What is the fine-grained topic of the following text: Researchers at Tufts University School of Engineering have developed magnetic elastomeric composites that move in different ways when exposed to light, raising the possibility that these materials could enable a wide range of products that perform simple to complex movements, from tiny engines and valves to solar arrays that bend toward the sunlight. Only return the topic.
Development of light-responsive magnetic elastomeric composites at Tufts University School of Engineering