Information Acquisition Circuit Design Of SPR Biosensors

High-sensitivity and high-throughput SPR (Surface Plasmon Resonance) micro-array detection technique, which is a powerful tool for the study of proteomics and drug discovery and development, is a hot research topic currently. Phase detection is the method having the highest resolution in all the SPR detection methods, while micro-array technique is an effective method for high throughput. The sensitivity and resolution of SPR micro-array detection technique is greatly dependent on high-sensitivity SPR biosensor chip, high-resolution signal acquisition system and advanced algorithm. This paper focused on high-sensitivity bio-information acquisition based on SPR micro-array real-time phase detection, and carried on principle analysis, theoretical modeling, numerical simulation, circuit designing, debugging and so on.Firstly, based on the principle of SPR, the paper analyzed the primary factors influenced the sensitivity and resolution of SPR detection system: SPR biosensor chip, micro-array image signal acquisition system and signal process. Biosensor chip is the source of the detection signal. Only the high-sensitivity chip can have the possibility of acquiring the high-sensitivity signal. The thickness of chip, particle-enhanced and fluorescence spectroscopy are analyzed based on the foundation of the original study. High-sensitivity sensor and circuit can make sure that high-sensitivity signal is acquired from biosensor chip. Then SPR micro-array sensor signal is carefully anaylzed and numerical simulator is carried on. The result shows that SPR phase detection can achieve the sensitivity of 10-6 RIU and SPR intensity detection can achieve the sensitivity of 10-4 RIU. The acquired high- sensitivity signal needs to be processed by advanced algorithms. Therefore, many kinds of data analysis algorithms are compared. The result shows the resolution of phase algorithm is higher than intensity algorithm.Based on theoretical analysis, the related circuit and program of image acquisition system is carried out. It mainly includes the CCD sensor driver, A/D circuit, data transfer and storage circuit and CPLD (Complex Programmable Logic Device) controlling circuit. The data transfer and storage circuit with a larger bandwidth PCI bus is realized, removing the bottleneck between the data acquisition system and the computer. The logic of the PCI bus is controlled by the CPLD. Moreover, LVDS interface is used to cut down the electrical noise between the data storage card from the front signal-process circuit. Whether the system runs successful also depends on robust software. The software mainly includes system driver and application program. The driver program completes the initialization of PCI card, DMA transfer, I/O transfer,interrupt disposal and so on.Finally, the circuit and the driver application are debugged respectively. The preliminary result shows that the system may have the ability of completing the image acquisition.