Application Cases

Application of Preamplifier for Weak Signals in Research on Fractal Eddy Current Sensors

【Overview】
In this study, the Aigtek ATA-5000 series preamplifier for weak signals was used to build an eddy current sensor experimental system, monitoring the transimpedance peak-to-peak data of the sensor under various excitation frequencies.

Experiment Name: Optimization Experiment of Single-Turn Coil Fractal Eddy Current Sensors

Research Direction: Eddy Current Testing, Flexible Planar Eddy Current Sensors, Coil Sensors

Experiment Objective:
By analyzing and comparing the response signals of single-turn flexible fractal eddy current sensors when scanning cracks, the best-performing sensor for detecting surface cracks on specimens was selected from six such sensors. The criterion for selecting the optimal sensor was based on comparing the transimpedance peak-to-peak values. A larger transimpedance peak-to-peak value indicates better crack detection capability. The transimpedance peak-to-peak value is obtained by denoising the collected data after scanning the crack and then calculating the result using a formula.

Testing Equipment:
Function signal generator, power amplifier, digital multimeter, ATA-5210 preamplifier for weak signals, lock-in amplifier, etc.

Figure 1: Photo of the Experimental Platform

Figure 2: Schematic Diagram of the Experimental Platform

Experimental Procedure:
The function generator outputs a sinusoidal excitation signal. One branch serves as a reference signal input to the lock-in amplifier, while the other branch is amplified by the power amplifier (with the amplified current monitored by a digital multimeter). The amplified signal is input into the excitation coil to generate a primary magnetic field. The conductor induces eddy currents, generating a反向 (反向,反向) secondary magnetic field. The two fields combine to form an alternating resultant magnetic field. The signal pickup coil collects the resultant magnetic field signal, which is amplified by the preamplifier. The amplified signal is then processed with the reference signal in the lock-in amplifier to obtain the real part, imaginary part, and R value (the square root of the sum of squares of the real and imaginary parts). The data are stored by a computer.

Experimental Results:
For detecting 90° cracks, the M6-K3 sensor exhibited the highest transimpedance peak-to-peak value across all excitation frequencies, making it the optimal sensor. For detecting 0° cracks, the M6-K3 sensor performed best at a frequency of 1000 kHz.

Advantages of Aigtek Amplifiers in This Application:

1. Ultra-low noise and high gain – Ensures weak signal fidelity and amplification accuracy.

2. Wide bandwidth and flat frequency response – Maintains consistent amplification across the operating frequency range.

3. Impedance matching and system synergy – Optimizes signal transmission and system integration.