Highly Dispersed, Adhesive Carbon Nanotube Ink for Strain and Pressure Sensors

Carbon nanotubes (CNT) with prominent electrical and mechanical properties are ideal candidates for flexible wearable devices. However, their poor dispersity in solvents greatly limits their applications as a conductive ink in the fabrication of wearable sensors. Herein, we demonstrate a kind of CNT-based conductive dispersion with high dispersity and adhesiveness using cellulose derivatives as the solvent, in which γ-aminopropyl triethoxy silane as a cross-linking agent reacts with cellulose to form copolymer networks, and simultaneously it also acts as an initiator to induce the self-polymerization of dopamine. Based on the conductive CNT ink, we also demonstrated textile-based strain sensors by stencil printing and sponge-based pressure sensors by the dipping method. The textile-based strain sensors could respond to external stimuli promptly. Then, the strain sensors were encapsulated via polydimethylsiloxane with the expansion of working ranges from less than 20 to nearly 70%. The encapsulated textile sensors exhibited excellent sensing performance as wearable strain sensors to monitor human motions including smile, throat vibration, finger folding, wrist bending, and elbow twisting. The sponge sensors hold high sensitivity and excellent durability as well. The conductive CNT-based ink provides an alternative idea in the development of flexible wearable devices.