The parents know that the baby bottle, which is too cold or too hot, above all, leads usually to loud protests from the child. New parents learn quickly how many seconds to the microwave, and that they will test the formula or milk at the back of the hand, but this type of low-tech test can be quite unreliable.
The baby bottle of designers Hung Cheng, Tzu-Yu Huang, Tzu-Wei Wang, and Yu-Wei Xiang Thermochromatic emblems used as a kind of Goldilocks automated, so you know, when the temperature is just right.
The baby bottle is just a design concept, but I think most parents would agree with this one anyway.