Research Of PCR Chip System Based On MEMS

Biochip is a landmark trace analytical techniques developed at the end of last century, which are widely used in disease diagnosis and treatment, drug genome atlas, drug screening, gene sequencing, crop dabbling optimization, food hygiene supervision and many other areas. As a kind of biological chip, PCR chip technology develops ceaselessly, which is a kind of DNA vitro expansion method.The Polymerase Chain Reaction (PCR) which can make specific DNA segments swell to millions of copies in a matter of hours has been widely applied in biology science, medicine and so on. DNA amplification process can be divided into degeneration (93 ~ 94℃), annealing (54℃), extension (72℃) three consecutive and circulates temperature operation process. Therefore, the temperature is one of the key factors of PCR chip.The paper designed a micro reaction chamber PCR chip based on MEMS technology in glass. The chip contained a DNA micro-reactor room, a heater and a temperature sensor, which size is about 10mm *10mm* 0.5 mm. Using wet etching methods in glass to etch out a 5mm *5mm * 0.15 mm micro-reactor room. On the other side of the PCR chip there is heater and temperature sensor in order to make the PCR chip miniaturization and integration. To make temperature more uniform, we used ANSYS software to simulate different structures of the heater on temperature field to search for optimal heater structure.The paper designed a cyclic temperature control system, which included both hardware and software. The hardware design included signal acquisition part, signal disposal part and control signal output part. To avoid platinum generate heating because of large current, signal acquisition circuit adopted 0.5 mA constant-current source circuit. Acquisition circuit transformed temperature signal into voltage signal, which is acquitted by SPCE061A I/O ports after enlargement and filtering. The collected voltage signal is transformed into the value of temperature .After comparing with the setting value and PID calculation, it got a PWM square-wave to control the solid state relay, which realized automatic temperature control.