I have seen these work. They are efficient. I would like to have some cubic in of air per $ figures compared to fans. My biggest question is the vibration frequency, resonance and harmonics. What kind/how much structure borne noise is generated. Do these have to be isolated fromt he chassis to prevent SBN transfer?
The question is whether such a movement of air can carry heat away from the target better than a rotational fan. More data should be shown. I also agree with katgod that the vibration stuff tends to break over time. How reliable this kind of fan can be?
Intresting to know how the sound is suppressed when it is vibrating. Wind is constant motion of air a particular direction. How this back and forth movement is imparting force on air particles in one direction only ?
PZ operated devices aren't new, nor are fan applications. For all sorts of interesting stuff, see the "Measurements Specialties" site. One of the interesting characteristics of piezo materials is that they tend to be voltage-operated. Another is that both "stiff" devices (lithium tantalate) and "flexible" devices (polymer piezo) materials are widely available. Ultrasonic transducers have been made for decades with both types. Now, some questions: how much power per how much air moved? And what is that ratio for a conventional rotating fan? How do they do for weight? Would like to see some numbers.
This invention, when developed fully may lead to what would be called as static fans, fans without any rotating parts. And that kind of a thing would a revolutionary one , just those pulsating blades of your ceiling or a table fan!