Toner sensor modules are provided. In one aspect, a toner sensor module has a first light source emitting a first light, a first light sensor that generates a sensed light signal that is indicative of a sensed light, and a frame. The frame positions the light source to illuminate a target area from a first side a plane that is normal to the target area so that illuminated portions of any toner particles at the target area direct a reflected a portion of the first light into the first side and positioning the first light sensor on the first side of the plane to which toner particles at the target area direct the reflected portion of the first light.