What are the common types of pressure sensors?

Common pressure sensors include: Strain gauge (piezoresistive) - most common, measures diaphragm deflection; Capacitive - measures capacitance change with diaphragm position, good for low pressure; Piezoelectric - for dynamic pressure measurement; Resonant - frequency changes with pressure, high accuracy; and Bourdon tube (mechanical) - used in gauges. Pressure references: gauge (relative to atmosphere), absolute (relative to vacuum), and differential (between two pressures). Selection depends on range, accuracy, media compatibility, and environment.