SEMINAR REPORT ON BIOSENSORS

Presented by: Faisal Ahmad B.E. 7th Semester Enroll. No.1122 Deptt. of ECE

ACKNOWLEDGEMENT

I am highly gratified to Almighty(the most beneficial andmerciful) by whose grace I am at the present position.

I would like to thank our Principal Dr. N.A. Shah for helping us from time to time.

I would also like to thank our H.O.D. Mr. Ghulam Jeelani and seminar incharge Mr. Manzoor Mir for their suggestions and valuable guidance.

I am also deeply indebted to my parents and friends for their affectionate encouragement and support all through my career.

Faisal Ahmad 7th Semester Deptt. of E & C

Parihaspora, Pattan

Certificate

This is to certify that Faisal Ahmad under Enrollment

No.1122 of B.E. 7th Semester Electronics & Communication has

successfully completed the seminar report entitled “Biosensors”

for partial fulfillment to the award of Bachelor of Engineering in

Electronics & Communication by University of Kashmir.

Seminar Incharge HOD ECEMr. Manzoor Mir Mr. Ghulam Jeelani

CONTENTS

Introduction

History

Recent Developments

Definition of Biosensors

Structure

Features

Applications

Advantages & Disadvantages

Conclusion

Future of Biosensors

INTRODUCTION

Improvement of "life quality" is one of the most important

objectives of global research efforts. Naturally, the quality of life is

closely linked to the control of diseases, food quality and safety, and

quality of our environment. In all these fields a continuous, fast and

sensitive monitoring is required to control key parameters.

The physician, environmental scientist, public health official,

industrial chemist and battlefield commander often have an urgent

need for precise measurements of minute quantities of substances in

blood, water, food, or other materials. Securing precise measurements

of minute quantities has traditionally required an extended time. Now,

however, new hybrids of biological and electrochemical components

seem likely to be the foundation of equipments providing highly

precise, nearly instantaneous measurements of substances in blood,

water, air, and soil.

Workers in hazardous environments such as mining are

continuously exposed to dynamic and unpredictable hazardous

conditions. For instance, slipping and tripping hazards are created by

mine conditions such as water, mud, uneven floors and mine floor

obstacles. Moving machinery in the confined mine environment creates

pinning and striking hazards. These environments also have limited

visibility due to line-of-sight restrictions, poor lighting, airborne dust

and smoke. Workers must be able to constantly monitor their

hazardous environments in real time so that they can be aware of

impending and existing dangers.

The youthful but rapidly developing device which promises to

revolutionize analytical procedures is the Biosensor. Biosensors, which

come in a large variety of sizes and shapes, are used to monitor

changes in environmental conditions. They can detect and measure

concentrations of specific bacteria or hazardous chemicals, they can

measure acidity levels (pH), biosensors can use bacteria and detect

them, too.

Biosensors promise more than a mere streamlining of the slow,

laborious process of identifying and measuring substances. They are

the key to number of advances in medical and scientific technology.

Researchers continue to exploit the potential of biosensors in

speeding new drugs trials, monitoring and regulating time released

medication, as well as the higher profile use of detecting toxic agents

and explosives that are the deadliest weapon in the arsenals of terrorists

and rogue states. Biosensors, combining a biological, recognition

element and a suitable transducer, represent very promising tools in

this context.

HISTORY

The idea for the first biosensor was conceived by Leland Clark in the

1960s and was based on trapping the enzyme glucose oxidase, which

catalyses the oxidation of glucose, at an oxygen electrode using a dialysis

membrane. The concentration of glucose present would then be

proportional to the measured decrease in oxygen concentration. The

biosensor itself developed around this idea would keep track of the

electrons passed through the electrode during the reaction and measure

the charge.

This technique was later changed to one which measured hydrogen

peroxide concentration instead, which is a product of the reaction. This

change was made due to possible variation of oxygen concentration in the

operating environment.

Three different generations of biosensors can be identified throughout the

history of these devices. In the first generation, the oxygen, acting as an

“electron shuttle”, diffused directly to the transducer and created the

electrical response. Faster second- generation devices used an artificial

“electron mediator” in place of oxygen to improve the response.

In third-generation devices, direct electron transfer from the reaction

causes the response without any need for diffusion of product or

mediator. Although the original biosensor design involved using an

enzyme as the biological response element, many other systems have

since been incorporated into biosensors, such as ligand binding and

antigen-antibody reactions.

