Polymer-based piezoelectric composites have shown a large potential in various fields of wearable electronics, man–machine interaction, transducers, etc., due to their integrated advantages of high piezoelectric properties, benign flexibility, and pressure sensitivity. As the representative polymer matrix in piezoelectric composites, polyvinylidene fluoride (PVDF) is characterized by its intrinsic piezoelectric response induced via the existence of ferroelectric β and γ phases. However, the most stable phase at ambient temperature and pressure is the nonpolar and paraelectric α phase, which serves as a long-standing issue. Herein, chitosan was introduced into the PVDF matrix to promote the transition from α phase to β phase via the interaction between the –OH and –NH₂ groups in chitosan and the H and F atoms in PVDF. As evidenced, the portion of the β phase increased from 47.9 to 63.7%. An electrospinning technique was adopted to prepare PVDF/chitosan composites with a chitosan content ranging from 1 to 4 wt %, and the correlation between structural characteristics and piezoelectric properties is illustrated in detail. Then, a flexible pressure sensor based on PVDF/chitosan composite was prepared, which presents a low detection limit of ∼220 Pa in a wide range of 220 Pa–81 kPa. The pressure sensor presents a good capability for detecting pulse signals and speech recognition accurately. As well demonstrated in this work, the treatment of PVDF with low-cost chitosan may boost its practical application in future flexible electronics.

中文翻译：

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用于压电传感的具有增强电活性 β 相的壳聚糖掺杂 PVDF 薄膜

聚合物基压电复合材料凭借其压电性能、良好的柔性和压力敏感性的综合优势，在可穿戴电子、人机交互、传感器等各个领域显示出巨大的潜力。作为压电复合材料中代表性的聚合物基体，聚偏二氟乙烯（PVDF）的特征在于其通过铁电β相和γ相的存在而引起的本征压电响应。然而，在环境温度和压力下最稳定的相是非极性顺电α相，这是一个长期存在的问题。在此，将壳聚糖引入PVDF基质中，通过壳聚糖中的-OH和-NH ₂基团与PVDF中的H和F原子之间的相互作用促进从α相向β相的转变。事实证明，β相的比例从47.9%增加到63.7%。采用静电纺丝技术制备了壳聚糖含量为 1 至 4 wt% 的 PVDF/壳聚糖复合材料，并详细说明了结构特性与压电性能之间的相关性。然后，制备了一种基于PVDF/壳聚糖复合材料的柔性压力传感器，该传感器在220 Pa-81 kPa的宽范围内呈现~220 Pa的低检测限。该压力传感器具有良好的脉搏信号检测能力和准确的语音识别能力。正如这项工作所证明的那样，用低成本壳聚糖处理 PVDF 可能会促进其在未来柔性电子产品中的实际应用。