Abstract

Recently, the demand for wearable sensors is growing due to their ability to help monitor motion and provide clinically relevant data for healthcare. Conductive elastic composites are generally elastomer matrices filled with conductive fillers. They combine the conductivity of metals and carbon materials with the flexibility of polymers.

In this work, liquid metal magnetorheological elastomers filled with magnetic particles, such as iron microparticles and nickel microparticles, were fabricated. Specifically, these particles were mixed with PDMS and liquid metal droplets and cured either on or without external magnetic field, forming both isotropic or unisotropic liquid metal based magnetorheological composites. Their microstructures were characterized via SEM images. Both mechanical and conductive properties of these new composites were investigated. Unlike conventional composites whose resistance increases under tensile strain, the resistance of this new composite is maximum when relaxed, and reduces sharply upon the application of either compressive or tensile strains. In other words, the resistivity of this new material decreases exponentially under compression, stretching, bending, and twisting.

We demonstrated several proof-of-concept applications based on this composite such as wearable joint sensors and intelligent heating devices. The Liquid metal hybrid composite can be used to detect the movement of human joints. This composite has the potential to be applied for developing highly sensitive flexible sensors for wearable devices.

Biography (Weihua Li)

Dr. Weihua Li is a Senior Professor and Director of Advanced Manufacturing Technologies research strength at the University of Wollongong. He completed his PhD at Nanyang Technological University (NTU) in 2001. After that, he worked as a Research Fellow at the School of Mechanical and Aerospace Engineering of NTU, before he joined the School of Mechanical, Materials and Mechatronic Engineering as a Lecturer in 2003. His research focuses on Dynamics and Vibration Control, Smart Materials and Structures, Microfluidics and Lab on a Chip. He serves as chief editor or editorial board member for >10 international journals.  He has published more than 400 journal papers with >21,000 citations and an h-index of 78 (Google Scholar).

He is a recipient of Fellow of Engineers Australia, Fellow of the Institute of Physics (UK), JSPS Invitation Fellowship, Australian Endeavour Fellowship, Vice-Chancellor's Award for Excellence in Research Supervision, Vice-Chancellor’s Award for Interdisciplinary Research Excellence and numerous Best Paper Awards.