Advantages of Using an Electronic Nose for Security

Electronic Sensor Technology, Inc. (“EST” or “the company”) manufactures and sells a product series of highly sensitive and fast screening devices under the brand name zNose®. These screening devices are able to test and identify volatile organic compounds (VOC) within a minute, with parts-per-billion sensitivity.

The patented technology uses a proprietary Surface Acoustic Wave (SAW) sensor and ultrafast Gas Chromatography (GC) technology to separate vapor samples based on their physical and chemical properties.

In contrast to conventional security devices such as “bomb-sniffing” explosive detectors (Ion Mobility Spectrometer), the zNose® is not limited in sensitivity or target specific; it can access, assess and identify any sample by converting output signals into precise visual images or chromatograms – trademarked as VaporPrints® - which enable skilled personnel to immediately identify and react to any illegal, dangerous or toxic compound present. Evidence of its utility and versatility, the zNose® has received validation from the United States Environmental Protection Agency (EPA) and the White House Office of National Drug Control Policy.

In 1995, the zNose® was developed by Electronic Sensor Technology and, internationally, has numerous installations and is used in applications for Homeland Security as well as for the life sciences and consumer products.

The Technology

In contrast to trace detectors, electronic noses identify fragrances and odors based upon their full chemical signature. An electronic nose can detect all compounds within an odor and offer a full chemical profile. Software includes an expandable library of more than 700 chemicals and odor signatures, enabling the zNose® to identify almost any target odor.

Using ultra-high speed chromatography to separate chemicals within an odor in near real time, trace detection and pattern recognition using virtual chemical sensors can be done at the same time. Trace detection coupled with odor profiling can be an effective technique for identifying the presence of contraband material of all kinds. Electronic odor profiles are not dependent on instruments and enable security users to distribute and share odor signatures.

Based on Surface Acoustic Wave sensors and Ultra-fast Chromatography, the patented zNose® can test chemical vapors in within 1 minute by separating vapors according to their physical and chemical properties. Instead of using physical sensors, the zNose® creates numerous user-defined, virtual chemical sensors for many applications. When a vapor is detected, the Company’s VaporPrint® software technology offers users with visual representations of the vapor, allowing for pattern recognition and easy interpretation.

Unlike conventional detection systems, the zNose® can adapt and learn to identify the chemical signature of practically any threat. In reality, the zNose® is an electronic dog, which can be trained to identify chemical vapor signatures. Unlike a dog however, it does not have to rest and electronic chemical signatures can be shared across a network of sensors.

EST’s zNose® offers full, real time analysis of any chemical vapor with part-per-trillion sensitivity. The company has sold more than 400 systems globally and they are listed as commercial-off-the-shelf (COTS) by the US government.

The zNose® technology is protected by four U.S. patents and is the only electronic nose technology to receive validation from both the White House Office of National Drug Control Policy and the U.S. EPA. It is considered as established and ready for deployment.

The Features and Capabilities of the zNose®

EST’s electronic nose, the zNose®, can be employed for the detection and identification of narcotics, explosives, and other contraband at maritime ports, the screening for a number of explosive compounds and chemical agents at on departing passengers and luggage at airports, vehicle check points (VCP), the screening of vehicles and shipments at entry and exit points. It can also be used to detect dangerous volatile organic compounds in the ambient air or HVAC system of an airport terminal.

EST manufactures a number of different models of zNose covering fixed site sensor networking as well as wireless and fully portable or mobile systems.

The ability to detect all chemical compounds is unique and enables the system to swiftly adapt and learn to identify any threat including conventional nitro-based compounds as well as such explosives as TATP. The total monitoring of ambient air within or around secure facilities by a network of sensors would offer full protection against all threats as well as identification of unusual or suspicious chemical emissions.

Using the zNose® at a VCP

Figure 1. Using the zNose® at a VCP

Current Security Applications

The zNose® has been used by the military at the Abugrab prison, and for the detection and defeat of improvised explosives devices (IED) in Iraq. It is being used with chemical weapons at military facilities such as Dugway Proving Ground and Aberdeen. It is also in use as a screening sensor at police and sheriff departments as well as embassies. A soldier scanning the trunk of an automobile can be seen in Figure 1.

The scanner on the zNose® can also be inserted into the passenger compartment of any vehicle to sample and test the chemical compounds in this compartment. The same approach can be used to scan a suitcase or to sample the bed of a truck for contraband vapors.

The zNose® instruments can also be used to sample the air in an airport terminal or a building to look for any changes in an established background profile. All these varied applications can be operated from a central operation location via connectivity by telephone modem or RF link.

Networking the zNose®

The zNose® can function within a wireless network using either Bluetooth, Wi-Fi or RF modems with ranges up to 1 mile. It can also be remotely connected using an Internet connection. At present, the latest model is fully mobile using a built-in connection.

