The whole article is massively misleading. The team used same basic design at three different scales: micro, meso, and macro (their terminology). They are 0.4mm

The whole article is massively misleading. The team used same basic design at three different scales: micro, meso, and macro (their terminology). They are 0.4mm, 2mm, 40mm in diameter respectively. The "IoT flier" used the macro scale design; in 40mm you definitely can already fit all sorts of antenna, although power is still an issue. All the other, smaller fliers did not have any microchips in them. So the title "Flying microchips size of sand grain" is just plain wrong here :(