The Signal Acquisition System And Temperature Control System Design Of The Microporous Counter

Since the size and number of the biological cells and micro-particle could be measured precisely by Coulter principle, this principle has been widely used in scientific research and industrial production. Now, the research of testing the sequence of the DNA and RNA using this principle has become a hot research point in the field of DNA sequencing testing.In this paper, the preliminary exploration to build microporous counter was been done according to the principle of Coulter. And the signal acquisition system is the key part to build a coulter counter, which is consist of three parts. The Cyclone IV series FPGA of the Altera is the core of signal acquisition system, and the signal conditioning circuit and A/D conversion circuit is in the front of the FPGA to realize the collection and conditioning of the signal. And the target to communicate with the computer through USB2.0 is achieved by controlling the USB control module. Finally, tests are conducted to verify that the system can meet the design requirements. In the test, the resistances are used to instead of the cavity and microporous to simulate the actual condition. From the results of the test, it could be found been the signal acquisition system could acquire the high speed signal, and the noise of which is very small. The rate of the noise is 1%, and the square wave of 1MHz can be collected. So it mean that the signal acquisition system can comply meet the design requirements.To research the how the temperature influence the precision of the Coulter counter, a precise temperature control system based on ARM and LabVIEW will be designed in this paper. The STM32 series ARM of the ST microelectronics is the controller of the temperature control system. The signal acquisition module which is based on Pt100 temperature sensor is in the front of the controller. And the temperature control execution module based on MAX1968 controller is at the end of the controller. Incremental PID will be used in this system. And the temperature control system could communicate with the computer by USART. In the computer, the real-time temperature curve could be displayed and the parameters of the PID could be modified online by using the LabVIEW. Finally, several tests are carried on to test the device, including the stability test, temperature dynamic response test and the temperature scope of the system test. The results of the tests show that the temperature control accuracy of the apparatus can reach ±0.3? in the temperature scope of 15? to 45?, and it has good features of high robustness, short response time and small overshoot.