Multifunctional selectivity and mechanical properties are always a focus of attention in the field of flexible sensors. In particular, the construction of biomimetic architecture for sensing materials can endow the fabricated sensors with intrinsic response features and extra-derived functions. Here, inspired by the asymmetric structural features of human skin, a novel tannic acid (TA)-modified MXene-polyurethane film with a bionic Janus architecture is proposed, which is prepared by gravity-driven self-assembly for the gradient dispersion of 2D TA@MXene nanosheets into a PU network. This obtained film reveals strong mechanical properties of a superior elongation at a break of 2056.67% and an ultimate tensile strength of 50.78 MPa with self-healing performance. Moreover, the Janus architecture can lead to a selective multifunctional response of flexible sensors to directional bending, pressure, and stretching. Combined with a machine learning module, the sensor is endowed with high recognition rates for force detection (96.1%). Meanwhile, direction identification in rescue operations and human movement monitoring can be realized by this sensor. This work offers essential research value and practical significance for the material structures, mechanical properties, and application platforms of flexible sensors.

中文翻译：

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基于 PU-TA@MXene Janus 架构的多功能柔性传感器，用于选择性方向识别

多功能选择性和机械性能一直是柔性传感器领域关注的焦点。特别是，传感材料的仿生结构的构建可以赋予所制造的传感器固有的响应特征和额外的衍生功能。受人体皮肤不对称结构特征的启发，提出了一种具有仿生Janus结构的新型单宁酸（TA）改性MXene-聚氨酯薄膜，该薄膜是通过重力驱动自组装制备的，用于二维TA的梯度分散@MXene 纳米片进入 PU 网络。所得薄膜具有优异的机械性能，断裂伸长率为 2056.67%，极限拉伸强度为 50.78 MPa，并具有自修复性能。此外，Janus 架构可以使柔性传感器对定向弯曲、压力和拉伸做出选择性多功能响应。结合机器学习模块，该传感器具有较高的力检测识别率（96.1%）。同时，该传感器还可以实现救援行动中的方向识别和人体运动监测。该工作对于柔性传感器的材料结构、力学性能和应用平台具有重要的研究价值和实际意义。