Electronic Senses to Touch Us All

Dr S.S. Verma is a professor at Department of Physics, Sant Longowal Institute of Engineering and Technology, Sangrur, Punjab

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Up to now, electronic senses have had straight industrial applications. For instance, food, beverage, pharmaceuticals, plastics, packaging and environmental industries have clear uses for electronic senses.

In food and beverage industry, e-noses can detect when flavours or odours in food are ‘off,’ and if there has been contamination or migration of compounds from plastic packaging into content. MOS odour sensors can also control how fast a flavour is diluted, ensure quality control or reverse-engineer an aroma. Electronic tongues can assess things like bitterness, taste stability over time or product adulteration.

Concrete applications of e-noses can be found in the analysis of meat flavours, volatile organic compounds (VOCs) formed during post-harvest ripening of fruits, ham product evolution during storage and olive oil defects, as well as identification of geographical origin of foodstuffs.

In the last decade, for example, Barilla has successfully implemented MOS-based e-noses in different quality control labs to recognise residual solvents and to continuously monitor the various plastic food-packaging materials adopted within bakery production sites. At Barilla, e-noses are, in fact, used as the first appraiser of packaging quality, which limits the number of gas chromatographic confirmatory analyses solely to the samples marked as uncertain or bad by the MOS instrument.

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e-tongues can be used to monitor and discriminate among mineral water, coffee and soft drink samples. Reported applications of e-tongues in food analysis cover process monitoring, foodstuff recognition/characterisation, evaluation of ‘freshness,’ quality control and authenticity assessments.

Electronic senses were applied to evaluate the effect of brewing temperature on sensorial properties of espresso coffees (ECs) produced by a bar machine that was able to work with constant, increasing and decreasing water temperature profiles. The ECs were analysed by e-nose, e-tongue and e-eye to depict their aroma and taste fingerprint, and to evaluate the visual characteristics of foam. Physicochemical analyses were carried out to determine the extraction rate of typical EC components and evaluate their antioxidant activity.

Electronic devices coupled with multivariate statistical analysis demonstrated a good ability to discriminate and characterise coffee samples on the basis of their sensorial properties in relation to the brewing temperature. According to these results, electronic senses can be applied to assess the influence of percolation parameters on the sensory attributes of ECs, thus resulting in useful tools for optimisation of processing conditions.

Sensory characteristics of food products are gaining importance in the international food research and industry to meet consumer needs. Food producers make efforts to improve the quality and offer a wide range of foods. Comparison with existing brands in sensory point-of-view and developing products in sync with consumer needs are essential for the successful new product launch.

Usually a trained sensory panel is used to evaluate product quality. However, the reliability of sensory results is highly dependent on panelists’ acuity and correct application of the sensory practice. Therefore sensory attributes measurement using instrumental methods is a desirable aim. A new concept has been introduced in the sensor development using several sensors of low selectivity simultaneously.

Scientists have devised a detector that can distinguish smells better than a service dog. This sensor can detect explosive vapours and identify them. Called electronic nose, the device is able to sense and recognise traces of almost all types of explosives, from saltpetre to hexogen (which cannot be detected by even the most advanced technology).

For individual use

In the very short-term future, sight, taste and smell sensors will be available to new industries for incorporation into their own products, or for individuals directly. So, refrigerators of the future may have sensors that detect when food is going bad. These might be connected to a food-management system that alerts the user, who can then check in order to make a grocery list.

Cars may have sensors that detect carbon dioxide. The level of carbon dioxide rises in a car when driving with the windows shut. That’s dangerous because carbon dioxide can make the driver sleepy. A sensor would alert the occupants to stop for fresh air.

Doctors in the future may test patients’ breath to detect the onset of diseases like diabetes or cancer. A new study shows that organic compounds in exhaled breath can indicate whether a person has lung cancer—as well as its stage—and distinguish cancer from chronic obstructive pulmonary disease.

Skin is probably one of the best wearable technologies that nature ever developed. Skin on our fingertips contains pressure sensors that produce voltage pulses when we touch things. The frequency at which these pulses are created gives the brain information about what we’re touching.

Prosthetic limbs could soon be covered with an electronic skin that mimics human touch. Scientists have developed a flexible plastic skin that can communicate a sense of pressure to brain cells. The plastic skin generates voltage pulses when pressure is applied. The higher the pressure, the closer the carbon nanotubes are pushed together. This increases the conductivity frequency of voltage pulses.

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