A standard electret microphone can detect sub-audio "sounds" when some simple equalization circuitry is added.

A defective parking sensor can be expensive. Here is a small circuit that you can use to quickly and easily detect defective ...

WASHINGTON, April 9 (Reuters) - Neuroscientists have produced the largest wiring diagram and functional map of a mammalian brain to date using tissue from a part of a mouse's cerebral cortex ...