Digital Scent Technology - Seminar Report

Digital scent technology

     Until now, online communication involved only two of our senses, sense of sight & sense of hearing. Soon it will involve the third, the sense of smell using an e-nose. Digital scent technology is the main application of e-nose. With digital scent technology, it is possible to sense, transmit& receive smell through internet. There is complete software and hardware solution for it. When applied to communications, scent becomes a new information channel. It allows us to perceive products and irate a previously unimagined emotionality and product credibility. Scents extend the myriad of multimedia possibility towards a new level. Scent communication will be one of the most important information tools of the future. 


      Until now online communication involved only two of our senses, sense of hearing and sense of sight. Soon it will involve the third, the sense of smell. A new technology is being developed to appeal to our sense of smell. Bringing alive our experience, technology now targets on the sense of smell.

     Using Electronic-nose we can sense a smell and with a technology called Digital scent technology it is possible to sense, transmit and receive smell through internet, like smelling a perfume online before buying them, sent scented E-cards through scent enabled websites, and to experience the burning smell of rubber in your favorite TV games etc.

     If this technology gains mass appeal no one can stop it from entering into virtual world. Just imagine you are able to smell things using a device connected to your computer. With Digital scent technology this can be made a reality. There is complete software and hardware   solution for scenting digital media and user.

Basic principle of E-nose

     An electronic nose can be a modular system comprising of active materials which operate serially on an odorant sample. These active materials can be classified into two: an array of gas sensors and a signal processing system.

      The output of the electronic nose can be the identification of the odorant, an estimation of the concentration of the odorant or the characteristic of the odor as might be perceived by the human.
     Fundamental of artificial nose is that each sensor in the array has different sensitivity. The pattern of response across the sensors is distinct for different odors. This distinguishably allows the system to identify the unknown odor from the pattern of sensor responses. The pattern of response across all the sensors in the array is used to identify the odor. Different e-noses use different types of gas sensors which form heart of e-nose.

Sensing an odorant
      In a typical e-nose, an air sample is pulled by a vacuum pump through a tube into a small chamber housing the electronic sensor array. Next the sampling handling units exposes the sensors to the odorant, producing a transient response as the VOCs interact with the surface and bulk of sensor’s active material. A steady state condition is reached in a few seconds to a few minutes.
     During this interval, the sensor’s response is recorded and delivered to the signal processing unit. Then a washing gas such as alcoholic vapor is applied to the array so as to remove the odorant mixture from the surface and bulk of sensor’s active material. Finally a reference gas is again applied to the array to prepare it for a new measurement cycle. The period during which odorant is applied is called the response time of the sensor array. The period during which washing and reference gases are applied is called the recovery time.
      The sensor’s response is converted into electronic signal by using a transducer and is processed by using the signal processing unit.

Types of sensors
Electronic nose sensors fall into four categories. They are
1. Polymer sensors
2. Quartz sensors
3. MOSFET sensors
4. Optical fiber sensors                                                                    

     The working of polymer sensors is based on the change in conductivity of the polymer when the odorant is applied. Response time is inversely proportional to the polymers thickness. The main drawback of this method is that it is difficult and time consuming to electro polymerize the active material, so they exhibit undesirable variations from one batch to another.

Here the vibration of the quartz is changed by a contact between the molecules and the surface. The response and recovery times are minimized by reducing the size and mass of quartz crystal along with the thickness of the polymer coating. The main disadvantage is that they have more complex electronics than of polymer sensors.

These are based on the principle that VOCs in contact with a catalytic metal can produce a reaction on the metal. The reaction products can diffuse through the gate of the MOSFET to change the electrical properties of the device. The sensitivity and selectivity of the device can be optimized by varying the type and thickness of the metal catalyst and operating them at different temperatures. The advantage is that they can be made with IC fabrication so that batch to batch variations can be minimized.

    A light source of single frequency is used to interrogate the active material, which in turn responds with color change in the presence of VOCs to be detected and measured. The active material contains chemically active fluorescent dyes immobilized in an organic polymer matrix. As VOCs interact with it, polarity of the fluorescent dyes is altered and they respond by shifting their fluorescent emission spectrum.
           These sensors are cheap and easy to fabricate. The disadvantage is that fluorescent dyes are slowly consumed by the sensing process.
The electronic nose has been used in a variety of applications and could help solve problems in many fields.
 The electronic nose can be applied by food manufacturers to such tasks such as freshness testing, quality screening of incoming raw material, and monitor for accidental or intentional contamination. 
   In the medical field, e nose has a variety of application such as rapid diagnosis of acute infection through breath analysis and screening of bacterial cultures for early detection of pathogens.
     E-nose can serve in safety and security applications such as hazard alarm for toxic and biological agents, screening airline passengers for explosives and drugs.
     Its military applications include land- mine detection, biological and chemical agent detection etc.



          It can be used without fall over hours, days, weeks and even months and can even circumvent problems associated with the use of human panels such as individual variability, adoption, fatigue mental state and exposure to hazardous material. The e-nose is a compact device and so it is portable and reliability is very high. It can identify simple molecules which cannot be accomplished by human nose. It can identify a smell objectively.


     There are a few disadvantages to the e-nose technology which includes the price.
     The cost of an e-nose ranges from $5000 to $100,000. Another disadvantage has been the delay between successive tests, the time delay ranging between 2 to 10 minutes during which time, the sensor is to be washed by a reactivating agent, which is applied to the array so as to remove the odorant mixture from the surface and bulk of the sensors active material.    

