Israeli engineers from the Center for Nanomaterials Research at Tel Aviv University and the School of Chemistry have created an “electronic nose.” The new product of Israeli scientists is 2-3 orders of magnitude more sensitive to various explosives than the nose of man's four-legged friends - dogs. According to the published report, the “nose”, invented in Tel Aviv, is a chip containing several hundred ultra-sensitive sensors. It is these sensors that are responsible for detecting explosive molecules in the air.
It is reported that the chip of the Israeli novelty contains nanotransistors that are able to change electrical conductivity when just one explosive molecule comes into contact with them. Based on the smallest changes in the electrical conductivity of installed nanotransistors, a mathematical algorithm developed by scientists analyzes the substance interacting with the nanotransistors. According to Israeli scientists, the device they presented, if mass produced, will cost less than the currently existing explosives detection systems.
At the same time, exact information about the sensitivity of the created chip is not provided, but it is said that it is able to operate at a concentration of even several molecules of explosive per quadrillion molecules belonging to other gases. In this case, the search for explosives is carried out in real time. According to Israeli engineers, the electronic chip is able to successfully differentiate explosives from other substances that may produce positive result.
In addition, the sensors installed on the chip are able to detect improvised explosive devices, which can use unconventional explosives. The "electronic nose" is reportedly able to detect hexamethylene triperoxide diamine or acetone peroxide, substances that are quite common in improvised explosive devices. At the same time, the Israeli chip, unlike many other explosives detection systems, can determine the type of explosive with very high accuracy. It is reported that the device from Tel Aviv can also work with liquids.
Similar studies are being conducted today not only in Israel, but also in the USA and Russia. So in October last year, American engineers from Vanderbilt University in Tennessee made a statement about the creation of new technology, aimed at searching for explosives of both high and low power. The method developed by American scientists uses a phased acoustic emitter, which makes it possible to direct an ultrasonic beam at the object being tested.
At the same time, a laser beam is aimed at the object being tested, which makes it possible to accurately measure the frequency of vibrations of its shell under the influence of ultrasound on the object. Based on the frequency and strength of the vibrations that occur, it is possible with a fairly high degree of probability to identify explosives. However, so far this method only works in cases with explosives that are placed in a plastic container. At the same time, the developers say that in the future the capabilities of the device will be expanded to include a tissue shell.
"Electronic nose" in Russia
Work on the creation of an “electronic nose” is also underway in Russia. Back in March 2013, Rossiyskaya Gazeta wrote that in our country an “electronic nose” was manufactured at one of the enterprises. At the same time, this device was given the most serious tasks - to capture molecules and atoms of matter in the air in order to then determine the presence of dangerous components and various explosives.
This extremely delicate work requires the use of a rather non-standard element base. This database was developed specifically for Russia by Belarusian colleagues representing the State Scientific and Production Association “Planar”. This is the only enterprise in the post-Soviet space today that carries out the complex process of development and production of equipment necessary for the production of microelectronic products. At the same time, this enterprise has teamed up with its Russian colleagues within the framework of the scientific and technical program “Microsystem Engineering” implemented in the union state.
According to Planar General Director Gennady Kovalchuk, one of the main objectives of this scientific and technical program is the creation of a variety of sensors and sensors that can be used in various areas of our lives. For example, they can be used to warn us about all critical changes in oil and gas pipelines, building structures, large mechanisms and machines. Such knowledge would prevent many disasters.
If we return to the “electronic nose,” then its main purpose is to work with prohibited chemicals. Prohibited chemicals are explosives, drugs, and various toxic substances. At the same time, the number of elements included in this unspoken table grows and evolves every year. The composition of the components used is changing, and new production methods are emerging. Therefore, recognizing such substances by traditional means is becoming more and more difficult every year.
Today, a huge amount of budget funds are spent on modernizing control systems at airports, customs and border services, and strategic facilities, and a large amount of new equipment is purchased. Although in an ideal case, only one would be needed, a universal device that could recognize a wide variety of substances, quickly learning and improving itself, would be simple and compact. It seems that Russian engineers can offer the industry just such a device.
It's about about a device called an “electronic nose” that works based on ion mobility spectrometry. According to Nikolai Samotaev, associate professor of the Department of Micro- and Nanoelectronics of the National Nuclear Research University, this is a fairly compact portable device that is able to detect thousands existing species explosives.
