Artificial Animalcules

In the microscopic realm, machines learn to swim

Some 300 years ago, microscope inventor Antony van Leeuwenhoek stunned the world when he became the first to observe “animalcules” that were “very prettily a-moving” in human saliva and other excretions. Now, a human-rigged device has joined the menagerie. To a red blood cell, scientists in France have attached a wavy tail that responds to magnetic fields.