A dual-mode fiber-shaped flexible capacitive strain sensor fabricated by direct ink writing technology for wearable and implantable health monitoring applications

Fabrication and characterization of the FSFCSS

As shown in Fig. 1a, b, FSFCSS presents a three-layer structure, namely, the elastic TPU fiber, parallel helical Ag electrodes, and BTO@Ecoflex encapsulation layer. The TPU fiber was selected as the substrate material due to its excellent elasticity (over 400%) and high rebound rate (>95%). A parallel helical structure can convert linear strain into bending strain uniformly, greatly enhancing the strain range of printed Ag ink electrodes. BTO@Ecoflex is used as the encapsulation layer and dielectric layer due to its high dielectric properties…