Portable, low cost smartphone-based potentiostat system for the salivary α-amylase detection in stress paradigm.

The aim of this study was to explore a novel, low-cost smartphone-based biosensor system and establish an efficient analysis method for the detection of potential stress biomarker, salivary α-amylase(sAA). This system consists of Smartphone with sAA-detection, Screen-printed electrodes(SPEs) and potentiostat module. The presented technique that using a small perturbation to obtain a linearized response could affect the composition of the sample as to cyclic voltammetry which repeatedly reduces and oxidizes the sample. For application, 6 healthy graduate students took a 5 minutes Trier Social Stress Test(TSST). Results show that this method could detect sAA activities conveniently and accurately. Calibration curve of sAA whose quantitative range is from 50 and 1200 U mL-1 with a limit of detection(LOD) of 1.6 U mL-1, is Y=-52.324X+295.63, R^2=0.9933. After psychological stress, sAA secretion was significant verified. It is concluded that this smartphone-based sAA detection system is reliable for determination of Salivary α-amylase and useful in the assessment of Psychological stress.