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

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. (c) 2022 Elsevier Ltd. All rights reserved.

Automated summary

This study addresses the challenges of low printing resolution and the inability to create structures with high electrical conductivity and mechanical flexibility in MXene-based printing. By utilizing high-resolution extrusion printing and fabricating composite structures, the researchers were able to expand the applications of MXene-based printing and create highly-sensitive strain sensors. These sensors are capable of monitoring various human activities.