Design For Feedback System For Micro-pore Sensor Signal Detection

Micro-pore sensor was developed from Coulter Counter invented at 1950 s and it's a powerful tool to analyze particles suspended in fluid medium. Micro-pore sensor exports current block pulse signal which combing the information of particles. With the development of micro/nano fabrication, it became possible to fabricate all kinds of solid micro-pores with different size and now how to conquer the randomness of the moving process of particles became the next important problem.The relations between block pulse signal and structure of micro-pore was studied and some research about the divergence happened in the fabrication of cone-structure with Focused Ion beam(FIB) was done to make foundation of fabricating cone-like pore with FIB. Then according to the feature of block pulse signal, a detection system with feedback function was designed. It added feedback loops to make it possible to control the movement of particles during the detection. This system mainly consists an analog circuit, A/D module, D/A module, FIR filter realized with FPGA and a Nios-II MCU running ?C/OS-II operating system.By considering the features of block pulse signal this system contains double FIR filter with FPGA, which could fulfill both the time-request and processing precision. By this design, it could also be adjusted easily to adapt to different kind of signals. By testing this system with different kinds of input signal, it's confirmed that this system could handle different applications and output feedback signals effectively.