Many living organisms track light sources and halt their movement when alignment is achieved. This phenomenon, known as phototropism, occurs, for example, when plants self-orient to face the sun throughout the day. Although many artificial smart materials exhibit non-directional, nastic behaviour in response to an external stimulus, no synthetic material can intrinsically detect and accurately track the direction of the stimulus, that is, exhibit tropistic behaviour. Here we report an artificial phototropic system based on nanostructured stimuli-responsive polymers that can aim and align to the incident light direction in the three-dimensions over a broad temperature range. Such adaptive reconfiguration is realized through a built-in feedback loop rooted in the photothermal and mechanical properties of the material. This system is termed a sunflower-like biomimetic omnidirectional tracker (SunBOT). We show that an array of SunBOTs can, in principle, be used in solar vapour generation devices, as it achieves up to a 400% solar energy-harvesting enhancement over non-tropistic materials at oblique illumination angles. The principle behind our SunBOTs is universal and can be extended to many responsive materials and a broad range of stimuli.

中文翻译：

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用于全向跟踪和收集光的人工光致性。

实现对齐后，许多生物会追踪光源并停止其移动。例如，当植物在一天中自我定向以面对太阳时，就会发生这种现象，即所谓的向光性。尽管许多人造智能材料会响应外部刺激而表现出非定向的鼻部行为，但没有任何合成材料能够固有地检测并准确跟踪刺激的方向，即表现出向性行为。在这里，我们报告了一种基于纳米结构的刺激响应性聚合物的人造光致变色系统，该聚合物可以在较宽的温度范围内在三维方向上对准并对准入射光的方向。这种自适应的重新配置是通过内置于材料的光热和机械特性中的内置反馈回路来实现的。该系统被称为向日葵状仿生全向跟踪器（SunBOT）。我们证明，原则上，SunBOT阵列可用于太阳能蒸汽发生设备，因为它在倾斜的照明角度上比非定向性材料可实现多达400％的太阳能收集增强。我们的SunBOT背后的原理是通用的，可以扩展到许多响应性材料和广泛的刺激中。