Detection of Taste Substances Using Impedance Change of Phospholipid Langmuir-Blodgett Membrane

Impedance changes in a phospholipid Langmuir-Blodgett (LB) membrane by several taste substances were measured. A recently developed multichannel taste sensor that uses lipid/polymer membranes responds to taste substances by the membrane potential change. The potential change is based on the change of a diffuse electric double layer near the membrane surface; the sensitivity to nonelectrolytes and weak electrolytes is lower than that to strong electrolytes. Although bitter substances include both electrolytes and nonelectrolytes, outputs of the taste sensor were quite different from each other. Therefore the "bitter" response of human gustatory sensation cannot be represented by the change of the diffuse electric double layer. In this work, most bitter substances were found to increase the resistance of the phospholipid LB membrane. This implies that the increase of membrane resistance is related to the generation of bitter taste in humans and that the sensing system based on impedance measurement is quite effective for the detection of bitterness.