The device analyzes a gas mixture using semiconductor sensors.
- Smell is determined by a combination of existing gases in the atmosphere. It is found that the conductivity of the semiconductor probe changes during sedimentation of the gas molecules from the atmosphere. This allows determining their presence - says Timur Muksunov. - During manufacture the sensor can be customized to react well to some gases, and react badly to the others.
However, according to the scientist, it is impossible to make a sensor that reacts to only one gas - the system is needed to achieve sensitivity and selectivity. This allows, when using certain processing techniques, accurately recognizing the gas mixture in the air. Experiments confirm this.
One of them was determining the freshness of fruits and vegetables. Fruits and vegetables emit hydrogen sulphide, ammonia, and other gases. The closer the date of writing off the products, the more of these gases are in the air.
- We investigated the apples: a control part we put in the refrigerator and the rest were left at room temperature, - says the scientist. - After 12 hours the device was able to identify that the second part emits gases more intensively than the control part. Now the vegetable warehouse receives products by their organoleptic characteristics, and using the device it will be able to more accurately determine the shelf life of products, which will affect its quality.
The device is fully developed, now there is a test of its effectiveness. The work is conducted in conjunction with the Radiophysics Faculty of Tomsk State University.
Russian Physics Journal