biosensor final
TRANSCRIPT
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.