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High Res TIFF (17.8 MB)
Electronic Nose - ENose
Biological systems often serve as models for technology. The electronic nose - called "Enose" - got its name because it operates like a human nose by containing a large number of sensors. The difference is that the JPL ENose is an array of chemical sensors that swell and shrink, depending on what trace vapors may be present in the air. This variation is measured, and certain elements in the air identified. The need to measure such trace vapors is especially important in closed environments like the Space Shuttle and the International Space Station.
John Glenn went through a series of physiological tests as an astronaut aboard the Space Shuttle in October of 1999. The JPL Enose unit was there testing the air quality of the shuttle cabin on this same flight. This was the first analysis of Space Shuttle air quality during flight. The tests involving both John Glenn and Enose were a success.
ENose technology has numerous medical, industrial and commercial applications in such fields as environmental monitoring, quality control, food processing, industrial environmental monitoring and medical diagnosis.
For additional information:
- ENose site and http://mishkin.jpl.nasa.gov/enose.html
Technical Description:
The Electronic Nose (ENose), now under development at JPL, is designed to monitor the air quality in human habitats such as the Space Shuttle and the International Space Station.
The electronic nose got its name because it operates similarly to a human nose. Both contain a large number of non-specific sensors. The JPL ENose is an array of chemical sensors made from 16 different polymer films. Each film has been loaded with carbon particles, which make it electrically conductive. The polymers swell and shrink as the composition of the air changes, with these changes altering the electrical resistance of the films. The ENose measures the change in resistance when the films swell or shrink.
The sensors are not specific to any one vapor. All of the sensors respond to a change in the air and the pattern of response is recorded. By comparing the pattern of response of the array with patterns which have
been recorded in the laboratory, gases and gas mixtures can be identified. The size of the response is related to the amount of contaminant in the air, so the quantity of contaminant can also be determined. Electronic Noses have been discussed by several authors, and have been applied to environmental monitoring and quality control in such wide fields as food processing, industrial environmental monitoring and medical diagnosis.
What is new about the JPL ENose is the small size and power requirement, and the ability to quantify gases and mixtures of gases at levels lower than the Spacecraft Maximum Allowable Concentration (SMAC). SMACs are the quantities of specific compounds that can be breathed by crewmembers for a specific length of time. SMAC levels have been determined by NASA toxicologists to ensure maximum health for crewmembers. For most compounds, SMACs are in the single to tens of parts-per-million regime. JPL has designed and built a device which is about 1.7 liters in volume, uses about 1.5 watts of power and weighs 1.4 kg. This device includes everything needed for it to operate, including a computer to control the device and take the data, all within a container approved for use in crew quarters.
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