"Vega Machine" measures an electro-chemical response extradermally?

The Vega machine is an instrument that measures an electro-chemical response by means of touching a specific nerve with a sensor and comparing the reaction with a control database.  Does anybody know anything about this?  My wife was tested again recently and I would like to learn more about the efficacy of this test.  Don't really know much about it, other than it is considered "alternative" and therefore not accepted or studied by general medicine practitioners.  The machine has a battery of substances and tests for many general and specific foods as well as Candida and other common allergies.  It also measures, extradermally, mineral and vitamin content in the bloodstream.  The machine is manufactured in Germany.