| Polymerase chain reaction (PCR) chip is a bio-chip which is a kind of DNA amplification technology outside the body. PCR has many advantages, such as large surface to volume ratio, fast heat transfer, small size, less reagent consumption, no pollution and easy operation, so PCR chip can achieve large-scale production. The PCR microfluidic chip is a micro-PCR reaction system, combines the advantages of the PCR technology and the microfluidic technology. Now, the PCR microfluidic chip has been widely applied to biomedicine areas and it has become an important research direction.PCR amplification is dependent on the temperature of the three different temperature regions. When the three different temperature regions reach the needed temperature, the reaction will be promoted automatically. In this way, it can reach the purpose of genes amplification. So a high-precision temperature control system was required in the PCR microfluidic chip.In this paper, PDMS micro channels, glass substrate, and the copper films as the heaters were adopted for the structure of continuous flow PCR microfluidic chip . IntelliSuite software is applied to make the analog simulation for the heaters. On the basis of the simulation of temperature distribution and thermal properties of heaters with different shapes and sizes, a curved heater structure was prepared on the glass slice.In addition, the temperature control system of PCR microfluidic chip is also designed which is based on AT89C51 microcontroller. In the control system, three-way digital temperature sensor DS18B20 is used as the data collect and input channels for the three different temperature zones. Meanwhile, by using incremental PID temperature control algorithm and PWM technology, the optocouple and the relay as well as the heater can be well controlled. Thus an accurate temperature control system for the PCR microfluidic chip was developed, which can meet the requirement of the temperature control for the continuous flow PCR microfluidic chip. |
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