pH indicating soap bubbles - more work needed

I thought it would be cool to have a colored soap bubble that responded to changes in pH.  I concentrated some phenol red (pH indicator), and mixed it with commercial bubble solution.  Unfortunately, it was not dense enough to actually show its color. While investigating this, I noticed that normal soap bubbles lose their color as they become thinner (due to evaporation) and eventually burst.  I tried to get footage of this color loss, but the bubble will not stay in the same place!  I started to develop a method to partially fill the bubble with helium to make it neutrally buoyant.

How a breathalyzer works (alcohol sensor)

I teardown a commercial, handheld breathalyzer and discuss how it works, then test a standalone ethanol sensor.
http://www.seeedstudio.com/depot/images/product/MQ303A.pdf
http://www.kosmodrom.com.ua/pdf/MQ303A.pdf
http://www.sparkfun.com/products/8880

http://www-personal.umich.edu/~mswool/publications/Gas_Sensors_preprints.pd.pdf

Self-cleaning glass windows

Alien technology?  No!  A thin coating of titanium dioxide on your windows will use the UV in sunlight to burn away dirt and wash itself clean with rainwater.

Cookie Perfection Machine

This machine allows me to mix a single cookie and vary the recipe for each cookie on the sheet. Hence, I can test many different recipe variations with one batch of ingredients in one afternoon.

Music:  Cool Vibes - Kevin MacLeod (incompetech.com)
Licensed under Creative Commons: By Attribution 3.0
http://creativecommons.org/licenses/by/3.0/

Ruby laser design process

I describe the basics of ruby laser design. I'm building a laser with about 8KJ of electrical pump energy.

http://www.susiebeesley.co.uk/wp-content/uploads/2013/11/PKIlampbrochure.pdf

http://www.perkinelmer.de/PDFS/downloads/dts_applicationnotehighperformanceflash_final071004.pdf

http://www.fenixtechnology.com/fenixcalc.html

http://www.i-fiberoptics.com/