A new continuous-flow PCR microchip has been developed that operates by cycling a prepared sample within a spatial temperature gradient. This design allows for minimal thermal residence times - a key feature of the protocols used by the fastest commercial PCR equipment. Since thermal gradients are a natural effect of heat dissipation, the appropriate temperature distribution for PCR can be generated by a minimum of one heater held at a steady state temperature. With a thermal gradient of more than 3°C/mm across the width of the chip, each complete PCR cycle requires approximately 2cm of channel length. These glass chips were manufactured using standard glass microfabrication methods as well as the Xurographic rapid prototyping technique. Targets of 110bp and 181bp were amplified from X174 plasmid DNA on these thermal gradient chips as well as on commercial PCR equipment, then subsequently analyzed by gel electrophoresis. Visual inspection of fluorescent images of the stained gels shows that the amplicon size and yield for the systems are comparable.© (2007) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.