High-speed CMOS image sensor for high-throughput lensless microfluidic imaging system

Abstract

The integration of CMOS image sensor and microfluidics becomes a promising technology for point-of-care (POC) diagnosis. However, commercial image sensors usually have limited speed and low-light sensitivity. One high-speed and high-sensitivity CMOS image sensor chip is introduced in this paper, targeted for high-throughput microfluidic imaging system. Firstly, high speed image sensor architecture is introduced with design of column-parallel single-slope analog-todigital converter (ADC) with digital correlated double sampling (CDS). The frame rate can be achieved to 2400 frames/second (fps) with resolution of 128×96 for high-throughput microfluidic imaging. Secondly, the designed system has superior low-light sensitivity, which is achieved by large pixel size (10μm×10μm, 56% fill factor). Pixel peak signalnoise- ratio (SNR) reaches to 50dB with 10dB improvement compared to the commercial pixel (2.2μm×2.2μm). The degradation of pixel resolution is compensated by super-resolution image processing algorithm. By reconstructing single image with multiple low-resolution frames, we can equivalently achieve 2μm resolution with physical 10μm pixel. Thirdly, the system-on-chip (SoC) integration results in a real-time controlled intelligent imaging system without expensive data storage and time-consuming computer analysis. This initial sensor prototype with timing-control makes it possible to develop high-throughput lensless microfluidic imaging system for POC diagnosis.