Conductive shear thickening gel/polyurethane sponge: A flexible human motion detection sensor with excellent safeguarding performance

A novel composite with excellent sensing property and safeguarding performance is fabricated by impregnating the carbon black (CB)/shear thickening gel (STG) hybrid into polyurethane sponge (PUS). This STG-CB/PUS composite presents typical shear thickening characteristic, as the storage modulus (G′) rises from 0.21 MPa to 1.52 MPa when shear frequency increases from 0.1 Hz to 100 Hz. Under external strain, the conductivity of STG-CB/PUS varies quickly, thus it can be applied as strain sensors. During the impact, STG-CB/PUS can detect impact stimuli (0.147-1450 mJ) and decrease attacking force by 63% simultaneously. Additionally, it is found that the 'BO cross bond' is responded for the shear thickening property and the structure-dependent electrical behaviors contribute to the sensing activity. Finally, a STG-CB/PUS enhanced kneepad is prepared. It possesses a reliable safeguarding performance by reducing 44% attacking force and can effectively trace human body motions such as walking, running and jumping.