Choosing microphone for texture sensing

Question

I'm looking for a microphone that will record the vibrations of different textures and then with some signal processing I will get frequency as output. However, I don't know which microphone which suits best for this kind of application. Does anyone have any suggestions? Should I look for MEMS or ECM? Is it important to choose a digital or analog microphone? I only want the microphone to record the texture of a surface and not the background noise.

hopefully a clearer description: Sorry for the lack of description, but yes, the point is to use a microphone and drag it over a surface with different textures to record the friction-induced vibrations. A previous study used microphones to pick up the friction-induced vibrations so the user can "hear the texture" through headphones and it works pretty well. They used an electret condenser microphone. And I have to use microphones as well for this project, I'm just not sure if there are other microphones that would work better for this type of application.

My thoughts so far (which I'm not sure if it's correct, so please let me know if I'm wrong). Since I'll be recording noise (friction-induced vibration from different surfaces/textures), an analog microphone would be a better choice since it captures the signal as is. I also guess that ECM would be preferable and not MEMS since MEMS reduces the mechanical vibrations, and I'm guessing the kind of friction vibrations you get from dragging the microphone on surfaces is kind of mechanical vibrations, or am I wrong?

Answer 1

Not sure what you mean exactly by "vibrations of different textures" but let's assume you want an instrument you would drag over a surface and record its texture.

A microphone is designed to sense vibrations in air, so it's not directly usable. But you could put it in a little chamber with a diaphragm on one end. If the diaphragm had a bump or stylus on the outside, you could drag it over the surface, causing pressure changes in the chamber, and the microphone would pick it up.

D Duck's suggestion of a phonograph cartridge is good, but they are a bit delicate. With either that or the microphone, I think the vibrations may be below the audio frequency range, unless the texture is fine and the dragging is fast. If you're old enough to remember -- the legs of corduroy pants rubbing against each other makes an audible sound.

An accelerometer may be a better low-frequency sensor for vibrations. Just mount it on a PCB and have a stylus that sticks out, in contact with the PCB. An analog accelerometer would give you an analog waveform output, and you can test the concept with an oscilloscope.

To build a practical device, a digital accelerometer would be better, in connection with a microcontroller such as an Arduino. You will need filtering to eliminate DC and low frequency components due to gravity.