基于时间延迟积分型CMOS图像传感器的光流体显微镜及其SOC技术研究

The appearance of Optofluidic microscope（OFM）makes the diagnosis of disease and health monitoring in the personal family become possible. However, OFM is still in its infancy, the existing system prototype has many defects. In view of the issues, such as low detection rate, poor image quality, low system integration, the image-collecting model of the OFM, image sensor will be studied in this project. First of all, Time-Delay-Integration (TDI) CMOS image sensor structure combining with microfluidic scanning technology are used for acquisition of the whole cell image, reducing the demand for light, and meanwhile, increasing the line frame rate. Secondly, a high-speed two-step ADC based on the column-parallel image sensor will be designed for ensuring the demand of the small size pixels and further increasing the line frame. Then, the oversampling and deblurring techniques will be used to improve cell resolution. Compared with the conventional super-resolution reconstruction algorithm based on multiple-frame, the proposed approach has higher integration in this project. And the whole super-resolution cell image will be collected from the CMOS image sensor  directly. Based on these researches, this project will design a nonlinear quantitative circuit to improve the cell image contrast and the gray precision of local cell. The study in this project lies the foundation for the realization of chip level OFM system, and has very broad application prospects in many aspects, such as the wise health, community health care, family health care, and remote medical treatment, and so on.

光流体显微镜的出现使疾病诊断和健康监测在个人家庭中普及成为了可能。然而光流体显微镜目前还处于起步阶段，针对现有系统雏形存在的检测速率、成像质量，系统集成度过低等问题，本项目将研究应用于光流体显微镜系统中的采集模块，图像传感器。首先，采用时间积分型CMOS图像传感器结构与微流控相结合的扫描技术采集整幅细胞图像，在减小光照需求的同时，提高行帧频；其次，设计基于列并行图像传感器的两步式高速模数转换器，在保证系统对于小尺寸像素要求的基础上，进一步提高行帧频；然后，采用过采样技术和时域去模糊方法提高细胞分辨率，得到具有超分辨率的整幅细胞图像。与传统多帧超分辨率重构算法相比，本项目提出的方法更具有可集成性；在此基础上，设计非线性量化电路，提高图像对比度的同时也提高细胞局部的灰度精度。本项目研究为实现芯片级光流体显微镜系统奠定基础，在智慧医疗、社区医疗等领域具有极为广阔的应用前景。

光流体显微镜（Optofluidic microscope，OFM）目前还处于起步阶段，针对现有OFM系统雏形存在的分辨率、对比度、系统集成度过低、功耗较大等问题，本项目重点研究了应用于光流体显微镜系统中的采集模块，图像传感器。.首先，采用时间积分型（Time-Delay-Integration，TDI）CMOS图像传感器结构与微流控相结合的扫描技术采集整幅细胞图像，在减小光照需求的同时，提高了系统信噪比。TDI传统方式成像的信噪比线阵高约6dB，与4级TDI提高6.02dB的理论值相符。4级TDI在2倍过采样频率图像信噪比与线阵成像相比提高了约8.89dB。.其次，设计了基于列并行图像传感器的两步式高速模数转换器，在保证系统小尺寸像素要求的基础上，提高了系统行帧频。相比于传统的SS ADC，该结构在列上只增加一个简单的数字反馈电路（电流源布局在非列电路），而列共用的斜坡发生电路由于分辨率的降低而变得简单。相比于MRSS ADC而言，该结构不会引入额外的斜坡电路。而相比于SS/SA ADC而言，该结构粗细量化的两种ADC结构具有更多可以复用的电路模块，因此列上的电路结构更为简单。UMC 180nm的工艺下完成了设计与流片，测试结果通过项目设计的两步式校正后，DNL和INL分别为+0.23/-0.56LSB和+1.4/-0.18LSB，有效位数为9.15-bit，SNDR为57.2dB。.然后，采用过采样技术和时域去模糊方法提高了细胞分辨率，实现了片内实时超分辨率的细胞图像采集。在此基础上，设计了细胞区域灰度值对比度拉伸非线性量化电路，提高图像对比度的同时也提高细胞局部的灰度精度。根据细胞灰度特点，通过列级一阶边缘检测电路，实现了上述对比度拉伸的自适应检测方法。本项目研究为实现芯片级光流体显微镜系统奠定基础，在智慧医疗 、社区医疗等领域具有极为广阔的应用前景。