The question arises: why is it necessary to invent such complex devices if a person has a free analogue that was created by nature itself? We are talking about dogs, which, in fact, are the same gas analyzer due to their very developed sense of smell. A dog's nose contains about 200 million olfactory cells, which allows this animal to find even just a few molecules of the desired element in the air. But even such a unique natural complex is not an ideal bloodhound.
Nikolai Samoteev notes that when training an animal, he is given an explosive to smell, rewarding the dog with something tasty. If a dog remembers that a tasty gift awaits him for finding explosives, he will spend his entire life looking for it. It is difficult for an animal to rebuild from this mission purely psychologically. Modern devices are a completely different matter. The “electronic nose” device is designed in such a way that by bringing this or that substance to the device once and pressing the “remember” button, you are guaranteed to leave in its memory all the necessary information, which will be stored in the device throughout its operation.
The very principle by which a small device with a thin plastic proboscis will work was introduced back in the 1960s. This technology was mainly used in the army in biological and chemical defense units. Today, thanks to the very rapid development of microelectronics, such a device no longer takes up a third of a truck. Modern devices not only weigh no more than 3 kilograms, they have become incredibly sensitive. Current instruments can easily show the presence in the air of nitroglycerin, RDX, nitrotoluene, C4 explosives and one of the most common explosives in Russia - hexogen.
Moreover, the devices can detect not only explosives, but also drugs even in the most microscopic doses. If necessary, the devices can also recognize people, since a person also has his own smell, and this is not the smell of his perfume, but the smell of lactic acid. It is this smell that the dogs used by the Ministry of Emergency Situations in search and rescue operations are trained to smell. If a person is buried under rubble in a tight, enclosed space, his smell gradually accumulates in this space. This smell will definitely seep through the rubble. This is another field of activity for the “electronic nose”. If a sample taken from a crevice in the rubble contains lactic acid, then you should look for a person under the rubble.
Moreover, in our country the device was not created for search operations at all. This is a kind of side effect of its creation. The initial task of the device is to protect the strategic facilities of the Rosatom company. It was for this reason that the National Nuclear Research University worked on the device.
Information sources:
http://lenta.ru/news/2014/07/25/nose
http://www.vesti.ru/doc.html?id=1164303
http://www.rg.ru/2013/03/14/kibernos.html
Any young family with a baby should have a nasal aspirator for sucking out snot in their home medicine cabinet. The device will help clean the nose of a newborn or infant, which is necessary to normalize the baby’s nasal breathing.
Nasal aspirator for newborns and infants: the benefits of a device for cleaning the nose from harmful accumulations
A nasal aspirator is a simple device designed to clean a child’s nose from accumulated dust, mucus and crusts. The process of formation of a certain amount of secretions is completely natural for the human body. The liquid moisturizes the nasal cavity and acts as the first barrier to viruses and bacteria that cause various diseases. Excessive secretions and dust make it difficult for the baby to breathe. Dry indoor air also negatively affects the condition of the mucous membrane - the resulting crusts cause rhinitis.
Problems with nasal breathing interfere with sleep and normal feeding. In addition, this can provoke disruption of gas exchange and cause hypoxia (insufficient oxygen supply), which negatively affects the functioning of the entire body.
The accumulation of mucus and the inability to independently cleanse the nasal passages lead to the fact that the secretion enters through the internal auditory tube into the cavity of the middle ear, and the child develops otitis media.
The appearance of rhinitis requires medical intervention and prescription medicines, and this is extremely undesirable for children of this age, since it is almost impossible to choose safe means.
You should clean your baby’s nose every day, and since the baby can’t do this on his own yet, the aspirator will become an indispensable assistant for young parents.
There are several types of mucus suction devices on the market, although the principle of their operation is almost the same. Before purchasing a “nozzle suction”, it is better to consult with your pediatrician or health visitor. They will tell you which device is right for your baby.
Types of devices for suctioning snot: pear, electronic, mechanical and others
- A syringe is the simplest and cheapest option. It is a regular rubber bulb with a silicone tip. Cleaning of the spout occurs due to the pressure difference that is formed during compression. After use, the tip must be boiled.
- Mechanical - have the form of an elongated tube with a reservoir for sucked mucus. The Otrivin baby model is especially popular among parents. Saline solution with drops helps clear the nose of accumulated mucus and has a preventive effect. The nasal aspirator is equipped with replaceable tips that are thrown away after use. Some manufacturers produce reusable aspirators or models with replaceable tips.
