We proposed a sensing–transducing coupled strategy by embedding the high piezoresponse Sm-PMN-PT ceramic into a moisture-sensitive PEI via electrospinning to conjugate the humidity perception and signal transduction synchronously and sympatrically.

The development of piezoelectric composite (PEC) gas sensors is progressing rapidly, driven by innovations that range from atomic-level material design to system-level integration.

Triboelectric nanogenerators (TENGs) have attracted widespread attention in recent years due to outstanding energy converting capability enabled by the coupling between the triboelectric effect and electrostatic induction. The excellent energy harvesting ability of TENG under low frequency and slight amplitude endows a unique superiority for self-powered respiratory detection. This Perspective systematically reviews recent progress on TENG motivated self-powered respiratory sensors. First, based on the four working modes of TENG, two types of self-powered respiratory sensors are discussed, including physical behavior monitoring and chemical reagents detection. Furthermore, the sensing mechanism, sensitive materials, device structures, and related application were comprehensively analyzed. Finally, the existing problems and development opportunities of self-powered respiration monitoring based on the triboelectric effect are interpreted in detail.

K_0.5Na_0.5NbO₃ is considered as one of the most promising lead-free piezoelectric ceramics in the field of wearable electronics because of its excellent piezoelectric properties and environmental friendliness. In this work, the temperature-dependent longitudinal piezoelectric coefficient $d_{33}^{*}$ was investigated in K_0.5Na_0.5NbO₃ single crystals via the Landau–Ginzburg–Devonshire theory. Results show that the piezoelectric anisotropy varies with the temperature and the maximum of $d_{33max}^{*}$ deviates from the polar direction of the ferroelectric phase. In the tetragonal phase, $d_{33max}^{t^{*}}$ parallels with cubic polarization direction near the tetragonal-cubic transition region, and then gradually switches toward the nonpolar direction with decreasing temperatures. The maximum of $d_{33}^{o^{*}}$ in the orthorhombic phase reveals a distinct varying trend in different crystal planes. As for the rhombohedral phase, slight fluctuation of the maximum of $d_{33}^{r^{*}}$ was observed and delivered a more stable temperature-dependent maximum $d_{33max}^{r^{*}}$ and its corresponding angle θ_max in comparison with tetragonal and orthorhombic phases. This work not only sheds some light on the temperature-dependent phase transitions, but also paves the way for the optimization of piezoelectric properties in piezoelectric materials and devices.