Study On Electrochemical Micro - Sensor Based On Carbon Fiber

Microsensor has outstanding electrical properties, such as fast mass transfer rate, low value of doubled-layered charging current,iR and time constant, etc. The process of measurement can be faster and test result can be more precise when it combines modern electrochemical techniques and computer technology. As one kind of novel tool of research and measurement, microelectrode has become a hot topic in the branch field of electroanalytical chemistry.In this paper, a low cost carbon fiber electrode was constructed and modified by poly (3,4-ethylenedioxythiophene) (PEDOT) by potentiostatic method. Electrochemical performance of PEDOT modified carbon fiber electrode was studied by FE-SEM, cyclic voltammetry and electrochemical impedance spectroscopy, etc. Good electric conductivity, sensitivity, selectivity, fast response time and excellent electrocatalytic ability of this electrode make it a powerful tool for monitoring with high temporal and spatial resolution.The process of determining hydroquinone (1,4-dihydroxybenze, HQ) and catechol (1,2-dihydroxybenze, CC), and their electrochemical behavior on PEDOT modified CFE was studied. It demonstrated that the conductivity of carbon fiber electrode was greatly enhanced under the help of the PEDOT film, exhibited excellent catalytic activity for the oxidation of HQ and CC, and two pairs of enhanced oxidation peaks can be observed on both differential pulse voltammetry (DPV) and cyclic voltammograms. DPV. DPV and Chronoamperometry were employed in the analysis of the two substrates, and satisfying results were obtained. Under the optimal working conditions, DPV provided sensitive analysis results in low concentration of HQ and CC, and linear relationships between the amperometric current response and concentration of substrates were obtained in the ranges of 5.3×10-7 M to 8.6×10-4 M for HQ and 5.2×10-7 M to 4.9×10-3 M for CC, with the detection limits (S/N=3) of 4.2×10-7 M and 1.6×10-6 M, respectively. The wide linear range, high sensitivity, fast and stable response to the substrate in case of a small amount of sample as well as the effective discrimination to the possible interferences at PEDOT modified carbon fiber electrode make it a promising candidate for designing a common platform for microsensor.