- Electronic ones will not only remove mucus, but also rinse the baby’s nasal passages. All you need to do is insert the tip into the spout and press the button.
- Vacuum is a fairly powerful and fast method of removing mucus from the nasal passages. The device appeared on the market not so long ago. A special feature of the device is that it needs to be connected to a regular vacuum cleaner through a special attachment. After use, removable tips are disinfected.
Types of nasal aspirators for pumping out mucus from the nasopharynx - gallery
The syringe is a rubber bulb with a soft tip. The electronic aspirator is battery-powered and can be musical, which kids really like. A mechanical aspirator in the form of an elongated tube with a reservoir for mucus. A vacuum aspirator instantly sucks out mucus; you can adjust the strength and speed of suction
Pros and cons of devices for sucking snot in babies
Each of these types of aspirators has its own advantages and disadvantages:
- a syringe effectively removes mucus, is sold in every pharmacy and is inexpensive. However, there is no limiter on the tip; it must be inserted by eye, so there is a possibility of damage to the mucous membrane of the nose. In addition, the pear is opaque, which does not allow assessing the success of the procedure;
- mechanical aspirators are transparent, so you can easily determine how the process of mucus suction occurs. They are easy to use: the tip is inserted into the nasal passage, and the adult takes the other end into the mouth and draws in air. The mucus remains in a special reservoir, which is thrown away after use. The tips are quite soft, so the risk of damage to the mucous membrane is minimal;
- electronic devices are considered the safest and most effective. The tip has a stopper that will prevent it from being inserted too far into the spout. The transparent reservoir shows the amount of mucus and its color. In addition, you can use it to rinse the spout with solutions, and its compactness allows you to take it on travel. The only negative is the fairly high cost of the device and its fragility;
- The advantage of a vacuum aspirator is that you can clean the baby’s nasal passages in a matter of seconds. Despite the strangeness of the connection, the device is considered absolutely safe.
Most parents prefer to use a whole complex system to clean their babies' noses: Otrivin baby drops and an aspirator. The droplets have a softening effect, and the aspirator clears the nose of accumulated mucus.
Attention! The Otrivin baby system has a shelf life of 5 years.
Is it possible to clean the nose with cotton swabs?
- the size of this hygiene item is too large for the baby’s nasal passages;
- an inexperienced mother can insert the stick very deeply, which will lead to damage to the mucous membrane;
- Cleaning the nose in this way causes discomfort in the child.
Video: How to clean your nose with the Otrivin Baby nasal aspirator
Using an aspirator to suck out mucus at home: how often can the product be used
Regardless of which type of aspirator you purchase, you should adhere to general recommendations for its use:
- read the instructions;
- Before first use, all removable parts should be sterilized;
- Don’t get carried away with cleaning your baby’s nose too often, as this can lead to drying of the mucous membrane and a decrease in its protective properties. Doctors recommend cleaning your nose every day before going to bed;
- if you are afraid to use an aspirator, you need to ask your health visitor to demonstrate how to properly suck out mucus from a baby;
- After use, all parts that came into contact with mucus are disinfected.
Step-by-step instructions for clearing thick mucus and dry crusts from the nose of an infant: depth of insertion of the aspirator, use of drops
What to do if you have problems using the sucker: blood from the nose, anxiety of the baby
Proper use of the device usually does not cause problems. If during use the baby bleeds or has blood in the discharge, it is likely that the nasal mucosa was injured by the tip of the device.
To stop bleeding, the baby's head is tilted forward, and the affected nostril is lightly pressed against the nasal septum.
To soften dry crusts and thick mucus, the use of saline solutions is recommended. However, you should be careful about the amount of liquid administered, since there is a possibility that it will get into the throat, which will cause a coughing attack in the child and a negative attitude towards the procedure.
If the baby cries during the procedure, you should not torture him. Perhaps you are doing something wrong and causing him pain. Do not forget that all manipulations should be carried out gently, talking to the baby in a gentle voice.
To prevent dry crusts in your baby's nose, use a humidifier. It will maintain the humidity in the room at the required level (30–60%) and protect the child from unwanted health problems.
Video: Doctor Komarovsky on choosing an aspirator for a small child
A nasal aspirator will help new parents clean their baby's nose without any problems. The device will not only remove the accumulation of mucus, dust and dried crusts, but will also provide timely assistance in eliminating rhinitis and preventing the development of dangerous diseases.
