If you happen to’ve ever questioned what lies beneath the hardly seen gap within the can of a MEMS microphone, you’re in luck, as a result of [Zach Tong] has a $10 pair of earbuds to sacrifice for the trigger and an electron microscope.
For the uninitiated, MEMS stands for microelectromechanical programs, the tiny silicon machines that energy a few of the extra miraculous capabilities of smartphones and different fashionable electronics. Probably the most acquainted MEMS gadget may be the accelerometer that offers your cellphone a way of the place it’s in area; [Zach] has a deep dive into MEMS accelerometers that we lined some time again.
MEMS microphones appear just a little bit simpler to know mechanically, since all they need to do is change vibrations in air into {an electrical} sign. The microphone that [Zach] tore down for this video is ridiculously small; the SMD gadget is just about 3 mm lengthy, with the MEMS chip beneath the can a fraction of a millimeter on a aspect. After some general views with the optical microscope, [Zach] opened the can and put the center beneath his scanning electron microscope. The SEM photographs are fairly superb, revealing a dimpled silicon diaphragm over a second layer with holes etched proper by means of it. The dimples on the diaphragm nest into the holes, forming an air-dielectric capacitor whose capacitance varies as sound waves vibrate the diaphragm.
Probably the most visually fascinating function, although, may be the deep cavity mendacity behind the 2 higher surfaces. The cavity, which [Zach] says bears proof of getting been etched by the deep reactive ion etching technique, has cool-looking corrugations in its partitions. The enormity of the cavity relative to the skinny layers protecting it suggests it’s a resonating cavity for the sound waves.
Due to [Zach] for this in-depth have a look at a tool that’s amazingly advanced but remarkably easy.
