Speaker: Prof. Ken Loh, University of California San Diego, United States

Chair: Dr. Jean-Sébastien Plante

Abstract: The safety, resiliency, and survivability of the warfighter, whether in a training or forward deployed environment, are of utmost importance for the military. For instance, musculoskeletal injuries are the leading cause of military disability discharge, which amount to ~1.6 million injuries per year within the U.S. Department of Defense. At sea, sailors and damage control personnel perform duties in hazardous conditions, especially when responding to shipboard emergencies because of smoke, fire, flood, and/or radiation. Similarly, resiliency at sea is further put to test during search and rescue of sailors fallen overboard. The goal of this presentation is to highlight three unique ongoing efforts in multifunctional and metamaterials development in the ARMOR Lab, all aimed at enhancing warfighter performance and protection. First, graphene nanosheet (GNS) piezoresistive sensors were integrated with firefighting equipment, specifically the self-contained breathing apparatus. The GNS sensors were strategically placed to measure the health, activities, and surrounding conditions of shipboard personnel during shipboard damage control operations. Laboratory and shipboard human subject tests were conducted and showed that gait, movement, and respiration rate could be accurately measured. The second example is the design of a wearable, passive, antenna uniform patch that changes shape (and thus its antenna signature) when a sailor falls overboard, so that the identity, location, and condition of the sailor could be quickly determined using remote sensing. Termed Active Skins, these additively manufactured mechanical metamaterials incorporated specific stimuli-responsive materials to detect parameters such as temperature changes and exposure to seawater. The last example showcases an additively manufactured field-responsive mechanical material (FRMM) that exhibits dynamic control and on-the-fly tunability. Specifically, complex structures of polymeric tubes were printed and infilled with magnetorheological fluid suspensions. Modulating applied magnetic fields resulted in rapid, reversible, and sizable changes of the FRMM's effective stiffness, which could be potentially used as a wearable adaptive armor.