Methods are described for increasing the sensitivity of particulate matter detection in an exhaust system of a vehicle. An example particulate matter sensor assembly comprises a pair of planar interdigitated electrode structures held at a voltage bias with respect to each other. An alternate embodiment may comprise a planar interdigitated electrode pair, and a conducting plate assembly again held at a voltage bias with respect to the planar interdigitated electrode pair. The bias may overlay an additional electric field drive, which improves the capture of soot particles on the sensor assembly surface thereby increasing sensitivity of particulate matter sensors.