Your garden variety motion detector uses IR, but these days, there are fancier technologies for achieving similar goals. If so desired, you can source yourself a microwave-based presence sensor ...

Spintronics exploits the intrinsic angular momentum of electrons—their spin—in addition to charge to create devices with novel functionalities. Key building blocks include magnetic tunnel junctions, ...

There's nothing worse than following directions precisely for a microwavable meal and taking it out only for it to need to go ...