Enhanced Interface\nbetween Conductive Fillers and\nElastomeric Ionomers for Highly Sensitive and Stretchable Strain Sensors\ntoward Human Motion Detection

Abstract

Flexible\nelastomer-based wearable sensors have gained\ntremendous\nattention due to their potential application in personal health diagnosis\nand human motion detection. However, challenges persist in achieving\nhigh sensitivity, stretchability, and antibacterial properties simultaneously.\nHerein, ionic cross-linked bromide butyl rubber (BIIR) filled with\nionic liquid butylimidazole (BI)-modified conductive carbon black\n(BCCB) is rationally designed and then fabricated into high-performance\nstrain sensors by a facile solution mixing method. The BI not only\nion-cross-linked the BIIR but also formed a strong interface between\nBIIR and conductive carbon black (CCB) through π–cation\ninteractions, which facilitated the uniform dispersion of CCB throughout\nthe BIIR matrix, leading to the formation of a conductive filler network.\nBased on the synergistic effect of the ionic cross-linking network\nand conductive filler network, the prepared BCCB/BIIR exhibited a\nlow percolation threshold (1.75 wt %), high electrical conductivity\n(21.3 S/m), high tensile strength (4.9 MPa) and elongation at break >1200%,\nhigh sensitivity with gauge factor values of 9.41 at strains levels\nwithin 5% and 2048.89 at high strain levels, and excellent durability\nunder cyclic working conditions. As a result, the BCCB/BIIR can be\nused as sensors for detecting both weak and large deformations induced\nby human activities, such as pulse, swallowing, and muscle and joint\nmovements. Additionally, the sensor demonstrated over 99% antibacterial\nefficacy against Escherichia coli and Staphylococcus aureus, which can improve wearable\ncomfort. The results suggest that the developed method provides a\npractical and large-scale production approach for fabricating high-performance\nsensors.