The highly sensitive detection of catecholamines using a microfluidic device integrated with an enzyme-modified pre-reactor for interferent elimination and an interdigitated array electrode

We developed a microfluidic device for the continuous monitoring of catecholamine levels and studied the performance of two components of the device, namely an enzyme-modified pre-reactor and an interdigitated array (IDA) electrode. The enzyme-modified pre-reactor and IDA electrode were integrated on a chip. The integrated pre-reactor with a 3D structure, consisted of rectangular-shaped micropillars immobilized with ascorbate oxidase, and was used for the enzymatic removal of the electroactive interferent, l-ascorbic acid (AA). It exhibited elimination efficiencies of 99.7% and 98% for AA concentrations of 10 and 100 μM, respectively. We used a carbon-based IDA electrode (2 μm line and space) fabricated in a microflow channel for the highly sensitive detection of CAs. Redox cycling at the IDA electrode and an increase in the mass transport to the electrode contributed to the highly sensitive detection of dopamine (DA) and adrenaline (AD). The detection limits of the device for DA and AD standard solution in the absence of AA were 108 and 440 pM, respectively.