Perhaps you will find this article interesting(attached pdf) . It was published in Wireless World late 80's or early 90's. I called Pennwalt to see if John Scott Strachan still worked there when I was director of research and development at another company during that period. They said he no longer worked there and had no record of how he might be contacted. They were kind enough to send me some samples of the piezofilm. I have not performed any of Strachan's experiments although this method, if it works, would be ripe for development. The magazine chose to place the words "Hypothesis" at the top of each page, I suppose as a disclaimer. John Scott Strachan has several patents. For this google CA 2003318 patent application.
http://www.padrak.com/ine/NEN_4_8_1.html
http://www.padrak.com/agn/
http://www.gyroscopes.org/forum/questions.asp?id=112
Curious that things stop working after a while. Joe Misiolek of the TVQ Group had a similar issue with a photoelectric device used to detect scalar waves. After a "rest period" they would work again, so you may let the film "rest" and try to determine what makes it stop working in the first place.
EDIT:
http://www.aetherscience.org/www-energyscience-org-uk/papers/bib/1994a.htm
Patent referenced is US 5,288,336
Might vortex cooling/heating devices be related?