The mouse used normally by us can detect about 1000 dots / inch of travel. A gaming mouse can detect 16000 dots / inch, a sensitivity 16x the normal. Why not use this instead of the regular mouse in our experiments? I did try and i wish it had succeeded. 

Here is the test setup. A vice holds a steel scale on one end, the other end is free and responds to vibrations in the building or the table. This moving tip is positioned directly above a highly sensitive gaming mouse.

While the mouse was connected to a laptop and was able to detect minute vibrations of people walking near it, it seemed it could be improved. The beauty is that such a setup is already quite sensitive even with such a simple setup. 

The con is that when i tried to remove the mouse lens and try to show some red laser onto it to incorporate it into my 1 meter long PVC cantilever setup, it just didn't work. Direct show of laser onto the sensor makes the mouse 'move' on the screen. However, when the laser passes through the mouse lens kept some distance apart, and the speckle interference pattern is formed on the mouse sensor, it seems to not be affected by it. I think its to do with its very narrow optical properties. With its built in IR laser, the chip might also be using some algorithm to detect surface features change which i am not able to replicate when used in my setup.

Incorporating such a nice mouse into the system could have been transformative for the project.