Pressure measuring instrument

A pressure sensor comprising:

• a body;
• a diaphragm separating a measured pressure cavity from a reference pressure cavity within the body;
• an electrode comprising a plate portion having a face separated from the diaphragm by a gap to form a capacitance there between, and further comprising a post extending from the plate portion through a body of the pressure sensor;
• circuitry supported by the body and electrically connected to the electrode to receive a capacitance signal;
• and
• a wire comprising a coil surrounding the electrode post at a first end and connected to the circuitry at a second end to conduct the capacitance signal.

A pressure sensor comprising:

• a body;
• a diaphragm separating a measured pressure cavity and a reference pressure cavity within the body;
• an electrode comprising a plate portion having a face separated from the diaphragm by a gap to form a capacitance there between, and further comprising a post extending from the plate portion through the body;
• a ceramic seal member disposed between the post and the body;
• and
• a hermetic seal between the post and the body comprising a braze joint comprising a buffer material between the ceramic seal member and at least one of the post and the body.

A pressure sensor comprising:

• a body;
• a diaphragm separating a measured pressure cavity and a reference pressure cavity within the body;
• an electrode comprising a plate portion having a face separated from the diaphragm by a gap to form a capacitance there between, and further comprising a post extending from the plate portion through the body;
• a ceramic seal member disposed between the post and the body;
• and a hermetic seal between the post and the body comprising a ceramic seal member and a braze interface joining the ceramic seal member to the post and to the body;
• wherein materials and axial length proportions of the ceramic seal member, braze interface, and electrode are chosen so as to match a thermal expansion characteristic of the body in order to substantially eliminate thermal offset sensitivity of the gap.