Model AS-PS Pressure Switch

FCI pressure elements use piezoresistive sensors (strain gage sensors) fabricated using silicon processing techniques common in the semiconductor industry. 

Piezoresistive sensors are often referred to as IC sensors (integrated circuit), solid state sensors, monolithic sensors (formed from single crystal silicon) or just silicon sensors.

FCI elements consist of four strain sensitive resistors ion implanted into silicon wafers. These resistors are connected in a wheatstone bridge configuration. Two resistors increase in ohmic value as pressure increases while the other two decrease. When pressure is applied, the resistors in the arms of the bridge change by an amount R. Alignment of the resistors on the silicon determines which resistors increase and which decrease with pressure.