A sensor assembly to measure particulate matter, the sensor assembly comprising: a voltage source; a convexly shaped sensor electrode (108, 136) couples to the positive side of voltage source to receive a voltage, wherein the convexly shaped sensor electrode (108, 136) is disposed within a directed and controlled exhaust flow within the sensor assembly to facilitate particle agglomeration into particulate matter structures at a surface of the sensor electrode (108, 136); a concavely shaped grounded assembly coupled to a ground reference and disposed at a distance from the sensor electrode; wherein the convexly shaped sensor electrode (108, 136) and concavely shaped grounded assembly are disposed such that the exhaust flow is directed between the convexly shaped sensor electrode and the concavely shaped ground assembly in the electric field between the convexly shaped sensor electrode and the concavely shaped ground assembly to facilitate particle agglomeration of particulate matter into particulate matter structures and dislodgement of said particulate matter structures; an integration capacitor coupled to a negative side of the voltage source, wherein the integration capacitor is configured to integrate in time current pulses from charge transfers from the sensor electrode (108, 136) to the particulate matter structures; and a current meter coupled to the voltage source to measure an integrated value of current supplied to the voltage source in response to the charge transfers from the sensor electrode (108, 136) to the particulate matter structures in the exhaust flow; wherein the voltage source is configured to apply the voltage to the sensor electrode (108, 136) between a lower voltage limit and an upper voltage limit, wherein the lower voltage limit is sufficient to facilitate self organizing of particle agglomerates into high surface-area-to-mass ratio structures, and the upper voltage limit is insufficient to cause an ionizing discharge from the sensor electrode (108, 136) or particulate matter structures through the exhaust flow. a voltage source; a convexly shaped sensor electrode (108, 136) couples to the positive side of voltage source to receive a voltage, wherein the convexly shaped sensor electrode (108, 136) is disposed within a directed and controlled exhaust flow within the sensor assembly to facilitate particle agglomeration into particulate matter structures at a surface of the sensor electrode (108, 136); a concavely shaped grounded assembly coupled to a ground reference and disposed at a distance from the sensor electrode; wherein the convexly shaped sensor electrode (108, 136) and concavely shaped grounded assembly are disposed such that the exhaust flow is directed between the convexly shaped sensor electrode and the concavely shaped ground assembly in the electric field between the convexly shaped sensor electrode and the concavely shaped ground assembly to facilitate particle agglomeration of particulate matter into particulate matter structures and dislodgement of said particulate matter structures; an integration capacitor coupled to a negative side of the voltage source, wherein the integration capacitor is configured to integrate in time current pulses from charge transfers from the sensor electrode (108, 136) to the particulate matter structures; and a current meter coupled to the voltage source to measure an integrated value of current supplied to the voltage source in response to the charge transfers from the sensor electrode (108, 136) to the particulate matter structures in the exhaust flow; wherein the voltage source is configured to apply the voltage to the sensor electrode (108, 136) between a lower voltage limit and an upper voltage limit, wherein the lower voltage limit is sufficient to facilitate self organizing of particle agglomerates into high surface-area-to-mass ratio structures, and the upper voltage limit is insufficient to cause an ionizing discharge from the sensor electrode (108, 136) or particulate matter structures through the exhaust flow.