The device has a main channel through which the grape juice winds its way. The yeast is placed in adjacent compartments and feeds into the main channel through a very thin membrane with holes called nanopores. It’s almost as if they were in little tea bags. When the grape juice reaches the yeasts, they absorb the sugar and give off alcohol and CO2 through the membrane. This process takes place very quickly, since the sugar and yeast are confined in such a small space.