RECENT DEVELOPMENTS

Now there are many developments with biosensors. Oak Ridge National

Laboratory (ORNL) has just recently developed a biosensor that follows

calcium ion levels. This could be very instrumental in detecting and

diagnosing diseases and may be useful in areas of chemical warfare.

“This biosensor consists of an optical fiber to which is attached a

synthesized hybrid molecule. One half of the hybrid molecule binds

calcium ions and the other half fluoresces when calcium ions are bound to

the molecule.”

Right now researchers at the National Cancer Institute are designing a

biosensor that if injected in to the bloodstream will hunt for cancerous

cells and destroy them. This will also enhance the care a doctor can give

to a patient. The doctor will be able to more closely and accurately

follow the patient’s reactions to therapy and they will also be able to get a

better image of the cancerous cells. Learning that the cells surrounding

cancerous cells experience many changes helped the researchers at NCI

to be able to work with this biosensor. For example the cells in the

mouth can be changed molecularly by tobacco and this might help predict

that the person has lung cancer.

NASA is also working on a biosensor for cancer because in the year 2020

they plan to send humans to Mars. However, the trip is very damaging to

the human body and could prove fatal. So in order to make this trip,

something must be done to stop the effects of microgravity on the major

systems of the body (skeletal, muscular, neural, and immune). Also there

needs to be some means of detecting infections and diseases before they

get out of control. A program just got started two years ago to do the

research necessary to detect cancer early. NASA eventually wants to put

a dose of medicine on the array of biosensors they are trying to make for

this trip so that the diseases can be cured while in space. Which is a more

effective method that just destroying the cells.

Technical Definition for Biosensors

Any detection device that incorporates a living component or product

derived from living systems to provide an indication, signal or other

form of recognition of the presence of a specific substance in the

environment. The biological indicator or component of a biosensor

may be an intact organism such as a sample of bacterium.

A biosensor is a device for the detection of analyte that combines a

biological component with a physicochemical detector component.

A biosensor is a device that detects records and transmits information

regarding a physiological change or the presence of various chemicals

or biological materials in the environment. More technically, a

biosensor is a probe that integrates a biological component, such as

whole bacterium or a biological product (e.g., an enzyme or antibody)

with an electronic component to yield a measurable signal.

The term 'biosensor' is often used to cover sensor devices used in order to

determine the concentration of substances and other parameters of

biological interest even where they do not utilize a biological system

directly, but it should be recognized that other biological systems may be

utilized by biosensors, for example, whole cell metabolism, ligand

binding and the antibody-antigen reaction.

Biosensor consists of 3 parts:

the sensitive biological element (biological material (eg. tissue,

microorganisms, organelles, cell receptors, enzymes, antibodies,

nucleic acids, etc), a biologically derived material or biomimic)

The sensitive elements can be created by biological engineering.

These elements interact selectively with the target analyte, assuring

the selectivity of sensors.

the transducer or the detector element (works in a physicochemical

way; optical, piezoelectric, electrochemical, etc.) that transforms

the signal resulting from the interaction of the analyte with the

biological element into another signal (i.e., transducers) that can be

more easily measured and quantified. The traditional transducers

are electrochemical, optical and thermal. Electrochemical

transducers measure changes in current or voltage; optical

transducers measure changes in fluorescence, absorbance or

reflectance; and acoustic transducers measure changes in frequency

resulting from small changes in mass bound to their surface.

associated electronics or signal processors that is primarily

responsible for the display of the results in a user-friendly way.

The selectivity of the biosensor for the target analyte is mainly

determined by the biorecognition element, whilst the sensitivity of the

biosensor is greatly influenced by the transducer.

STRUCTURE

Schematic diagram showing the main components of a biosensor is

shown. The biocatalyst (a) converts the substrate to product. This reaction

is determined by the transducer (b) which converts it to an electrical

signal. The output from the transducer is amplified (c), processed (d) and

displayed (e).

The electrical signal from the transducer is often low and superimposed

upon a relatively high and noisy (i.e: containing a high frequency signal

component of an apparently random nature, due to electrical interference

or generated within the electronic components of the transducer) baseline.

The signal processing normally involves subtracting a ‘reference’

baseline signal, derived from a similar transducer without any biocatalytic

membrane, from the sample signal, amplifying the resultant signal

difference and electrically filtering (smoothing) out the unwanted signal

noise. The relatively slow nature of the biosensor response considerably

eases the problem of electrical noise filtration. The analogue signal

produced at this stage may be output directly but is usually converted to a

digital signal and passed to a microprocessor stage where the data is

processed, converted to concentration units and output to a display device

or data store.

