  We performed a numerical analysis of the material parameters required for
realizing a heat flux sensor exploiting the anomalous Nernst effect (ANE). The
results showed the importance of high thermopower of ANE ($S_{\text{ANE}}$) and
small saturation magnetization. This motivated us to investigate the effect of
Al substitution of Fe on ANE and found $S_{\text{ANE}} =$ 3.4 $\mu$V/K in
Fe$_{81}$Al$_{19}$ because of the dominant intrinsic mechanism. Using this
material, we made a prototype ANE-based heat flux sensor on a thin flexible
polyimide sheet and demonstrated accurate sensing with it. This study gives
important information for enhancing sensor sensitivity.
