The invention provides a sensor device which comprises an input flow channel (10) for receiving a gas flow with entrained matter to be sensed. A thermophoretic arrangement (14a, 14b) is used to induce a thermophoretic particle movement from a first, warmer, region (16) of the input flow channel to a second, cooler, region (18) of the input flow channel (10). A sensor (24) comprises a particle sensor component at or downstream of the first region (16) of the input flow channel (10). The invention provides the benefit of pre-filtering (e.g. removal of most suspended solids/liquids) without the need for a physical filter that can become blocked.

The invention provides a sensor device which comprises an input flow channel (10) for receiving a gas flow with entrained matter to be sensed. A thermophoretic arrangement (14a, 14b) is used to induce a thermophoretic particle movement from a first, warmer, region (16) of the input flow channel to a second, cooler, region (18) of the input flow channel (10). A sensor (24) comprises a particle sensor component at or downstream of the first region (16) of the input flow channel (10). The invention provides the benefit of pre-filtering (e.g. removal of most suspended solids/liquids) without the need for a physical filter that can become blocked.