In Situ Thermal Aging Calibration Corrections for High Temperature MEMS Transducer Arrays
Dynamic matrix corrections combine in situ reference tracking and Arrhenius modeling to eliminate unbudgeted high temperature MEMS recalibration cycles.
Traceable Pressure Balance
Calibration Reference
Primary standard instrument determines pressure values by calculating the force exerted by a known mass on a piston of measured area. A traceable pressure balance provides a direct link to the international system of units through the fundamental quantities of mass, length, time, and local gravity.
Gravitational Correction
Local gravity at the laboratory site affects the weight of the masses used in the measurement. Using a traceable pressure balance requires precise knowledge of the gravitational acceleration at the exact elevation and latitude of the instrument. Variations in air density also create buoyancy effects that must be subtracted from the total force to maintain accuracy.
Metrologists use specialized software to apply these corrections and ensure that the resulting pressure value is accurate to within parts per million.
Piston Cylinder
Fit between the piston and the cylinder determines the leakage rate and the friction within the system. High-quality traceable pressure balance sets use tungsten carbide or ceramic materials to minimize wear and thermal expansion. The piston is rotated during operation to maintain a thin film of oil or air, which centers the assembly and eliminates static friction.
As the temperature of the laboratory changes, the effective area of the piston must be adjusted using a known coefficient of thermal expansion.
Hierarchy Transfer
National metrology institutes use these balances to maintain the primary pressure scale for a country. A traceable pressure balance acts as the origin for a chain of comparisons that ends with the sensors used on an industrial shop floor. Each step in this chain adds a small amount of uncertainty to the final measurement.
By starting with a primary balance, a laboratory can guarantee that its calibrations are recognized and accepted by international standards bodies.