Strand displacement amplification (SDA) was described in 1992 [23] and was improved in the same year [24] . There are four sequence-specific primers used in this isothermal amplification. The first set of primers (S 1 and S 2 ) is designed to have single-stranded restriction enzyme recognition site overhangs, and the second set of the primers (B 1 and B 2 ) represent the bumper primers. The DNA target is first denatured by heat and each strand is allowed to hybridize with two primers (S 1 and B 1 ), which are annealed to the DNA template. The B 1 extended product displaces the extension from the S 1 primer, which can hybridize to the opposite strand primers (B 2 and S 2 ). Thus, newly synthesized DNA that has been extended from the primers is cleaved by a corresponding restriction endonuclease, and the amplification is repeated by the polymerase, thus generating the newly synthesized strands rolling-circle and circle-to-circle amplification and the subsequent microchip electrophoretic analysis of bacterial genes (Figure 3 (B)) [60, 61] . A clinical sample was detectable in less than 65 min after the reaction was initiated.