Particulate matter sensors have several applications in many different industries. For example, a particulate matter sensor can be placed in the exhaust stream of a diesel engine, where it senses incomplete burn of the diesel fuel. When used in a diesel engine, it can be placed before or after any diesel particulate filter (DPF) that is used in connection with the diesel engine. When used in connection with diesel engines, sensor probes must maintain their sensitivity over a broad temperature range, and they must be robust in relation to fuel quality variation and fuel additives.