Roll‐to‐Roll Printing of Anomalous Nernst Thermopile for Direct Sensing of Perpendicular Heat Flux

Abstract

The anomalous Nernst effect (ANE) converts heat flux perpendicular to the plane into electricity, in sharp contrast with the Seebeck effect (SE), enabling mass production, large area, and flexibility of their devices through ordinary thin‐film fabrication techniques. Heat flux sensors, one of the most promising applications of ANE, are powerful devices for evaluating heat flow and can lead to energy savings through efficient thermal management. In reality, however, SE caused by the in‐plane heat flux is always superimposed on the measurement signal, making it difficult to evaluate the perpendicular heat flux. Here, ANE‐type heat flux sensors that selectively detect a perpendicular heat flux are fabricated by adjusting the net Seebeck coefficient in their thermopile circuit with mass‐producible roll‐to‐roll sputtering methods. The direct sensing of perpendicular heat flux using ANE‐based flexible thermopiles, as well as their simple fabrication process, paves the way for the practical application of thin‐film thermoelectric devices.

Direct‐Contact Seebeck‐Driven Transverse Magneto‐Thermoelectric Generation in Magnetic/Thermoelectric Bilayers

“…[11,14,[16][17][18]20] These advantages have also been exploited for other applications, such as flexible heat flux sensors with low thermal resistance. [21][22][23][24] However, the transverse thermopower for ANE is still small compared to the thermopower of SE of thermoelectric materials, and further enhancement is strongly required for creating practical applications.…”

Anomalous Nernst thermoelectric generation in multilayer-laminated coiled magnetic wires

“…The open-circuit voltage generated by ANE is proportional to the length of the magnetic material along E ANE . Owing to this feature, ANE enables thermoelectric power generation in simple sheet or block structures 19,21) and coiled wires 7,11) as well as heat-flux sensing in lateral zigzag structures, 15,19,22) which are conceptually different from module structures based on the Seebeck effect. In the ANE device based on coiled wires, the magnetic material is magnetized along the axial direction and a temperature gradient is applied along the radial direction to satisfy the symmetry of Eq.…”