A particle sensing system is for sensing particles entrained in a fluid. The system comprises a flow channel having a longitudinal direction along which the fluid is to be passed, a heating arrangement for heating the fluid and thereby applying a positive thermophoretic force on the fluid in a direction perpendicular to the longitudinal direction of the flow channel and a first sensor for sensing the particles in the fluid after heating by the heating arrangement. The thermophoretic force increases the concentration of the particles at the first sensor.