New Gas Sensors Patterned with Conducting Polymer

Apr 12, 2005
These colorized scanning electron micrographs show a portion of the NIST microheater device before (left) and after (right) appl

A n improved method for depositing nanoporous, conducting polymer films on miniaturized device features has been demonstrated by researchers at the National Institute of Standards and Technology (NIST).
Described in the April 6 issue of the Journal of the American Chemical Society,* the method may be useful as a general technique for reproducibly fabricating microdevices such as sensors for detecting toxic chemicals.

These colorized scanning electron micrographs show a portion of the NIST microheater device before (left) and after (right) application of the sponge-like polyaniline coating.

Unlike most polymers, conducting polymers have the electrical and optical properties of metals or semiconductors. These materials are of increasing interest in microelectronics because they are inexpensive, flexible and easy to synthesize.

Polyaniline is a particularly promising conducting polymer for microelectronics applications, but it is difficult to process because it doesn't dissolve in most solvents. NIST researchers have circumvented this problem by dispersing nanoscale particles of polyaniline into a mild solvent.

Two NIST microheater devices
Two NIST microheater devices, each about 100 micrometers wide. On the left is a microheater coated with a conducting polymer, polyaniline, which is naturally green in color. On the right is an identical microheater with no coating.

"The beauty of the method,” says NIST guest researcher Guofeng Li, “is that the polyaniline chain carries a natural positive charge.” Once the particles are formed, electrostatic repulsion prevents them from clumping together. Moreover, the positively charged particles then can be manipulated and patterned on complex device structures by applying an electrical field.

The process produces a sponge-like coating that efficiently captures gaseous molecules. So far NIST researchers have demonstrated that such coatings can detect the difference between methanol and water vapor. Additional tests will be needed before the polymer devices could be used for detecting toxic gases.

NIST holds patents for previous work using microheaters coated with nanostructured tin oxide films. As the microheaters cycle through a series of temperatures, changes in electrical resistance are used to detect toxic gases at part per billion levels. Ultimately, NIST researchers hope to develop inexpensive arrays of microheater sensors coated with both polymer and inorganic oxide films optimized to identify the components of gas mixtures.

*G. Li, C. Martinez, S. Semancik. Controlled electrophorectic patterning of polyaniline from a colloidal suspension. Journal of the American Chemical Society, April 6, 2005.

Source: NIST

Explore further: Audi to develop Tesla Model S all-electric rival

add to favorites email to friend print save as pdf

Related Stories

Man pleads guilty in New York cybercrime case

54 minutes ago

A California man has pleaded guilty in New York City for his role marketing malware that federal authorities say infected more than a half-million computers worldwide.

NASA issues 'remastered' view of Jupiter's moon Europa

9 hours ago

(Phys.org) —Scientists have produced a new version of what is perhaps NASA's best view of Jupiter's ice-covered moon, Europa. The mosaic of color images was obtained in the late 1990s by NASA's Galileo ...

Dish restores Turner channels to lineup

9 hours ago

Turner Broadcasting channels such as Cartoon Network and CNN are back on the Dish network after being dropped from the satellite TV provider's lineup during contract talks.

LiquidPiston unveils quiet X Mini engine prototype

14 hours ago

LiquidPiston has a new X Mini engine which is a small 70 cubic centimeter gasoline powered "prototype. This is a quiet, four-stroke engine with near-zero vibration. The company said it can bring improvements ...

Recommended for you

Audi to develop Tesla Model S all-electric rival

3 hours ago

The Tesla Model S has a rival. Audi is to develop all-electric family car. This is to be a family car that will offer an all-electric range of 280 miles (450 kilometers), according to Auto Express, which ...

A green data center with an autonomous power supply

9 hours ago

A new data center in the United States is generating electricity for its servers entirely from renewable sources, converting biogas from a sewage treatment plant into electricity and water. Siemens implemented ...

After a data breach, it's consumers left holding the bag

9 hours ago

Shoppers have launched into the holiday buying season and retailers are looking forward to year-end sales that make up almost 20% of their annual receipts. But as you check out at a store or click "purchase" on your online shopping cart ...

Can we create an energy efficient Internet?

10 hours ago

With the number of Internet connected devices rapidly increasing, researchers from Melbourne are starting a new research program to reduce energy consumption of such devices.

Brain inspired data engineering

10 hours ago

What if next-generation ICT systems could be based on the brain's structure and its cognitive and adaptive processes? A groundbreaking paradigm of brain-inspired intelligent ICT architectures is being born.

User comments : 0

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.