Temperature cycle and surface treatment study of thermoelectric based micro PCR

In this work, a rapid thermo-cycling micro PCR system with low reagent loss is developed. Peltier thermoelectric devices were used to provide fast heating and cooling for polydimethylsiloxane (PDMS) based micro PCR chamber. The temperature control was accomplished by PID controller. A single PCR microchamber was fabricated by PDMS casting on SU-8 micromold and oxygen plasma assisted bonding of PDMS on a glass substrate. The PDMS chamber was treated by tween 20 polymer in order to suppress the loss of reagent in PCR chamber. The treatment condition was optimized to yield minimum reagent loss. The PCR process began with preheat treatment at 92°C for 180 s. After preheating, thermocycling was then performed for 30 cycles. Each temperature cycle consists of denaturation at 92°C for 30 s, annealing at 54°C for 30 s, and extension at 72°C for 30 s. After thermocycling process, the temperature was maintained at 72°C for 180 s before cooling down to room temperature. The fast heating and cooling rate of ~2°C/s and ~1°C/s were achieved. The whole process was completed in about 2.5 h. Therefore, the developed themocycling micro PCR system is potential for PCR-on-a-chip applications.