A pressure sensor assembly includes a pressure sensor having a support structure and a sapphire isolation member coupled to the support structure and forming a region between a first surface of the sapphire isolation member and the support structure. A second surface of the sapphire isolation member has a sapphire etch surface formed thereon and is positioned to interface with fluid from or coupled to a process. A process seal is positioned against the second surface of the sapphire isolation member to prevent fluid from passing by the pressure sensor assembly. Electrical leads couple to a polysilicon strain gauge pattern positioned in the region on the first surface of the sapphire isolation member, and the polysilicon strain gauge pattern is configured to generate electrical signals indicative of the pressure of the fluid when the sapphire isolation member deflects responsive to the pressure.