This paper discloses two high-sensitivity probes for Eddy Current Nondestructive Test (NDT) of buried and surface defects. These probes incorporate eight and 32 magnetoresistive sensors, respectively, which are optimized for high sensitivity and spatial resolution. The signal processing and interfacing are carried out by a full-custom application-specific integrated circuit (ASIC). The ASIC signal chain performs with a thermal input-referred noise of 30 nV/$\sqrt{\text{Hz}}$ at 1 kHz, with 66 mW of power consumption, in a die with 3.7×3.4 mm$^2$. NDT results are presented, showing that there is an increase in spatial resolution of surface defects when contrasted to prior art, enabling the probes to resolve defects with diameters of 0.44 mm, pitches of 0.6 mm, and minimum edge distance as low as 0.16 mm. The results also show that the probe for buried defects is a good all-round tool for detection of defects under cladding and multiple-plate flat junctions.

中文翻译：

---

基于磁阻传感器的高分辨率无损测试探头

本文公开了两种用于埋藏缺陷和表面缺陷涡流无损检测 (NDT) 的高灵敏度探头。这些探头分别包含 8 个和 32 个磁阻传感器，它们针对高灵敏度和空间分辨率进行了优化。信号处理和接口由全定制的专用集成电路 (ASIC) 执行。ASIC 信号链在 1 kHz 时以 30 nV/$\sqrt{\text{Hz}}$ 的热输入参考噪声执行，功耗为 66 mW，在 3.7×3.4 mm$^2$ 的裸片中. 展示了无损检测结果，表明与现有技术相比，表面缺陷的空间分辨率有所提高，使探头能够解决直径为 0.44 毫米、节距为 0.6 毫米和最小边缘距离低至 0.16 毫米的缺陷。