Oriental spices, sandalwood bark and a little fruit - this is Addict, a classic scent Christian Dior. Here's what Carven's Ma Griffe smells like: cut grass, fresh leaves and flower buds. It is not easy to distinguish all these notes the first time and without a hint - you need a well-trained nose. Or high technology.
The Portuguese chemist Alirio Rodrigues compiled descriptions of famous perfumes without straining his sense of smell at all. A computer connected to a complex system of sensors tasted perfumes for the scientist. So Rodriguez tested his method of automatic aroma analysis in action. The tests were successfully completed several months ago, and now, the chemist claims, his invention can greatly facilitate the work of perfumers.
Rodriguez is not the only one who has managed to develop an “electronic tasting” system. Over the past few years, researchers have learned to create devices that closely mimic the functioning of the human olfactory and gustatory systems. It is no longer only scientists who are involved in testing; winemakers have begun to participate in experiments.
Here's how they taste scents in Rodriguez's lab: First, the chemist carefully draws eau de toilette or perfume into a syringe and injects it into the receiving hole of the device. For the experiment you need very little liquid - one tenth of a drop hanging on the tip of the needle is enough. The sample enters a special chamber, where it quickly heats up and forms vapor. Then a gas chromatograph and a mass spectrometer come into play - instruments for precise chemical analysis. They allow you to find out what exactly and in what proportions perfumers added to their product. And then - pure mathematics.
The database of the computer that controls the analysis contains information about the smell of thousands of substances often used in perfumery. The Portuguese chemist took the data from catalogs compiled by specialists from perfume companies. Knowing the smell of each ingredient, you can calculate what aroma the entire mixture will have. You just need to take into account the peculiarities of the human sense of smell.
“Even a very good expert can identify at most three or four of the brightest components in a complex odor,” explains Rodriguez. “They determine the aroma.” The nose perceives all other components as minor nuances. This is what the Portuguese chemist uses. Rodriguez's know-how is a computer program created in his laboratory. It calculates which substances make the greatest contribution to the smell of perfume. Here you have to take into account not only the proportions of the ingredients, but also their Chemical properties, such as volatility. As a result, the computer produces a description of the aroma in the form of short definitions: “citrus”, “herbal”, “floral”. These estimates do not differ much from the opinions of experts.
Analyzing the aroma of well-known perfumes is the first steps. Using the new method, it is possible to obtain the characteristics of completely new combinations of aromatic substances. To do this, it is not necessary to prepare the mixture itself - just enter the list of components into the computer and indicate the proportions. “Perfumers create new scents through expensive trial and error,” says Rodriguez. “With the help of virtual tasting, you can quickly select the most suitable recipes, and then work with them the old fashioned way, by hand.” The chemist admits that a computer is not yet able to completely replace a person. The need to constantly refer to catalogs created by experts is the weak point of an electronic perfumer.
In the laboratory of Israeli neurophysiologist Noam Sobel, they are working to teach technicians to evaluate odors completely independently. Sobel and his colleagues are testing an “electronic nose,” a device that simulates the functioning of the sense of smell. This device is a set of miniature chemical sensors that react to organic substances present in the air. Now such devices are used to detect drugs and explosives. Israeli scientists are going to search for new aromas using an electronic nose. To do this, they taught the device to imitate human tastes. A group of 56 volunteers acted as a role model.
Scientists asked laboratory visitors to smell test tubes containing 123 different chemicals and rate their sensations on a special scale. The smells in the experiment were very different. “I tried them all on myself,” says Rafi Haddad, one of the authors of the project. - They smelled the best essential oils citrus plants." The most disgusting thing Haddad had to smell was pure valeric acid. The smell is very reminiscent of two things - “rotten cheese and dirty socks.”
After people gave the substances their ratings, the samples were given to the device to “sniff.” Haddad and Sobel discovered a simple pattern - one group of sensors responded to unpleasant odors for humans, and completely different ones to pleasant ones. Scientists took this observation and wrote a new program for the electronic nose. Now it gives ratings even to odors that it has never encountered before. For example, the device definitely won’t like rotten fruit or acetone, but strawberries will.
