A sensor package and method are described. The sensor package includes an enclosure, a diaphragm coupled to the enclosure. The diaphragm is configured to receive vibrations from an ambient environment. Further, the sensor package includes a pressure sensing element disposed inside the enclosure, and a pressure transfer medium disposed inside the enclosure and proximate the pressure sensing element, where the pressure transfer medium includes a fluid, and a plurality of filler particles suspended in the fluid. The filler particles serve to reduce a coefficient of thermal expansion of the pressure transfer medium.