Multi-sensorized pneumatic artificial muscle yarns

Soft actuators, particularly pneumatic artificial muscles (PAMs), have been widely applied to construct soft robotics owing to their superiorities of inherent compliance, lightweight, and high force density. However, it is still challenging to endow the PAMs with sensing capabilities towards unknown and complex environments due to their compliant mechanism and system. Herein, inspired by the skeletal muscle and skin, a novel multi-sensorized pneumatic artificial muscle yarn (mPAMy) is fabricated for multimodal proprioceptive sensing by a combination of textile braiding technology and hierarchical manufacturing method. The results and finite-element analysis reveal that the soft mPAMy have the endowed sensing capabilities towards diverse forces, including self-contraction, strain and vertical pressure. The mPAMy can detect force changes ranged from 0 N to 14 N by the yarn relative resistance change from 0 to 14.0%. Contractile sensing exhibits an increased range of resistance change (0–20.1%) compared with force sensing (0–14.0%), resulting in a greater resolution of 0.34% pressure to present change in resistance. In addition, the strain of mPAMy ranged from 0 to 57% can be stably detected. The excellent and durability pressure sensing merits of mPAMy can be ascribed from the change in resistance due to the PPy layer fracture. Furthermore, in several proof-of-concept attempts, the prepared mPAMy successfully detected precise signals of human motion and provided effective feedback during actuation. This approach opens a reliable strategy for PAMs towards multimodal sensing strategies in the healthcare, transportation and wearable electronics.