FEATURES

A successful biosensor must possess at least some of the following

beneficial features:

1. The biocatalyst must be highly specific for the purpose of the

analyses, be stable under normal storage conditions.

2. The reaction should be as independent of such physical parameters

as stirring, pH and temperature as is manageable.

3. The response should be accurate, precise, reproducible and linear

over the useful analytical range, without dilution or concentration.

It should also be free from electrical noise.

4. If the biosensor is to be used for invasive monitoring in clinical

situations, the probe must be tiny and biocompatible, having no

toxic or antigenic effects.

5. The complete biosensor should be cheap, small, portable and

capable of being used by semiskilled operators.

6. There should be a market for the biosensor.

APPLICATIONS

There are many potential applications of biosensors of various types. The

main requirements for a biosensor approach to be valuable in terms of

research and commercial applications are the identification of a target

molecule, availability of a suitable biological recognition element, and

the potential for disposable portable detection systems to be preferred to

sensitive laboratory-based techniques in some situations. Some examples

are given below:

Ring Sensor

It is a pulse oximetry sensor that allows one to continuously monitor

heart rate and oxygen saturation in a totally unobtrusive way. The device

is shaped like a ring and thus it can be worn for long periods of time

without any discomfort to the subject. The ring sensor is equipped with a

low power transceiver that accomplishes bidirectional communication

with a base station, and to upload data at any point of time.

Each time the heart muscle contracts, blood is ejected from the ventricles

and a pulse of pressure is transmitted through the circulatory system. This

pressure pulse when traveling through the vessels, causes vessel wall

displacement which is measurable at various points. In order to detect

pulsatile blood volume changes by photoelectric method, photo

conductors are used. Normally photo resistors are used, for amplification

purpose photo transistors are used.

Light is emitted by LED and transmitted through the artery and the

resistance of photo resistor is determined by the amount of light reaching

it. With each contraction of heart, blood is forced to the extremities and

the amount of blood in the finger increases. It alters the optical density

with the result that the light transmission through the finger reduces and

the resistance of the photo resistor increases accordingly. The

photoresistor is connected as a part of voltage divider circuit and

produces a voltage that varies with the amount of blood in the finger and

voltage that closely follows the pressure pulse.

Ring sensor is used for wireless supervision of people during hazardous

operations e.g: military, fire fighting, overcrowded emergency. It is also

used for monitoring the hypertension and chronic surveillance of

abnormal heart failure. It can be used for continuous monitoring and is

easy to use.

Medical telesensor chip

A chip on your fingertip may someday measure and transmit data on your

body temperature. An array of chips attached to your body may provide

additional information on blood pressure, oxygen level, and pulse rate.

These chips may be attached at various points on a soldier using a

nonirritating adhesive like that used in waterproof band-aids. These

medical telesensors would send physiological data by wireless

transmission to an intelligent monitor on another soldier's helmet. The

monitor could alert medics if the data showed that the soldier's condition

fit one of five levels of trauma. The monitor also would receive and

transmit global satellite positioning data to help medics locate the

wounded soldier.

Microcantilevers

An interesting alternative to the optical fiber is the microcantilever,

which measures the presence of substances by nonoptical methods. It can

act as a physical, chemical, or biological sensor by detecting changes in

cantilever bending or vibrational frequency. Microcantilevers are a

million times smaller but molecules adsorbed on a microcantilever cause

vibrational frequency changes.

Schematic of a microcantilever sensor, which can be adapted to detect physical, chemical, or biological activity.

Viscosity, density, and flow rate can also be measured by detecting

the changes in vibrational frequency. Another way of detecting molecular

adsorption is by measuring curling of the cantilever due to adsorption

stress on just one side of the cantilever. Because of the small size

and;versatility of the microcantilever, arrays of sensors can be fabricated

on a single chip to conceptually mimic the five sensory facilities: sight,

hearing, smell, taste, and touch.

Detecting Cancer and Health Abnormalities

Another type of biosensor uses sophisticated technology to detect a

specific trait or abnormality in a living organism. A new laser technique

for nonsurgically determining whether tumors in the esophagus are

cancerous or_benign.

