Preparation and Properties of High-Temperature Transient Thin-Film Thermopile Heat Flux Sensor

The thermopile of the sensor consists of 192 pairs of Pt-PtRh10 thermocouples with length 1 mm and width 100 μm in serpentine series were deposited on Al₂O₃ ceramic substrates by a photolithography coating process. The thermal resistance layers with the proposed low thermal conductivity feature a meshed cavity structure, with four thermal resistance layers spaced over the thermopile contacts to enhance the sensitivity of the sensor. Calibration of the sensor’s sensitivity was performed by a flat-plate radiative heat flux device, while its response time was measured by a pulsed laser. Finally, the sensor’s performance in an actual application environment was simulated using a wind tunnel. The results showed that the thin-film heat flux sensor can operate in environments ranging from 200°C to 1500°C, with a sensitivity of 0.03067 m² μV/W, the maximum relative error was 8.5% with an average response time of 12.7 μs. The sample exhibited stable performance during wind tunnel testing, responding quickly to changes in heat flux.