Fiber-optic flow sensor based on a laser-heated silicon Fabry-Pérot interferometer (FPI) exhibits a strong directivity owing to the cylindrical shape of the sensor head. In this work, a new sensor structure has been designed to effectively reduce the directivity. The proposed sensor embeds the laser-heated silicon FPI in a Tin microsphere (diameter ∼1mm). Due to the circular shape of the outer metal layer, a more symmetric response to flow from different directions is achieved. In the meantime, the high thermal conductivity and small footprint of the metal sphere helps maintain the good responsivity of the silicon FPI to the flow. Directivity of the newly designed sensor has been tested in water flow. Experimental results suggest that deviation in the directional response is reduced to 4% at a speed of ∼1.4 ms-1, in comparison to the 44% for the original sensor without the metal shell. The directivity can be reduced further by improving the fabrication techniques for the metal sphere.