Isolated Silicon Pressure Cell Oil Dosing Volume Tolerances and Temperature Hysteresis
Isolated silicon cell thermal hysteresis depends directly on micro-dosing oil volume accuracy and outer diaphragm compliance balance.
Isolation Diaphragm Mechanics
Pressure Transfer
Metallic foils located at the process interface protect the internal sensing elements from corrosive or high temperature media. These isolation diaphragm mechanics involve the linear deflection of the metal under an applied load. The foil must be flexible enough to transfer the pressure to the internal oil without adding measurable resistance.
It acts as a physical barrier while remaining transparent to the force being measured.
Elastic Deformation
The metal stretches and moves when pressure is applied to the outer surface. Proper isolation diaphragm mechanics rely on the material remaining within its elastic limit. If the foil is pushed too far, it suffers permanent deformation and shifts the zero point of the sensor.
Fluid Coupling
Fill oil transmits the movement of the foil to the silicon chip located deeper in the housing. Because isolation diaphragm mechanics are influenced by the viscosity of this oil, the sensor response time may slow down in cold weather. The volume of oil must be kept to a minimum to reduce thermal errors.
Non-Linearity Source
Imperfections in the shape of the foil or the tension of the weld can cause the output to deviate from a straight line. Correcting for isolation diaphragm mechanics often requires a mathematical compensation in the sensor electronics. This correction is verified during the final calibration at the factory.