A method for mixing two reagents to produce a detectable reaction in a microfluidic chip, comprising: providing a microfluidic chip comprising: a first reagent inlet in fluid communication with a first reagent channel, said first reagent channel having a height, a width and a length, said first reagent channel having a first reagent flow rate defined by the height, the width and the length of the first reagent channel; a second reagent inlet in fluid communication with a second reagent channel, said second reagent channel having a height, a width and a length, said second reaction channel having a second reagent flow rate defined by the height, the width and the length of the second reagent channel; said first reagent channel and said second reagent channel meeting at a first junction point, said first junction point in fluid communication with a reaction channel, and said reaction channel in fluid communication with an outlet; applying a quantity of a first reagent solution to the first reagent inlet; applying a quantity of a second reagent solution to the second reagent inlet; applying a quantity of oil to the first reagent inlet and the second reagent inlet, said first reagent flowing along the first reagent channel at the first reagent channel flow rate and said second reagent flowing along the second reagent channel at the second reagent channel flow rate and mixing at the first junction point, thereby producing the detectable reaction; and detecting the detectable reaction within the reaction channel; characterized in that said oil has a density that is slightly lower than a density of the first reagent solution and slightly lower than a density of the second reagent solution so that said oil floats on top of the first reagent solution in the first reagent inlet and the second reagent solution in the second reagent inlet. providing a microfluidic chip comprising: a first reagent inlet in fluid communication with a first reagent channel, said first reagent channel having a height, a width and a length, said first reagent channel having a first reagent flow rate defined by the height, the width and the length of the first reagent channel; a second reagent inlet in fluid communication with a second reagent channel, said second reagent channel having a height, a width and a length, said second reaction channel having a second reagent flow rate defined by the height, the width and the length of the second reagent channel; said first reagent channel and said second reagent channel meeting at a first junction point, said first junction point in fluid communication with a reaction channel, and said reaction channel in fluid communication with an outlet; a first reagent inlet in fluid communication with a first reagent channel, said first reagent channel having a height, a width and a length, said first reagent channel having a first reagent flow rate defined by the height, the width and the length of the first reagent channel; a second reagent inlet in fluid communication with a second reagent channel, said second reagent channel having a height, a width and a length, said second reaction channel having a second reagent flow rate defined by the height, the width and the length of the second reagent channel; said first reagent channel and said second reagent channel meeting at a first junction point, said first junction point in fluid communication with a reaction channel, and said reaction channel in fluid communication with an outlet; applying a quantity of a first reagent solution to the first reagent inlet; applying a quantity of a second reagent solution to the second reagent inlet; applying a quantity of oil to the first reagent inlet and the second reagent inlet, said first reagent flowing along the first reagent channel at the first reagent channel flow rate and said second reagent flowing along the second reagent channel at the second reagent channel flow rate and mixing at the first junction point, thereby producing the detectable reaction; and detecting the detectable reaction within the reaction channel;