请设想一下:有一种机器人只有蚊子般大小,它能在人体血管中自由通行;其使命是纠正或修复心脏里的缺陷。不久前,这还仅仅是科学幻想故事中的话题。可现在,世界上一些国家的某些实验室里,科学家们已在精心地制作这样的装置。科学家们正在制造极微小的齿轮、涡轮机和马达,小到可以在一平方英寸的面积上放置六万台马达。如果我们把微型机器 Consider the following: There is a robot that is only mosquito-sized and that it can pass freely through human blood vessels; its mission is to correct or repair defects in the heart. Not too long ago, this was just a topic in a science fiction story. But now, in some of the laboratories in some countries in the world, scientists have been making such devices meticulously. Scientists are making tiny gears, turbines and motors that are as small as 60,000 motors in a square inch of space. If we put a miniature machine