Image: RANDY MONTOYA/Sandia National Laboratory

Imagine a remote-controlled swarm of roach-sized tanks storming into a building through the pipes and vents. Armed with the proper sensors, cameras and communication devices, these tiny tanks could seek out chemical weapons, mines or bombs planted in hard-to-reach places. They could also detect survivors after an accident, or track human movements.

It's a vision that could become reality thanks to the work of Ed Heller and colleagues at Sandia National Laboratories. The group recently unveiled what may be the world's smallest robot, which they say "turns on a dime and parks on a nickel" (see image). The new mini-robot is the latest in a series from Sandia. To make it even smaller than its predecessors, the scientists used a new technique to package the electronics, a different wheel design and a change in the body material.

The result measures a mere quarter of a cubic inch and weighs less than an ounce. Three watch batteries power its two motors, which drive the tank-like track wheels on either side. It also features an 8K ROM processor and a temperature sensor. In tests, the mini-robot--which travels at a pace of about 20 inches a minute--has successfully navigated through obstacle courses built from loose change. And the scientists have several plans for improving its capabilities. They are now considering adding in a miniature camera, microphone, communication device and chemical micro-sensor.