Scientists at Cornell University in the United States have developed the smallest known walking robot that can operate at the visible light diffraction limit. It can travel to specific locations, such as within tissue samples, for close-up imaging in a way that ordinary microscopes cannot achieve. This is the product of the combination of micro robot technology and diffractive optical imaging technology. The relevant paper was published in the latest issue of the journal Science. The research team cleverly combined mechanical films with nanoscale thickness, programmable nanomagnets, and diffractive optical elements to create this new type of robot, opening up new solutions for tasks that were previously impossible to achieve. These tasks include high-resolution imaging, tunable, mobile sub diffractive optics, and ultra small force sensing. Previously, the diameter of the smallest walking robot was between 40 microns and 70 microns, but the diameter of the new diffraction robot is only between 2 microns and 5 microns. Experiments have shown that under the precise control of magnets, these robots can wriggle on hard surfaces like inchworms and freely "swim" in liquids. The walking speed of larger robots is 16 micrometers per second, while the walking speed of smaller robots is as high as 34 micrometers per second, both surpassing previous micro robots. The test results show that this robot can assist in high-resolution imaging beyond traditional optical limitations, with extremely high sensitivity and the ability to detect forces as small as 1 piconewt (10-12 newtons). These outstanding features make this robot suitable for basic research (such as exploring DNA structure) and can also be deployed in clinical environments. The team emphasizes that the latest research has established an intersection between micro robot technology and optical engineering. These diffraction robots have demonstrated excellent performance in terms of motion performance, optical manipulation, and sub nanometer force sensitivity detection. (New Society)