This study presents a microfabricated device for polymerase chain reaction (PCR) with a flow-through manner for use in environmental microbiology. The device was developed utilizing photolithography and softlithography techniques and evaluated as one component of a totally integrated in situ gene analysis system. The developed device was composed of a glass-based "temperature control chip" and polydimethylsiloxane (PDMS)-based "microchannel chip". For the temperature control chip, six heaters made from indium tin oxide (ITO) are placed on a glass substrate to define three uniform temperature zones for flow-through PCR. On the each heater, a platinum (Pt) line was placed as a temperature sensor. The PDMS microchannel structure was fabricated by using a molding method with a negatively patterned mold master. The width and depth of folded microchannel was 100 mum and total length for 30 cycles of flow-through PCR was approximately 3.0 m. With the flow-through PCR device, 580 and 1450 bp (base pairs) of DNA fragments were successfully amplified from Escherichia coli genomic DNA and directly from untreated cells. (C) 2003 Elsevier B.V. All rights reserved.