Improved optical taste sensing system using LB films, which consists of arachidic acid layers doped with potential-sensitive dye and methyl-stearate layers, has been proposed and tested to detect a bitter taste substance such as quinine. Two types of sensor heads were fabricated in which one is named as type-A with 5 layers arachidic-acid LB films doped with Rhodamine-B derivative (RB-C{sub}18) and another is named as type-B with hetero-structured LB films deposited several methyl-stearate layers on the top of the type-A. When these sensor heads were excited by a green He-Ne laser, the measured fluorescence intensity from both types of sensors increased with increasing quinine hydrochloride concentration in the region of 10{sup}(-5) mol/l order. Especially, sensitivity in the type-B sensor was improved remarkably as compared with type-A. These results will be useful to construct a multi-channel taste sensor or a computer-assisted taste substance sensor.
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