In the 1972 science fiction story The Unknown by Christopher Anvil, three space pilots find themselves plagued by “ultra-miniature spy-circuits.” Tiny computers used for espionage and no bigger than a speck of dust.

“They drift in like dust motes,” one space pilot says. “But you have no control over where they drift. An air current, or a static charge, can completely foul up your arrangements.”

In 1972, dust-sized electronic spies were far-out stuff. But in 2014, it’s not so far out at all.

Coined by University of California, Berkeley professor Kristofer Pister, the term “smart dust” refers to tiny electronic bundles of power, sensors, computing and communications electronics that are cheap and abundant enough to scatter like, well, dust.

These tiny machines sense their environment, perform basic data processing and communicate with each other—to serve medical, industrial and military purposes.

Once a science-fiction idea, the smart dust concept caught the imaginations of geeks and investors a few years ago. When Pister coined the term in the late 1990s, the concept attracted funding from DARPA, the Pentagon’s advanced research outfit.

It’s easy to see why the military wants smart dust. During the Vietnam War, the military deployed a slew of remote sensors to detect and track North Vietnamese troops. Although the planned “McNamara Line” along the DMZ never fully materialized, the sensors proved their worth during the Siege of Khe Sanh in early 1968.

Better sensors airdropped over the Ho Chi Minh Trail—capable of detecting motion, sound, metal and even smell—guided the massive U.S. air campaign against North Vietnamese supply lines.

But these sensors were huge in comparison to what’s possible now. Over the past dozen years, miniature sensor network technology progressed enough to bring specialized commercial devices to market. Used to monitor high-value packages, monitor machinery and building environments, these units are more cigarette-box sized than dust-sized.