Diffusion-based PCR in a 24 nl reaction chamber starting with genomic DNA purified from GM12878 cells. The detection targeted GAPDH gene and the amplification run for 30 cycles. The copy number of the PCR product was quantified using qPCR. The results with various loading times (grey bars, 0, 1, 3, 10 and 30 min) are compared with those of on-chip PCR with various Taq polymerase concentrations (0, 0.2, 2, 13 and 38 U/ml) and primers concentrations (0, 3, 20, 120, 400 nM) (striped bars, these values were generated by COMSOL modelling of the diffusion process for the corresponding loading times) to confirm the impact of the diffusion on PCR results.