Microfluidic thermocyclers for genetic analysis

Improved thermocycler design can increase the efficiency of genetic analysis based on the polymerase chain reaction. In this report, strategies for chip-based microfluidic thermocyclers are discussed, and the design and performance of devices employing buffer joule heating for thermocycling are presented. Novel joule heating methods involving transfer of electric current directly into the PCR buffer within microchannels are introduced. These methods utilize in-channel platinum electrodes to transfer AC heating current into the buffer under conditions of minimal oxidation-reduction and water electrolysis. Key features of the approach include, (i) very small, nanoliter-level reaction volumes for decreased reagent consumption, (ii) an integrated reagent accession microcapillary for continuous-flow processing and on-chip, run-time reaction assembly options, (iii) rapid thermocycling for better PCR performance, and (iv) simple and fully integrated reaction buffer heating and temperature sensing provided by buffer joule heating technology.