Aluminum Nitride Piezoelectric Transducer
The electric current in a wall outlet is like water in a high-pressure pipe. To power a delicate chip, the pressure needs to be reduced, and this is usually done by bulky coils with iron cores.
A Film That Catches Invisible Light
A film of aluminum nitride, as thin as a soap bubble, hangs above a mirror with a micrometer-sized air gap between them. When invisible infrared light with a wavelength of about 15 micrometers hits it, the film starts to vibrate in sync with the light, like a string that responds only to its own note.