Humidity-responsive bilayered actuators which can dynamically change their shapes under humidity gradients, have recently motivated significant interest in a wide variety of emerging fields, including artificial muscles, intelligent sensors, and smart devices. However, this kind of actuators frequently suffer from slow responsiveness, prolonged actuating period, and small deformation, which is due to the dense structure hindering the diffusion of water molecules. Herein, we employ a simple programmable electrospinning approach to fabricate a highly porous polyvinyl alcohol/polyvinyl butyral (PVA/PVB) bilayered actuator for achieving excellent humidity-triggered deformation. Benefiting from the differential affinity of the two layers to water and the elaborately structural design, the porous bilayered actuator exhibits superior actuating performance in response to humidity gradient. Briefly, only 283 ms is needed for driving the shape change, and the whole deformation merely requires 10 s; besides, large bending amplitude with the curvature of 11.2 cm⁻¹ is achieved, and the shape deformation process can be repeated at least 30 times without fatigue. Finally, we demonstrate the porous nanofibrous actuator can be used as artificial plants to perform opening and closing motions and a self-driven detector for monitoring humidity in real-time.

能够在湿度梯度下动态改变其形状的对湿度敏感的双层执行器，最近引起了人们对各种新兴领域的极大兴趣，包括人造肌肉，智能传感器和智能设备。然而，由于致密的结构阻碍了水分子的扩散，这种致动器经常具有响应速度慢，致动周期延长和变形小的缺点。本文中，我们采用简单的可编程电纺丝方法来制造高度多孔的聚乙烯醇/聚乙烯醇缩丁醛（PVA / PVB）双层致动器，以实现出色的湿度触发变形。得益于两层对水的不同亲和力以及精心设计的结构，多孔双层致动器响应湿度梯度表现出卓越的致动性能。简而言之，只需283 ms即可驱动形状变化，整个变形仅需10 s。此外，弯曲幅度大，曲率达11.2 cm达到^-1，并且形状变形过程可以重复至少30次而不会疲劳。最后，我们演示了多孔纳米纤维致动器可以用作人造植物来执行打开和关闭运动，以及可以自动监测湿度的自驱动检测器。