High-resolution extrusion printing of Ti3C2-based inks for wearable human motion monitoring and electromagnetic interference shielding

Abstract

This work addresses two major challenges of MXene-based printing; that is, its low printing resolution (i.e., filament spreading >120%) and its inability to create structures with simultaneously high electrical conductivity and mechanical flexibility. We first report high-resolution extrusion printing of Ti3C2 and composite of Ti3C2/poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS). The printing has a negligible filament spreading (<25%) and low thickness and width variations (<20%) compared to their average values. We then fabricate Ti3C2/PEDOT:PSS composite structures that possess simultaneously exceptional electrical conductivity and flexibility (conductivity of 1600 ± 400 S/cm for 80 wt% Ti3C2, which can withstand up to 3000 bending cycles). Addressing the two challenges expands the applications of MXene-based printing. For instance, micrometer-thick grids printed with our method show excellent EMI shielding effectiveness and superior specific EMI shielding effectiveness, reaching 38.4 dB and 43,000 dB cm2 g−1 in the case of pure Ti3C2 and 28.1 dB and 32,000 dB cm2 g−1 for the composite containing 80 wt% Ti3C2. The printed structures of pure Ti3C2 also perform as highly-sensitive strain sensors with a gauge factor of 11,300 at a strain of 4%. The prepared sensors are capable of monitoring various human activities, including breathing, facial muscles movements, and talking.