Earth Cube, innovative satellite solution company (http://www.earthcube.eu/), initiated a stratospheric balloon launch, to validate monitoring solution and test payload .
“The test included a genuine version of the sensor, prototype optics and electronics (FullScale M1018P proxy board and CLink-C+ digi board). Thermal control and calibration shutter had to be included in order to maintain the sensor in the right environmental condition and compensate for temperature variation.”
http://www.earthcube.eu/blog/almost-half-way-to-space-in-less-than-6-months