In order to take advantage of the high sensitivity in magneto-resistance based field sensor, 1/f noise must be minimized for low frequency field measurement. We propose a novel thermally modulated flux concentrator design, which can mitigate the 1/f noise by shifting the measurement frequency to kHz range. The proposed flux concentrator is made of the materials with Curie points around operation temperature. Numerical simulation demonstrated the feasibility of kHz temperature modulation of 20degC around the Curie temperature. Modulation efficiency can be significantly higher than state-of-the-art flux concentrators. In addition, the numerical simulation also demonstrated the robustness of the thermal modulation on flux concentrator against various nonidealities.