A study on electrode for amperometric measurement of human stress with flow injection analysis biosensing system

This paper presents a study on electrode for the amperometric detection of human stress based on salivary alpha amylase, emulated with different concentration of glucose, with the flow injection analysis biosensing system. Amperometric detection is an electrochemical voltammetric measurement approach, where the current intensity in a detection cell is regarded as a function of the concentration of the analyte. Flow injection analysis is a chemical analysis method that injects a test sample into a flowing carrier stream. The screen printed electrode is used to detect the amount of glucose concentration, which is proportional to the amount of output current. The objective of the study is to conduct a comparative study between the gold and carbon electrode, as a choice for amperometric detection of human stress with flow injection analysis biosensing system. It has been found that, the [initial, steady state current output at first injection of glucose, current output at second injection of glucose] for carbon and gold printed electrode are [0–80, 0–20, 0–20] μA and [0–35, 0–10, 0–5] μA respectively. This shows measurement resolution of the carbon screen printed electrode is better, which results in higher measurement sensitivity. However, it is found that the gold printed electrode exhibits higher rate of reaction with the steeper gradients and the current reaches its steady state values faster. Yet, in view of the cost, the gold printed electrode is about three times more than the carbon printed electrode and also the ease in handling the zero baseline, the latter is thus made as the choice electrode.