The novel CO2 microsensor strikes again

Niels Peter Revsbech’s lab at Aarhus University has developed a novel CO₂ microsensor. This sensor has a typical tip size of 30 µm and responds linearly from the detection limit of 0.0005 and up to 5 kPa pCO₂. In addition to providing the first radial concentration profiles of CO₂ in roots (Box 3 in the paper), we also used the CO₂ microsensor to establish fluxes of respiratory CO₂ between the roots and the surrounding medium. Based on simultaneous measurements of CO₂ and O₂ in the diffusive boundary layer enveloping the root (photo in Box 1 in the paper), the CO₂ efflux can be calculated using a modified version of Fick’s 1st Law. Our study shows that the respiratory quotient of the roots increases from slightly above 1 with external O₂ in the liquid medium at air equilibrium to around 5, when the external O₂ supply is lowered to 3.7 kPa.

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