Of these biosensors, the most publicized is the optical biopsy sensor. In

the past, determining accurately whether a patient has cancer of the

esophagus has required surgical biopsy. However, our laser-based

fluorescence method has eliminated the need for biopsy, reducing pain

and recovery time for patients.

Miniaturized Devices

Another class of biosensors uses various techniques to turn a

biological system into a tiny electronic device, to analyze biological or

physiological processes, or to detect and identify bacteria. Some of

these techniques produce or are carried out in miniaturized devices.

The best known miniaturization feat is "lab on a chip".

Body Sensors

Wearable body sensor systems are available to continuously measure

and monitor the physiological conditions of workers in real time. Body

Media has produced a wearable body sensor system that acquires,

analyzes, transmits and stores physiological data such as energy

expenditure, duration of physical activity, number of steps, distance

traveled, sleep/walk states, movement, heat flux, skin temperature and

galvanic skin response. The system is used mainly as a health and

safety research tool. For instance, industries can use Body Media

system to monitor the activity level and energy expenditure trends of

their shift workers. The data obtained can be used to reduce job-related

fatigue and improve the economic design of equipment. Fatigue is a

significant health and safety hazard for shift workers in general, but it

is of special concern for miners who must keep alert to recognize

moving machinery hazards, slip hazards and potential falls of ground

from the roof, ribs and back areas. The Body Media system has

applications beyond that of a research tool. For instance, the system

can monitor workers and alert them of potentially dangerous

physiologic conditions from over-exertion. This same application

crosscuts to first responders such as firefighters who while wearing

protective equipment, expend large amounts of energy for sustained

periods in hazardous atmospheres of heat and smoke. The Body Media

system can also be used in person down applications. The

physiological data can be used to indicate that a person has become

incapacitated because of an accident or a health condition. The system

would then wirelessly alert other workers or rescue personnel of the

worker’s condition.

Anthropometry

Perhaps the most unusual biosensors are a new technique to measure

human body surfaces. Such measurements, called anthropometry, are

used by tailors, artists, and scientists. Its accuracy could facilitate the

creation of clothes that fit.The accuracy of the measurements is within

1 mm.

Application of biosensors in heavy metal detection

As environmental concentrations of heavy metals are reduced, increasing

sensitive analytical methods are required to monitor their distribution. In

this respect biosensors are useful analytical tools since they are able to

monitor the available fraction of heavy metals, whish is considered to be

the one that actually interacts with the biorecognition element (e.g.

receptor, enzyme). A new biosensor to monitor explosives such as TNT

and RDX has been developed by the US naval research laboratory.

Environmental applications of biosensors

Environmental applications e.g. the detection of pesticides and

river water contaminants, Detection of pathogens. Other promising

applications for environmental biosensors include groundwater

monitoring, drinking water analysis, and the rapid analysis of extracts of

soils and sediments at hazardous waste sites.

Food Analysis

Determination of drug residues in food, such as antibiotics and growth

promoters, particularly meat and honey.

Optical biosensors help spot bird-flu

Current methods of identifying infected flocks suffer from a series of

disadvantages such as high costs, long processing times and low

sensitivity.

On 1st September 2005 bird flu was declared to have out broken

and it was conveniently spotted with help of optical biosensors. A low

cost and portable optical waveguide sensor could help control avian

influenza during an outbreak.

Bioreporters

Yet another example of a biosensor is based on detection of light emitted

by specially engineered microorganism that is involved in biomediation.

Biomediation can be defined as any process that uses microorganisms or

their enzymes to return the environment altered by contaminants to its

original condition.

ADVANTAGES

The International Union of Pure and Applied Chemistry (IUP AC)

is defining biosensors as a subgroup of chemical sensors in which a

biologically based mechanism is used for analyte detection but these

devices have several advantages over other sensors. Some of them can be

mentioned as:

One characteristic of biosensor that distinguishes them from other

bioanalytical methods is that the analyte tracers or catalytic products

can be directly and instantaneously measured.

These devices are more accurate

Continuous monitoring capability

Biosensors can regenerate and reuse the immobilized biological

recognition element.

Since biosensors are relatively small, they can be used separately or as

modular detectors in larger systems

They can be used in remote areas to note changes regarding

environment and in places where manual, monitoring is not safe.

They can monitor changes at low concentrations.

These devices are sensitive, inexpensive, stable and cost effective.

Don't need to be used by professionals only.

Different types based on different principles make it applicable in

almost all fields.

