PBAT/CNTs/PBAT yarn strain sensor with fully degradable, thermal repair, acid and alkali resistance, and waterproof functions

Flexible wearable strain sensors have attracted much attention in the field of health monitoring due to their advantages of simple preparation process and good comfort. However, in daily use, factors like friction, sweat during exercise, or harsh environments such as rain may lead to the failure of the strain sensor. Therefore, this study designed a strain sensor that is waterproof, wear-resistant, resistant to various corrosive fluids and has biodegradation characteristics. The strain sensor was prepared by using carbon nanotubes (CNTs) with high length-to-diameter ratio as conductive filler and environment-friendly polybutylene terephthalate (PBAT) as matrix and packaging materials. The CNTs/PBAT strain sensor has reversible and repeatable resistance at 5 %–30 % strain, stable cycle durability (2500 cycles), and low carbon nanotube content (0.45 %). Moerover, it has thermal repair properties that can eliminate creep caused by long-term use of polymers and extend their service-life. In addition, the PBAT/CNTs/PBAT strain sensor operates safely within the safe voltage range of the human body, can monitor body movement in air and water, and has a wide range of applications in wearable sports health.