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The polymerase chain reaction ͑PCR͒ chips of different metal film thicknesses were fabricated, and the PCR machine with/without a top heater and the single-side/double-side heater PCR chips were compared. Before fabricating the chips, one simulated the effect of various thin-film thicknesses and the temperature distributions of various powers, and it helped one to find the optimum parameters. The total substrate material was cyclic olefin copolymers, and the gold film was fabricated on the substrate by evaporation. The results after PCR for the deoxyri bonucleic acid ͑DNA͒ of an Escherichia coli TG-1 cell were obtained. The results of the DNA amplifying 225 bps were 0.84-0.92 ng/ l, and these were 78-85% of the result of PCR machine with a top heater. There was no PCR product in the PCR machine without a top heater and single-side PCR chip. The thermal deformation temperature, thermal conductivity, and substrate thickness are the important parameters in a polymer substrate PCR chip, and the thermal deformation temperature is the key parameter.

This study presents the effect of fluidic temperatures and velocities on improving DNA hybridization. The efficiency of hybridization could be improved by introducing elevated temperature in the hot region and velocity in the cold region. Compared with the conventional methods, this hybridization microchip was able to increase the hybridization signal 4.6-fold within 30 min. The 1.4-kb single-stranded target DNA was tested. The increasing tendency of the fluorescence intensity was apparent when the temperature was higher than 82 degrees C, and the fluorescence intensity reached an asymptotic value at T>90 degrees C. A mathematical model was proposed to relate the fluorescence intensity of DNA hybridization with the hot-region temperature and the cold-region velocity. Based on these results, the new hybridization chip with the processes of temperature and velocity differences will improve efficiency of DNA detection. The microchip combined with hot-region temperature and cold-region bulk flow velocity effects could provide additional efficiency in DNA hybridization.

We fabricated PCR chips of different metal film thicknesses. The PCR machine with/without top heater and the single-side/double-side heater PCR chips were compared. The substrate was transparent COC (Cyclic Olefin Copolymers), and the gold film was fabricated on the substrate by evaporation without any adhesive layer. Then the results after polymerase chain reaction for the DNA of Escherichia coli TG-1 cell were obtained. The concentrations of amplifying 225 bps DNA were 0.78–0.82 ng/μl (64% of the result of PCR machine).