Bioinspired piezoelectric amino acids and peptides are attracting attention due to their designable sequences, versatile structures, low cost, and biodegradability. However, it remains a challenge to design amino acids and peptides with high piezoelectricity. Herein, a high piezoelectric amino acid by simple fluorination in its side chain is presented. The three phenylalanine derivatives are designed: Cbz-Phe, Cbz-Phe(4F), and Cbz-pentafluoro-Phe. The effect of fluorination on self-assembly and piezoelectricity is investigated. Cbz-Phe(4F) can self-assemble into crystals with a C2 space group, while Cbz-Phe and Cbz-pentafluoro-Phe form aggregated self-assemblies. Moreover, Cbz-Phe(4F) crystals exhibit a remarkably higher piezoelectric coefficient ($d_{33}^{eff}$) of ≈17.9 pm V⁻¹ than Cbz-Phe and Cbz-pentafluoro-Phe. When fabricated as a piezoelectric nanogenerator, it generates an open-circuit voltage of ≈2.4 V. Importantly, Cbz-Phe(4F) crystals as a flexible piezoelectric sensor for the classification of various nuts and their quality sorting, which includes those as small as individual pumpkin seeds with high sensitivity and accuracy of sorting and quality checks. When mounted onto soft grippers, the sensor performs the tactile self-sensing functions. This work provides a promising approach to designing high piezoelectric amino acids by simple fluorination, offering exciting prospects for advancements in bioinspired piezoelectric materials in the application of smart agriculture and soft robotics.

中文翻译：

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通过氟化促进氨基酸中的压电性


仿生压电氨基酸和肽因其可设计的序列、多功能结构、低成本和可生物降解性而备受关注。然而，设计具有高压电性的氨基酸和肽仍然是一个挑战。在此，通过其侧链中的简单氟化提出了一种高压电氨基酸。设计了三种苯丙氨酸衍生物：Cbz-Phe、Cbz-Phe（4F） 和 Cbz-五氟-Phe。研究了氟化对自组装和压电的影响。Cbz-Phe（4F） 可以自组装成具有 C2 空间群的晶体，而 Cbz-Phe 和 Cbz-五氟-Phe 形成聚集的自组装。此外，Cbz-Phe（4F） 晶体表现出比 Cbz-Phe 和 Cbz-五氟-Phe 高得多的压电系数 （$d_{33}^{eff}$） 为 ≈17.9 pm ^V-1。当制造为压电纳米发电机时，它会产生 ≈2.4 V 的开路电压。重要的是，Cbz-Phe（4F） 晶体作为柔性压电传感器，用于各种坚果的分类及其质量分类，包括小到单个南瓜籽的坚果，具有高灵敏度和分拣和质量检查的准确性。当安装在软抓手上时，传感器执行触觉自感应功能。这项工作提供了一种通过简单氟化设计高压电氨基酸的有前途的方法，为仿生压电材料在智能农业和软机器人应用方面的进步提供了令人兴奋的前景。