The design of chemomechanical self‐oscillators, which execute oscillations in the presence of constant stimuli lacking periodicity, is a step toward the development of autonomous and interactive soft robotic systems. This work presents a simple design of prolonged chemomechanical oscillatory movement in a microgel system capable of buoyant motility within stratified chemical media containing spatially localized sinking and floating stimuli. Three design elements are developed: a stimuli‐responsive membranized calcium alginate microgel, a Percoll density gradient for providing stratified antagonistic chemical media, and transduction of microgel particle size actuation into buoyant motility via membrane‐mediated displacement of the Percoll media. The presence of citrate or calcium ions in different layers of the Percoll media gives rise to swelling (buoyancy) or contraction (geotaxis), respectively, which in turn mediate the shuttling of the microgels between the layers to produce prolonged or damped chemomechanical oscillatory trajectories. The concentration‐dependence of the oscillatory behavior in the stratified media, the density gap between the Percoll layers, and the kinetic asymmetry of microgel swelling and deswelling are studied. The illustrated modular design allows for the development of chemomechanical self‐oscillators responsive to light, pH, or temperature, which will find applications in interactive soft robotics, autonomous microbots, and intelligent materials.

中文翻译：

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分层化学介质中的化学力学自振微凝胶运动


化学机械自振荡器的设计在缺乏周期性的恒定刺激下执行振荡，是朝着自主和交互式软机器人系统发展迈出的一步。这项工作提出了一种在微凝胶系统中长时间化学力学振荡运动的简单设计，该系统能够在包含空间局部下沉和浮动刺激的分层化学介质中产生浮力运动。开发了三个设计元素：刺激响应膜化海藻酸钙微凝胶、用于提供分层拮抗化学介质的 Percoll 密度梯度，以及通过膜介导的 Percoll 介质置换将微凝胶粒径驱动转导为浮力运动。Percoll 介质不同层中存在柠檬酸盐或钙离子分别引起膨胀（浮力）或收缩（趋地性），这反过来又介导微凝胶在各层之间的穿梭，以产生延长或阻尼的化学力学振荡轨迹。研究了分层介质中振荡行为的浓度依赖性、Percoll 层之间的密度间隙以及微凝胶溶胀和溶胀的动力学不对称性。图示模块化设计允许开发对光、pH 值或温度有响应的化学机械自振荡器，这将应用于交互式软机器人、自主微型机器人和智能材料。