A simple capacitive biosensor device for histamine measurement

Purpose - The purpose of this paper is to describe a capacitive biosensor device consisting of an enzyme electrode and a simple detector which has been developed for histamine measurement. Design/methodology/approach - In this analysis, degradation of histamine through enzymatic reaction produces signal that is monitored using a simple detector equipped with astable multivibrator operation circuit (in capacitor-resistor circuit). Findings - Different frequency (f) readings have been obtained for glucose, alcohol and histamine in different concentration levels, showing the ability of this simple device system to measure their dielectric constant (k) as formulated by the equation f = (1.44d)/[kA (R1 + 2R2)]. The analysis using smaller electrode gap (d) produces higher value of f, indicating that d, is directly proportional to f. For histamine, by using immobilized enzyme electrode, the results show that the change of dielectric properties during the 300-second reaction period could also be monitored. A linear relationship is obtained between concentration and frequency from 50 to 200 ppm. Practical implications - Based on this result, an enzyme electrode and astable operation circuits have the potential to be used in the development of a simple capacitive biosensor device. Originality/value - The paper is an outcome of experimental work carried out to observe capacitive sensing behavior using an immobilized enzyme, to measure biological samples, especially histamine.