A wide-linear-range and low-hysteresis resistive strain sensor made of double-threaded conductive yarn for human movement detection

Yarn-based flexible strain sensors with advantages in wearability and integrability have attracted wide at-tention.However,it is still a big challenge to achieve yarn-based strain sensors with a wide linear strain range,low hysteresis,and durability synchronously that can be used for full range detection of human body motions.Herein,a new structure,double-threaded conductive yarn with rhythmic strain distribu-tion,is reported to markedly widen the linear strain range of microcrack-based stretchable strain sensors.A new method of winding and thermally adhering hot-melt filaments on the surface of the elastic fiber is used to achieve double-threaded yarn(DTY)with rhythmic strain distribution.The proposed strategy,the integration of heterogeneous materials,is reported to significantly reduce the mechanical hysteresis of composite yarns.Rhythmic strain distribution of the DTY during stretching causes multi-level micro-cracks in different regions of the carbon nanotube(CNT)conductive layer deposited on the surface of the DTY.Besides,the sensing performance of DTY-based strain sensor can be adjusted by designing the structural parameters.The final prepared flexible strain sensor has the advantages of a wide linear strain range(100%),great sensitivity(GF=12.43),low hysteresis,rapid response(158 ms),high repeatability(>2000 cycles at 50%strain),and hydrophobicity,etc.The sensor can monitor human motion repeatedly and stably well,and shows great advantages in flexible wearable devices.

Novel Concentric Tube Robot Based on Double-Threaded Helical Gear Tube

Nasopharyngeal carcinoma is a malignant tumor originating from the nasal mucosa. It is a malignanttumor of the head and neck. Concentric tube robot (CTR), as it can form a complicated shape and access hardto-reach lesions, is often used in minimally invasive surgeries. However, some CTRs are bulky because of theirtransmission design. In this paper, a light CTR based on double-threaded helical gear tube is proposed. Sucha CTR is less cumbersome than the traditional CTR as its actuation unit is compact and miniaturized. Themapping relationship between the gear tube attitude and motor output angle is obtained by kinematic analysis.The precision, stability, and repeatability of the driving mechanism are tested. The experimental results showthat the positioning error in the translation test is less than 0.3 mm, the rolling angle error in the stability testis less than 0.6◦, and the error in the translation repeatability test is less than 0.005 mm. Finally, a tip-targetingtest is performed using the new CTR, which verifies the feasibility of the CTR for surgeries.