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 multicha nnel taste sensor that uses lipid/polymer membranes responds to taste substances by the membrane potential change. The potential change is b ased on the change of a diffuse electric double layer near the membran e surface; the sensitivity to nonelectrolytes and weak electrolytes is lower than that to strong electrolytes. Although bitter substances in clude both electrolytes and nonelectrolytes, outputs of the taste sens or were quite different from each other. Therefore the ''bitter'' resp onse of human gustatory sensation cannot be represented by the change of the diffuse electric double layer. In this work, most bitter substa nces were found to increase the resistance of the phospholipid LB memb rane. This implies that the increase of membrane resistance is related to the generation of bitter taste in humans and that the sensing syst em based on impedance measurement is quite effective for the detection of bitterness.