Piezoresistive Pressure Sensor Zero Drift under Variable Atmospheric Humidity
Dynamic atmospheric humidity alters gel swelling stress and dielectric passivation properties in piezoresistive sensors, driving measurable zero baseline drift.
Parasitic Resistance
Unwanted Impedance
The undesirable electrical resistance present within the conductive paths, connectors, or silicon traces of a measurement circuit degrades signal transmission. This characteristic, known as parasitic resistance, limits the accuracy of high-precision electronic instruments.
Signal Attenuation
In low-voltage sensor circuits, voltage drops across interconnects reduce the amplitude of the measured signal. When parasitic resistance exists in the wiring of a strain gauge bridge, it reduces the overall sensitivity of the sensor and introduces measurement offsets. These losses can be particularly severe in long cable runs where the wire resistance becomes a significant fraction of the sensor impedance.
Temperature Interference
The resistance of metallic conductors varies with temperature, causing the unwanted circuit impedence to change as the environment fluctuates. This drift in parasitic resistance alters the sensor calibration and introduces thermal offset errors. Laboratory measurements must account for this behavior to maintain high precision.
Compensation Technique
To eliminate the effects of cable and connector resistance, instrument designers implement four-wire Kelvin connection techniques. This method separates the current-driving paths from the voltage-sensing paths, ensuring that parasitic resistance does not affect the voltage measurement. By utilizing this approach, precision meters can accurately measure sub-ohm resistances and maintain stable calibrations even with long connection lines.