Yu Hyun, Park Sang J, Lee Inho, Shim Ji Hoon, Jin Hyungyu
Department of Mechanical Engineering, Pohang University of Science and Technology (POSTECH), Pohang, South Korea.
Department of Chemistry, Pohang University of Science and Technology (POSTECH), Pohang, South Korea.
Sci Technol Adv Mater. 2025 Aug 7;26(1):2544649. doi: 10.1080/14686996.2025.2544649. eCollection 2025.
Heat flux sensors based on the anomalous Nernst effect (ANE) have emerged as a promising solution for achieving thin and flexible designs. ANE-based heat flux sensors typically employ thermopile structures composed of two ANE materials with opposite signs, connected in series to enhance sensing performance. However, a mismatch in the Seebeck coefficient between the two ANE materials causes a considerable offset voltage due to the Seebeck effect (SE) under oblique heat flux. This parasitic sensing voltage hinders direct sensing of heat flux in the intended direction. In this study, a sign-reversed ANE with matched Seebeck coefficient is examined in FeLn (Ln = Gd, Tb, Dy, Ho, and Er), enabling a thermopile structure free from the SE-induced offset voltage. Based on density functional theory calculations, Fe₃Ln is selected as a suitable candidate for exhibiting sign reversal of ANE while maintaining the Seebeck coefficient. At 300 K, FeLn (Ln = Gd, Tb, Dy, and Ho) exhibits a positive ANE sign, whereas FeEr exhibits a negative ANE sign, facilitating the combination of two sign-reversed ANE materials. Among these, FeHo and FeEr demonstrate the lowest Seebeck coefficient difference of 0.45 μV K, minimizing the offset voltage-induced relative uncertainty, as confirmed by COMSOL simulations - comparable to that of other SE-based heat flux sensors. This study paves the way for the development of ANE-based heat flux sensors by introducing a novel approach to pairing opposite-ANE-sign materials with matched Seebeck coefficient, enabling direct and accurate heat flux sensing via thermopile structures.
基于反常能斯特效应（ANE）的热流传感器已成为实现薄型和柔性设计的一种有前景的解决方案。基于ANE的热流传感器通常采用由两种具有相反符号的ANE材料组成的热电堆结构，串联连接以提高传感性能。然而，在倾斜热流下，由于塞贝克效应（SE），两种ANE材料之间的塞贝克系数不匹配会导致相当大的偏移电压。这种寄生传感电压阻碍了对预期方向热流的直接传感。在本研究中，在FeLn（Ln = Gd、Tb、Dy、Ho和Er）中研究了具有匹配塞贝克系数的符号反转ANE，从而实现了一种不受SE诱导偏移电压影响的热电堆结构。基于密度泛函理论计算，选择Fe₃Ln作为在保持塞贝克系数的同时表现出ANE符号反转的合适候选材料。在300 K时，FeLn（Ln = Gd、Tb、Dy和Ho）表现出正的ANE符号，而FeEr表现出负的ANE符号，便于两种符号反转的ANE材料的组合。其中，FeHo和FeEr表现出最低的塞贝克系数差0.45 μV K，将偏移电压引起的相对不确定性降至最低，正如COMSOL模拟所证实的那样——与其他基于SE的热流传感器相当。本研究通过引入一种将具有相反ANE符号的材料与匹配的塞贝克系数配对的新方法，为基于ANE的热流传感器的发展铺平了道路，从而能够通过热电堆结构直接且准确地感测热流。
