E NOSE

INTRODUCTION

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.  

       

                                                                                     

    PHYSIOLOGICAL ASPECTS OF SMELL
 

    Before we describe the possibilities of olfactory displays, we should take a glance at the physiological aspects of smell. How does the nose work and what is its function? Naturally we can breath, smell and additionally taste with our nose. First of all we are interested in the anatomy of the nose.

     

    Odor consists of many different molecules, for e.g. the aroma of coffee is made up of 20 various molecules. Nonetheless our nose perceives only 15 odors which is enough to identify the smell as coffee. 

    At first the odor molecules reach the olfactory mucosa. The receptors for the molecules are placed at the olfactory hairs. When the molecules reach the receptors, an electric impulse is sent directly to the brain to the olfactory bulb. Then the information gets to the olfactory glomeruli, a part of the olfactory bulb. The glomeruli is able to associate the information to the intensity. The olfactory bulb consequently processes the odor and can send the impulse to the olfactory brain. We notice that we have a direct connection between our sense of smelling and our brain. Those scent impulses reach the area of our brain that handles emotions and memories. That explains the link between smelling and being reminded of something. 

    We percept smell very individually. Every human perceive a difference between a pleasant and unpleasant odor. Humans are not capable to distinguish odors in terms of intensity. Roughly we can only distinguish between three concentrations of some odor whereas we should actually be able to differentiate 1000types of odors. Another problem for olfactory display is the fast acclimatization of humans to scents.  

    What makes it even more difficult to construct olfactory display is that a set of primary odors has not really been found. There was an attempt to define seven such of primary odors but had to be extended to 100 odors. For vision, three base colors are sufficient to display any color. Unfortunately this cannot be applied to olfaction as our nose has thousands of receptors and apart from that the odors are not orthogonal. That means you will not necessarily get a new one by mixing two odors. Due to these big problems there is still research in examining our scent.                                   

    

    ELECTRONIC NOSE

          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                                                                      

1. POLYMER 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. 

2. QUARTZ SENSOR 

      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.

    

3. MOSFET 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. 

4. OPTICAL FIBRE SENSORS 

          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.
                                                                                                 

      APPLICATIONS OF ELECTRONIC NOSE 

      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.
 

E-NOSE: ADVANTAGES AND DISADVANTAGES

ADVANTAGES

          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.

DISADVANTAGES

     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.     









 

DIGITAL SCENT COMMUNICATION 

      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 

     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.

CATRIDGE USED IN PERSONAL SYNTHESIZERS

     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.   

                                                                                                           

                                                                                                    Anode

                                                             Outlet                    Cathode   Electrolyte
 

                                                                       
 

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.

                                                                                                                  

AIR CANNON
 

     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.

  

FIRST PROTOTYPE 

     It is simply an elementary electromechanically driven air cannon equipped with a scent generator. It consists of an acrylic box, a scent diffuser and an air pump. The acrylic box is endowed with an aperture at the front and a rubber membrane at the back. The rubber membrane is pushed by two solenoids in parallel. The scented air is injected near the aperture so that the injected air could be immediately launched from the aperture. 

 
 

     Using this prototype, we could display the scent to a restricted area approximately 1m away from the air cannon. The scent is recognized only by the target user.
 

SECOND PROTOTYPE 

     A noise tracking feature is added in the Second prototype system. The system consist of a camera, an air cannon, a set of control circuits and a personal computer for vision based nose tracking and platform control.

  

     A vision based nose tracker was used to detect and track the target user’s nose position. After detecting the position of both the eyes, the nose position was detected by searching for the brightest spot within the estimated region in which the nose exists. Once the nose position was detected, the system traces the nose position by template matching and finding the brightest spot.

  

  An ELMO QN 42H micro CCD camera is used for image capturing. The camera was placed just above the air cannon. The nose tracker could trace the nose position at video rate, i.e. 30 times per second.

    

      The detected nose position was then converted to the desired orientation of the air cannon, which is fed to the motor driver. The platform that carries the air cannon has 2 degrees of freedom and is equipped with a dc motor and a potentiometer for each axis. The rotation speed was 60 degree per second for pan and 75 degree per second for tilt when driven at the rated control voltage. The outputs of potentiometers are used for position control at the motor drivers. With this configuration, the air cannon could continuously trace the nose of the seated user, even if he moved his upper body. 

     The design of second prototype is nearly equivalent to that of first, except that the driving unit replaces the loud speaker used. This change was intended to suppress the sound when the solenoids impacted the plate attached to the rubber membrane. The scent generator is also same as the first. The operator activates the scent generator before he launches the clump of scented air.

THIRD PROTOTYPE 

     A scent switching mechanism is incorporated in the third prototype system. In the previous prototypes, we could present only a single kind of scent to the user because some portion of scented air diffuse into the air cannon body, where it was difficult to eliminate previously injected scent.  

       To solve this problem, they attached a short cylinder with the same diameter as the aperture of the air cannon and equipped with mechanical shutters at both the ends. There are 5 holes on the surface of the cylinder for air intake and evacuation. A tube is connected to each hole, through an air valve to a pump. There is also a valve on the body of the air cannon for intake of fresh air. 

        The body of air cannon is composed of a bellows so that it can generate a larger volume change for its entire size. A stepping motor is used to drive the crank for pushing the bellows.  

        The system is also equipped with 2-degrees of freedom platform and a CCD camera. The pumps and valves are controlled through controller units that communicate with the PC via an RS232C communication line.

 
 

     The ATR Media Laboratories demonstrated this system at the ATR Research expo. They succeeded in delivering different smells with each shot of air cannon. Most the visitors could tell the difference between these odors.

FUTURE WORK 

     They proposed a naval configuration of an olfactory display that does not require user’s to put anything on the face and that localizes the effective space of the displayed scent. The technical key to realizing this concept is to transfer a clump of scented air from a place near the nose, and we confirmed that this is possible by using air cannon. The constructed prototype system successfully displayed the scent to the target user, even if the user moved his head. 

     They are going to propose another choice in methods to enjoy scent in interactive applications. The wider the variety of olfactory displays, the wider the variety of applications will emerge to make our VR experience rich and realistic. 

     Improvement of scent generation is necessary to extend the variety of displayed scent and we can learn a lot from preceding research efforts on scent blending and generation. Also precise theoretical analysis of a toroidal vortex might be effective for optimal design of the air cannon. They are planning a step by step in order to construct a transparent, easy to use olfactory display system.

APPLICATIONS 

APPLICATIONS FOR SCENT ON THE WEB 

     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. 

E-COMMERCE   

     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. 

ADVERTISING 

     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. 

COMMUNICATIONS 

       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. 

EDUCATION 

      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. 

MEDICINE 

      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.
 

ENTERTAINMENT 

      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.

CONCLUSION 

     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.