A continuous droplet flow microfluidic system, comprising: a microfluidic chip comprising an optical detection section; a stage assembly comprising a microfluidic chip holder configured to receive said microfluidic chip and a plurality of heating elements arranged to heat a plurality of separate sections of said microfluidic chip to a corresponding plurality of different temperatures; and an optical detection system arranged to detect fluorescent light emitted from said optical detection section of said microfluidic chip, wherein said microfluidic chip comprises: a substrate; a channel control layer attached to said substrate; and a fluid flow layer attached to said channel control layer on an opposite side of said control layer from said substrate such that said fluid flow layer and said channel control layer define fluid channels within said fluid flow layer, said channel control layer and said fluid flow layer being formed from all-silicone polymer material, wherein said channel control layer and said fluid flow layer define a main channel extending from a droplet generating section, extending through a reagent injection section, passing through a plurality of incubation sections, each incubation section having a separately selectable temperature, and passing through said optical detection section, wherein said main channel has a serpentine path in each incubation section of said plurality of incubation sections to transport droplets through serpentine channels affixed at different temperatures to perform continuous-flow PCR, wherein said main channel increases in width and height between said reagent injection section and said plurality of incubation sections, and wherein said optical detection section of said main channel has at least one of a decreased width or decreased height relative to said plurality of incubation sections to stretch droplets for detection. a microfluidic chip comprising an optical detection section; a stage assembly comprising a microfluidic chip holder configured to receive said microfluidic chip and a plurality of heating elements arranged to heat a plurality of separate sections of said microfluidic chip to a corresponding plurality of different temperatures; and an optical detection system arranged to detect fluorescent light emitted from said optical detection section of said microfluidic chip, wherein said microfluidic chip comprises: a substrate; a channel control layer attached to said substrate; and a fluid flow layer attached to said channel control layer on an opposite side of said control layer from said substrate such that said fluid flow layer and said channel control layer define fluid channels within said fluid flow layer, said channel control layer and said fluid flow layer being formed from all-silicone polymer material, a substrate; a channel control layer attached to said substrate; and a fluid flow layer attached to said channel control layer on an opposite side of said control layer from said substrate such that said fluid flow layer and said channel control layer define fluid channels within said fluid flow layer, said channel control layer and said fluid flow layer being formed from all-silicone polymer material, wherein said channel control layer and said fluid flow layer define a main channel extending from a droplet generating section, extending through a reagent injection section, passing through a plurality of incubation sections, each incubation section having a separately selectable temperature, and passing through said optical detection section, wherein said main channel has a serpentine path in each incubation section of said plurality of incubation sections to transport droplets through serpentine channels affixed at different temperatures to perform continuous-flow PCR, wherein said main channel increases in width and height between said reagent injection section and said plurality of incubation sections, and wherein said optical detection section of said main channel has at least one of a decreased width or decreased height relative to said plurality of incubation sections to stretch droplets for detection.