MEMS design and Micro-fabrication LabMML

Micromachined Flow-through Polymerase Chain Reaction Chip Utilizing Multiple Membrane-activated

MicropumpsChih-Hao Wang1, Chia-Sheng Liao2, Gwo-Bin Lee1,2

1Department of Engineering Science, 2 Institute of MEMS, National Cheng Kung University, Tainan Taiwan 701Abstract This study reports a new micromachined flow-through polymerase chain reaction (PCR) chip for applications of rapid pathogen diagnosis. The PCR chip comprised a micro thermal control module and a microfluidic control module fabricated using MEMS technology. The micro thermal control module was formed with three individual heating and temperature-sensing sections, each modulating a specific temperature for denaturation, annealing and extension process, respectively. The membrane-activated micropumps were used to transport sample fluids through three reaction regions to adjust the time ratio and cycle numbers for PCR. The experimental results showed that S. pneumoniae detection gene (273 bps) could be amplified successfully using the new flow-through PCR chip. The new PCR chip could be promising for rapid clinical diagnosis of DNA-based infectious disease.

Design and Fabrication

Schematic diagram of the flow-through PCR chip

Experimental

Conclusions

The movement of the PCR product in the microchannel was dependent on the time ratio of membrane-activated micropump and cycle numbers.

The micro thermal control module was formed with three individual heating and temperature-sensing sections, each modulating a specific temperature for denaturation, annealing and extension process, respectively.

The PCR chip integrated with the three heaters/sensors and membrane-activated micropumps successfully solve the problems in previous researches including a fixed time ratio.

Acknowledgements

The authors gratefully acknowledge the financial support provided to this study by the National Science Council of Taiwan (NSC 94-3112-B-006-002) and by the MOE Program for Promoting Academic Excellence of Universities (EX-91-E-FA09-5-4).

Simplified fabrication process of the flow-through PCR chip. (a) Thermal control module, and (b) formation of microfluidic channels using SU-8 and PDMS casting process.

Photograph of the PCR chip after assembly

The schematic illustration of a pneumatic-driven 3-zone flow-through PCR chip.

Primers designed to detect (S. pneumoniae) (F: forward primer; R: reverse primer)

Photograph and SEM image of the micro heaters and sensors

Slab-gel electrophoregram for detection of respiratory tract infection microorganisms. In each electrophoregram, there are DNA ladders (L), products from a portable PCR system (C), and conventional PCR machines (M).

2006