In this paper we report the novel assembly method of a biosensor unit based on 64 pixel photodetector array with a proprietary semiconductor quantum dots (QDs) quantum well (QW) hybrid structure. There is significantly lower dark current for optimized high sensitivity detector. The capacitive trans-impedance amplifier (CTIA)-correlated double sampling (CDS) readout circuit can readout weak optical signal which respond by photodetector. To minimize the packaging size of our biosensor unit, a double-sided printed circuit board designed to decrease noise by special package making photodetector array can operate at room temperature and lower temperature for get better performance. The readout circuit is bonding on the backside of substrate through silicon via (TSV) structure, and the photodetector array bonding on the front side of substrate for making the optic signal through to photosensitive window of detector. A highly integrated Cortex-M4 MCU (STM32F407) has build the data acquisition and analysis unit providing Wi-Fi interface to communicate with the PC software for biosensor unit rapid diagnosis infectious disease and more easy carry.