choosing the cuts and geometry correctly, we show folding into the third dimension, known as kirigami. The kirigami structures can be rendered pluripotent, that is changing into different 3D structures from the same 2D sheet. We explore their potential applications in energy efficient building facade, super-stretchable and shape conformable energy storage devices and medical devices, as well as bioinspired robotics. Programmable shape-shifting materials can take different physical forms to achieve multifunctionality in a dynamic and controllable manner. Through designs of geometric surface patterns, e.g. microchannels, we program the orientational elasticity in liquid crystal elastomers (LCEs), to direct folding of the 2D sheets into 3D shapes, which can be triggered by heat, light, and electric field. Taking this knowledge of guided inhomogeneous local deformations in LCEs, we then tackle the inverse problem – pre-programming geometry on a flat sheet to take an arbitrary desired 3D shape. Lastly, I will show the prospective of taking geometry to create smart fabrics and tendon-like filaments for soft robotic applications.
Prof. Shu Yang (Department of Materials Science & Engineering, University of Pennsylvania)
Shu Yang is a Professor in the Departments of Materials Science & Engineering, and Chemical & Biomolecular Engineering at University of Pennsylvania. Her group is interested in synthesis, fabrication, and assembly of polymers, liquid crystals, and colloids with precisely controlled size, shape, and geometry; investigation of the dynamic tuning of their sizes and structures, and use geometry to create highly flexible, stretchable, super-conformable, and foldable devices. Her lab explores the potential applications of the smart and bioinspired materials, including self-cleaning coatings, dry adhesives, smart windows, sensors, actuators for robotics, and biomedical devices. Yang received her B.S. degree from Fudan University, China in 1992, and Ph. D. degree from Chemistry and Chemical Biology while researching in the Department of Materials Science and Engineering at Cornell University in 1999. She worked at Bell Laboratories, Lucent Technologies as a Member of Technical Staff before joining Penn in 2004. She received George H. Heilmeier Faculty Award for Excellence in Research from Penn Engineering (2015-2016). She is Fellow of Division of Soft Matter (DSOFT) from American Physical Society (APS), Fellow of Division of Polymeric Materials: Science and Engineering from American Chemical Society (ACS) (2018), Fellow of Royal Chemical Society (2017), Fellow of National Academy of Inventors (2014), and TR100 as one of the world’s top 100 young innovators under age of 35 by MIT's Technology Review (2004).