Development of Taste Sensor to Detect Non-Charged Bitter Substances

A taste sensor with lipid/polymer membranes is one of the devices that can evaluate taste objectively. However, the conventional taste sensor cannot measure non-charged bitter substances, such as caffeine contained in coffee, because the taste sensor uses the potentiometric measurement based mainly on change in surface electric charge density of the membrane. In this study, we aimed at the detection of typical non-charged bitter substances such as caffeine, theophylline and theobromine included in beverages and pharmaceutical products. The developed sensor is designed to detect the change in the membrane potential by using a kind of allosteric mechanism of breaking an intramolecular hydrogen bond between the carboxy group and hydroxy group of aromatic carboxylic acid (i.e., hydroxy-, dihydroxy-, and trihydroxybenzoic acids) when non-charged bitter substances are bound to the hydroxy group. As a result of surface modification by immersing the sensor electrode in a modification solution in which 2,6-dihydroxybenzoic acid was dissolved, it was confirmed that the sensor response increased with the concentration of caffeine as well as allied substances. The threshold and increase tendency were consistent with those of human senses. The detection mechanism is discussed by taking into account intramolecular and intermolecular hydrogen bonds, which cause allostery. These findings suggest that it is possible to evaluate bitterness caused by non-charged bitter substances objectively by using the taste sensor with allosteric mechanism.

A novel potentiometric immunoassay for carcinoma antigen 15-3 by coupling enzymatic biocatalytic precipitation with a nanogold labelling strategy

Methods based on potentiometric measurement have been developed for immunoassays, but most exhibit low sensitivities and are unsuitable for early diagnosis of disease.

Degradation of thin-film lithium batteries characterised by improved potentiometric measurement of entropy change

Entropy profiling is sensitive to structural changes in the electrodes during cycling, and complementary to other techniques for studying degradation.

Potentiometric measurement of entropy change for lithium batteries

Entropy change can be employed to track battery degradation compared with EIS and CV.