A heat flux sensor with both fast response and high sensitivity

Heat flux sensors are of great significance for measuring heat transfer processes. However, due to the limitations of the thermal resistance thickness and the number of thermopile junctions, it is often difficult to combine the high sensitivity and fast response time in one heat flux sensor. In this work, we design the thermopile array based on the principle of hexagonal dense arrangement to increase the number of junctions in a limited area, and at the same time, we set up films with different functions at the hot and cold junctions to increase the temperature difference. Tests on multiple sensors show that in the range of 0-207 kW/m², the coefficient of determination R² of the quadratic fit between sensor output and heat flux is greater than 0.999. In the linear operating range from 114 to 201 kW/m², the sensor exhibits a maximum heat flux sensitivity of 91.13 μV/(kW/m²); the response times of the sensors are faster than 2.85 ms under different laser powers and durations. The sensor exhibits a good response to heat fluxes such as respiration, flame, and hot air, and is expected to be applied to the measurement of high-temperature and rapidly varying heat transfer.