Additional Lecture 5 Madam Noorulnajwa Diyana Yaacob

INTRODUCTION TO

BIOSENSORSAdditional Lecture 5

Madam Noorulnajwa Diyana Yaacob

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Overview1. Introduction to biosensors

1.1 Definition1.2 Biosensors1.3 Components of a

biosensor1.4 Classification of

biosensors1.5 Performance factors of a

biosensor1.6 Applications of biosensors

PTT104 BioSensors noorulnajwa@UniMAP

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1.1 DefinitionA sensor is defined as a

measuring device that exhibits a characteristic of an electrical nature (charge, voltage or current) when it is subjected to a phenomenon that is not electric.

The electrical signal it produces must carry all the necessary information about the process under investigation.

ERT 419 Sensors & control bblee@UniMAP

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DefinitionA sensor could be regarded as

a transducer, since it is a system that transforms one physical quantity into another. (which is a function of the first definition).


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DefinitionTransducer:A device that is actuated by power

from one system and supplies power usually in another form to a second system (a loudspeaker is a transducer that transforms electrical signals to sound energy).

A substance or device, such as a piezoelectric crystal, that converts input energy of one form into output energy of another.


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DefinitionActuator: A mechanism for moving or

controlling something indirectly instead of by hand.

One that activates, especially a device responsible for actuating a mechanical device such as one connected to a computer by a sensor link.


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Connection of sensors/actuators

The processor should be viewed as a general block Microprocessor Amplifier Driver, Etc.

Matching: between sensor/processor and processor/actuatorPTT104 BioSensors noorulnajwa@UniMAP

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Connection of sensors/actuators

Example:Temperature control

Sense the temperature of a CPUControl the speed of the fan to keep the

temperature constant


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1.2 BiosensorsIn a biosensor, the phenomenon is recognized by a biological system called a bioreceptor, which is in direct contact with the sample and forms the sensitive component of the biosensor.

The bioreceptor has a particularly selective site that identifies the analyte.


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BiosensorsA commonly cited definition is: A biosensor is a chemical

sensing device in which a biologically derived recognition entity is coupled to a transducer, to allow the quantitative development of some complex biochemical parameter.


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Biosensors A biosensor is an analytical

device incorporating a deliberate and intimate combination of a specific biological element (that creates a recognition event) and a physical element (that transduces the recognition event).


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BiosensorsCurrent definition: A sensor that integrates a biological

element with a physiochemical transducer to produce an electronic signal proportional to a single analyte which is then conveyed to a detector.


Biological element + Sensor element

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BiosensorsA biosensor is a special type of

sensor often used in bioanalysis.

Humankind has been performing bioanalysis since the dawn of time, using the sensory nerve cells of the nose to detect scents and those of the tongue to taste dissolved substances.


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BiosensorsAnalogy with the nose as a

sensor (it is actually a biosensor).


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Biosensors


Old time coal miners’ biosensor

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BiosensorsAs time has progressed, so has our

level of understanding about the function of living organisms in detecting trace amounts of biochemicals in complex systems.

The abilities of biological organisms to recognize foreign substances are unparalleled and have to some extent been mimicked by researchers in the development of biosensors. PTT104 BioSensors noorulnajwa@UniMAP

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Biosensors The biosensor was born over fifty

years ago, when Clark and Lyons (1962) had the idea of carrying out specific glucose concentration measurements by detecting the oxygen consumed during the enzymatic oxidation of this metabolite, catalysed by glucose oxidase, using an electrochemical sensor.


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Biosensors The enzyme was used in solution,

confined to the end of the sensor. In parallel, during the 1960s, more & more studies were being carried out on the properties of immobilised enzymes & their use.


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Biosensors


Father of

biosensor

Professor Leland C Clark Jnr

(1918–2005)

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Biosensors

General arrangement of a biosensor


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1.3 Components of a BiosensorA biosensor can be generally defined as

a device that consists of two basic components connected in series: (1) a biological recognition system

(bioreceptor) (2) a transducer.

The basic principle of a biosensor is to detect analyte (molecular recognition) and to transform it into another type of signal using a transducer.PTT104 BioSensors noorulnajwa@UniMAP

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Component of a Biosensor

Concept of a

biosensor


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Components of a Biosensor

1. The Analyte (What do you want to detect?)

Molecule - Protein, toxin, peptide, vitamin, sugar, metal ion.

2. Sample handling (How to deliver the analyte to the sensitive region?)

(Micro) fluidics – Concentration increase / decrease, Filtration/selection


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Components of a Biosensor3. Detection/Recognition (How do you specifically recognize the analyte?)

