Miniaturized Heat-Flux Sensor Based on a Glass-Insulated Bi–Sn Microwire

Thermoelectric-energy conversion based on a single element made of an anisotropic material is considered. In such materials, the heat flux generates a transverse electric field. We fabricate an experimental heat-flux sensor (HFS) sample consisting of a 10-m-long glass-insulated single-crystal tin-doped bismuth microwire (outer diameter D = 18 μm, microwire diameter d = 4 μm). The microwire is wound into a flat spiral after recrystallization in a strong electric field, during which the main crystallographic axis C3 is oriented at the optimum angle with respect to the microwire axis. The sensor sensitivity reaches 10–2 V/W with the time constant τ ≈ 0.2 s. The sensor fabrication technology is rather simple and reliable for industrial applications.