An Electrochemical Compact Disk-type Microfluidics Platform for Use as an Enzymatic Biosensor

A novel centrifuge-based microfluidic device coupled with an electrochemical detector for the determination of glucose in control human serum is described. The electrochemical compact disk (eCD) platform was based on a poly(dimethylsiloxane) (PDMS) material containing reservoir, a mixing chamber, a spiral channel, a carbon-paste electrode (CPE) detector, and a waste reservoir. For electrode fabrication, a mixture consisting of cobalt phthalocyanine (CoPC), graphite powder, PDMS, and mineral oil was printed and formulated into a PDMS-based electrode pattern. To enhance electrochemical sensitivity, a graphene-polyaniline (G-PANI) nanocomposite solution was cast onto the working electrode surface. During the rotation of the eCD platform at a rotation speed of ∼1000 rpm, a glucose solution and a glucose oxidase solution in separated reservoirs were mixed in a spiral channel to produce hydrogen peroxide by an enzymatic reaction. The produced hydrogen peroxide was determined using the electrode detector set at an applied potential of +0.4 V vs. CPE (pseudo reference electrode). Under optimal conditions, a linear calibration ranging from 1 to 10 mM with a limit of detection (LOD) of 0.29 mM (S/N=3) and a limit of quantitation (LOQ) of 0.97 mM (S/N=10) was obtained. Various common interference compounds including ascorbic acid, uric acid, paracetamol, and L-cysteine were tested. Finally, glucose in control serum samples containing certified concentrations were amperometrically determined and validated. Glucose levels measured using the eCD system matched actual values for the certified reference serum samples with satisfactory accuracy.