Looking at the supplementary material, the "IoT macroflier" is pretty close to https://www.ti.com/tool/TIDM-RF430-TEMPSENSE https://www.ti.com/tool/TIDM-RF430-T

Looking at the supplementary material, the "IoT macroflier" is pretty close to https://www.ti.com/tool/TIDM-RF430-TEMPSENSE https://www.ti.com/tool/TIDM-RF430-TEMPSENSE with some wings stuck to it.. The scale is pretty similar too, that patch is about 35mm maybe. The sensor is different (photodiode vs temperature) but that doesn't really change the overall design much.