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 .
(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.
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
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.
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).