The bilayer hydrogel actuators have attracted extensive attention for their unique stimulus-responsive properties. Most of the current research studies only focused on changing the constituent materials of two layers in the fixed bilayer structure to enhance the responsive deformability of bilayer hydrogels without involving the exploration on a structural level, which limited its further development. In this study, we proposed a novel bilayer-co-gradient structure constructed via a simple and low-cost structural programming strategy, which was self-assembled by introducing an embedded gradient structure into a single bilayer structure with the assistance of gradient-dissolved oxygen in nature. This multistructure endowed the hydrogel with a faster bending response than a single bilayer structure due to the synergistic asymmetry of the simple bilayer structure and the embedded gradient structure. It was found that the prepared hydrogels exhibited significantly anisotropic electrical conductivity and swelling properties. Moreover, the stimulus-responsive shape deformation exhibited superior temperature- and pH-based deformation programmability. Additionally, this hydrogel could serve as a hydrogel gripper to perform grasping behavior, which demonstrated that our study opens up a new route for designing and fabricating smart actuators.

中文翻译：

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通过新型双层共梯度结构策略构建的各向异性水凝胶实现可编程形状变形

双层水凝胶致动器因其独特的刺激响应特性而受到广泛关注。目前的研究大多只集中于改变固定双层结构中两层的组成材料来增强双层水凝胶的响应变形能力，而没有涉及结构层面的探索，这限制了其进一步发展。在这项研究中，我们提出了一种通过简单且低成本的结构编程策略构建的新型双层共梯度结构，通过在梯度溶解氧的帮助下将嵌入式梯度结构引入单个双层结构中进行自组装在自然界。由于简单双层结构和嵌入式梯度结构的协同不对称性，这种多结构赋予水凝胶比单一双层结构更快的弯曲响应。发现所制备的水凝胶表现出显着的各向异性导电性和溶胀性能。此外，刺激响应形状变形表现出优异的基于温度和 pH 的变形可编程性。此外，这种水凝胶可以作为水凝胶抓手来执行抓取行为，这表明我们的研究为设计和制造智能执行器开辟了一条新途径。刺激响应形状变形表现出优异的基于温度和 pH 的变形可编程性。此外，这种水凝胶可以作为水凝胶抓手来执行抓取行为，这表明我们的研究为设计和制造智能执行器开辟了一条新途径。刺激响应形状变形表现出优异的基于温度和 pH 的变形可编程性。此外，这种水凝胶可以作为水凝胶抓手来执行抓取行为，这表明我们的研究为设计和制造智能执行器开辟了一条新途径。