Electroanalytical instrumentation for Graphene viral biosensor applications
This work details the process of characterizing the biosensor's response for viral detection. The
biosensor constructed is based on an electrochemical cell that has three electrodes, a working
electrode (WE), a reference electrode (RE) and a counter electrode (CE). The ET was fabricated
using reduced graphene oxide (RGO) and the other two metal electrodes are Au. In this system,
we developed the required instrumentation to perform the electroanalytical methods in order to
be able for detecting and quantifying viral RNA present in the microfluidic of the constructed
electrochemical cell. We developed and studied the characterization techniques to obtain the
biosensor's response, such as: cyclic voltammetry, linear sweep and chronoamperometry;
studying its relationship in the detection and quantification of the target analytes. Thus, the
instrumentation developed consists of a function generator, a potentiostat, and a data acquisition
system. The potentiostat controls the voltage between the WE and the RE within the cell, and
collects the current between the WE and the CE. The voltage is supplied by the function
generator and the current is sent to the acquisition system. Using an Op-Amps based
architecture, the potentiostat was built from the Matos, Angnes and Lagos circuit. The
modifications in the base circuit aim to improve the voltage control, increase the current reading
range and reduce potential interferences and noise. The results obtained with the
instrumentation developed in this thesis present results comparable to commercial equipment.
Thus, electrochemical analyses according to the biosensor's response performed with the
system presented in this work show good selectivity in detecting the target analyte and an
increase in current with increasing analyte concentration.