Gas Mask Sensor

Firefighters put their lives on the line everyday protecting us from harm. Now, a new device helps protect them. A fire that reduces a building to a pile of rubble can be seen for miles. Firefighter Al Hernandez knows it is a risky job, "We knew there was going to be some burning materials that were going to produce some really toxic gases." Breathing respirators protect against toxic gases, and cartridges on the respirator filter the air. Over time, the cartridges need to be changed, and without knowing it users could be inhaling deadly gases.

Gary Fedder, Ph.D., an electrical engineer from Carnegie Mellon University in Pittsburgh says, "They currently have no good mechanism for knowing when their carbon cartridges in their respirators are spent." Electrical engineering student Sarah Bedair developed a microscopic device that detects harmful chemicals. Bedair, an electrical engineering Ph.D. student at Carnegie Mellon University, says, "It will tell us what's in the air around. Ultimately, you'll know what you're being exposed to."

Here's how it works: The tiny sensor fits inside the cartridge. Back at the fire station, the speed of the wires on the sensor is checked. If the wires have slowed down -- that's a warning the cartridge needs to be changed before the next fire. "It can save long-term health of first responders," Fedder says. "It's going to be another safety net for them. They've got plenty to worry about in a crisis."

Gas Mask Sensor - Inside Science
BACKGROUND: Engineers at Carnegie-Mellon University in Pittsburgh have developed a sensor to alert firefighters and emergency responders when it is time to change the cartridge in their gas mask. These teams rely on gas masks to protect them from dangerous toxins.
HOW IT WORKS: The sensor currently under development would be placed inside the respirator's carbon filter and would monitor when it became saturated with dangerous gases. It would act like an "electronic nose," sorting and identifying the chemicals present, because its chip is imprinted with a special conductive polymer coating that is sensitive to differences in chemicals.

E-noses analyze gas samples using an array of electrodes coated with various conducting polymers. After the electrodes are surrounded by the gas, each electrode reacts to a particular substance by changing its electrical resistance. The microchip's neural network then combines all the signals to give a "smell-print" of the chemicals present in the gas mixture. The food industry uses e-noses to detect rotten ingredients, and similar devices are being developed to sniff out specific infections in hospital settings.

WHAT ARE MEMS: Microelectro-mechanical systems (MEMs) integrate electronic and moving parts onto a microscopic silicon chip, making them ideal for new sensor technology. The term was coined in the 1980s. A MEMS device is usually only a few micrometers wide; for comparison, a human hair is 50 micrometers wide. Among other everyday applications, MEMs-based sensors are used in cars to detect the sudden motion of a collision and trigger release of the airbag. They are also found in ink-jet printers, blood pressure monitors, and projection display systems.