Piezo-electric paint

I am not certain this is possible. I believe there is sintering involved in producing piezo-ceramics.

But to fuel your idea for energy harvesting,there are piezo based commercial products, so the idea to accumulate electrical charges is not at all impossible. I let you see on the commercial viability...

There are piezo-electric fibers that may be suitable or look into passive infrared sensors, they are thin foils exhibiting piezo-electric properties for cheap. They are available at DigiKey.

Thanks...I also found this out there:

http://www.advancedcerametrics.com/pages/harvestor_power_module/

You never know what's next - I recently happened on an amazing web site:

http://www.lessemf.com/paint.html

I figure this kind of paint may exhibit amazing properties if the piezo-electric fibers were integrated. I've dealt with conductive powder coats for years in EMC work but those are not practical for large areas. This integration of a transducer (mechanical to electrical) that then charge-couples and acts as a harvesting surface with current migration through a conductive paint film might actually go somewhere.

I envision lighting power supplied by the noise of the subway trains or something like that.

I would put more hopes towards piezo wallpaper or wallboard than paint. Ends of the fiber need to be connected to the harvesting module while not being shorted.

Your wall could also become a microphone and speaker, to make active noise cancellation. See similar: http://www.etrema-usa.com/products/audio/

At destruction, the piezo films produce very high voltages. Once I put one like what is sold at DigiKey in an air flow to measure the frequency and correlate with speed. The air flow was too high and the sensor ripped like an old flag, transforming my Fluke DMM into a door stop.

Could be a shocking experience to someone breaking thru the wall...

This EDN design idea about energy harvesting from a piezo buzzer may be of interest.