Anyone have any ideas on what type of sensor I should use to measure the alcohol percent in vodka or other booze? If I were at a bar and ordered a shot of straight booze (nothing with sugar or sugar added) what sensor could I use to confirm the strength? Liquid is the key, not vapor.
Gunpowder is a tried and tested method.
Might raise (and singe) a few eyebrows though.
I'm looking for something with a bit greater sensitivity range and that does not contaminate the sample. The fun factor certainly drops though.
I'd go the conductance route. Simple, cheap, easy. May even work.
Capacitative measurement might well work at low voltages - water has a dielectirc constant of around 80 at room temp, while alcohol is closer to 35. A 40% spirit will therefore have a dielectric constant 22%-ish lower than pure water.
The simplest test for alcohol purity is a hydrometer. Does not affect the product and requires no external power supplies but is slightly influenced by product temperature.