Jen-Tzong Jeng

National Kaohsiung University of Science and Technology

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Chih‐Cheng Lu

National Taipei University of Technology

Chiu‐Hsien Wu

National Chung Hsing University

H. E. Horng

National Taiwan Normal University

Van Su Luong

Phenikaa University

Shieh‐Yueh Yang

National Chung Hsing University

Van-Dong Doan

Da Nang University of Technology

H. E. Horng

National Taiwan Normal University

H. C. Yang

University of Electronic Science and Technology of China

Huu-Thang Nguyen

Thai Nguyen University

Xuan Thang Trinh

Hung Yen University of Technology and Education

Cooperative Institutions

National Taiwan University

National Taipei University of Technology

National Taiwan Normal University

IBM (United States)

National Kaohsiung University of Science and Technology

GlobalFoundries (United States)

National Tsing Hua University

National Kaohsiung University of Applied Sciences

National Chung Hsing University

National Cheng Kung University

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Detection of Surface and Subsurface Flaws with Miniature GMR-Based Gradiometer

Sensors (2022)

Huu-Thang Nguyen Jen-Tzong Jeng Van-Dong Doan Chinh-Hieu Dinh Xuan Thang Trinh

The eddy-current (EC) testing method is frequently utilized in the nondestructive inspection of conductive materials. To detect the minor and complex-shaped defects on the surface and in the underlying layers of a metallic sample, a miniature eddy-current probe with high sensitivity is preferred for enhancing the signal quality and spatial resolution of the obtained eddy-current images. In this work, we propose a novel design of a miniature eddy-current probe using a giant magnetoresistance (GMR) sensor fabricated on a silicon chip. The in-house-made GMR sensor comprises two cascaded spin-valve elements in parallel with an external variable resistor to form a Wheatstone bridge. The two elements on the chip are excited by the alternating magnetic field generated by a tiny coil aligned to the position that balances the background output of the bridge sensor. In this way, the two GMR elements behave effectively as an axial gradiometer with the bottom element sensitive to the surface and near-surface defects on a conductive specimen. The performance of the EC probe is verified by the numerical simulation and the corresponding experiments with machined defects on metallic samples. With this design, the geometric characteristics of the defects are clearly visualized with a spatial resolution of about 1 mm. The results demonstrate the feasibility and superiority of the proposed miniature GMR EC probe for characterizing the small and complex-shaped defects in multilayer conductive samples.

Wheatstone bridge

10.3390/s22083097

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Citations (1)

Effects of modulation schemes on the performance of directly coupled high-T/sub c/ dc SQUID magnetometers

IEEE Transactions on Applied Superconductivity (2001)

Jau-Han Chen Kuen-Lin Chen Hsiao-Wen Yu Ming-Jye Chen Chiu‐Hsien Wu

We have designed and fabricated the directly coupled YBa/sub 2/Cu/sub 3/O/sub 7-/spl delta// dc SQUID magnetometers with two different modulation schemes to study the crosstalk effect in the on-chip multi-channel magnetometers. In one of the modulation schemes, the modulation current was directly injected into the SQUID body and the pick-up coil. The modulation efficiency was changed by the ratio of the modulation current flowing through the SQUID to the pick-up coil. In the other schemes, the modulation flux is mutually coupled through an external coil, and the modulation efficiency was changed by the mutual inductance of the external coil and the magnetometer. The results show that the modulation efficiency was varied when the value of self-inductance or the mutual inductance of SQUIDs change. Usually, lower modulation efficiency results in a higher crosstalk. The performance of magnetometers was also influenced by different modulation schemes. Their noise spectrum was compared as evidence.

Modulation (music)

10.1109/77.919542

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Citations (3)

Application of GMR Based Probe – for Eddy Current in Flaw Testing System

Lecture notes in mechanical engineering (2021)

Xuan Thang Trinh Jen-Tzong Jeng Trung Thanh Bui Ngoc Thai Tran Quoc Tuan Hoang

Spin valve

Modulation (music)

10.1007/978-3-030-69610-8_108

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Citations (0)

High-Tc SQUID magnetometers and gradiometers for NDE application

Physica C Superconductivity (2002)

Jen-Tzong Jeng H. E. Horng H. C. Yang

Shielded cable

SIGNAL (programming language)

10.1016/s0921-4534(01)01148-0

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Citations (11)

Classification of steel balls by resonant eddy-current sensor

Measurement Science and Technology (2021)

Duy-Vinh Dao Jen-Tzong Jeng Van-Dong Doan Chinh-Hieu Dinh Thi-Trang Pham

Abstract Objective: The quality and work-life of ball bearings depend on the material properties of the steel ball, hence it is necessary to carefully classify their properties for bearings and related applications. This paper presents the classification of steel balls based on the subtle differences in their electromagnetic properties. Approach: The conductivity and magnetic susceptibility for steel balls of the same kind are measured to investigate their correlation with eddy-current (EC) signals. Main results: The developed EC sensor works at the resonant frequency of 117 kHz with an optimal readout resistance of 15 kΩ, which helps to boost the signal level without a high-gain preamplifier. To detect the EC signal, the steel ball under test moves through the pickup coil, and the recorded data are used to build a voltage probability map (VPM) for the classification of the steel ball properties. Experimental results show that the steel balls with and without the hardening process can be identified by the change in the amplitude and phase of the EC signal, which is consistent with the observed change in the electromagnetic properties of steel balls. Significance: The built system can be applied to the related industries to check the quality of steel balls before use.

Electrical steel

Ball (mathematics)

SIGNAL (programming language)

Hardening (computing)

10.1088/1361-6501/ac32ed

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Citations (4)

Real-Time Thickness Measurement Using Resonant Eddy-Current Sensor

IEEE Transactions on Instrumentation and Measurement (2021)

Chinh-Hieu Dinh Jen-Tzong Jeng Guan-Wei Huang Jingyuan Chen Yi-Shian Chiang

In this work, we propose a real-time noncontact thickness measurement system for conductive materials based on an inductor-capacitor (LC) resonant eddy-current sensor. For the aluminum, copper, stainless steel 304, and carbon steel samples of various thicknesses, the in-phase and quadrature components of the sensor output taken during liftoff scans are found to be a series of quadratic-like curves on the phase versus logarithmic amplitude diagram. These curves can be used to generate the standard phase-amplitude relations for thickness conversion. The phase-amplitude relations of the thickness between the values of standard samples are calculated by cubic spline interpolation. With the standard database of phase-amplitude relations, the noncontact thickness measurement was implemented in real time for the copper foil sample with an error of ±3% when the liftoff distance is less than 5 mm. The liftoff tolerance is as large as 100% of the probe diameter, indicating that the proposed method is useful for online quality inspection of conductor films on flexible substrates.

Eddy-current sensor

Quadrature (astronomy)

10.1109/tim.2021.3077997

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Citations (11)

High-Resolution Flaw Detection using Eddy-Current Probe Array Based on Giant Magnetoresistance Sensors

Long-Vu Bui Jen-Tzong Jeng Hua‐Chih Huang Huu-Thang Nguyen Van-Dong Doan

10.1109/intermagshortpapers61879.2024.10576750

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Citations (0)

Studies of High-T c YBa2Cu3Oy SQUIDs

Chinese Journal of Physics (2000)