The company offers online support for all its products using an internet network connection. This capability could be used inside an airport security system to offer over site by a central monitoring station as well as updating of new threat signatures to every zNose placed in the facility.

Linking zNoses within a wireless network

Figure 2. Linking zNoses within a wireless network

Improvements in Situational Awareness

In contrast to conventional security sensor systems, the zNose® technology would offer a detailed analysis capability enabling monitoring of the full chemistry of the environment within the airport both in time and space. This would result in significantly enhanced situational awareness for these facilities as well.

As an example, the ability to detect alterations within the environment could be used to detect chemical emissions or odors which were not customary and result in early warning of a suspect or dangerous chemical emission. The ability to detect alterations in the environment in the airport would be crucial issues for an airport Security Operations Center (SOC).

Integration into Geographic Information Systems (GIS)

GIS is a group of computer software, hardware, and geographic data for capturing, controlling, analyzing, and displaying all forms of geographically referenced information. With a geographic information system (GIS), information (attributes) can be linked to location data, such as buildings to parcels, people to addresses, or streets within a network. Users can then layer that data to get a better understanding of how it all functions together. What layers to be combined can be selected based on what questions need to be answered.

The zNose® is well-matched to GIS systems because it works wirelessly and because it adds GPS data into its chemical analysis database. When operating and examining the chemical content of vapors, the GPS coordinates of each analysis are connected to the chemicals and their reported concentrations.

This ability would enable fixed and mobile chemical sensors to provide a situational awareness by measuring the chemical content of ambient air all over the airport facility. Practical applications might be for early detection and tracking the progression of toxic chemicals, dangerous materials, or smoke inside the facility from a fire.

Situational awareness in public buildings, subways, and aircraft

Figure 3. Situational awareness in public buildings, subways, and aircraft

Comparison IMS vs. zNose®

Note: The above chart was provided in part by SUNOCO and the US Military. Both are users of the EST- Vapor Tracer.


Ion Mobility Spectrometry (IMS) Technology is a lot slower, less accurate process. It is much less sensitive than the GC technology and requires using a swab to wipe off specific areas outside the surface of the suspected objects like; briefcases, packages, luggage etc., trying to pick up traces of dangerous or harmful substances which are presumably performed within the object. Then this cotton-type or paper material (swab) is kept inside a special chamber where it is analyzed.

However, the issue with this technology is that it can only detect traces and deposits of hazardous particles on the outside of the objects left most probably by the person handling it. This process can only generate good results if the person who deposited the hazardous substance does not wash his hands regularly or does not wear gloves while handling the hazardous materials. Terrorists these days are well aware of this technology, and they know how to protect themselves from being detected.

The human error factor has to also be taken into consideration, which can very easily happen when they are too busy, sometimes under very hard and stressful circumstances, like at border crossings, large public gatherings, government, airports and military installations. A slight human error can easily result in a huge human catastrophe. Personnel using IMS technology should give a lot of attention to each step during the whole process of examination as a slight mistake can cost a number of lives.

Examples of probable human errors and faults by using IMS technology

  • Mixing or forgetting up the test swabs
  • Wiping off the wrong area of the objects surface
  • Users need to only wipe and test what is on the outside of the surface
  • The cost is on the high end as each swab can only be used once
  • Baggage and parcels are handled (being touched) by numerous personnel

The EST-4300 Vapor Tracer employs a well-known gas chromatography (GC) technology. This super-sensitive, vapor vacuum process can sniff-out and detect one-millionth (Pico-grams) of any vapor (smell) traces emitted by organic, chemical and biological compounds.

It tests and identifies them rapidly and very accurately. It can actually smell and recognize harmful contents of containers, postal packages, briefcases, luggage and all types of cargo including automobile trunks and even the undercarriage of vehicles without the need to open them and without wiping or swabbing, suitable for use by customs, governmental, cruise ships and military installations and vehicles.

It can accurately detect and identify:

  • All types of military, commercial, and home-made explosives including: PETN, RDX, TNT, Tetryl, DNT, NG, HMX, Black Powder, Ammonium Nitrate, nitromethane and others
  • All types of drugs and illicit narcotics including: LSD, Cocaine, Heroin, PCP, Marijuana, THT, Methamphetamines and others
  • All types of chemical, nerve, and biological agents including: Soman, Sarin, Mustard Gas and others

Due to its versatility and sensitivity, the SAW/GC Vapor Tracer can effectively replace a number of sniffing dogs at seaports custom departments and borders, since each dog can be trained to sniff-out and detect only a single substance at a time, either narcotics or explosives.

The zNose® is all solid state, durable and very rugged construction. It is the most sensitive technology (down to pico-grams) on the market. There are no radioactive elements used. It is well-established by the US Military as the most sensitive portable contraband/ explosive/ narcotics/chemical agents detector on the market.


This information has been sourced, reviewed and adapted from materials provided by Electronic Sensor Technology.

For more information on this source, please visit Electronic Sensor Technology.

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