4. Signal (How do you know there was a detection?)


Microfluidic device

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Components of a BiosensorA bioreceptor is a biological molecular species

(e.g., an antibody, an enzyme, a protein, or a nucleic acid) or a living biological system (e.g., cells, tissue, or whole organisms) that utilizes a biochemical mechanism for detection / recognition.

The sampling component of a biosensor contains a biosensitive layer that can contain bioreceptors or be made of bioreceptors covalently attached to the transducer.


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Biosensors

Examples of biosensor:


Pregnancy test: To detects the hCG protein in urine.

Glucose monitoring device (for diabetes patients):To monitor the glucose level in the blood.

Infectous disease biosensor

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BiosensorsExamples of biosensor:


Biosensor for

research works

Ring Sensor Smart Shirt

http://images.google.se/imgres?imgurl=http://www.scieng.flinders.edu.au/images/faal/biacore.jpg&imgrefurl=http://www.scieng.flinders.edu.au/research/faal/instruments.html&h=643&w=852&sz=15&hl=no&start=14&sig2=yvN3tOeuYSTb7RZhWmeMiQ&um=1&tbnid=BPMGktcsbr648M:&tbnh=109&tbnw=145&ei=7rL7RqzNNqauwAH5j53lDw&prev=/images?q=biacore&svnum=10&um=1&hl=no

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1.4 Classification of BiosensorsBiosensors can be classified

by either bioreceptor or transducer type.

Transduction can be accomplished through a large variety of methods.


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Classification of Biosensors


Biosensor classification schemes

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Classification of BiosensorsIn this course, we focus on THREE

main classes: (1) optical detection methods, (2) electrochemical detection

methods, (3) mass and acoustic based

detection methods. Other detection methods include

voltaic, magnetic, thermal methods. PTT104 BioSensors noorulnajwa@UniMAP

1.5 Performance factors of a biosensor

1. Selectivity:It is rare to find a sensor which will respond to only one analyte, although some do exist.

It is more usual to find a sensor that will respond mainly to one analyte, with a limited response to other similar analytes.

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Performance factors of a biosensor

2. Sensitivity:Range,

Linear Range and Detection Limits. 32

Linear

range

Range

Performance factors of a biosensor

3. Time Factors: While it is desirable for a sensor

to have a rapid response time and to recover rapidly, ready for the next reading, this is not always the case in practice. Most sensors, whether chemical or biological, have a limited lifetime.


Performance factors of a biosensori) Response time: Many analytical devices require some

‘settling-down’ time, i.e. time to allow the system to come to equilibrium.

ii) Recovery time: the time that elapses before a

sensor is ready to be used for another sample measurement.


Performance factors of a biosensoriii) Lifetimes:

All organic material deteriorates with time, especially when taken out of its natural environment.

This means that one of the main drawbacks of biosensors is that the biological material usually has a fairly limited lifetime before it needs replacing.

Generally pure enzymes have the lowest stability, whereas tissue preparations have the highest.PTT104 BioSensors noorulnajwa@UniMAP 35

Performance factors of a biosensor4. Precision, Accuracy and

RepeatabilityFor any analytical instrument,

including sensors, the analytical value must have sufficient precision for the required purpose, i.e. the random errors must be

below a certain level, so that repetitive measurements are reproducible within a certain range.

The sensor must also be capable of measurements of values with an accuracy close to the expected value.

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Performance factors of a biosensor This means that the systematic

errors must be below certain limits. This can be a particular problem

where biological selective elements are used, as one sample can differ from another, thus giving systematic errors.

Sufficient controls and standards must be used to enable repeatable results of sufficient accuracy to be obtained over an extended period.PTT104 BioSensors noorulnajwa@UniMAP 37

1.6 Applications of biosensorsArea Example Remarks

Health care

1. Measurement of Metabolites

2. Diabetes

Blood chemistry: instant assays

Insulin Therapy: glucose-insulin management

Industrial Process Control

1. Bioreactor Control

Real-time monitoring of carbon sources, dissolved O2, CO2 &products of metabolism: optimization, ↑ product yields, ↓processing & material cost

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1.6 Applications of biosensorsArea Example Remarks

Military & Homeland Security

1. Detection of chemical and biological warfare agents

Rapid analysis: monitoring hazards due to terrorist activity.

Environmental Monitoring

1. Environmental Protection Agency (EPA) Air and Water Monitoring

Environmental analytes:biological oxygen demand (BOD), atmospheric acidity, and river water pH, detergent, herbicides, & fertilizer concentrations in drainage and river

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Schemes for insulin therapy


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Additional Lecture 5 Madam Noorulnajwa Diyana Yaacob