Green business, green careers and job training
Solutions that build smart communities with green careers and sustainable businesses!
HOME
EDITOR'S BLOG
FEATURE ARTICLES
GET STARTED

Save on Career Education through Lorman Education

Our readers are offered a discount on Lorman seminars and courses. Check out their business, management and legal offers at this link to qualify for our discounts. They also offer green business training opportunities. Please visit http://www.lorman.com/training/CaliforniaGreenSolutions for a complete listing of courses. Register online or call Lorman at 866-352-9539.
Home > By DEPARTMENTS > Green Operations > Standard Operating Procedures for Green and Sustainable Business Operations > Pollution Prevention > Pollution Prevention - P2

VOC - membrane measurement onsite

Microsensor Measures Volatile Organic Compounds In Water And Air On-Site

Find green business solutions

Microsensor Measures Volatile Organic Compounds In Water And Air On-Site

9/18/2007 Atlanta -- Researchers at the Georgia Institute of Technology have developed a miniature sensor that uses polymer membranes deposited on a tiny silicon disk to measure pollutants present in aqueous or gaseous environments. An array of these sensors with different surface coatings could be used during field-testing to rapidly detect many different chemicals.

Since this new sensor allows water and air samples to be analyzed in the field, it is an improvement over classical techniques that require samples be carried back to the laboratory for analysis. This research, funded by the National Science Foundation, was presented on August 20 at the American Chemical Society’s 234th National Meeting.

The heart of the disk-shaped sensor is a microbalance that measures the mass of pollutant molecules.

“When pollutant chemicals get adsorbed to the surface of the sensor, a frequency change of the vibrating microbalance provides a measure of the associated mass change,” said Oliver Brand, associate professor in Georgia Tech’s School of Electrical and Computer Engineering.

Cantilever-type balances, which move up and down like a diving board, are common when measuring the amount of a chemical in the gas phase. However, the mechanical vibrations of the balance used to detect the mass changes are damped in liquids, causing the sensitivity of the balance to decrease. Thus, Brand and graduate students Jae Hyeong Seo, Stuart Truax and Kemal Safak Demirci searched for structures whose vibrations were less affected by the surrounding medium.

The researchers chose a silicon disk platform for the sensor. The disk shears back and forth around its center with a characteristic resonance frequency between 300 and 1,000 kHz, depending on its geometry. With proper actuation and sensing elements integrated onto the microstructures, Brand can electrically excite the resonator and sense these rotational oscillations.

Since each sensor has a diameter of approximately 200-300 microns, or the average diameter of a human hair, an array of a dozen sensors is only a few millimeters in size.

To determine how to selectively detect multiple pollutants in the same sample, Brand began collaborating with Boris Mizaikoff, an associate professor in Georgia Tech’s School of Chemistry and Biochemistry and director of its Applied Sensors Laboratory.

Mizaikoff and graduate students Gary Dobbs and Yuliya Luzinova selected commercially available hydrophobic polymers and deposited them as thin film membranes on the sensor surface. They continue to investigate innovative ways to consistently deposit the polymers at the disk surface, while ensuring sufficient adhesion for long-term field applications.

“By modifying the silicon transducer surface with different polymer membranes, each sensor becomes selective for groups of chemicals,” explained Mizaikoff.

An array of these sensors, each sensor with a different chemically modified transducer surface, can sense different pollutants in a variety of environments ranging from industrial to environmental and biomedical monitoring applications.

Brand and Mizaikoff aim to detect volatile organic compounds (VOCs) in aqueous and gaseous environments. VOCs are pollutants of high prevalence in the air and surface and ground waters. They are emitted from products such as paints, cleaning supplies, pesticides, building materials and furnishings, office equipment and craft materials.

A common VOC is benzene, with a maximum contaminant level set by the Environmental Protection Agency (EPA) at five micrograms per liter in drinking water. Many VOCs are present at similar very low concentrations, so effective sensors must accurately measure and discriminate very small mass changes.

“We’ve been able to measure concentrations among the lowest levels that have been achieved using this type of resonant microsensor,” noted Brand. “While we have not achieved the required sensitivity yet, we are constantly making improvements.”

Brand and Mizaikoff have tested their sensor device in the laboratory by pumping water with specific pollutant concentrations through a simple flow cell device attached to the sensor.

A typical test begins by flowing a water sample containing a known amount of pollutant over a sensor coated with a polymer membrane. When the sample flows through the cell, the mass of the microstructure increases, causing its characteristic vibration frequency, or resonance frequency, to decrease. By monitoring this resonance frequency over time, Brand and Mizaikoff can detect the amount of aromatic hydrocarbons such as benzene present in water.

The researchers plan to run field trials to investigate the use of this new microsensor in aqueous and gaseous environments for rapid on-site screening of multiple pollutants.

“With benzene and other VOCs high on the EPA priority pollutant list, it would be a major advantage to get a rapid reading of VOC concentrations directly in the field,” said Mizaikoff.

SOURCE: Georgia Institute of Technology



Edited by Carolyn Allen, owner/editor of California Green Solutions
Green Solution Providers
Green companies directory
Submit
your green solutions - business, nonprofit, government program.
It's free.
| voc | pollution prevention |

Share in Social Media

Sign Up For News & Information
Subscribe to our free solutions newsletter
BONUS DOWNLOAD (PDF)
"Ten+ Tips for Greening Your Office"

SUBSCRIBE HERE
Read prior issues: California GreenLines

Search For Green Solutions

Custom Search
Green Career Center
Green Job Wizard
Career Certifications Directory

green job training certifications
Green Biz Center
Solutions For Green
Directory of Green Companies

Solutions for Alternative Energy

rose in natural systems
Green Living Center
Solutions for Green: Consumers

Solutions for Remodeling

Backyard Nature Center

INSTANT GREEN POLL

"Knowing is not enough; we must apply. Willing is not enough; we must do." Goethe
RECENT ARTICLES
SITE NAVIGATION
ABOUT US

Related Articles

China and the US EPA Collaborate on Emerging Priorities

Small Truck Fleets Could Qualify for CARB Pollution Prevention Funds from Prop 1B

EPA Names New Superfund Sites

Related Green Resources

Marcom Tips
Interactive & Video Tips

Career Resources

We encourage lifelong learning to support sustainable communities and provide these select resources to help you pursue green and sustainable self-development:

Lorman Business Training Directory of On-line Business and Compliance Classes

Green Job Wizard Job and Career Certifications Directory

Job & Career Resources

Governance
Management
Manufacturing
Operations
Facilities
Transportation
Finance
Sales & Marketing
Human Resources

Green Economy

Business Sectors
Natural Resources

Solutions For Green

About Us ~ Privacy Policy
Contact Us ~ Home

Text Link Ads

AD: Place your link here

ABOUT CALIFORNIA GREEN SOLUTIONS

We help you green your career, workplace and community by connecting you to quality green, sustainable and high performance resources. California Green Solutions focuses attention on effective solutions that sustain our natural systems. You can support our editorial work by supporting our advertisers and spreading the word about best practices and green solutions.
California Green Solutions is a publication of Carolyn Allen ~ Copyright ©2006-2030 Carolyn Allen

B2B | Job Certifications | Alternative Energy | Events | Green Directory | LED Lights | Remodeling |
CONSUMERS | Backyard Nature | Senior Health | MultiMedia Marketing | Marketing | Networking Events | Japan |