which is labeled as 102 flow in a direction 104 a dna template 106 has an itp electromigration direction 108 that is opposite to direction 104 as a result of this counter flow process template 106 experiences a chemical cycling that can mimic the denaturing and then annealing effects caused by thermal cycling in classical pcr locally high denaturant concentration regions melt double stranded nucleic acid while locally low denaturant regions allow for polynucleotide annealing and extension during the denaturation annealing and enzyme aided extension process the nucleic acid can be kept stationary in a microfluidic channel by balancing flow velocity 104 with itp velocity 108 while being exposed in a counter flow stream to a series of individual clouds of moving denaturant this exposes the nucleic acid to alternately high and low concentrations of denaturant itp provides focusing of the nucleic acids and protects the nucleic acids from being dispersed during amplification the nucleic acid can remain stationary with respect to the laboratory frame of reference while denaturant clouds move with the counter flow the chemical cycling process can be facilitated through spatial fluctuations in the concentration of the chemical denaturants along a microchannel which can be created by a flow control scheme and results from the high electrophoretic mobility of nucleotides and the electrical neutrality of denaturants since denaturant clouds are electrically neutral they are driven forward toward through and then away from the nucleic acid zone the velocity of the nucleic acid zone can be greater or less than that of the u201c.