Photodriven Self-Excited Hydrogel Oscillators
Photodriven Self-Excited Hydrogel Oscillators
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DOI：
10.1103/physrevapplied.17.014007
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发表时间：
2022-01
影响因子：
4.6
通讯作者：
Chen Xuan;Yu Zhou;Yusen Zhao;Ximin He;L. Jin
中科院分区：
文献类型：
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作者：
Chen Xuan;Yu Zhou;Yusen Zhao;Ximin He;L. Jin
刺激响应材料是为自我维持的软机器人设计的。以光热响应水凝胶悬臂梁为模型系统，研究了恒定光源下自激振荡的机理和能量流。基于一个分析模型，我们表明，周期性的光动量，所产生的不均匀的水浓度在整个悬臂的厚度驱动的扩散，施加在悬臂的顶部和底部表面之间的不断切换的光入射。当振动时间尺度与自由振动周期相当时，光动量和振动之间的协同作用确保了对悬臂的正功输入。当输入能量大于阻尼能时，振动幅值增大;当输入能量小于阻尼能时，振动幅值减小。基于量纲能分析，确定了稳定的振荡振幅，构造了振荡振幅增大和减小的相图，并通过实验得到了进一步证实。建立了一个受位移相关激振力作用的质量-弹簧-阻尼器系统，研究了广义自激振动系统的特性。这一工作为理解自激振荡奠定了坚实的基础，并为自维持软机器人的设计提供了指导。
Stimuli-responsive materials are designed for self-sustained soft robots. Using a photothermally responsive hydrogel cantilever as a model system, this paper investigates the mechanism and energy flow in self-excited oscillation under a constant light source. Based on an analytical model, we show that a periodic photomoment, produced by nonuniform water concentration across the cantilever’s thickness driven by diffusion, is imposed on the cantilever by the ever-switching light incidence between the top and bottom surfaces. The synergy between the photomoment and oscillation ensures positive work input to the cantilever when the diffusion timescale is comparable to the period of free oscillation. When the input energy is higher than the damping energy, the oscillation amplitude increases, while, when the input energy is lower, the amplitude decreases. Based on dimensional energy analysis, we determine the stable oscillation amplitude and construct phase diagrams for the increase and decrease of the oscillation amplitude, which are further confirmed experimentally. A mass-spring-damper system subjected to a displacement-dependent excitation force is developed to investigate the features in generalized self-excited oscillating systems. This work lays a solid foundation for understanding self-excited oscillation and provides design guidelines for self-sustainable soft robots.