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OPTICAL BIOSENSORS. A. Erol Fazlıoğlu. Idea Behind Biosensors. M edical D iagnostics Ch emical and bioterrorism threat . H ealth danger posed by new strands of microbial organisms and spread of infectious diseases .

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Optical biosensors

  • A. Erol Fazlıoğlu

Idea behind biosensors
Idea Behind Biosensors

  • Medical Diagnostics

  • Chemical and bioterrorism threat.

  • Health danger posed by new strands of microbial organisms and spread of infectious diseases.

  • Optical biosensors utilize optical techniques to detect and identify chemical or biological species.

T wo i mportant c omponents of b iosensing
Two Important Components of Biosensing

(i) a biorecognition element to detect chemical or biological species

(ii) a transduction mechanism which converts the physical or chemical response of biorecognition into an optical signal.

Definition and its applications 1
Definition and Its Applications-1

  • Biosensors are analytical devices that can detect chemical or biological species or a microorganism.


  • Clinical diagnostics

  • Drug development

  • Environmental monitoring (air, water, and soil)

  • Food quality control

Definition and its applications 2
Definition and Its Applications-2

  • A biosensor utilizes a biological recognition element that senses the presence of an analyte (the specie to be detected) and creates a physical or chemical response that is converted by a transducer to a signal.

Main components of an optical biosensor
Main Components Of An Optical Biosensor

  • (i) a light source

  • (ii) an optical transmission medium (fiber, waveguide, etc.)

  • (iii) immobilized biological recognition element (enzymes, antibodies or microbes)

  • (iv) optical probes (such as a fluorescent marker) for transduction,

  • (v) an optical detection system.

Advantages of optical biosensor s
Advantages of Optical Biosensors

  • Selectivity and specificity

  • Remote sensing

  • Isolation from electromagnetic interference

  • Fast, real-time measurements

  • Multiple channels/multiparameters detection

  • Compact design

  • Minimally invasive for in vivo measurements

  • Choice of optical components for biocompatibility

  • Detailed chemical information on analytes


The biorecognition elements are biologies such as enzymes, antibodies, and even biological cells and microorganisms that selectively recognize an analyte.

Some of the molecular bioreceptors used for biorecognition

  • Enzymes

  • Antibodies

  • Lectins

  • Neuroreceptors


Fluorescence sensing
Fluorescence Sensing

  • Direct Sensing

  • Indirect Sensing.


  • Physical Methods

  • Ionic Binding

  • Physical Entrapment

  • Chemical Immobilization

Fiber optic biosensors
Fiber-optic Biosensors

Fiber-optic biosensors are widely used because of their convenient geometry.

—for example, longer interaction length and compatibility with instruments used for in vivo biosensing.

Planar waveguide biosensors
Planar Waveguide Biosensors

  • Planar waveguides are media in which the propagation of an optical waveguide is confined in a dimension comparable to the wavelength of light.

Evanescent wave biosensors
Evanescent Wave Biosensors

These sensors rely on the light that is not confined within the waveguide itself, but penetrates into the surrounding medium of lower refractive index (cladding or air or into a surface immobilized biorecognition element) and thus senses the chemical environment on the surface of the waveguide (or fiber).

Interferometric biosensors
Interferometric Biosensors

  • Utilizes interference between the light from a waveguiding channel with a sensing layer on its surface, and that from a reference channel.

Surface plasmon resonance biosensors
Surface Plasmon Resonance Biosensors

  • It is an extension of evanescent wave sensing, except that a planar waveguide is replaced by a metal-dielectric interface.

  • Surface plasmons are electromagnetic waves that propagate along the interface between a metal and a dielectric material such as organic films.

Some recent novel sensing methods
Some Recent Novel Sensing Methods

  • Photonic Crystals Sensors

  • Optical Sensor Array and Integrated Light Source

  • Hybrid Transduction Biosensors

  • Time Domain Sensing

  • Surface-Enhanced Raman Sensors

Future directions
Future Directions

  • Multianalyte Detection

  • New Biorecognition Molecules

  • Fluidics

  • In Vivo Sensors

  • Chemical Identification Biosensors

  • Data Processing, Pattern Recognition, and Automation

Thanks for your attention
Thanks for your attention!

  • Any questions?

  • A. Erol Fazlıoğlu