Skip to Content
77 Mass Ave

Draw Your Own Sensor

Carbon nanotube pencils could simplify gas detection
January 2, 2013

A new fabrication method created by MIT chemists—one as simple as drawing a line on a sheet of paper—may lead to a powerful new way to detect harmful gases in the environment. Gas-detecting sensors can be inscribed on any paper surface with a pencil in which a compressed powder of carbon nanotubes serves as the lead.

Sensors are drawn with carbon nanotube “lead.”

The sensor detects minute amounts of ammonia gas, an industrial hazard, but could be adapted for nearly any type of gas, says chemistry professor Timothy Swager, who led the research team.

Carbon nanotubes are one-atom-thick sheets of carbon rolled into cylinders that allow electrons to flow without hindrance. Such materials have been shown to be effective sensors for many gases, which bind to the nanotubes and impede electron flow. However, manufacturing these sensors can be hazardous.

Inspired by pencils on her desk, Katherine Mirica, a postdoc in Swager’s lab, had the idea of compressing carbon nanotubes into a graphite-like material. To create sensors, the researchers use that material in a regular mechanical pencil to draw a line of carbon nanotubes on paper imprinted with small electrodes made of gold. They then apply an electrical current and measure the current as it flows through the carbon nanotube strip, which acts as a resistor. If the current is altered, it means gas has bound to the nanotubes.

The researchers are now tailoring sensors to detect a wide range of gases, including ethylene, which would be useful for monitoring the ripeness of fruit as it is shipped and stored.

Keep Reading

Most Popular

computation concept
computation concept

How AI is reinventing what computers are

Three key ways artificial intelligence is changing what it means to compute.

still from Embodied Intelligence video
still from Embodied Intelligence video

These weird virtual creatures evolve their bodies to solve problems

They show how intelligence and body plans are closely linked—and could unlock AI for robots.

We reviewed three at-home covid tests. The results were mixed.

Over-the-counter coronavirus tests are finally available in the US. Some are more accurate and easier to use than others.

conceptual illustration showing various women's faces being scanned
conceptual illustration showing various women's faces being scanned

A horrifying new AI app swaps women into porn videos with a click

Deepfake researchers have long feared the day this would arrive.

Stay connected

Illustration by Rose WongIllustration by Rose Wong

Get the latest updates from
MIT Technology Review

Discover special offers, top stories, upcoming events, and more.

Thank you for submitting your email!

Explore more newsletters

It looks like something went wrong.

We’re having trouble saving your preferences. Try refreshing this page and updating them one more time. If you continue to get this message, reach out to us at customer-service@technologyreview.com with a list of newsletters you’d like to receive.