Electronic tongue

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An electronic tongue is a device designed to electronically mimic the sense of taste.

The keyword electronic tongue is an overall concept of sensors and data processing . The sensors are responsible for the actual data acquisition. However, this data must first be meaningfully interpreted in order to arrive at a concrete result. In the case of the electronic tongue, the sensor system consists of several ion-sensitive electrodes. However, these electrodes not only have a specific sensitivity to a single ion , but also react sensitively to a large number of different ions and chemical compounds. This property is known as cross sensitivity . The cross-sensitivity of the electrodes to individual ions differs from one another, however, so that each electrode reacts differently to ions present. The “electronic tongue” concept can only be implemented, however, because this cross-sensitivity is specific and reproducible. Similar data are thus obtained for a repeated measurement. A pattern specific to the analyte results from the “overall picture” of all this data. This pattern can be compared with patterns that are already known, which enables an analyte to be identified.

The overall concept tries to copy the biological senses, both in sensor technology and data analysis, and to implement them electronically. Therefore, in addition to the electronic tongue, there is also an electronic nose for gaseous substances. The evaluating electronics correspond to those of the electronic tongue. However, gas-sensitive detectors are used for the sensors.

concept

The electronic tongue consists of the following elements:

  1. a sensor array
  2. a signal recording electronics with A / D converter
  3. Signal processing in the PC
  4. Signal analysis

Further research is being strongly promoted in the field of sensors. A miniaturization of the electrodes is particularly important here. Further developments are also necessary in the area of ​​signal analysis.

The following are used for signal analysis:

  1. Clustering methods (PCA: Principal Component Analysis) (→ principal component analysis )
  2. Fuzzy logic
  3. ANN (Artificial Neural Networks, Artificial Neural Networks )

The evaluating electronics must be able to recognize patterns. Since the results, depending on the number of sensors used in the sensor array, extend over several dimensions (3 sensors = 3-dimensional output vector) and unavoidable measurement errors always occur, the electronics must be able to process this multidimensional and fuzzy data.

Fields of application

The electronic tongue is able to differentiate between different mixtures / or. to compare different mixtures with each other. These capabilities open up a very wide range of applications for this technology. Areas of application would be for example:

1. Industrial analytics

In the field of industrial applications, the electronic tongue enables online monitoring of various processes. The electronic tongue is able to determine the degree of aging of lubricants. In the automotive industry, the point in time at which the engine and transmission oil is worn out can thus be determined. Routine oil changes could thus be dispensed with and the oil would only have to be changed at the point in time at which it has lost its lubricity. The use of the electronic tongue would thus both reduce the maintenance costs for a motor vehicle and relieve the environment, since waste oil would be minimized.

2. The clinical analysis

In the clinical area, the electronic tongue offers the possibility of reducing laboratory costs and performing many examinations almost in real time. Many complex chemical analyzes could be dispensed with, since the electronic tongue is able to detect various compounds and ions in the body fluids or to monitor their concentration. A direct comparison can also be made between the body fluids of a sick patient and those of a healthy patient. Urinalysis in particular is an interesting field of application here, as routine online urine monitoring could even be implemented.

3. Food analysis

The food industry is a very important area of ​​application for the electronic tongue. As this technology is closely based on the biological senses, it is ideal for differentiating between various foods. The use of the electronic tongue in the field of process monitoring in the industrial production of food and beverages appears sensible . In the case of drinks in particular, the process can be monitored online. If you calibrate an electric tongue in the same way as the human sense of taste, it is possible to recognize deviations in taste while the process is running. As a result, a deviation can be counteracted relatively quickly, so that production losses can be minimized. Another area of ​​application is protection against plagiarism. Since the electronic tongue is able to differentiate between substances with high reliability, investigations can be carried out directly on site and counterfeit products can be detected with a high degree of probability. The electronic tongue minimizes laborious laboratory tests and speeds up decisions. This minimizes the costs of plagiarism protection.

4. Environmental analysis

The electronic tongue can also lower costs in the field of environmental analysis and reduce possible environmental pollution through online monitoring. They can be used to monitor wastewater from sewage treatment plants and industrial plants. Even small amounts of contamination can be detected at an early stage, so that action can be taken before the environment is actually endangered. The electronic nose can, as an electronic tongue for gases, enable specific monitoring of odor nuisance. If it is calibrated according to the human sense of smell, scientifically based statements can be made about the pollution of the environment with unpleasant smells.

See also

Web links