Scientists are confident that their system is ready for practical use. The use of such devices will speed up the development of aromatic substances many times over. Chemists are constantly synthesizing new components for perfumes. Perfumers simply do not have time to evaluate them all. “An expert might work on aromatic samples for two to three hours and then need a long rest,” Haddad says. “Automatic analyzers can evaluate odors 24 hours a day.”
It's not just perfumers who can benefit from the use of high technology. Electronic tasters can make life easier for wine connoisseurs. Portuguese chemist Jose Marques is sure of this. He adapted an analyzer of the chemical composition of liquids for tasting Madeira. The device detects organic substances in wine that are formed during the maturation of the drink. Now an electronic taster can determine the age of Madeira with an accuracy of 1.8 years. This is just the beginning. “The next challenge is to teach the device to predict what will happen to ripening wine in the future,” says Marques. For now, only very good specialists can give such forecasts. “An experienced taster only needs to taste young wine once, and he will tell you what it will taste like in a couple of decades,” says the chemist.
Márquez is conducting his research together with the association of Madeira exporters - Madeira Wine Company. The scientific approach to tasting intrigued not only the Portuguese. “We’ve already had several contacts famous manufacturers French cognac,” says Marquez. “They asked us to send our work for review.”
Electronic tongue, which Marquez uses in his work, can be easily adapted for a wide variety of drinks. “All that is needed is to replace some of the sensors,” explains chemist Alisa Rudnitskaya, one of the creators of the device. She began working on the device at St. Petersburg State University, and then moved to Portugal with the development. “In Russia there was no way to find an investor for the project,” she explains. “And here we are already preparing for the commercialization of the device.”
Electronic tongues and noses hold great promise, says American chemist and wine specialist Bruce Zucklein. “In the future, automatic analyzers will be used to control the origin of wine - for example, to find out in which region the grapes from which it was made grew and what variety it was.” All this is now done by professional tasters, but they have their drawbacks. “Even the best experts are subjective in their assessments,” explains Zucklein. “The great advantage of electronics is that they are impartial.” Zucklein now works for the Virginia state government and oversees wine production throughout the region. But he also has his own scientific developments. A few years ago, Zucklein adapted an electronic nose to detect the best time to pick grapes by smell. “This idea came to me as a child - I loved wandering through the vineyards then,” the chemist recalls. “You know, when the berries ripen, their aroma completely changes!” Winemakers have been eyeing Zucklein's research for a long time - some even allowed him to conduct experiments directly in their vineyards. One of these producers is the American winery Pollak Vineyards. The results of the experiments of businessmen are impressive, but they are not yet in a hurry to adopt electronics. “Probably, it’s all about the specifics of this industry,” says the scientist. “You won’t find more conservative people in the world than winemakers!”
The structure of the electronic nose
As a rule, an electronic nose consists of three functional units:
_ sampling systems;
_ matrices of sensors with specified properties;
_ processor processing unit for signals received from sensors.
The test sample is pumped by an air pump into the cuvette compartment, where a ruler or matrix of sensors is installed. There, a portion of the gas mixture is divided into separate fractions, which are driven through a system of special receptors and, depending on the composition and quantity, change themcharacteristics. In one of the electronic nose options, attach- application of a specific molecule to the sensor surface,representing the finest igloo - a cantilever 100 nm thick and 50 microns long causes a change in the resonant frequency due to a change in its mass. Measuring newvibration frequency of the cantilever, the presence of specific groups of molecules can be determined.
The readings of each detector are transmitted toprocessor module. A special program analyzesreceived data and produces results in the form of unique“blots” _ chromatograms (actually these are graphs of odor intensities in the central coordinates).
Figure 121. Visual images of the VaporPrint™ program for
pathogens, explosives,
drugs and flammable liquids
After tasting, flushing vapors are supplied to the system.gas (for example, alcohol) to remove odorous substances from the surface of the sensors and prepare the device for new testing.
th measuring cycle.
The period of time during which the electronic nose sensors analyze the injected air sample is calledresponse time . Modern samples are characterized by fairly high performance. Response time for some of themthey are about 10 seconds.
The period of supply of flushing gas to the cell is calledrecovery time (latent period). Recovery time typically ranges within a minute.
It should be noted that the problem of identifying odors withfrom an algorithmic point of view is quite complex (each odor is a complex complex of chemical connect - niy), therefore, to recognize odor patterns, the system“electronic nose” uses elements of artificial intelligence. In particular, the most promising are considered to be:called artificial neural networks (ANN).
