What are piezoelectric plates ?

 So piezoelectric plates are very versatile piece of tech. They are basically special crystals made of atoms having considerable difference in electronegativities like most basic quartz crystal, which is silicon dioxide crystal, in which the oxygen atoms are more electronegative then silicon thus making dipoles but the net arrangement of system in hexagonal shape the two charge centers coincide making net dipole effect to be zero thus when there is no strain in crystal viz no deformation the net charge effect of all dipoles cancels each other. But when we apply an external force in a particular direction which disturbs this coinciding neutrality and generates dipoles in similar direction forming a potential difference between its two faces. These small dipoles can be thought of as small cells connected together in crystal forming a piezo electric plate.

 There are wide areas of application of this tech including the quartz watch on your wrist to the microphone in your laptop. But in my opinion still a lot can be done by making a crystal composed of atoms having very high difference in electro negativities to make a viable piezoelectric fan for us on earth. 

People might be thinking the reason why I wrote on earth as its used in space shuttles to cool electronics as there is no gravity in space thus no buoyant force for convection.