Enhanced Interface between Conductive Fillers and Elastomeric Ionomers for Highly Sensitive and Stretchable Strain Sensors toward Human Motion Detection

Flexibleelastomer-based wearable sensors have gainedtremendousattention due to their potential application in personal health diagnosisand human motion detection. However, challenges persist in achievinghigh sensitivity, stretchability, and antibacterial properties simultaneously.Herein, ionic cross-linked bromide butyl rubber (BIIR) filled withionic liquid butylimidazole (BI)-modified conductive carbon black(BCCB) is rationally designed and then fabricated into high-performancestrain sensors by a facile solution mixing method. The BI not onlyion-cross-linked the BIIR but also formed a strong interface betweenBIIR and conductive carbon black (CCB) through & pi;-cationinteractions, which facilitated the uniform dispersion of CCB throughoutthe BIIR matrix, leading to the formation of a conductive filler network.Based on the synergistic effect of the ionic cross-linking networkand conductive filler network, the prepared BCCB/BIIR exhibited alow percolation threshold (1.75 wt %), high electrical conductivity(21.3 S/m), high tensile strength (4.9 MPa) and elongation at break >1200%,high sensitivity with gauge factor values of 9.41 at strains levelswithin 5% and 2048.89 at high strain levels, and excellent durabilityunder cyclic working conditions. As a result, the BCCB/BIIR can beused as sensors for detecting both weak and large deformations inducedby human activities, such as pulse, swallowing, and muscle and jointmovements. Additionally, the sensor demonstrated over 99% antibacterialefficacy against Escherichia coli and Staphylococcus aureus, which can improve wearablecomfort. The results suggest that the developed method provides apractical and large-scale production approach for fabricating high-performancesensors.