1D Nanomaterial-Based Highly Stretchable Strain Sensors for Human Movement Monitoring and Human-Robotic Interactive Systems

This paper describes a facile strategy of micromolding-in-capillary process to fabricate stretchable strain sensors wherein, the sensing material is wrapped within silicone rubber (Dragon Skin [DS]) to form a sandwich-like structure. Two different 1D sensing materials are exploited to fabricate and study strain sensing performance of such device structure, namely multi-walled carbon nanotubes (MWCNTs) and silver nanowires (AgNWs). The fabricated strain sensors using MWCNT exhibits wide sensing range (2-180%), and moderately high sensing performance with outstanding durability (over 6000 cycles). It is found that MWCNT presents a strong strain-dependent character in the 45-120% elongation regime. On the other hand, very high gauge factor of >10(6)is achieved using AgNWs at 30% strain with good stability (over 100 cycles). Sensing mechanisms for both 1D conductive sensing materials are discussed. They can be applied for human motion monitoring such as finger, knee, and wrist bending movements to enable human physiological parameters to be registered and analyzed continuously. They are also employed in multichannel and interactive electronic system to be used as a control mechanism for teleoperation for robotic end-effectors. The developed sensors have potential applications in health diagnosis and human-machine interaction.