A particulate matter sensor includes a sensing element with a first electrode and a second electrode, an inner shield with the sensing element disposed therein, and an outer shield with the inner shield disposed therein. The inner shield includes a first portion with an inner shield inlet and a second portion which is smaller in diameter that the first portion such that the first and second electrodes are within the second portion. The outer shield includes an outer shield inlet which communicates exhaust gases to the inner shield inlet.