ZNOSE - Chemical vapour analysis technology

EST’s main product line, the zNose®, provides comprehensive, realtime analysis of any chemical, vapor, or toxin in less than ten seconds with part-per-trillion sensitivity.

EST products have extensive commercial as well as defense applications, and are currently being utilized by companies such as Lockheed Martin, Honeywell Corporation, SC Johnson, and the United States Armed Forces.

The concept of an electronic version of the human nose, to remove the subjectivity, variability and potential for toxicity, has been a target of research groups for many years. The human version utilises an array of sensors with selective sensitivities to the different compounds which lead to an odour. Typically the selectivity is produced by applying a coating or doping to select chemical types.

Attempts to model this approach using an array of electronic sensors have achieved only limited success, mainly due to the inability to cope with different backgrounds and histories. Humidity can have a profound effect, and most sensors are found to drift with time. Correction algorithms are necessary to offset such effects, and turn the exercise of producing a validated method a very expensive and time consuming one. Tests typically take 30 minutes or more, to allow the sensors to return to a stable baseline, and in fact most testing is done in triplicate because of poor reproducibility. In addition, sensitivity and selectivity have to be achieved on the same sensor surface, so there is limited flexibility to vary temperatures and other parameters which might assist in optimising either one. As a result the sensors respond typically to ppm levels, while many odour compounds are detected by the human nose at the ppb or ppt level.

The EST ZNose was developed using a surface acoustic wave chip as a sensor, which is one of the technologies used in sensor array electronic noses. But rather than coat the sensor and reduce the response and sensitivity by a factor of 100, EST put the coating inside a very short GC column. This allows the column to be heated to change its selectivity characteristics, and allows measurement in times as short as 10 seconds, and with sensitivities which can go as low as the parts per trillion (ppt) level.

• First gas chromatograph (GC) based on Surface Acoustic Wave (SAW) technology.
• zNose® can recognize vapor mixtures containing hundreds of different chemical and biological threats in seconds.
• Provides simple visual display of vapor analysis enabling ease of use by non-specialists.
• zNose® is programmable to detect any type of vapor, toxin, or compound.