Flexible polymers have garnered significant interest in the field of flexoelectricity due to their capacity to endure substantial strain gradients. However, the flexoelectric coefficients of these polymers are generally lower than those of ferroelectric ceramics, thereby restricting their application potential in sensor technologies. In this study, we propose a method to augment the flexoelectric coefficients of polyvinylidene fluoride (PVDF) films through the incorporation of silver niobate (AgNbO₃) nanoparticles and nanofibers. Owing to the enhancement in dielectric constant resulting from the introduction of AgNbO₃, the flexoelectric coefficients of the PVDF composite films increased with the concentration of AgNbO₃ achieving a maximum value of 20.6 nC/m, which represents a 2.6-fold increase compared to pure PVDF. Based on this, a multilayer flexible sensor embedded with the PVDF composite films was designed for monitoring human joint motion. The measured flexoelectric current was found to increase with the finger bending angle, and the result was in good agreement with the theoretical prediction. This research provides an effective method for enhancing the flexoelectric response of flexible PVDF-based polymer films and offers novel insights into the development of wearable flexible electronic devices.

Twist provides a new degree of freedom for nanomaterial modifications, which can provide novel physical properties. Here, colloidal two-dimensional (2D) twisted CdSe nanoplatelets (NPLs) are successfully fabricated and their morphology can change from totally flat to edge-twisted, and then to middle-twisted with prolonged reaction time. By combining experiments and corresponding theoretical analyses, we have established the length-dependent relationships between the surface energy and twist, with a critical lateral dimension of 30 nm. We found that the defects formed during the synthesis process play a vital role in generating intense stress that develops a strong torsion tensor around the edges, resulting in edge-twisted and final middle-twisted NPLs. Furthermore, due to the geometric asymmetry of twisted NPLs, the dissymmetry factor of single particle NPLs can reach up to 0.334. Specifically, quantum coupling occurs in middle-twisted NPLs by twisting one parent NPL into two daughter NPLs, which are structurally and electronically coupled. This work not only further deepens our understanding of the twist mechanism of 2D NPLs during colloidal synthesis, but also opens a pathway for applications using twistronics and quantum technology.