Patent ID: 8225640

Claim:
A sensing element for a soot sensor, comprising: a pair of peripheral edge sensing electrodes each having a portion disposed on a peripheral edge of a non-conductive substrate of the sensing element; a first pair of side sensing electrodes disposed on a first side of the sensing element, the first side having a first area partially bounded by the peripheral edge, wherein a resistance between the pair of peripheral edge sensing electrodes decreases as soot accumulates on portions of the pair of peripheral edge sensing electrodes and a resistance between the first pair of side sensing electrodes decreases as soot accumulates on portions of the first pair of side sensing electrodes; wherein the pair of peripheral edge sensing electrodes are configured to have a plurality of individual and discrete portions each having an electrode sensing edge located on the peripheral edge of the non-conductive substrate of the sensing element and each of the plurality of portions located on the peripheral edge are oriented such that a plurality of gaps are disposed between each adjacent pair of the plurality of individual and discrete portions and its electrode sensing edge located on the peripheral edge, wherein the sensing element comprises a plurality of non conductive layers and the plurality of individual and discrete portions are only located on one of the plurality of non conductive layers of the sensing element.