SMELL OF SUCCESS FOR NANO BIOSENSORS D.Sowmya ( ) INTERNAL GUIDE:Mrs.Sunitha Reddy

Introduction What is biosensor? An analyte is a substance or chemical constituent that is determined in an analytical procedure like while in blood glucose testing, the analyte is glucose A biosensor is a device for the detection of an analyte which that combines a biological component with a physicochemical detector component

What is smell of success for Nano biosensors? Modern-day doctors may soon start using smell to detect the early warning signs of different illnesses thanks to technology that replicates - and improves upon - the human olfactory system thanks to tiny bioelectronic sensors. These nanobiosensors will react to a few molecules of odorant with a very high degree of accuracy. These tiny bioelectronics sensors represent a ‘major leap forward’ in smell technology.

What is electronic nose? An electronic nose is a device intended to detect odors or flavors. Over the last decade, “electronic sensing” or “e-sensing” technologies have undergone important developments from a technical and commercial point of view. The expression “electronic sensing” refers to the capability of reproducing human senses using sensor arrays and pattern recognition systems

Why electronic nose? Think of the day when we can retire those dogs that go around sniffing bags and people for bombs or drugs, possibly irritating the people who are being targeted at. Instead, we have this machine overhead scanning and “sniffing” for bombs and drugs An electronic nose basically detects chemicals in the air, given off by odorous substances, and finds a pattern of the chemicals to determine what the smell in the air is.

Human smell system and molecules The olfatory system has mucus membrane which contains small segments, nerve cells, the actual sensory organs. The dendrites, some type of fiber, are covered from the nerve cells to nasal cavity with a thin layer of moisture. The smell particles are the source of what we smell. The moisture dissolves microscopic particles that are carried in by air from the odor-emitting substance to the nose The dissolved particles in the mucus stimulate the olfactory nerve cells through chemical reactions.

Electronic nose working principle A sample delivery system:enables the generation of the headspace (volatile compounds) of a sample, which is the fraction analyzed. A detection system:which consists of a sensor set, is the “reactive” part of the instrument. When in contact with volatile compounds, the sensors react. A computing system:works to combine the responses of all of the sensors, which represents the input for the data treatment

Performing analysis As a first step, an electronic nose need to be trained with qualified samples so as to build a database of reference. Then the instrument can recognize new samples by comparing volatile compounds fingerprint to those contained in its databaseto perform analysis. Odour handling system Sensor array chamber Signal conditioning Data aquistion Signal processing

Block diagram

Application At the space station-for detecting ammonia at few parts of million(ppm). Working: All of the polymer films on a set of electrodes (sensors) start out at a measured resistance, their baseline resistance. If there has been no change in the composition of the air, the films stay at the baseline resistance and the percent change is zero e-e- e-e- e-e- e-e- e-e- e-e-

If a different compound had caused the air to change, the pattern of the polymer films' change would have been different: e-e- e-e- e-e- e-e- e-e- e-e- e-e- e-e- e-e- e-e- e-e- e-e- The Electronic nose smells something

More applications These include with an example of using dogs to detect to sniff out bombs, drugs, or fugitives. Another useful usage of electronic noses is measuring environmental contamination and detect hazardous chemicals identifying chemical spills, diagnose strep infection, hunt for truffles, keep toast from burning, or detecting bad batches of food or drink. Currently we have humans to test for quality of foods, beverages, perfumes, tobaccos, washing powders, or even air quality, but using human testers is expensive and is prone to errors since human sense of smell may change with age, health, or diet

Cyrano Sciences A company that currently produces electronic noses is Cyrano Sciences. Cyrano Sciences makes handheld electronic noses that use a type of polymer technology licensed from California Institute of Technology (CalTech )

Problems in development of e-nose Firstly classification of smell is based on subjective perception such as this odor smells fruity, which is imprecise. The second major problem is classification of the physiochemical properties describing each molecule will be huge. Smell composing of similar compounds with slightly different ratios of each of these compounds will result in a different smell. Ex:Coffee, tea, and cocoa all contain the same 670 compounds with different ratios and to a normally functioning nose, each beverage drink smells differently.

Conclusion In conclusion, electronic noses can be very beneficial to our everyday life.. A more precise electronic nose might one day be used to “smell” viral or bacterial infections. With the development and usage better electronic noses, the days using dogs to sniff bombs and drugs passing through our airports will soon be over.

References se.htm se.htm cns- web.bu.edu/pub/laliden/WWW/Papers/nose.html