中文导读 大多数机器人用金属和塑料制成，要靠电池或电线才能动。荷兰代尔夫特理工大学的研究团队换了一个思路：他们在《自然·通讯》上介绍了一种由活体微藻驱动、用光来控制的小型软体“机械臂”。它其实是一条约2厘米长、1毫米厚的绿色软条，由两层“水凝胶”（一种含大量水分的柔软材料）组成，表面长着微藻。有光时，微藻利用光和二氧化碳制造糖分，同时吸收氮，使水凝胶的酸性降低；两层材料对这种变化反应不同、膨胀程度不同，软条就弯曲起来。关灯后，微藻“燃烧”储存的能量、释放二氧化碳，10秒内软条就开始向反方向弯曲。研究者用它在水下钩起橡胶圈、夹住小金属球，并设想将来用于随光调整的百叶窗或农业装置，但这些用途尚未实际测试。文章按“发现—原理—演示—局限”展开，阅读时可留意 Because、When、Together 等词如何说明因果和过程，以及 could、suggests、has yet to be proved 如何区分已经做到的事和仍待证明的设想。
正文 Most robots are made of metal and plastic , and they need batteries or cables to move . A team at Delft University of Technology in the Netherlands has tried a very different idea . In a study published in the journal Nature Communications , the researchers describe a small , soft robot arm that is moved by living algae and controlled by light .
本段译文 大多数机器人由金属和塑料制成，需要电池或电线才能移动。荷兰代尔夫特理工大学的一个团队尝试了一个截然不同的想法。在发表于《自然·通讯》期刊的一项研究中，研究者介绍了一种由活体藻类驱动、用光控制的小型软体机械臂。
The arm is a thin green strip , about 2 centimeters long and 1 millimeter thick . It is made of two layers of hydrogel , a soft material that holds a lot of water , and tiny algae grow on its surface . When the light around it changes , the strip bends one way and then back again . The researchers say its shape can easily be changed to produce different movements
本段译文 这条机械臂是一条细长的绿色软条，约2厘米长、1毫米厚。它由两层水凝胶制成——水凝胶是一种含有大量水分的柔软材料——表面生长着微小的藻类。当周围的光线发生变化时，软条会先向一边弯曲，然后再弯回来。研究者说，它的形状可以很容易地改变，从而产生不同的动作。
The secret is in the way the algae live . When light shines on them , they use it , together with carbon dioxide , to make sugars , which act as their fuel . They also take in nitrogen to build parts of their cells . Together , these processes change the chemistry of the hydrogel and make it less acidic . Because the two layers react differently to this change , one swells more than the other , and the strip bends . When the light is turned off , the algae burn their fuel and release carbon dioxide , so the chemistry moves back . Within 10 seconds , the strip begins to bend the other way .
本段译文 秘密在于藻类的生存方式。光照到它们身上时，它们利用光和二氧化碳制造糖分，糖分就是它们的燃料。它们还吸收氮来构建细胞的组成部分。这些过程共同改变了水凝胶的化学状态，使其酸性降低。由于两层材料对这种变化的反应不同，一层比另一层膨胀得更多，软条就弯曲了。关灯后，藻类燃烧燃料并释放二氧化碳，化学状态随之回变。10秒之内，软条就开始向另一个方向弯曲。
To show what the arm can do , first author Fan Jiang and the team used it underwater to hook and lift a rubber ring and to hold a small metal ball . Soft and gentle handling like this could be useful in water , where hard machines may damage delicate objects . The team also suggests that the same bending could one day be used in window blinds or farm devices that turn toward or away from light . These ideas , however , have not been tested as real products
本段译文 为了展示这条机械臂的能力，第一作者 Fan Jiang和团队在水下用它钩起一个橡胶圈，并夹住一个小金属球。在水中，坚硬的机器可能损坏易碎的物体，因此这样柔软、轻柔的操作可能很有用。团队还提出，同样的弯曲动作将来或许可以用于朝向或背向光线转动的百叶窗或农业装置。不过，这些设想还没有作为真正的产品接受测试。
Lead researcher Marie-Eve Aubin-Tam admits that the project did not begin with a practical goal . “We wanted to explore what becomes possible when living cells are integrated into functional materials ,” she said . Because algae are largely self sustaining and get their energy from light , she believes such systems could run for a long time with little outside energy . Still , the study is only a first step . The reports did not give figures on how long the arm can keep working , so that promise has yet to be proved
本段译文 首席研究者 Marie-Eve Aubin-Tam承认，这个项目一开始并没有实用目标。她说：“我们想探索把活细胞整合进功能材料后，会有哪些新的可能。”由于藻类在很大程度上能自我维持，并从光中获取能量，她认为这类系统可以在很少外部能量的情况下长时间运行。不过，这项研究只是第一步。相关报道没有给出这条机械臂能持续工作多久的数据，因此这一前景仍有待证明。
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