Shape Programmable Three-Dimensional Mesostructures and Functional Devices by Prof. Yonggang HUANG

A rapidly expanding research area involves the development of routes to shape programmable three-dimensional (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 control the properties of materials systems and the function of devices, through not only static architectures, but also morphable structures and shape-shifting processes. Soft matter equipped with responsive components can switch between designed shapes, but cannot support the types of dynamic morphing capabilities needed to reproduce continuous shape-shifting processes of interest for many applications. Challenges lie in the establishment of 3D assembly/fabrication techniques compatible with wide classes of materials and 3D geometries, and schemes to program target shapes after fabrication. In this talk, I will introduce a mechanics-guided assembly approach that exploits controlled buckling for constructing complex 3D micro/nanostructures from patterned two-dimensional (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 allow realization of 3D mesostructures that are capable of qualitative shape reconfiguration, we devise a loading-path controlled strategy that relies on elastomer platforms deformed in different time sequences to elastically alter the 3D geometries of supported mesostructures via nonlinear buckling. I will also introduce a recent work on shape programmable soft surface, constructed from a matrix of filamentary metal traces, driven by programmable, distributed electromagnetic forces that follow from the passage of electrical currents in the presence of a static magnetic field. Under the guidance of a mechanics model-based strategy to solve the inverse problem, the surface can morph into a wide range of 3D target shapes and shape-shifting processes. The compatibility of our approaches with the state-of-the-art fabrication/processing techniques, along with the versatile capabilities, allow transformation of diverse existing 2D microsystems into complex configurations, providing unusual design options in the development of novel functional devices.

Speaker: Prof. Yonggang Huang (Northwestern University, McCormick School of Engineering)