A microchip-based PCR device using flexible printed circuit technology

Rapid heat transfer is crucial for an efficient polymerase chain reaction (PCR), and this makes temperature control one of the most essential features in a micro-PCR system, which always includes a heater and a sensor composing a closed-loop. Yet, the fabrication of the heater and the sensor often prevented micro-PCR systems from achieving both cost-effectiveness and fabrication-easiness. For most of the early researches micromachining techniques were used to allow sensors and heaters be integrated on a silicon or glass chip. However, the cost prevented them from wide applications. The work described in this paper is part of our effort to solve the cost/fabrication dilemma. An innovative digital temperature control system was developed by introducing a heater/sensor switching procedure. Only one temperature controlling element fabricated by flexible printed circuit technology was utilized in the constructed PCR device with minimum fabrication steps. The glass chip-based device was made from low cost materials and assembled with adhesive bonding. Through seemingly simple steps, we obtained both disposability and portability at the same time. Temperature stability within ±0.3 °C and a transitional rate of 8 °C/s during heating/cooling was achieved. A 244 bp DNA fragment of hepatitis C virus was successfully amplified in our device by a three-stage thermal cycling process. Further improvement was assisted by finite element analysis, and demonstrated by experiment.