A micro-reactor adapted to host chemical reactions having at least one microfluidic layer, said micro-reactor comprising a fluid inlet and a fluid outlet; a plurality of micro-reaction chambers arranged in rows and columns, each micro-reaction chamber comprising a chamber inlet and a chamber outlet; a plurality of supply channels for supplying fluid from said fluid inlet to said micro-reaction chambers and further arranged for draining said micro-reaction chambers to said fluid outlet, said supply channels extending in a first direction along the columns of micro-reaction chambers and arranged such that there is one supply channel between adjacent columns; and further wherein the micro-reaction chambers in the columns are arranged such that the chamber inlets of a column are in fluid contact with the same supply channel and the chamber outlets are in fluid contact with the supply channel adjacent to the supply channel arranged in fluidic contact with the chamber inlets, and wherein the plurality of supply channels comprises a first end supply channel arranged for supplying fluid to a first end column of the micro-reaction chambers and a second end supply channel arranged for draining fluid from the second, opposite, end column of said micro-reaction chambers; and wherein the micro-reactor further comprises at least one reagent inlet in fluid contact with the first end supply channel and a reagent outlet in fluid contact with the second end supply channel such that reagents introduced to the at least one reagent inlet fill the plurality of micro-reaction chambers in a second direction along the rows of micro- reaction chambers to the reagent outlet. a fluid inlet and a fluid outlet; a plurality of micro-reaction chambers arranged in rows and columns, each micro-reaction chamber comprising a chamber inlet and a chamber outlet; a plurality of supply channels for supplying fluid from said fluid inlet to said micro-reaction chambers and further arranged for draining said micro-reaction chambers to said fluid outlet, said supply channels extending in a first direction along the columns of micro-reaction chambers and arranged such that there is one supply channel between adjacent columns; and further wherein the micro-reaction chambers in the columns are arranged such that the chamber inlets of a column are in fluid contact with the same supply channel and the chamber outlets are in fluid contact with the supply channel adjacent to the supply channel arranged in fluidic contact with the chamber inlets, and wherein the plurality of supply channels comprises a first end supply channel arranged for supplying fluid to a first end column of the micro-reaction chambers and a second end supply channel arranged for draining fluid from the second, opposite, end column of said micro-reaction chambers; and wherein the micro-reactor further comprises at least one reagent inlet in fluid contact with the first end supply channel and a reagent outlet in fluid contact with the second end supply channel such that reagents introduced to the at least one reagent inlet fill the plurality of micro-reaction chambers in a second direction along the rows of micro- reaction chambers to the reagent outlet.