Optodes Fibre Sensors with a Chemical Receptor

Optodes Fibre Sensors with a Chemical Receptor 8.3.1 

It has long been known that colour changes caused by chemical interactions may lead to conclusions about the concentration of samples. The well-known test strips make use of this fact. 

The preceding chemical reaction is the decisive source of sensor selectivity. In many cases, sensor designers benefited from achievements in the field of ISEs. On the other hand, there are good reasons to switch from electric to optical measurement technology, i.e. to apply optodes rather than electrodes. Commonly, the following advantages of optodes are cited (Wolfbeis 1990)  

On the other hand, optical sensors have some disadvantages  

The mediator present at the front end of the optode must be able to form an optically active compound in an amount which definitely depends on sample concentration. Useful optical effects are either spectral light absorption (formation of coloured products) or luminescence. 

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