Particulate Matter Sensing in Diesel Engine Systems
Summary
Particulate matter (PM) emissions from diesel engines pose significant health, environmental and regulatory challenges, driving the development of advanced sensing technologies. Central to exhaust after-treatment is the diesel particulate filter (DPF), which traps soot but requires reliable monitoring to ensure integrity and performance. Sensors may be installed upstream of the DPF to gauge engine-out emissions or downstream to detect filter leakage or substrate damage. Key sensing principles include conductometric and resistive measurements, where soot deposition between interdigital electrodes alters electrical properties; microwave transmission through the filter substrate, which varies with soot loading; and model-based approaches that combine sensor signals with algorithms to diagnose filter status in real time. Sensor performance hinges on rapid response, sensitivity to low soot concentrations and stability under fluctuating exhaust conditions. Advances in sensor materials, electrode design and integration with on-board diagnostics (OBD) have enhanced accuracy and enabled compliance with tightening PM limits worldwide. Emerging strategies exploit electrophoretic enhancement of soot capture, thermophoretic effects and optimised operation protocols to reduce detection delay. Taken together, these developments underpin smarter engine control, more effective regeneration strategies and improved air-quality outcomes on urban and interurban transport corridors.
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Particulate Matter Sensing in Diesel Engine Systems publication trend
The graph below shows the total number of articles in particulate matter sensing in diesel engine systems across all publications each year (not limited to Nature Index journals).
Technical terms
Particulate Matter (PM): Solid and liquid particles in exhaust, characterised by mass or number concentration.
Diesel Particulate Filter (DPF): A porous ceramic device that captures soot from diesel exhaust to reduce PM emissions.
On-Board Diagnostics (OBD): A system for continuous monitoring of engine and after-treatment performance to meet regulatory requirements.
Conductometric Sensor: A sensor measuring changes in conductance caused by soot deposition between electrodes.
Resistive Soot Sensor: An accumulation-type device in which soot bridges between interdigital electrodes reduce resistance.
Electrophoresis: The motion of charged particles under an electric field, used to enhance soot collection on sensors.
Thermophoresis: Particle movement along temperature gradients, influencing deposition patterns on sensor surfaces.
References
- Characteristics of Resistive PM Sensors for Onboard Diagnostics of Diesel Particulate Filter Failure. Sensors (2022).
- Comparative Study of Different Methods for Soot Sensing and Filter Monitoring in Diesel Exhausts. Sensors (2017).
- Uncertainties in Model-Based Diesel Particulate Filter Diagnostics Using a Soot Sensor. Sensors (2019).
- Optimization of soot deposition by high-temperature prepolarization of a resistive particulate matter sensor. Journal of Sensors and Sensor Systems (2020).
- Conductometric Soot Sensors: Internally Caused Thermophoresis as an Important Undesired Side Effect. Sensors (2018).
- Simulation and Experimental Research on the Charged Characteristics of Particulate Matter in the Sensor under Different Exhaust States. Sensors (2020).
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