Figure 2.

Typical shape of the sensor’s raw signal during one sensing cycle with increasing current I after a certain “blind” time before the percolation threshold is reached and a regeneration peak after increasing the sensor’s temperature for soot burn off. The regeneration peak is due to the increased soot conductivity when heating up. The slope of the linear increasing current during soot deposition, which is proportional to the conductance, often acts as the sensor signal.