A particle sensor for detecting particles in a flow of a measuring gas for detecting soot particles in an exhaust gas channel of a burner or of an internal combustion engine. The particle sensor includes a device for generating or for supplying laser light, a device for focusing laser light, and a device for detecting or transferring thermal radiation. The particle sensor includes at least one optical access, which separates an area exposed to the measuring gas from an area facing away from the measuring gas not exposed to the measuring gas, the device for generating or supplying laser light and/or the device for detecting or for transferring thermal radiation being situated in the area facing away from the measuring gas, wherein the particle sensor removes a sub-flow from the measuring gas flow and supplies it to the laser focus and further fluidically shields the optical access from the sub-flow.