      The e-nose detects the smell molecules and it is indexed based on two parameters. The scent is indexed according to its chemical make up and its place in the scent spectrum. The chemical make up can be detected by the electronic nose which otherwise act as the receiver. Like the color spectrum, there is also scent spectrum and any smell will be the indexed smell of primary smells in the scent spectrum. The indexed scent is digitized into a small file by olfactory signal processing. This file is sent as an attachment to the recipient’s computer. At the receiving end, there will be a personal scent synthesizer and air cannon. The personal scent synthesizer reproduces the smell and the air cannon direct the smell to user’s nose. The data about the smell is given by the digitally encoded file which is transmitted. The smell emitted will be in the form of vapors.

     Scent synthesizers are devices which are used to generate the smell in accordance with the digitized file that is transmitted through the web. The scent synthesizers are interfaced with our PC through a USB port. It can be programmed or installed and it generates a small quantity of smell vapors into the surrounding that is enough to feel the smell. All scent synthesizers will have a removable cartridge which is used to mix different primary odors in different scent synthesizers. Digi scent is the company which identified the most number of primary scents about 128 primaries and they could create up to 1000 smells using these primaries.


     The personal synthesizers that produces the desired smell has a cartridge inside it which is disposable as the chemical inside it wear out. Different types of cartridges are manufactured according to the primary smells it can contain.
      There will be 19 types of smell creating chemicals in the cartridge and by using different proportions of these smells we can create many secondary smells. The principle of operation of each cartridge is the same.   

The cartridge use direct molecular heating or static heating technology. The cartridge shown above has a container whose sides are made up of glass plate. The electrodes can be arranged as follows. There is a common cathode which is situated at the bottom. The container has 19 partitions and separate anodes are dipped into each partition. The electrolytes taken in each separate partition are chemicals which could produce the primary smells. The chemicals are either derived from bacteria or from plants. These electrolytes contain those odor molecules which could lock with the proteins triggering the neuron, which sends a signal that the brain recognizes the smell.

     These chemicals are partially conducting. Also electrolytic heating of these chemicals is used here. All electrolytes should be heated simultaneously. When dc voltage is given across the electrodes the electrolyte will start to get heated. According to the different anode voltages applied across each anode, the electrolyte get heated differently and the heated electrolyte from each chamber produces different volatile molecules in different proportions to give different smells. The amount of heating is restricted by the current flow through the anode which is in accordance with the data file encoded about the particular scent. The different primary smell proportions produced by different chambers are combined to give a particular smell.

     One of the problems of olfactory display is that users would have to wear something on their faces to smell the odor. The air cannon will help us to solve this problem. Air canon is used to transport the scented air directly to the user’s nose without the help of any head mounted device. The user and the air cannon are standing in a remote position and the scent is aimed at the user. The distance between the user and the air cannon is about 1-2m. The user can freely move. The air cannon aim directly at the user’s nose. The odor will not simply diffuse into a room. This prevents that everyone staying in the room from smelling as the target person notices the odor. This way directed delivery of scent is provided with a device that is located on your table, not on your head.
The air cannon consist of

  1. Face tracker
  2. Air clump launcher
  3. Scent generator
     The ATR Media Information Science Laboratories developed 3 prototype systems of air cannon.


     In addition to revolutionizing gaming, digital scent technology will bring consumers more life like and memorable experiences with scented movies and music, websites, e-mail, e-commerce and online advertising.

     Scent will bring the online shopping experience to life. Scent-enabled shopping sites will be more compelling if you can actually smell perfumes, flowers, food and beverages, cigars and exotic place.

     Vendors of food, cosmetics, home care products and travel related services can use scent to make advertisements more engaging and memorable. Eventually, like musical jingles and graphical logos, scented banner ads will make it possible to communicate the key feature of scented products or to simply evoke a certain feeling.

       Scent offers developers as well as consumers another medium for creativity and self-expression. For eg: scented websites, electronic greeting cards and        e-mail. With smell technology you can travel anywhere in the world or to any time period in the past.

      Scent is an effective teaching tool for subjects such as Geography, History and Sciences. With digiscents technology, you can travel anywhere in the world or to any time period in the past.

      Aromatherapy is a kind of curing certain diseases by using different types of smell. It helps in identifying dementing brain disorders including Huntington’s and Parkinson’s and for differentiating them from other mental disorders. This method is based on detecting the olfactory defaults that are diagnostic of the dementing diseases.

      Scent will make music, movies and interactive games life like and immersive. Scent tracks will be synchronized with movies, much liked musical score and sound track, in order to create foreshadowing and to establish atmosphere, mood, sense of place and character.

     New medium in the world of communication: scent. Scents have an immediate and compelling effect. They touch our soul, consciously or unconsciously, and allow us to fell deeply. Scents are unambiguous and unmistakable. The integration of all the senses, in how we create and imagine the universe of goods, is becoming more important. The consumer is always searching for experiences. Enter into a new form of dialogue with your customers. Offer him a cache of new impulses to purchase, through the power of scent.

       When applied to communication, scent becomes a new information channel. It allows us to perceive products and create a previously unimagined emotionality and product credibility. At the same time seeing and hearing, scents extend the myriad of multimedia possibilities to a new level? Scent communication will be one of the most important information tools of future.

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