A pressure transmitter for measuring a pressure of a process fluid includes a pressure sensor, a hydraulic relay system and a pressure sensor fill fluid. The pressure sensor senses the pressure of the process fluid, and the hydraulic relay system provides a communication channel between the process fluid and the pressure sensor. The pressure sensor fill fluid in the hydraulic relay system comprises a first hydraulic fluid and a first volume of nano-particles. The first hydraulic fluid transmits a change in the pressure of the process fluid to the sensor. The first volume of nano-particles is suspended within the first hydraulic fluid and alters properties of the pressure sensor fill fluid.