Characterization of a laminar flow cell for the prevention of biosensor fouling

A flow cell using dual parallel laminar flows was designed and fabricated with the aim to prevent biosensor fouling. Y-shaped entrances allowed the introduction of sample and electrolyte streams, with the electrolyte serving as a mobile protective layer near the biosensor. Potassium permanganate was used to quantify the diffusion in the flow cell. Optical intensity analysis of potassium permanganate along a series of transverse lines across the flow cell was carried out under different flow conditions. It was found that the error function, erf(y/√(Dt)), where y was the position along the transverse line, D the diffusion coefficient of the solute and t was the time, gave reasonable approximation to the diffusion of potassium permanganate in the cell. The diffusion coefficient of potassium permanganate was determined in stop–flow measurements and the value, D = 4.0 × 10−5 cm2/s, agreed to previously reported values. Velocity distribution in the flow cell was simulated numerically to reveal the development of two inflows into one single laminar flow. Results from the study provided preliminary data on solute diffusion characteristics in the flow cell and supported the working principle of laminar flow cells in preventing biosensor fouling.