Scientific

      

New Chemical Sensor, Electronic Nose ARTINOS

 


Micro-Nose: Key Technology for Intelligent Systems:


The KAMINA is a compact electronic nose based on a unique and highly integrated gradient micro array chip developed at the Karlsruhe Research Center (FZK). It has been devised to implement a universally integrable gas analytical tool for household and industry. High gas analytical power has thus become available in the form of a small and inexpensive module capable of characterizing chemical states immediately on the spot. Continuous operation of the KAMINA allows long-term monitoring and its subsystem integration can realize intelligent control systems.

Product checks or continuous process monitoring in industry, environmental analysis or medical diagnostics offer various fields of application. SYSCA further intends to realize the vision of offering KAMINA-based gas analytical performance at an inexpensive price and space-saving dimensions, be it for household appliances, building systems (air quality monitoring, fire alarms), automobiles or instruments for home medical care (breath analysis as a health monitor). This opens up new possibilities, since then objects of daily use can be equipped with autonomous intelligence and then offer more safety, less waste of energy, material and time, an improved comfort or even individual health care.

The heart of the KAMINA device is a unique, fingernail-sized gas sensor chip with an array of gradually different gas sensors. The latter produce signals, creating gas characteristic patterns that are typical of kind and quantity of the ambient gas composition. The chip carries a single metal oxide film, e.g. of tin dioxide, tungsten trioxide or similar materials. At higher temperatures (approx. 300 °C in the case of tin dioxide), the electrical conductivity of the metal oxide sensitively and reversibly depends on the composition of the ambient gas.

Figure 1 schematically shows design and functionality of the chip. By simple partitioning of the metal oxide film with parallel electrode strips, an array of individ­ual gas sensor segments is formed. These segments are differentiated in their sensitivity spectrum by the so-called gradient technique. On the rear side of the chip four heating meanders maintain a temperature differ­ence of about 50°C across the micro array. Moreover, the metal oxide layer is coated with a gas permeable membrane of which the thickness varies across the microarray.

Thus, each sensor segment is heated to a slightly different temperature and further differs in its membrane thickness from its neighboring sensor segments. Consequently, the individual sensor segments have a different sensitivity spectrum.

 

Chemical Gas Sensor with Gradient Micro Array Concept:

 
Fig. 1: Outline of the patented Karlsruhe gradient microarray. a) Front side with the gas sensitive metal oxide (mox) film divided into 38 sensor segments by 39 electrode strips. Two temperature sensors are placed adjacent to the mox film, one above and one below it. b) Rear side with four heating meanders. In the middle, the gradient technique is depicted: By applying a temperature and a thickness gradient of the gas permeable SiO2 coating across the array, each sensor segment receives a gradually different gas selectivity compared to adjacent segments.

 

Although all segments respond to nearly all gases, they do so with a gradually different sensitivity, depending on the gas. Not only does this inimitable gradient micro array provide a high gas discrimination power for product- and process-characteristic gas ensembles and offer a high sensitivity towards nearly all gases (except for nitrogen and rare gases) - at the same time its micro technical fabrication is unbelievably simple and inexpensive.

Thanks to the difference in sensitivity of the individual sensor segments, gas characteristic conductivity patterns can be measured that inform us of kind and quantity of the components of the ambient gas. Thereby the entire gas mixture is considered as an entity, just as an odor is that often consists of several components but all the same is treated as single characteristic ensemble, with a single concentration. The conductivity pattern then immediately reflects kind and quantity of the gas ensemble. Sometimes, however, characterizing the individual components of a gas mixture might be of importance. The conductivity pattern can then be broken down into a series of fractions that correspond to the concentrations of the gas mixture components. The quality of fractioning and the number of separately detectable components depends on their chemical difference and concentration. Both methods for the characterization of gas ensembles can be carried out online and in continuous operation.

 

Easy and Portable Setup:

 

 

Quality Control Applications:

At present, the gradient microarray together with its entire operating electronics fits in a housing the size of a mobile phone and is thus counted among the world’s smallest electronic noses. Every second conductivity at the sensor segments is measured, creating signal patterns, which allow sensitive recognition and quantification of gases. The standard metal oxides used are tin dioxide and tungsten trioxide. They permit detection of a wide range of gases (as CO, NO2, NH3, H2S, organic gases) even at concentrations below 1ppm. Detection of individual gases is often not required. Instead, reporting certain conditions that arise whenever gas compositions change is relevant, for instance for monitoring food quality (freshness), burning of food, gum bleeding or a defective engine function. The latter for instance can be reported by the KAMINA when employed for exhaust gas monitoring. Fig. 2 shows the standard chip with its 38 sensor segments in a PGA package.

 

 

Equipment and Operation Specifications:


Detection Specifications:

Download your Electronic Nose ARTINOS Brochure (PDF)

Manufacturer:

 

Application Notes:

Chemical Gas Detector System

Chemical Sensor for Mobile Odor Testing

Process Control Application Examples

Kamina Gas Detector System

Air Quality Monitoring and Fire Detection

Condition Monitoring For Intelligent Household Appliances

 

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