Development Of ARM-based System For LAMP Amplification And Detection

Instruments for gene amplification play an important role in gene research, which are also one of the basic equipments in the field of life science. In our country, the development of gene amplification instrument is highly costly, and the performance index of such instrument is not as good as its imported counterparts. Thus, most gene amplification equipments are imported. Therefore, it is crucial to develop integrated and portable equipment for gene amplication. LAMP stands for Loop-mediated Isothermal Amplification. It is a novel method for isothermal nucleic acid amplification. Compared to traditional PCR, LAMP can avoid the difficulties of wide temperature fluctuations, due to the advantages of high sensitivity, specificity and efficiency.A temperature control system and fluorescence detection system were built in consideration of portable, intelligent, high throughput and easy integration. A rotating slip chip is used as sample carrier, and the temperature control device was designed with a high-power semiconductor to heat and cool the system. An optical detector was designed to use LED lights as the excitation source and a photoelectric diode to monitor the changes in fluorescence of the samples on the chip.The ARM processor is cheap, high performance and fast, widely used in control field.The hardware adopted a Cortex-M3-based ARM processor(STM32), including temperature control circuit, the conditioning circuit of weak signal, LED driving circuit of constant current, LCD display, key and LED indicator, ect. In addition, the DS18B20 sensor was used to detect temperature. The software adopted PID control algorithm in consideration of the temperature precision requirement. With real-time temperature monitoring and its built-in PWM output, it can direct realize the semiconductor heating and refrigeration. The small photoelectric signal adopted hardware filter and butterworth filter. Software filter can overcome the shortcoming of the hardware filtering, due to the advantages of stability and anti-interference. Experimental results showed that the system can work stably for a long period of time. The precision of the temperature control system was ±1?, and the detection limit for calcein was 2?M, satisfying the temperature anddetection requirements for LAMP amplification and detection. Finally, various modules were attempted to realize a portable device prototype for LAMP amplification with compact structure and reasonable performance. LAMP amplification and detection were conducted for a pathogen using the developed prototype. The success rate was 100%,satisfying the desired effect.