Micro Radiation Heat Flux Sensor Using Pt-RTDs and Reflective Films

Abstract

Most heat flux sensors have a large thickness of thermal resistance materials, and hence the sufficient temperature gradients along the thicknesses. They also require heat sinks and cooling methods to maintain the temperature gradients. In this work, we presents a small chip sized radiation heat flux sensor which is composed of two Pt-RTDs where one is gold-coated and the other is not. The gold film reflects radiation heat flux, so that the steady state temperature of the temperature sensor is different from that of the sensor without the gold film. This temperature difference can be correlated with radiation heat flux. Micro-fabricated Pt-RTDs showed an approximate TCR (Temperature Coefficient of Resistance; between 100 oC and 300 oC) of 2830 (Ω/Ω/oC). The sensors can be used up to 350 oC, and the heat flux of 3.5 kW/m2 with a convection heat transfer coefficient of 10 W/m2K at 50 oC. This heat flux sensor can be attached to smart clothes for firefighters and measure temperature as well as the radiation heat flux with a fast response time in a harsh environment.