To provide a method for reducing or eliminating formation of an oxide which becomes hindrance in manufacturing or operation, in regard to a fluid switch.

This method comprises (i) a step providing a switching fluid on a first substrate under low oxygen partial pressure which is low oxygen partial pressure which is below a critical value reducing formation of oxide and (ii) a step fitting the first substrate and a second substrate to delimit a cavity holding the switching fluid between them. The cavity is made in a size allowing movement between first and second states of the switching fluid.