The authors used the Unisense O2 and N2O microsensors both having a tip diameter of 25 µm (OX-25 and N2O-25). The microsensors were connected to an Unisense amplifier and mounted on the motorized Unisense MicroProfiling System (Figure 1). The glass vials containing the freshly expectorated sputum samples were kept at 37 °C during the measurement. The sensors were first positioned manually at the upper surface of the sputum sample using the micromanipulator (MM33) to define the surface of the sample as the zero depth. Then the motorized MicroProfiling System was used to do automated microprofiles vertically through the sputum samples.
The SensorTrace Profiling software controlled the movement of the microsensors and the authors used a step size of 100 or 200 µm, a waiting time between measurements of 3 seconds for the O2 profile and 5 seconds for the N2O profile, and a delay time between each cycle of profile measurements of 10 seconds. Data acquisition and analysis were done with the SensorTrace Profiling software that logs the measured analyte concentration together with the depth position of the micromanipulator