Select your localized edition:

Close ×

More Ways to Connect

Discover one of our 28 local entrepreneurial communities »

Be the first to know as we launch in new countries and markets around the globe.

Interested in bringing MIT Technology Review to your local market?

MIT Technology ReviewMIT Technology Review - logo


Unsupported browser: Your browser does not meet modern web standards. See how it scores »

{ action.text }

Safer Soil

Off-the-shelf devices that detect contaminants are bulky and expensive and require frequent recalibration. At the University of California, Los Angeles, engineers Tom Harmon and Jack Judy have built a tiny sensor that could improve soil monitoring of nitrates, which can leak into ground water and cause health problems. The sensor consists of a carbon rod coated with a mix of polymer and nitrate. Placing it in water or moist soil generates a voltage that corresponds to the difference between the nitrate concentrations of the soil and the coating.

The hair-thin, 1.5-centimeter-long device could be mass-produced on silicon chips, says Harmon, lowering the cost to one-tenth that of conventional nitrate detectors. Eventually, the sensor will self-calibrate based on models of how environmental factors, such as temperature, affect the signal. In five years, Harmon says, the effort could yield arrays of cheap, reliable sensors that need little human intervention once deployed.

0 comments about this story. Start the discussion »

Tagged: Computing

Reprints and Permissions | Send feedback to the editor

From the Archives


Introducing MIT Technology Review Insider.

Already a Magazine subscriber?

You're automatically an Insider. It's easy to activate or upgrade your account.

Activate Your Account

Become an Insider

It's the new way to subscribe. Get even more of the tech news, research, and discoveries you crave.

Sign Up

Learn More

Find out why MIT Technology Review Insider is for you and explore your options.

Show Me