Neural networks are computer simulations of interacting neurons in the human brain and consistfrom a series of interconnected simple processing
information of units – neurons. Layers of neurons that receive external information I call you input, outputting the final result -on weekends, intermediate layers- internal- them, or hidden. In this case, each neuron has several inputs and only one output. The main advantageneural networks is theirlearning ability, that is, the possibility
targeted minimization of output signal errors.
If a medieval king was afraid of becoming a victim of the “game of thrones,” he got himself a court taster. You can imagine with what caution he sniffed the suspicious dish! Now electronic noses and tongues are ready to take on this risky work - devices that can sense the faintest smell of poison, explosives or disease.
In 2014, the European consortium PHOTOSENS presented a prototype of an electronic nose made by nanoimprint lithography. The effect of surface-enhanced Raman scattering makes it possible to obtain precise spectral “fingerprints” of the substances present in the mixture, which are deposited on a specially prepared rough layer of gold.
Valeria Kuzyk
Human perception of smell and taste is even more complex than vision or hearing. The reason for this is the great diversity of receptor cells: in the nose their number reaches 50 million, in the tongue - 400-500 thousand, and each has its own set of sensitive receptors. Upon contact with certain molecules, some of them are activated, exciting the receptor. This signal arrives at “higher” neurons, each of which is connected to many receptor cells at once. Perception creates a specific pattern, a pattern of neuronal activation, that is interpreted by the brain.
The idea to imitate these principles began decades ago. All that was required was to create an “electronic nose” - a set of sensors that, interacting with the gas mixture, would react to various odorant components in its composition. When triggered, the sensors can create a “pattern” of aroma (fingerprint), which can be compared with a set of pre-prepared standards. The “electronic tongue” should act in much the same way, except that the sample in this case will be liquid and the substances will not necessarily be odorous.
Peres “electronic noses” recognize more than a hundred volatile substances in food products, determining their degree of freshness and purity. Lithuanian developers, who presented the concept in 2014, have already brought it to the market under the name FOOD Sniffer.
"Heart" of the nose
The creators of such systems follow two fundamentally different paths. The former achieve high specificity for each sensor in the array, so that each one responds to its own—and only its—connection. The latter, appealing to the principles of brain function, use less “discriminating” sensors that respond to groups of similar molecules. The implication is that if each sensor responds slightly differently, their combined response will form a unique fingerprint. It can already be compared with a set of reference spectra and roughly estimate the content of substances.
But in any case, the key element of electronic noses and tongues is sensors. Their task is to convert a signal that arises in the form of chemical reactions into a form more convenient for recording and interpretation: electrical, chemical, magnetic, temperature... For this, eight main types of sensors are used - conductometric, ampero- and voltmetric, potentiometric, impedometric, piezoelectric and optical (colorimetric and fluorimetric) - based on the principles of chromatography and/or mass spectrometry. The development and implementation of biosensors based on organic polymers and even whole cells is underway.
Elements that operate on different principles are often combined in one device, enriching its capabilities—and making it difficult to interpret the received signal. However, even without this complication, analyzing the data obtained by an array of “electronic nose” sensors remains a difficult task. The latest trend in this area is the use of artificial neural networks. They are especially useful if the result of a particular analysis is unpredictable or there are no precise standards to compare the data with. In the process of learning from test data and tasting something unfamiliar, the connections between individual elements of the artificial neural network will strengthen or weaken, and the “brain” of the device will learn to recognize the new smell.
Nose in milk
It was not in vain that we started with the story of the tasting. Today, testing the safety and quality of food is becoming the “hottest” area for the implementation of these devices. Indeed, it’s one thing to try a piece of a king’s bun, another thing is to check whether a batch of beef is spoiled, whether the wine contains harmful impurities, or whether there are pathogenic bacteria and fungi in the wheat. The chemical and biochemical, microbiological and immunological methods used for this purpose are quite accurate, but not cheap or fast. The latter is especially critical given the current boom in fresh food without preservatives.
Let's imagine a dairy plant producing unpasteurized - "live" - milk. Common pathogens of whole milk are salmonella and listeria, E. coli and shigella, pathogens of brucellosis and campylobacteriosis. Diagnostic bacterial culture will require, at best, two days of time: perhaps, little good will remain from unprocessed milk during this time. However, not just milk. With careful selection of sensors, these electronic noses can quickly evaluate different products. Moreover, production is becoming cheaper, bringing their entry into the mass market closer. For example, the Peres company is already offering to purchase Food Sniffer for less than $150, declaring its ability to detect spoilage or contamination of food with pathogens. But this is clearly just the beginning.
