Single-Ended Eddy Current Micro-Displacement Sensor with High Precision Based on Temperature Compensation.

Area of Science:

• Instrumentation and Measurement
• Sensor Technology
• Materials Science

Background:

• Reliable micro-displacement measurement requires high precision sensors.
• Eddy current sensors offer non-contact measurement capabilities.
• Temperature variations can significantly impact sensor accuracy.

Purpose of the Study:

• To develop and evaluate a single-ended eddy current sensor with integrated temperature compensation.
• To analyze the sensor's performance in terms of resolution, repeatability, and temperature stability.
• To demonstrate the feasibility of the proposed design for precise micro-displacement applications.

Main Methods:

• Detailed study of eddy current sensor principles and probe manufacturing.
• Design of a processing circuit converting output signal variations to digital pulses.
• Implementation of a digital phase discriminator, low-pass filter, and amplification stage.
• Development of a temperature-compensating circuit using a digital potentiometer and embedded temperature sensor.

Main Results:

• The sensor exhibits nonlinearity at large measurement ranges.
• Achieved a resolution of 46 nm for a 500 μm range with ±0.70% FR repeatability error.
• Temperature compensation reduced voltage fluctuation from 586 mV to 44 mV across a +2 °C to +58 °C range.

Conclusions:

• The developed temperature-compensated eddy current sensor is feasible for high-precision micro-displacement measurement.
• The sensor demonstrates improved accuracy and stability under varying temperature conditions.
• Consideration of measurement range, precision, and target material is crucial for practical implementation.