Dopamine-Modified Barium Titanate Nanowires /PVDF-HFP Coaxial Electrospun Piezoelectric Sensor for Human Motion Detection

Sensors for physiological signals and body motion status need a high level of sensitivity and quick response. A multiscaled piezoelectric structure constructed by nanofibers that can detect minuscule pressures is expected to be made into wearable sensors. In this article, a hierarchical nanofiber structure, including barium titanate nanowires (BNWs) and polyvinylidene fluoride-hexafluoropropylene (PVDF-HFP) with dopamine-modified nanofiber membrane, was prepared by coaxial electrospinning, and the sensitivity of the piezoelectric response was improved by introducing barium titanate nanowires and modifying dopamine (DA). To determine the optimal parameters, a high-speed camera was introduced to explore the impacts of different spinning needles, flow rates, and core-shell solution concentrations. Then, the optimal parameters were used to encapsulate the membrane into a sandwich-structure piezoelectric sensor, and the dynamic response to human body motion signals was tested. The sensing performance of the sensors has been thoroughly studied, including bending sensitivity (0.2025 V/°), maximum output voltage (0.93 V), hysteresis of dynamic signal capture (81 ms), and cyclic pressing durability (5 h and 49 min at 1 Hz). In addition, the sensor was integrated into the knit elbow straps and the insoles of sports shoes, providing a valuable resource for the analysis of human motion signals in smart wearable devices.