Dual-Nozzle Extrusion Printing of Highly Sensitive and Durable Strain Sensor Based on MWCNT/Ecoflex Composites

Flexible strain sensors have made great progress and been applied tentatively in recent years. However, there are still many challenges and problems hindering their widespread application, including incompatible high sensitivity and wide detection range, poor durability, and time-consuming fabrication procedures. In this work, a dual-nozzle-assisted one-step strategy for the fabrication of integrated flexible strain sensors is proposed. During the fabrication, Ecoflex and its composite multi-walled carbon nanotube (MWCNT)/Ecoflex were extruded and thermally cured from the two nozzles, respectively. Taking advantage of the same base resin, the strain-sensitive and the insulating components in the fabricated flexible strain sensors are chemically bonded firmly and form an integrated device. The fabricated sensor exhibits good performance in terms of high gauge factor (GF = 165.3), good stability, low hysteresis, fast response time (60 ms), wide detection range (0%–300% strain), and ultralow detection limit (0.1% strain), showing promising applications in health monitoring and human–computer interaction.