High‐Voltage Electrospun P( VDF ‐ TrFE )/ TiO 2 /Gr Flexible Piezoelectric Sensors and Their Exploratory Application in Respiratory Training Prior to DIBH Radiotherapy for Breast Cancer

In this study, a flexible piezoelectric composite film was fabricated via high‐voltage electrospinning using P(VDF‐TrFE)/TiO 2 /Gr as active functional materials. Scanning electron microscopy (SEM) and X‐ray diffraction (XRD) analyses indicate that the incorporation of TiO 2 and Gr optimizes the fiber microstructure and promotes the formation of the piezoelectric β‐phase. Experimental results show that as the TiO 2 content increases from 0% to 3%, the piezoelectric performance of the composite film first improves and then deteriorates, reaching an optimum at 2%. On this basis, with the addition of Gr, the piezoelectric response exhibits a similar trend, increasing and then decreasing as the Gr content varies from 0.05% to 0.2%. When the TiO 2 and Gr contents are 2% and 0.1%, respectively, the composite film achieves maximum open‐circuit voltage and short‐circuit current of 37.95 V and 23.42 μA, which are approximately 2.35 and 2.16 times those of the P(VDF‐TrFE)/TiO 2 (2%) composite film, and about 4.69 and 4.12 times those of pure P(VDF‐TrFE) film. Based on the optimized composite film, a flexible piezoelectric sensor was further developed and applied to the acquisition and feedback of abdominal respiratory signals during deep inspiration breath‐hold (DIBH) training for breast cancer radiotherapy. The results demonstrated that the sensor could stably acquire respiratory signals and extract physiological parameters such as respiratory rate through filtering and spectral analysis, indicating its feasibility for wearable respiratory training monitoring. For home‐based pre‐breathing training before DIBH radiotherapy, the sensor may serve as an auxiliary monitoring tool to help users become familiar with the breath‐hold procedure, observe respiratory status changes, and obtain respiratory signal feedback. This study expands the application scenario of flexible piezoelectric sensors in respiratory monitoring and radiotherapy‐assisted training, and provides a reference for the design of home‐based respiratory training monitoring devices.