CAREER: Electro-Mechanical Behaviors of Soft Conductive Composites Embedded with Liquid Metal Fiber Networks

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This Faculty Early Career Development (CAREER) grant will support fundamental research on the electro-mechanical behaviors of liquid metal fiber network composites. This new paradigm of soft conductive composites is super-stretchable, highly conductive, lightweight, and low cost due to its unique microstructural architectures. Therefore, such liquid metal fiber network composites will greatly benefit the flexible electronics industry in the USA and will have other important technological applications such as soft sensors and actuators, soft robotics, energy harvesters, etc. This research will first provide characterization and better understanding of the microstructural evolution and electro-mechanical behaviors of liquid metal fiber network composites under large deformation. Such new knowledge is critical to the microstructural design, material processing, and engineering analysis of liquid metal fiber network composites for future engineering applications. The integration of research and education will focus on student training and industry engagement to educate more engineers doing research and design for liquid metal materials. The education and outreach program will offer interactive and hands-on activities for K-12 and undergraduate students to invent their own soft electronics. Other key education objectives involve developing a new curriculum, hosting online webinars, and maintaining a webpage for liquid metal materials. The specific goal of the research is to discover the influence of network geometry on electro-mechanical behaviors of liquid metal fiber network composites. An integrated experimental-theoretical-computational approach will be employed to uncover the network geometry evolution under extremely large deformation, characterize electro-mechanical behaviors across fiber and network scales, and establish a multiphysics constitutive modeling framework considering material anisotropy and non-affinity. The effects of microstructural architectures, fiber and junction morphologies, and mechanical deformation on the network geometry evolution and electro-mechanical behaviors of liquid metal fiber network composites will be elucidated and modeled. The researched constitutive models and computational micromechanics models will be verified by various experimental techniques involving micro- and nano-computed tomography imaging, in-situ network geometry tracking, and synchronized electro-mechanical testing. Liquid metal fiber network composites with different microstructural architectures will be fabricated and characterized using techniques uniquely developed by the PI. The researched theoretical models, simulation tools, and experimental methodology will be applicable to a broad class of soft conductive composites.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.