Abstract: Embodiments disclosed herein provide a surgical cassette including pump assemblies with improved contact between a displacement sensor disposed within a surgical console and a diaphragm disposed within the surgical cassette. Each pump assembly includes a diaphragm retainer ring that provides a sufficient creepage and clearance margin, acts as a lead-in for the displacement sensor, assists in preventing misalignment, and provides robustness for the ultrasonic welding process which couples the diaphragm retainer ring to the surgical console. The diaphragm retainer ring is impregnated with a lubricant so to facilitate seating of the displacement sensor with the cassette. A cantilever portion of the diaphragm retainer ring increases a creepage and clearance margin, as well as increases overall part strength in the event of a collision with the displacement sensor and during ultrasonic welding. An insulator is also provided that further increases the creepage and clearance margin.