The larger and more complex sensor systems become, the sooner electronic noses and tongues will begin to compete with even professional tasters. There is a rational grain in this: human perception is subjective and capricious, so that in some sensational experiments, even the best specialists, placed in an uncomfortable situation, were unable to distinguish red wine from tinted white, or strawberry yogurt from chocolate. The device will not work differently because you had a quarrel with your wife, didn’t get enough sleep, can’t stand spinach, or there is a dish on the plate that is not very attractive.
Sick smell
The sense of smell is a valuable diagnostic tool in medicine. You can recall a lot of scenes from historical films in which the doctor cautiously sniffs the wound: has gangrene begun? At all infectious diseases and neoplasms are often associated with metabolic changes that can be detected by the sense of smell. For example, the detection of lung and mammary cancer, hypoglycemia and asthma using trained dogs is described, as well as the detection of tuberculosis by trained rats (“Popular Mechanics” wrote about these methods in an article on animal diagnostics, No. 4 "2016. - Ed. ).
The creators of electronic noses were also interested in the smells of the disease. Surely many have heard that the smell of acetone from the mouth can indicate such unpleasant diseases as diabetes or thyrotoxicosis. In addition, ammonia compounds, a sign of kidney failure, can be recorded. The electronic nose can also detect infectious agents, very effectively and at very early stages. For example, a modern immunoassay requires three times more influenza virus envelope proteins than an “olfactory” biosensor using antibodies.
Inspired by the sniffing abilities of sniffing dogs, scientists at the University of Santa Barbara decided to imitate their noses to detect explosives and drugs. All advantages: safety is under control, and there is no need to walk and feed. The resulting “dog-on-a-chip” is a miniature spectrometer-detector, supplemented with nanoparticles that amplify the signal by binding marker molecules (thanks to this, the device is able to detect substances at a concentration of one molecule per billion!). Initially, the “dog-on-a-chip” was conceived as an explosives detector. But it turned out that it is not difficult to “adjust” him to drugs and other illegal substances. Prototypes of the device have already been created at several US universities - it is noteworthy that they are barely larger than a smartphone in size, and some are equipped with Bluetooth, GPS and WiFi modules.
The method did not bypass oncological diagnostics. The most logical application for an electronic nose would be to detect lung cancer. It has long been noted that with this cancer (as well as with asthma, as well as cystic fibrosis), acidification of the exhaled condensate is observed. The simplest electronic tongue can cope with determining changes in pH, giving a quick, although far from unambiguous result. However, by comparing condensate samples from patients and healthy people(as well as building models of these samples), scientists have already identified a spectrum of 17 volatile substances that serve as accurate markers of lung cancer development and can be recognized using mass spectrometry, chromatography and other methods.
Wide profile nose
However, truly discriminating electronic noses may be powered by DNA. As many developers note, these molecules are not particularly selective in recognition, but due to slight differences in structure, they are capable of responding differently to the same compound. DNA offers enormous combinatorial complexity and the ability to easily synthesize a “receptor” molecule from any desired sequence of nucleotides. A working prototype of such a device has already been created; it uses a huge array of DNA molecules associated with fluorescent tags.
Such perfect electronic noses and tongues could become the basis for the development of worthy implants to replace natural ones - or equip robots with them. After all, robot chefs are already working in some kitchens. But to fully replace people, following recipes and being able to operate a frying pan is not enough, and a robotic cook will need to learn how to simply determine the quality of ingredients by smell, and the readiness of a dish by taste. In the future, technology development includes modification and improvement of the sensor part: its sensitivity, selectivity and stability. Particularly active in this process are carbon nanomaterials with their promising properties - single-crystal structure, precisely defined chemical composition and spatial structure, as well as unique characteristics of nanocompounds associated with surface effects. Perhaps it is graphene and fullerene bio- and chemical sensors that should become the next step in the research and commercial application of electronic noses and tongues. And, of course, gadgets have not been canceled either: a Chinese student has already proposed the concept of an electronic nose combined with a small printer. You scan the dish, the device searches the database for a picture associated with its smell, and prints it on a postcard using aromatic ink. Well, why not?