DRAWBACKS

It is hard to find any drawback in any system as every system is made

with the hope that it is the best one. As all systems have some drawbacks

for this following can be:

Biocompatibility and biofouling are critical issues in case of in-vivo

measurements. All the products might be consumed if a subproduct of

such form is produced.

Reactions depend on reactants and if all the reactants are consumed

the processing may stop.

The products might react with reactants and result ill some other

product that may be harmful ( usually occurs in biosensors involving

whole cell)

CONCLUSION

Sensing systems in the form of burglar alarms, pressure sensors and

medical diagnostic kits, etc., have been around for decades, but suddenly

the sensor business seems ready to take a great leap forward. The drivers

for this growing market are very diverse. For example, concerns about

national security are pushing the need, for sensors that warn against

chemical or biological attacks or dangerous items hidden in luggage. In

the transportation industry the need to make cars and planes safer, more

fuel efficient and more comfortable for passengers is spawning new

generations of mechanical and chemical sensors. In medicine, with its

growing emphasis on early prevention, new biosensors and labs-on-a-chip

offer an especially cost effective means of diagnosis. Meanwhile, the next

big thing in computing will supposedly be pervasive computing in which

always on mobile and fixed computers will process information from a

myriad different sources including weather sensors and security sensors.

Although the sensor market is so fragmented, nanotechnology has some

unique capabilities that suggest that it will have a large impact in many of

the market's most important segments.

Nanosensors are inherently more sensitive than any other kind of

sensor, making them a future choice where lives are at stake. In addition,

their small size and potentially low cost means that they can be widely

deployed -- perhaps being embedded in construction materials -- thereby

providing more comprehensive readings than a few scattered

"macrosensors". Nanotechnology also promises to create integrated

devices that combine both the sensor itself and the mechanism that

converts what is sensed into useful information.

Future prospects

Researchers agree that a number of problems must be solved before

biosensors can fulfill their potential. These include the development of

sensors that are biocompatible and will function safely and accurately for

along periods of time while implanted in the human body. The human

body is salty, hostile environment that attacks and destroys materials used

in biosensors-coating or encapsulating sensor tips, for example, so they

fail after a relatively brief period. Another limitation of existing

biosensors is that they generally are capable of monitoring only a single

parameter. These "single-channel" devices, which monitor brood glucose

but not gases, for example, would require inserting numerous individual

sensors to get complete picture of a patient's blood chemistry.

Researchers are trying to use microelectronics technology to develop

sensors with the ability to measure a dozen or more parameters at the

same time.

Future goals

There are future applications that make biosensors ideal input devices:-

Possible use of prosthetic limbs where just the bioelectric activity

to the nerve endings of a missing limb could be used to control an

artificial limb. In cases of paralysis, the nerves, prior to loss of transport

ability or brainwaves might be electrically monitored for instructions to

control/move a mechanical device attached to the paralyzed limb.

Biosensors can measure muscle electrical activity, brain electrical

activity, and eye movement. Biosensors are electrodes that sit on the. skin

over the muscle or nerve being sampled. Eye movement, for example, is

determined from biosensors placed strategically on the forehead and

under the eyes."

Electrical signals have many measurable qualities, including

intensity and spectral characteristics. Energy is also measurable from a

multitude of motor units. Just as the brain uses these signals to control

functions of the human body, these signals can be detected by biosensors

and then interpreted by software to control electronic devices external to

the human body.

Taste and smell for robots

Biosensors will likewise be the key to fabricating industrial robots

endowed with a complete complement of the five human senses. Robotics

research has focused primarily on robots with sisual and tactile

capabilities and advances have been made in voice synthesis and

recognition devices. Robots may now get the remaining two human

senses-taste and smell from biosensors.

Using blue crab antennules

Some of today's biosensors do utilize organisms or parts of organisms as

the indicator e.g. a prototype biosensor from the antennules of the blue

crab when attached to an electrode, the antennules are capable of

detecting amino acids, the components, of proteins. It is believed. to be

the first biosensor made from the intact sense organs of an animal that can

detect substances in a solution. Scientists believe the approach may

produce a biosensor capable of detecting the hormones and nucleotides

that are the components of the genetic materials. DNA and RNA.

Other biosensors are based on much smaller biological elements.

The indicator usually is some functional product of living cells such as

enzyme, cell surface receptors, or antibodies that react in a specific

fashion with a specific agent in the environment.