Keaner,
In basic terms, as you increase the number of discrete components while continuing to reduce the chip size the widths of the conductors and the insulation between them get smaller. The higher the voltage the more leakage current you have between the conducting traces inside the chip. If the voltage gets to high you will fry the chip.
As an example the quad core in my computer is running on 1.136 vdc,
Also I think the point that @Moors7 was trying to make was even the newer Arduinos are operating at lower voltages.
One other choice is to use something like a ADS1115 module that is a 16 bit ADC with four channels (I2C connected).
There are companys that make a board for the Photon or Electron that provide level shifted (to 5 vdc, I2C standard voltage) and ADS1115 module at very reasonable prices.
Chuck