Oxygen consumption of cell suspension in a poly(dimethylsiloxane) (PDMS) microchannel estimated by scanning electrochemical microscopy

Abstract

A quantitative analysis of the oxygen concentration profile near a poly(dimethylsiloxane) (PDMS) microfluidic device was performed using scanning electrochemical microscopy (SECM). A microchannel filled with sodium sulfite (Na₂SO₃) aqueous solution was imaged by SECM, showing that the oxygen diffusion layer of the PDMS microchannel was observed to be hemicylindrical. Based on a theoretical analysis of the hemicylindrical diffusion layer of the microchannel, the total oxygen mass transfer rates of oxygen to the PDMS microchannel filled with the Na₂SO₃ solution was calculated to be (4.01 ± 0.30) × 10⁻¹² mol s⁻¹. This is the maximum value of the oxygen transfer rate for this PDMS microchannel device. The oxygen consumption rate increased almost linearly with the logarithm of the concentration of E. coli cells (10⁶∼10⁸ cells). The respiratory activity for a single E. coli cell was estimated to be ∼4.31 × 10⁻²⁰ mol s⁻¹ cell⁻¹.